the catalyst technical handbook
be selective
© 2008 Johnson Matthey Plc
Contents 1
INTRODUCTION
page 3
2
CATALYST RANGE
page 4
2.1
Heterogeneous Catalysts
2.4
Smopex® – Metal Scavengers 2.4.1
General Description
2.4.2
Smopex® Application
page 20
page 4
3
CATALYST SERVICES
page 21
Platinum Group Metal (PGM) Catalysts 2.1.1
General Description
3.1
Saving Time in Process Development
2.1.2
Liquid Phase Reactions
3.2
Catalyst Kits
2.1.3
Gas Phase Reactions
3.3
Chemical Development and Optimization
2.1.4
Choice of Catalyst Support
3.4
Metal Recovery Evaluation Service
2.1.5
Choice of Metal
3.5
Supply of Catalysts
2.1.6
Choice of Metal Location
3.6
2.1.7
Catalyst Deactivation
Partnership in Catalyst Development/Production
2.1.8
Safety and Handling
3.7
Technical Support for Catalytic Processes
2.1.9
Packaging and Storage
3.8
Refining of Catalyst Residues Smopex®
2.1.10 Catalyst Recovery and Shipment
Traditional Refining
Base Metal Catalysts 3.9
2.1.11 General Description and Applications
Metal Management
Sponge Metal™ Catalysts 2.1.12 General Description
4
2.1.13 Liquid Phase Reactions
CHEMISTRIES
page 24
2.1.14 Choice of Metal
4.1
2.1.15 Choice of Catalyst Particle Size
Hydrogenation
page 24
2.1.16 Catalyst Deactivation 2.1.17 Safety and Handling
4.1.1
2.1.18 Packaging and Storage
4.1.2
Aromatic Ring Compounds
4.1.3
Carbonyl Compounds
2.1.19 Catalyst Recovery and Shipment
2.2
Homogeneous Catalysts 2.2.1 2.2.2
2.3
2
page 15
General Description The Catalytic Cycle
2.2.3
Choice of Catalyst
2.2.4
Product/Catalyst Separation
2.2.5
Catalyst Deactivation
2.2.6
Safety and Handling
2.2.7
Transport and Storage
2.2.8
Catalyst Recovery and Shipment
2.3.1
General Description
2.3.2
Catalyst Leaching and Recycle
4.1.4
Nitro and Nitroso Compounds
4.1.5
Halonitroaromatics
4.1.6
Reductive Alkylation
4.1.7
Reductive Aminations
4.1.8
Imines
4.1.9
Nitriles
4.1.10 Oximes 4.1.11
Hydrogenolysis Debenzylations Hydrodehalogenations Rosenmund Reductions
4.1.12 Transfer Hydrogenations
®
FibreCat Anchored Homogenous Catalysts
Carbon-Carbon Multiple Bonds
page 18
4.2
Dehydrogenation
page 41
4.3
Hydroformylation
page 43
4.4
Carbonylation
page 45
4.5
Decarbonylation
page 46
© 2008 Johnson Matthey
2
4.6
Hydrosilylation
4.12.1 Organic Synthesis
page 47
4.12.2 Gas Purification
4.7
Cross-Coupling Reactions page 48 4.7.1
Heck Reaction
4.7.2
Suzuki-Miyaura Coupling
4.7.3
Alpha-ketone Arylation
4.7.4
Carbon-heteroatom coupling – e.g.
4.13 Chiral Catalysis 4.13.1 Asymmetric Hydrogenation 4.13.2 Enantioselective Hydroamination 4.13.3 Enantioselective Alkyne Addition 4.13.4 Asymmetric Michael Addition
Buchwald-Hartwig amination
4.8
4.7.5
Organometallic Reactions
4.7.6
Sonogashira Reaction
4.7.7
Palladacycles
Cyclopropanation and Carbene Reactions
4.13.5 CATAXA™ Anchored Catalysts
5
TABLE : HETEROGENEOUS CATALYSTS
page 69
TABLE : HOMOGENEOUS CATALYSTS
page 73
TABLE : SMOPEX ® METAL SCAVENGING PRODUCTS
page 86
8
GLOSSARY OF TERMS
page 87
9
OTHER PUBLICATIONS
page 88
10
ADDRESSES OF LOCAL OFFICES
page 89
page 53
6 4.9
Isomerization
page 54
7
4.10 Oligomerization and
Polymerization
page 55
4.11 Selective Oxidation
page 56
4.11.1
Alcohols to Carbonyls or Carboxylic Acids
4.11.2
Dihydroxylation of Alkenes
4.11.3
Oxygen Insertion Reactions
4.11.4
Acetoxylation
4.12 Particulate Catalysts
3
page 63
© 2008 Johnson Matthey Plc
page 59
3
1. Introduction Johnson Matthey is a recognized world leader in precious
The catalysts and technologies described herein are widely
and base metal catalysis. With staff in 38 countries, our
used in processes ranging from hydrogenation through
extensive network of resources enables us to provide a
carbonylations, coupling reactions and selective oxidations.
full range of services and products. These include the
In general, PGM catalysts combine high activity with
development and manufacture of catalysts and chemicals,
milder reaction conditions to give high selectivities for
analytical and characterization techniques, and the
specific transformations. Sponge metal catalysts (Ni, Cu,
recovery and refining of Platinum Group Metals (PGMs)
Co) offer our customers alternative process options,
from spent catalysts.
particularly in hydrogenation, reductive alkylation and dehydrogenation. Most importantly, we offer a range of
We are committed to providing our customers with the
solutions in chiral catalysis, including a unique range of
best technology for optimizing catalytic processes. In this
ligands and anchored chiral catalysts.
latest edition of our Catalyst Handbook, you will find our most recent developments in the areas of:
We continue to invest in state-of-the-art equipment for manufacture, testing, recovery and refining of spent
• Chiral Catalysis
catalysts. Our staff offers a high level of technical support,
• Coupling Catalysis
including catalyst recommendations and design, catalyst
• Metal Scavenging products – Smopex®
handling and metal management. The Johnson Matthey
• Anchored Homogeneous Catalysts – FibreCat®
name remains synonymous with accuracy, reliability and
• Sponge Metal™ Catalysts
integrity. Let our catalysis knowledge and experience
• Precious Metal Recovery Technology
work for you to improve and optimize your manufacturing processes.
4
© 2008 Johnson Matthey
4
2. Catalyst Range 2.1
HETEROGENEOUS CATALYSTS
2.1.2 Liquid Phase Reactions with PGM Catalysts
Johnson Matthey offers a full range of heterogeneous catalysts:-
Liquid phase hydrogenations employing heterogeneous catalysts are multiple phase (gas – liquid – solid) systems
• Platinum group metal catalysts (PGM)
containing concentration and temperature gradients. In order
• Sponge metal (or skeletal) catalysts
to obtain a true measure of catalytic performance, heat
• Other base metal catalysts
transfer resistances and mass transfer resistances need to be understood and minimized. Mass transfer effects can
Platinum Group Metal (PGM) Catalysts 2.1.1 General Description
alter reaction times, reaction selectivity and product yields. The intrinsic rate of a chemical reaction can be totally obscured when a reaction is mass transport limited. For a reaction to take place in a multi-phase system, the
Heterogeneous PGM catalysts are in a different phase to
following steps must occur:-
the reactants and can be easily separated at the end of the reaction. Examples are:-
(i) dissolution of gas (e.g. H2) into the liquid phase (ii) diffusion of dissolved gaseous reactant through the bulk
• catalyst powder (Pd/C) slurried with liquid phase
liquid to the catalyst particle
reactants in a batch or continuous process which can be separated by filtration.
(iii) diffusion of the liquid reactants to the catalyst particle (iv) in-pore diffusion of the reactants to the catalyst surface
• catalyst granules – often called particulates – (Pt/Al2O3) as a bed through which reactants pass in the gas or liquid phase.
(v) adsorption of reactants on the catalyst, chemical reaction and desorption of products (vi) diffusion of products from the catalyst pores
The key properties of a catalyst are :High activity: for fast reaction rate, low catalyst
This figure illustrates the three potential mass transfer resistances in a multi-phase catalyst system.
loading and a short reaction time to maximize production throughput.
products and reduce purification costs.
Products
A (gas) + B (liquid)
High selectivity: to maximize the yield, eliminate by-
LIQUID
GAS
STAGNANT LIQUID LAYERS
A
POROUS CATALYST PARTICLE
A
High recycle capability: to minimize process costs.
B
Fast filtration rate: to separate rapidly the catalyst and
STAGNANT GAS LAYER Concentration A (g)
Concentration B (l)
final product, ensuring maximum production rates.
Heterogeneous catalysts are usually supported on a choice of materials such as activated carbon or alumina to
RESISTANCE TO GAS/LIQUID MASS TRANSPORT
RESISTANCE TO LIQUID/SOLID MASS TRANSPORT
{
{
{
Concentration A (l)
RESISTANCE TO DIFFUSION IN PORES OF CATALYST PARTICLE
improve metal dispersion, activity and catalyst durability. Supported PGM catalysts are used mainly in hydrogenation, dehydrogenation and selective oxidation
Mass Transport
reactions. Guidance is provided in Section 4 for the most
Rates of reaction will be affected by different process
appropriate catalyst for each specific reaction type.
variables depending on which step is rate limiting. A
Section 2.1 indicates the most important technical and
reaction controlled by gas–liquid mass transport i.e. rate
economic factors that will be of concern to the industrial
of mass transport of the gaseous reactant into the liquid,
user of these catalysts.
will be influenced mainly by reactor design, hydrogen pressure and agitation rate.
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© 2008 Johnson Matthey Plc
5
A reaction controlled by liquid–solid mass transport i.e.
are preferred when the presence of water in the reaction
the rate of mass transport of either gaseous reactant or
system is not detrimental. Handling paste is much easier
substrate from the bulk liquid to the external surface of
as it greatly reduces dusting and metal loss. The fire
the catalyst particle, will be influenced mainly by gas or
hazard, which occurs when organic vapors are present, is
substrate concentration, weight of catalyst in the reactor,
also reduced. When the use of a dry powder is
agitation and catalyst particle size distribution.
unavoidable, adequate precautions should be taken during handling. (see section 2.1.8.) Ceramic-based catalysts such
A reaction controlled by pore diffusion–chemical reaction
as those supported on alumina, silica or zeolites, are
i.e. the rate of reactant diffusion and chemical reaction
intrinsically safer and easier to handle because the support
within the catalyst particle, will be influenced mainly by
is denser than carbon and also is non-combustible.
temperature, reactant concentration, percent metal on the
However, different supports may change the catalyst
support, number and location of active catalytic sites,
activity.
catalyst particle size distribution and pore structure. To evaluate and rank catalysts in order of intrinsic catalyst activity, it is necessary to operate under conditions where mass transfer is not rate limiting.
For maximum economy in the use of PGM catalysts, it is important that the catalyst should be filtered from the reaction system without loss. Various types of leaf, cartridge and centrifuge filters are suitable for this
Reactors
operation, often in conjunction with a polishing filter. The recovery and refining of carbon-based catalyst residues is
A reactor used for liquid phase hydrogenations should
made easier if any filter precoat that may be required is of
provide for good gas–liquid and liquid–solid mass transport,
a combustible material such as cellulose. Many companies
heat transport and uniform suspension of the solid catalyst.
supply equipment suitable for filtering catalysts and
To facilitate this, a well agitated reactor is essential. The
Johnson Matthey can provide a list of contacts on request.
most effective means of agitation at any scale is stirring in
Johnson Matthey also offers Smopex® metal scavenging
a reactor fitted with suitable baffles.
fibers. (see section 2.4).
Alternatively, the reactant gas stream may be used to agitate the system and this may be particularly effective when combined with a centrifugal or turbo impeller.
2.1.3 Gas Phase Reactions with PGM Catalysts
Another very effective reactor design is the loop reactor. In this system the reactants are recirculated around a loop by means of a pump and the reaction occurs at the injection nozzle in the reactor. There is very effective gas/liquid/solid mixing at this nozzle.
Granular and pelleted catalysts are used in fixed bed gas phase reactions. The disposition of the catalyst beds, the reactor design and the size and shape of the pellets are dictated by the requirements of the heat transfer, fluid flow and pressure drop in the system. For example,
Many hydrogenation reactions are exothermic and it is necessary to remove the heat of reaction to maintain a constant reaction temperature. This can be achieved with an
highly exothermic reactions are usually performed in multi-tubular reactors with a coolant fluid surrounding the tubes to remove the heat generated.
internal cooling coil or tubes, a cooling jacket or in the case of a loop reactor, an external heat exchanger. A loop reactor system is particularly suitable for highly exothermic reactions.
Today, many industries demand high-purity gases for a wide range of uses. Besides chemical process feedstreams, other applications are in the electronics and
Continuous liquid phase reactions may be carried out in
nuclear industries. Contaminants, such as oxygen or
trickle columns using granular or extrudate catalysts. The
hydrogen, frequently need to be reduced in order to
reactant, dissolved in a suitable solvent if necessary, is
prevent the occurrence of problems such as:-
pumped to the column packed with catalyst. The reacting gas, generally hydrogen or oxygen, is passed co-currently or counter-currently through the catalyst bed. The product is collected continuously from the catalyst bed.
Catalyst Handling and Recovery
(i) promotion of unwanted side reactions (ii) corrosion (or chemical attack) of reactor materials or components (iii) unwanted modification of semiconductor properties in electronic components.
Activated carbon-based powder and paste catalysts are both used for liquid phase reactions but paste catalysts, containing approximately 50–60% water within the pores,
This has led to the development of a range of PGM catalysts on alumina supports for gas purification. These function by promoting catalytic combination of the contaminants within
6
© 2008 Johnson Matthey
6
the gas stream. For example, oxygen may be removed by combination with the stoichiometric quantity of hydrogen to
2.1.4 Choice of Catalyst Support for PGM Catalysts
form easily-removable water vapor. Section 4.12 provides detailed information on particulate catalysts and their use.
Although the main function of the catalyst support is to extend the surface area of the metal, the selection of the best type of support for a particular catalytic metal is
Catalyst Charging Care should be exercised when charging particulate catalysts to fixed bed reactors to minimize physical damage (generation of fines). Note that the catalyst should not fall more than 50–100cm. It should be evenly distributed as the bed is filled and not raked level. One of the best ways to fill a reactor evenly is with a canvas sock connected to an external hopper. The sock should be kept full and lifted slowly so that the catalyst flows out gently. The sock should be moved around the reactor to distribute the catalyst evenly and not left to discharge into a pile in one position. An alternative method is to fill the reactor with water and slowly add the catalyst such that it sinks gently down through the water.
Catalyst Activation
important as, in many reactions, the support can also substantially alter the rate and course of the reaction. The type of physical support is largely determined by the nature of the reaction system. When supported on a high surface area carrier, such as activated carbon, the catalytic metal is present in the form of discrete crystallites (typically a few nanometers diameter) and these give a very high catalyst area per unit weight of metal. For liquid phase reactions, powdered supports are invariably used, while in gas phase or continuous liquid phase reactions, a particulate support is used. The pore structure of the support may modify the role of the metal since the course of a reaction is often greatly influenced by the rates of diffusion of reactants and
Fixed-bed catalysts are sometimes supplied in the
products within the catalyst pores. In addition, the surface
unreduced form. These need to be activated before use in
area of a support can limit the PGM concentration that can
the following manner:-
be usefully employed.
(i) Load the catalyst carefully into the reactor and flush away air with flowing nitrogen (or other inert gas) at ambient temperature. (Ensure the volume of nitrogen exceeds 5 x the volume of the reactor)
Many of the commonly used catalyst supports, particularly carbon and alumina, are available in a large range of particle sizes, each with a range of surface areas and pore size distributions.
(ii) Introduce hydrogen at a concentration of 1% into the flowing nitrogen. Check for an exotherm in the catalyst
Reaction conditions may limit the choice of support.
bed. If it does not exceed 20˚C, then slowly increase the
The support should be stable at the temperature used
temperature (over >60 minutes) to the desired
and should not react with the solvent, feedstock or
reaction temperature. The low hydrogen concentration
reaction products.
will prevent a large exotherm when the catalyst species undergoes reduction.
2.1.4.1 Powdered Supports
(iii) Check for any exotherm and gradually increase the hydrogen concentration until 100% hydrogen.
A good powder catalyst will exhibit high attrition resistance to reduce catalyst losses by fines generation, good
(iv) Slowly introduce the feed to minimize any exotherms until the desired feed rate is achieved.
suspension characteristics for high catalyst activity and a fast filtration rate to minimize work–up time.
Note: minimum temperatures of 100˚C for Pd, 120˚C for Ru and 200˚C for Pt catalysts are generally required to ensure complete reduction.
These properties are functions of particle size and shape, pore volume, pore size distribution, surface area, activation procedure and material base. Values of these parameters may be optimum for one property but less good for another, e.g. a large catalyst particle size will produce a fast filtration rate but poor suspension characteristics.
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© 2008 Johnson Matthey Plc
7
Thus, Johnson Matthey catalyst supports are selected to
PGM supported on alumina may prove to be more
incorporate a compromise of properties to generate
selective than the same metal supported on carbon.
catalysts of fast filtration with high activity and selectivity.
Silica is sometimes used when a support of low absorptive capacity with a neutral, rather than basic or
The following types of powder supports are most
amphoteric character is required. Silica-alumina can be
commonly used for PGM catalysts:
used when an acidic support is needed.
Carbon
Calcium Carbonate
Activated carbon powder is principally used as a support for catalysts in liquid phase reactions. As carbon is derived
Calcium carbonate is particularly suitable as a support for
from naturally occurring materials there are many variations,
palladium, especially when a selectively poisoned catalyst
each type having its own particular physical properties and
is required. The surface area of calcium carbonate is low
chemical composition. These differences can often be
but it finds applications when a support of low absorption
related to how the carbon is activated. The two traditional
or of a basic nature is required. The carbonates of
methods in use are steam and chemical activation of the
magnesium, strontium and zinc generally offer no
carbon char. In general, chemical-activated carbons tend to
advantage over calcium carbonate.
have higher BET surface areas than those of steamactivated carbons. By using different activation methods, the surface areas of different carbons can range from 500
Barium Sulfate Barium sulfate is another low surface area catalyst support. This support is a dense material and requires
m2g-1 to over 1500 m2g-1.
powerful agitation of the reaction system to ensure Trace impurities that may be present in certain reaction
uniform dispersal of the catalyst. A palladium on barium
systems can occasionally poison catalysts. The high
sulphate catalyst was traditionally used for the conversion
absorptive power of carbons used as catalyst supports
of acid chlorides to aldehydes (Rosenmund Reduction)
can enable such impurities to be removed, leading to
together with an in situ partial poison to improve the
longer catalyst life and purer products.
selectivity. In this application, however, it is being replaced
Carbon catalysts are produced in two physical forms, dry
increasingly by palladium on carbon catalysts for more
powder or paste. The latter form contains approximately
reproducible results.
50–60% by weight of water which is held within the pores of the carbon. There is no supernatant liquid and the ‘paste’ catalyst has the consistency of a friable powder.
2.1.4.2 Particulate Supports The use of granular or pelleted supports enables catalytic reactions to be carried out continuously in fixed bed
Graphite and Carbon Blacks
reactors. Vapor phase reactions have been carried out in Graphite powder and carbon blacks have a lower surface
this way, on an industrial scale, for many years.
area than activated carbon with graphite, generally in the range 5 m2g-1 to 30 m2g-1 (although special high surface
The advantages of this technique have been extended to
area graphites are available in the range 100 m2g-1 to 300
liquid phase reactions by the use of trickle-column
m2g-1). Graphites and carbon blacks are made synthetically
reactors. Since the formation of fine particles by attrition
and are therefore of higher purity than activated carbons,
must be kept to the minimum, high mechanical strength is a basic requirement of these catalysts. Such supports are
which are manufactured from naturally-occurring feedstocks. They are used for selective hydrogenation reactions or when a low porosity support is required to
available in various forms, such as spherical or cylindrical pellets, extrudates or irregular shaped granules.
minimize mass transfer problems or absorption of high
The metal may be deposited on or near the surface, or it may
value products.
be uniformly impregnated throughout the support. For most purposes, the diffusion of reactants into the pellet is slow, so
Alumina and Other Oxides
that surface impregnation is generally preferred. The quantity
Activated alumina powder has a lower surface area than most carbons, usually in the range 75
m2g-1
to 350
m2g-1.
It is a more easily characterized and less absorptive material than carbon. It is also non-combustible. Alumina is used instead of carbon when excessive loss of
of metal that may be deposited on the surface is dependent on the nature of the support. Catalyst life and performance are often affected by the method of preparation.
Alumina
expensive reactants or products by absorption must be
The most commonly-used pelleted support, alumina,
prevented. When more than one reaction is possible, a
exists in several phases, but the type usually employed is gamma–alumina. The type and form of the alumina
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© 2008 Johnson Matthey
8
support may play a vital role in determining the overall course of the reaction, as may certain ions, which may be
CATALYST PARTICLE
deliberately added during catalyst manufacture. SECTION THROUGH CATALYST PARTICLE
When a support of high mechanical strength is required, or when a much more inert support is necessary, alpha–alumina with a surface area of less than 10 m2g–1 is available. In some continuous vapor phase processes the catalyst may eventually become deactivated, due to masking of
ENLARGED SECTIONS
the catalytic sites by the deposition of carbonaceous
EGGSHELL
INTERMEDIATE
UNIFORM
matter. The catalyst may be regenerated in situ by the controlled oxidation of this carbon, taking care to avoid large exotherms in the catalyst bed.
Carbon CATALYTIC METAL PARTICULATES AND SUPPORT PORE STRUCTURE
Carbon is usually not strong enough mechanically to
CARBON METAL ATOMS
withstand the arduous conditions encountered in an industrial gas phase reaction. However, granular carbon is particularly suitable for use as the support in trickle column reactors. Unlike alumina-based catalysts, carbon catalysts cannot be regenerated by a controlled oxidation process.
2.1.5 Choice of PGM
Eggshell shows palladium located on the exterior surface. Intermediate shows palladium located deeper within the pore structure. Uniform shows palladium evenly dispersed throughout the support structure.
Catalyst performance is determined mainly by the PGM component. A metal is chosen based both on its ability to
The catalysts are designed with different metal locations
complete the desired reaction and its ability not to perform
for reactions performed under different conditions of
unwanted side reactions. Palladium is the most versatile
pressure and temperature.
of the PGMs. It is typically the preferred metal for the hydrogenation of alkynes, alkenes, carbonyls in aromatic
Hydrogenation reactions are generally first order with
aldehydes and ketones, nitro compounds, reductive
respect to hydrogen. Thus, the reaction rate is directly
alkylations, hydrogenolysis and hydrodehalogenation
proportional to hydrogen pressure. With intermediate and
reactions. Platinum is typically the preferred metal for the
uniform catalyst types, an increasing proportion of the
selective hydrogenation of halonitroaromatics and
metal becomes accessible as the pressure increases.
reductive alkylations. Rhodium is used for the ring
When all the metal is available, the catalyst properties
hydrogenation of aromatics, while ruthenium is used for
closely parallel those of an eggshell catalyst. Therefore at
the higher pressure hydrogenation of aromatics and
higher pressures, intermediate and uniform catalysts have
aliphatic carbonyl hydrogenation. The use of mixed-metal
a higher activity than eggshell ones because of their
catalysts may also provide additional benefits in either
intrinsic greater metal dispersion due to metal located
selectivity and/or activity by a synergistic effect through the presence of both PGM metals.
The Effect of Hydrogen Pressure on the Hydrogenation Activity of Catalyst
2.1.6 Choice of PGM Location
Uniform Intermediate
Catalyst performance can be altered significantly by the
Eggshell
appropriate choice of support material, metal location and Matthey has developed techniques to deposit the metal selectively in the desired location and this is illustrated for a 5% palladium on carbon catalyst in the schematic.
ACTIVITY
dispersion within the pore structure of the support. Johnson
PRESSURE (PH 2 )
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© 2008 Johnson Matthey Plc
9
deeper within the support pore structure. Thus, eggshell
“coking” on fixed-bed particulate catalysts. Fixed-bed
catalysts would be chosen for high activity at low
(except carbon supported) catalysts can be reactivated by
hydrogen pressure and uniform catalysts at high pressure.
the controlled combustion of the coke using an inert gas stream and/or steam with a low concentration of air. The
The location of catalytic metal deep into the support may lead to large in–pore diffusion resistance to reactants. This will result in increases in residence time and possible changes in selectivity. Thus the variation of the metal
combustion exotherm should be controlled not to exceed 20˚C. Powder catalysts can sometimes be reactivated by washing with suitable solvents, treating with oxidizing agents to breakdown the polymeric materials to smaller,
location can be used to adjust the selectivity of the catalyst. Eggshell catalysts have high activity at low reaction pressures in systems substantially free from catalyst poisons. If a catalyst poison is present, this can be overcome by locating the catalytic metal deeper into the support structure and hence increasing the metal dispersion. Such a catalyst will exhibit greater poison resistance because:-
more soluble species, and reducing to metal. Sintering occurs when crystallite growth of the catalytic metal decreases the metal surface area. This can arise by thermal sintering, particularly when operating above the Hüttig Temperature (see table below) or by a metal dissolution/re–precipitation mechanism. Thermal sintering can sometimes cause the collapse of the support pore structure e.g. a phase transition from
(i) the poison molecules often have high molecular weights and, unlike the smaller reactants, are
gamma to alpha-alumina resulting in encapsulation of the
unable to penetrate the pores where the catalytic
metal crystallite. Catalyst deactivation by sintering is
metal is located.
usually irreversible.
(ii) the increased metal area counteracts the constant area of metal rendered inactive by the poison.
Catalyst deactivation by physical loss of metal can arise in several ways. Metal may dissolve in the reaction medium
Variation of metal location, metal dispersion, metal loading (0.5–10%), catalyst pH and pore structure of the support has enabled the development of a large range of catalysts which are widely used in numerous liquid–phase and vapor–phase industrial processes.
2.1.7 PGM Catalyst Deactivation There are four main mechanisms for catalyst deactivation, namely poisoning, fouling, sintering and physical loss of metal.
and be stripped from the support. Metal may volatilize in high temperature gas phase reactions. The support material may be attacked and start to dissolve in some liquid-phase reactions and the insoluble catalyst fines pass through the filter system. Excessive movement of fixedbed catalysts due to pressure fluctuations can cause loss of catalyst fines by abrasion. The above forms of catalyst deactivation can be overcome by a more suitable choice of catalyst and/or reaction conditions.
2.1.8 Safety and Handling of Supported PGM Catalysts
Poisoning is caused by the irreversible adsorption of species on the catalyst surface. Such species include
Carbon-supported dry powder catalysts can undergo dust explosions in the same manner as carbon itself – and
heavy metals such as lead, copper and zinc; sulfur-
other carbonaceous powdered materials, such as flour or
containing species such as hydrogen sulfide and mercaptans; arsenic; amines and carbon monoxide. In general, it is not possible to remove the poisons by a washing or oxidation procedure (an exception is carbon monoxide).
stearic acid. The problem is minimized by avoiding dust formation during handling operations. Dusting is a bad practice in any case, giving rise to metal losses. As stated earlier, most of the platinum group metal catalysts supported on activated carbon can be used as
Fouling occurs when the catalyst surface is masked by polymeric materials or tars, and is often referred to as
water-wet pastes, which nevertheless behave as free
Table: The Hüttig Temperature of the Platinum Group Metals
10
Metal Hüttig
Pd
Pt
Rh
Ru
Ir
Os
Temperature (°C)
275
340
398
484
542
718
© 2008 Johnson Matthey
10
flowing powders. Paste catalysts are intrinsically safer and easier to handle and use than their dry powder analogues.
2.1.10 PGM Catalyst Recovery and Shipment
Pastes should always be used in preference to powders unless the presence of water is incompatible with the
When the catalyst has come to the end of its active life,
reaction system. The pastes are often more active
the spent material can be sent back to Johnson Matthey
catalysts than the corresponding powders.
for recovery of the PGM values. Each batch of residues received is rendered into a form suitable for evaluating the
Fresh PGM catalysts are essentially non–pyrophoric and can
exact metal content.
safely be exposed to air (in the absence of organic vapors). After use, the filtered supported catalyst should be After use, all catalysts containing absorbed hydrogen may
washed with a suitable solvent, followed by water (to
ignite if dried in air, especially in the presence of organic
reduce the organics content to a minimum) and returned
materials. A used, filtered catalyst should therefore be
as damp cake to the bags and drums. These should be
kept water-wet and out of contact with combustible
sealed and stored away from any combustible vapors.
solvents and vapors. PGM catalysts are extremely efficient at catalyzing the oxidation of low flash point organic
Since many supported catalysts are more pyrophoric after
compounds and can cause spontaneous combustion in
use in hydrogenation reactions due to hydrogen
the presence of these organic liquids (or their vapors) and
adsorption, they should ideally be filtered under an inert
oxygen (or air).
atmosphere. If this is not possible then the filter cake should not be allowed to ‘dry out’ during filtration, such
Care should always be taken when mixing catalysts and
that air is drawn through the cake before it is washed
organic materials. The risk of spontaneous ignition can be
thoroughly with water (to minimize the organics content)
reduced by cooling both the catalyst and the organic
and transferred as a damp cake to the drums for storage.
material(s) before mixing and performing the mixing operation under a blanket of inert gas, such as nitrogen. It is
Other materials contaminated with PGMs, such as wipes,
much safer to add solvent to catalyst than catalyst to solvent.
filter cloths or distillation residues should be returned in a separate marked drum for metal reclamation.
2.1.9 Packaging and Storage of PGM Catalysts
Gas-phase pelleted catalysts can usually be returned without any pretreatment for recovery of metal values.
Johnson Matthey catalysts are normally supplied in polyethylene bags (sealed with plastic clips) which are
Spent catalyst residues returned to Johnson Matthey are
packed in heavy-duty fiberboard drums. If required, steel
classed as materials for recycling and the transport of
or plastic drums can be employed. Also, on request, the
these residues is subject to current waste regulations.
catalysts can be packaged in pre–weighed quantities for
Johnson Matthey can offer advice about the regulations
batch-type processing requirements.
that apply to different materials, but the classification of any waste material is dependent upon the composition
PGM heterogeneous catalyst samples for laboratory
and characteristics of that material and is
evaluation are available packed in glass or plastic bottles.
the responsibility of the originator of the waste.
The catalysts should be stored in their sealed drums to prevent ingress of air and foreign gases until required for use. The drums should be kept in a cool, dry place under reasonable conditions (not exposed to the elements of weather and extremes of temperature – ideally keep between 5 to 30°C). They should not be stored near oils or flammable liquids or exposed to combustible vapors.
In addition to the regulations governing waste shipments, all movements of catalyst residues must be classified and labeled according to current international transport regulations. Material originating within the European Union should be classified and labelled for supply in accordance with Directive 1999/45/EC (as amended). To ensure safe treatment of the residues, Johnson Matthey requires a Material Safety Data Sheet for each residue returned.
After use, the empty bags and drums should be retained for return of the spent supported catalyst.
Further information and assistance on procedures for the return of residues and on the refining service can be obtained by contacting Johnson Matthey. The refining service is described in Section 3.8.
© 2008 Johnson Matthey Plc
11
and loading of additives, the selectivity and activity of the
Base Metal Catalysts
catalyst can be further tuned by altering the support, metal
2.1.11 General Description and Applications
depositioning technique, and reduction and passivation
PRICAT® Supported Base Metal Catalysts
The table below shows some typical compositions and
method.
physical appearances of the main catalysts in the PRICAT®
Johnson Matthey’s PRICAT® products are supported base metal catalysts for applications in the agrochemical, fine
range. The table shows only the most widely used PRICAT® catalysts, and thus does not reflect the full range. Custom catalysts are available on request.
chemical, pharmaceutical intermediate and flavor & fragrance markets. These base metal catalysts are utilized in a vast range of reactions. The varying types and
Reactions performed by PRICAT®‚ catalysts include:
applications include copper based catalysts for dehydrogenation in slurry phase or fixed bed, powdered nickel for miscellaneous hydrogenations and alumina powders for dehydration . The main PRICAT® products are
-
Hydrogenation of sterically-hindered olefins
-
Hydrogenation of phenols
-
Ammonolysis of alcohols
-
kieselguhr and silica supported Ni, Cu and Co catalysts
Selective hydrogenation of phenol to cyclohexanol
functionalized with dopants. Most of the catalysts in the -
PRICAT® range come in tablet and powdered form. This
Hydrogenation of mono nitro-aromatics to the amine
allows the products to be applied in slurry phase, trickle -
bed and fixed bed reactors. The powdered catalysts are
Ring hydrogenation of alkyl-substituted phenols and aromatics
easy to handle since they are non-pyrophoric, free flowing -
and have excellent filtration qualities. The PRICAT® tablets,
Hydrogenation of aldehydes, ketones and aldoses to the corresponding alcohols
used in trickle and fixed-bed applications, usually come in -
the following sizes:
Reduction of nitriles to primary and secondary amines
-
-
3 x 3 mm
-
5 x 4 mm
-
6 x 5 mm
-
6 x 10 mm
Selective dehydrogenation of alcohols to the corresponding aldehydes and ketones
All PRICAT® catalysts are reduced and air passivated, allowing for ease of use. In general, activation can be done in situ under mild process conditions and low hydrogen partial pressures. PRICAT® catalysts are doped with cocatalytic metals and other additives in order to enhance performance in specific reactions. In addition to the type
PRICAT
Metal
Promotors MgO
Al2O3
Tablet
%
Ni 52/35
x
x
50
Kieselguhr
x
Ni 55/5
x
x
55
Kieselguhr
x
Ni 56/5
x
55
Kieselguhr
x
Ni 62/15
x
60
Kieselguhr
x
x
Ni 60/15
x
x
60
Kieselguhr
x
x
x
51
Silica
Cu 60/35
x
x
62
Silica
x
Co 40/55
x
x
40
Kieselguhr
x
ZrO2
Cr2O3
Powder
Cu 51/8
12
Support
MnO
x
x x
© 2008 Johnson Matthey Plc
Sponge Metal Catalysts
Sponge Metal Catalyst Handling and Recovery
2.1.12 General Description Typically, Sponge Nickel catalysts are provided as a powder Sponge Metal
TM
catalysts are used for many of the same
covered in water (a slurry). The slurry contains
heterogeneous chemistries as PGM catalysts. The most
approximately 58-60% catalyst solids by weight. Catalyst
common type of reaction are three phase, gas-liquid-solid,
weight can be accurately determined using displacement.
reactions. Sponge Metal catalysts can be easily separated
Information on this method can be provided on request.
at the end of the reaction. For slurry phase Sponge Metal catalysts, settling, filtration and decantation are common
Activated Sponge Metal catalyst is shipped as an aqueous
ways to separate the catalyst. Other methods less
slurry, packaged in steel drums. The material is pyrophoric
commonly used in the industry are centrifugation and
and classified as hazardous. All packaging meets UN
magnetic separation. (activated Sponge Nickel
TM
catalysts
performance packaging guidelines for UN 1378.
are magnetic). Proprietary Johnson Matthey AMCAT® catalysts are Sponge Metal catalysts are prepared from alloys of
activated powdered encapsulated catalysts in which water
transition metals and aluminum. The aluminum is leached
has been displaced by an aliphatic amine. AMCAT
from the alloy structure, leaving behind an active metal
catalysts are in the form of solid 1/2 inch (13mm) cubes
surface covered in adsorbed hydrogen. The activated
that are nonpyrophoric. The active catalyst powder is
catalysts are stored under water to protect them from
released after charging into the desired feedstock and/or
oxidation. Sponge Metal catalysts are in the fully active
solvent.
form when shipped and require no preactivation prior to use.
In some reactions, to gain maximum catalyst efficiency, the catalyst is allowed to settle after reaction and the
Sponge Metal catalysts are used mainly in hydrogenation,
product is decanted off the top using a dip tube. When
reductive alkylation and dehydrogenation reactions.
this is not appropriate, the entire reaction mixture including product, solvent and catalyst can be fed to a
2.1.13 Sponge Metal Liquid Phase Reactions
filter or other separation device. If the catalyst will remain in the reactor for re-use, it may also be possible to incorporate filters into the reaction vessel to prevent
The principles which govern the use of Sponge Metal
downstream catalyst carryover.
catalysts are very similar to those described in Section 2.1.1 for heterogeneous PGM catalysts.
The filtering of Sponge Metal catalysts after use is recommended for maximum economy. Various types of
Considerations in the Industrial Use of Catalyst Reactors
leaf, cartridge, magnetic and centrifugal filters and separators are suitable for this operation. Downstream polishing filters are often used. If the catalyst settling and
Sponge Nickel catalysts are most often utilized in slurry-
product decantation steps are efficient, it may be possible
phase, batch, stirred tank reactors. Reactant, solvent (if
to use only a polishing filter.
present) and catalyst are charged to the vessel, air is replaced with an inert gas and the vessel is put under hydrogen pressure. The mixture is mechanically agitated, then heated to reaction temperature. After reaction, the mixture is cooled, agitation stopped and the catalyst allowed to settle. Product can be removed via diptube. Slurry-phase Sponge Metal catalysts are sometimes used in continuous stirred reactors with continuous catalyst separation and recycle. Continuous stirred reactors are beneficial for very fast reactions (e.g.dinitro and dinitrile reductions) prone to by-product formation.
© 2008 Johnson Matthey Plc
13
Sponge Metal Catalyst Charging
2.1.15 Choice of Sponge Metal Catalyst Particle Size
Catalyst can be charged to the reaction vessel by several methods. In the simplest process, the catalyst drum is
Sponge Metal catalyst performance can be altered
placed in proximity to the opening of the reactor, the lid is
significantly by varying the particle size of the grind. The
removed and the entire contents are poured into the
standard mean particle size for Sponge Metal catalysts is
vessel. Alternately, the slurry is stirred with a shovel or
35 microns, however, other particle sizes are available
scoop and metered into the vessel. If a drum is overturned
upon request. Smaller catalyst particle size will, in general,
into another vessel, it is recommended that a sturdy 2 inch
increase catalyst activity but will reduce the ease of
to 4 inch steel grating be placed over the opening to
catalyst filtration or separation.
prevent the drum or drum liner from falling into the vessel.
2.1.16 Sponge Catalyst Deactivation Alternatively, the catalyst drum is emptied into an intermediate mechanically-stirred charge tank. The stirred
There are four main mechanisms for Sponge Metal
slurry would then be pumped or educted into the reaction
catalyst deactivation, namely poisoning, fouling, sintering
vessel in a separate step. Rather than overturning a drum
and chemical and physical degradation. Poisoning is
and pouring catalyst from the drum to a vessel, it is also
caused by the irreversible adsorption of species on the
possible to stir the catalyst mechanically in the drum and
catalyst surface. Such species include heavy metals such
then pump or educt the slurry into another vessel.
as lead, iron or mercury; sulfur containing species such as hydrogen sulfide and mercaptans; arsenic; amines and
Sponge Metal Catalyst Activation
carbon monoxide. Most poisoning is irreversible, i.e. it is not possible to remove the poisons by washing or other
Since activated Sponge Metal catalysts are already provided in the reduced state, no further pre-activation or
treatment. However, catalyst poisoning by carbon monoxide can be reversible.
pre-reduction treatments are necessary prior to the actual reaction step.
2.1.14 Choice of Sponge Metal
Sponge Metal active surfaces can be fouled by polymeric materials such as tars or “heavies” . Powder (slurry phase) catalysts can sometimes be reactivated by washing with suitable solvents.
The most common primary base metals formulated into Sponge Metal catalysts are nickel, cobalt and copper. Other base metals can be made into Sponge Metal catalyst formulations. Sponge Metal catalysts often
Loss of metallic surface area via sintering is more prevalent in copper catalysts than with nickel catalysts. Catalyst deactivation by sintering is irreversible.
contain other base metal promoters. Catalyst deactivation by chemical degradation can occur in Sponge Nickel catalysts, used mainly for hydrogenations, are supplied in both unpromoted and promoted forms. The most common promoters are molybdenum (A-7000 series) and iron and chromium (A-4000 series).
two ways. The active metal may dissolve in the reaction medium, or the residual aluminum in the catalyst structure can be leached away to the point where the activity decreases unacceptably. It may also be possible for catalysts to mechanically abrade in high-shear reaction
Sponge Cobalt™ catalysts find application in selective
systems.
hydrogenation, e.g. hydrogenation of nitriles to primary amines without the addition of ammonia as selectivity enhancer, or nitro group reduction in the presence of other functional groups such as halide. Sponge Cobalt catalysts can also be unpromoted and promoted. Copper is also incorporated into Sponge Metal catalysts as a primary component. Sponge Copper™ catalysts are more commonly used in dehydrogenation rather than reduction chemistries.
14
© 2008 Johnson Matthey Plc
2.1.17 Safety and Handling
2.1.19 Catalyst Recovery and Shipment
Activated Sponge Metal catalysts are all potentially pyrophoric. Fresh catalyst is shipped under a protective
When the catalyst has come to the end of its active life,
layer of water to prevent immediate oxidation by air.
Johnson Matthey offers services for reclamation of metal value. Each batch of residues received is rendered into a
In the event of a splash or spill, immediately flush with
form suitable for evaluating the exact metal content.
water to prevent catalyst drying. Dry catalyst can selfheat and serve as an ignition source for other flammable
After use, the filtered supported catalyst should be
materials. Contaminated cleaning materials should be
washed with a suitable solvent, followed by water to
disposed of in a safe place where they cannot cause a fire.
reduce organics content to a minimum. Spent catalysts should be sealed and stored away from any combustible
Sponge Metal catalysts contain adsorbed hydrogen on
vapors. Many supported catalysts are more pyrophoric
their surfaces. Depending on the history and storage
after use in a hydrogenation reaction due to hydrogen
conditions of the catalyst, small amounts of hydrogen can
absorption. Catalyst filtration should be done under an
evolve from the catalyst into the drums. Even though the
inert atmosphere and the filter cake should not be
drums are equipped with a self-venting mechanism, care
allowed to ‘dry out’. The filter cake should be washed
must be taken when opening containers. No ignition
thoroughly with water.
sources should be present in areas where drums are stored, handled and opened.
Other materials contaminated with base metals, such as wipes, filter cloths, distillation residues etc., should be
After use, all catalysts containing absorbed hydrogen may
returned in a separate marked drum for metal reclamation.
ignite if dried in air, especially in the presence of organic materials. A used, filtered catalyst should therefore be
Spent catalyst residues returned to Johnson Matthey are
kept water-wet and out of contact with combustible
classed as materials for recycling and the transport of
solvents and vapors.
these residues is subject to current waste regulations. Johnson Matthey can offer advice about the regulations
Please refer to the Material Safety Data Sheet for detailed
that apply to different materials, but the classification of
up-to-date information about hazards and safe handling
any waste material is dependent upon the composition
recommendations.
and characteristics of that material and is the responsibility of the originator of the waste.
2.1.18 Packaging and Storage In addition to the regulations governing waste shipments, Sponge Metal catalysts are typically supplied in open-head
all movements of catalyst residues must be classified and
steel drums. For high-purity requirements, custom drums
labeled according to current international transport
are available with a polyethylene insert. To accommodate
regulations. Material originating within the European Union
customers’ particular processes, the catalyst is available in
must also be classified and labeled for supply in
a variety of drum sizes, from 3-gallon (11 litre) to 55-gallon
accordance with Directive 1999/45/EC.
(208 litre). Also, on request, catalysts can be packaged in pre–weighed quantities to match batch size requirements.
To ensure safe treatment of the residues and to meet
Sponge Metal heterogeneous catalyst samples for
European Health and Safety legislation Johnson Matthey
laboratory evaluation are available packed in plastic bottles.
requires a Material Safety Data Sheet for each residue returned.
Catalyst should always be stored in sealed containers to prevent ingress of air and foreign gases until required for
Further information and assistance on the procedures for
use. Drums should be kept in a cool, dry place under
the return of residues and on the refining service offered
reasonable conditions (not exposed to the elements of
can be obtained by contacting your local Johnson Matthey
weather and extremes of temperature – (ideally keep
office. (see section 10).
between 5 to 30°C). Drums should not be stored near oils or flammable liquids or exposed to combustible vapors due to the risk of fire. After use, empty drums can often be retained for shipment of spent catalyst.
© 2008 Johnson Matthey Plc
15
2.2
HOMOGENEOUS CATALYSTS
2.2.1 General Description
For example, a reaction with reagent 1 (R1) reacting with reagent 2 (R2) in the presence of a catalyst (M) to form product (P), where P=R1R2, could be written as
A homogeneously-catalyzed reaction contains the catalyst in the same phase as the reactants. Almost invariably the
R1 + R2
catalyst is dissolved in a liquid phase. Homogeneous
[M] → P
catalysis is an area of increasing importance within the chemical industry both for the manufacture of large-scale
The following scheme describes the catalytic cycle
industrial chemicals and complex fine chemicals. Examples of large-scale applications are:• acetic acid manufacture by methanol carbonylation using a rhodium complex and the more advanced technology using an iridium catalyst. • butyraldehyde and plasticizer alcohol (2–ethylhexanol) production by the hydroformylation of propylene using a rhodium catalyst. For PGM-catalyzed reactions, the advantages of a homogeneous system over a heterogeneous process are:(i) better utilization of metal – all of the catalytic metal is equally available to the reactants and hence a lower catalyst loading is required. (ii) exploitation of different metal oxidation states and ligands – offering a wide range of activity and, in particular, selectivity in a complex molecule. (iii) elimination of in–pore diffusion allowing kinetic rather than mass transfer control of reaction rates – ease of process scale–up. (iv) easy exotherm removal – no localized overheating and hence long catalyst lifetime.
The reaction intermediates involved in the catalytic cycle may or may not be capable of being isolated. The catalyst [M] is a metal atom with various chemical species bonded to it. These are called ligands. If the coordination number of the central metal atom is maintained during the catalytic cycle, it may be necessary for ligands to become detached during the course of the reaction. This is called ligand dissociation. In this example, the central metal atom has two ligands (L) which dissociate and then reattach later on in the catalytic cycle: P [ML2 ]
2.2.2 The Catalytic Cycle
R
1
For materials to act in a catalytic, as opposed to a stoichiometric mode, the catalyst must be recycled whilst
L
reactants are continuously forming product(s).
L 2
1
[R MR ]
1
[LMR ]
R
16
2
© 2008 Johnson Matthey Plc
The ligands (L) may be the same, or different, and could
For example, compounds such as Rh4(CO)12, Rh6(CO)16,
include the solvent in which the reaction is being
Rh2Cl2(CO)4, Ru3(CO)12 and RuCl2(CO)6 are not readily
performed. In such cases, the solvent forms part of the
available in bulk quantities.
catalyst cycle and hence choice of solvent can be crucial in homogeneous catalysis.
In industry, stainless steel reactors are commonplace, so the addition of halide, even at ppm levels, can sometimes
Platinum Group Metals and all transition metals can form
cause plant corrosion. Hence, halide free catalysts or
such intermediates in which the nominal oxidation state
precursors might well be preferred in practice even though
and coordination number can be systematically varied.
the catalytic performance of the halide containing and
Transition metals have partially filled d–electron shells
non–halide containing materials may be identical,
which can form hybridized bonding orbitals between the central metal atom and the ligand. Suitable ligands are those capable of forming bonds with σ – and π – character such as carbonyls, alkenes and organophosphines. These ligands play a crucial role in homogeneous catalytic chemistry.
e.g. • Pd(acac)2, Pd-70 or [Pd(OAc)2]3, Pd-111 rather than palladium chloride solution • RhH(CO)(PPh3)3, Rh-42 rather than RhCl(CO)(PPh3)2, Rh-40 • Ruthenium nitrosyl nitrate solution rather than ruthenium chloride solution Although a specific reaction may be catalyzed by one
Much academic research has focused on the interaction of
particular compound, it is often more convenient to use
transition metal complexes with organic molecules. Many
a precursor and produce the actual catalyst in situ.
spectroscopic techniques have been used to identify the
Johnson Matthey can offer specific advice in reagent
transient catalytic intermediates. Precise knowledge of the
choice based on extensive experience in catalyst
intermediates and mechanisms involved can often help
selection.
process optimization. In some cases it has been possible to construct molecular
Precursor
Catalyst
Pd-111, [Pd(OAc)2]3 + PPh3
Pd-101,
Pd-101 is heat, light & air
Pd(PPh3)4
sensitive
RhI3
[Rh(CO)2I2]-
catalyst not readily available
less important than that of a heterogeneous catalyst.
RuCl3xH2O + oxidant
RuO4
RuO4 not commercially available
2.2.3 Choice of Catalyst
PPh3 = triphenylphosphine;
OAc = acetate ;
dba = dibenzylideneacetone
models of reaction intermediates whose conformation will lead to the formation of one particular product. This is particularly applicable to the synthesis of enantiomerically-
Reason for using precursor rather than catalyst
pure isomers. The homogeneous catalyst (or its precursor) is supplied as
or Pd-92, Pd(dba)x + PPh3
a chemical compound whose characteristics, i.e. purity, can be readily determined and controlled. It is dissolved in the reaction medium, hence its original physical form is
Many factors affect the selection of a particular homogeneous catalyst (or precursor). Reactions reported in the chemical literature will not necessarily have been
For a complete list of homogenous catalysts mentioned in
optimized with respect to reagent choice or operating
this handbook, see Section 6.
conditions. Reagents will have been chosen because they were readily available to the researcher and not because they were most suitable, e.g. • use of argon instead of oxygen-free nitrogen • use of PGM catalysts or precursors which do not lend themselves to economic scale-up • use of expensive reagents when cheaper ones would be just as effective
© 2008 Johnson Matthey Plc
17
2.2.4 Product/Catalyst Separation
Poisoning is where the catalyst reacts irreversibly with an impurity e.g. the presence of carbon oxysulfide in carbon
A key consideration for homogeneous catalyst users is
monoxide will eventually deactivate the catalyst.
product/catalyst separation with subsequent product work–up and catalyst recycling.
Cluster formation can occur when there is insufficient ligand present to stabilize the catalyst, particularly when in a low
All common separation techniques have been employed in full-scale commercial operations as well as on the laboratory scale. These include :(i) product distillation, usually under reduced pressure (ii) liquid-liquid solvent extraction, particularly in applications where the spent catalyst is rendered soluble in water. (iii) crystallization of the product by addition of a precipitating solvent, such as diethyl ether, or a hydrocarbon, such as hexane. (iv) flash chromatography on neutral alumina or silica gel,
oxidation state. Eventually the catalyst activity will decline, but if the reason for this is known, it may be possible to reactivate in situ. In other cases this will not be possible. In extreme cases of cluster formation the catalyst may be precipitated. Also, when operating at high temperatures (above 100˚C) the catalyst may become unstable and decompose, resulting in precipitation. The fourth mechanism for deactivation is due to changes occurring to the ligand e.g. exposure of the catalyst to air, oxidizing triphenylphosphine (TPP) ligands to triphenyl phosphine oxide (TPPO).
2.2.6 Safety and Handling
using various solvents including acetone, hexane, ethyl acetate and mixtures of these. The spent catalyst is
Johnson Matthey has always been concerned to ensure that
retained on the column while the desired product
those products which are intrinsically hazardous are provided
passes through.
with sufficient information to permit safe handling and usage.
(v) catalyst adsorption followed by removal by filtration. Users should note that there is an obligation upon (vi) selective precipitation of the catalyst and removal from the reaction medium by filtration.
everyone involved in the use and handling of these materials to acquaint themselves with the potential hazards involved. Johnson Matthey will be pleased to offer
The desired product is then further purified by vacuum distillation or recrystallization. In addition to the separation techniques listed above, Johnson Matthey offers Smopex©, a unique metal scavenging system where metal binding functionality has
specific advice as necessary. Some of the compounds listed in this handbook have only been prepared on a relatively small scale for research purposes, and a complete investigation of their chemical, physical and toxicological properties has not been made.
been grafted onto fibers allowing the effective recovery of a range of precious metals. For more information on
2.2.7 Transport and Storage
Smopex© see section 2.4. Johnson Matthey will dispatch these compounds in a To be reused, a catalyst has to be rendered soluble again,
manner which conforms to all transport regulations. Steps
so further processing is essential. Such systems can be
will be taken to ensure their secure transportation. Each
quite complex, but the chemical transformations that are
batch of product is accurately sampled and analyzed to
made possible with homogeneous catalysis may justify
ensure batch to batch consistency. Johnson Matthey can
this extra processing.
dispatch material in pre–packed lots – either a fixed weight of compound or PGM per package. This can be done for
In some cases, the PGM homogeneous catalyst is so active that there is no economic need to recover the metal values due to the very low catalyst loading.
2.2.5 Catalyst Deactivation
both solid and liquid products. The materials should be kept in their original containers, protected from extremes of temperature until just before use. The containers should be resealed after dispensing.
All catalysts will eventually deactivate. There are four main mechanisms for deactivation namely: poisoning, cluster formation, precipitation and changes to the ligands. 18
© 2008 Johnson Matthey Plc
2.2.8 Catalyst Recovery and Shipment
lengths, (0.3mm) is standard) giving materials with different physical characteristics suited to a variety of reactor and filter combinations. For all fiber lengths,
When the catalyst has come to the end of its active life, the
recovery and recycle of the fiber-supported catalyst after
spent material can be sent back to Johnson Matthey for
reaction is readily achieved. Anchoring of the active
recovery of the platinum group metal values. It is in the
polymer chain to an inert polymer support ensures
catalyst user’s interest to concentrate any catalyst containing
excellent accessibility of the catalytic sites. This allows
liquors as much as possible before shipment, thereby:-
easy diffusion of the starting materials and products to
• reducing freight charges • reducing residue treatment charges However, in some instances, material can be more dilute and processed in AquaCat®. (see section.3.8). Spent catalyst materials returned to Johnson Matthey are classed as materials for recycling and the transport of these residues is subject to current waste regulations. Spent homogeneous catalyst residues typically contain over 50% organic compounds. Johnson Matthey has considerable experience in handling these types of materials. It is advisable that Johnson Matthey is consulted at the earliest possible opportunity to ensure that the material can be transported with a minimum of delay. In addition to the regulations governing waste shipments, all movements of catalyst residues must be classified and labeled according to current transport regulations. Material
and from the catalytic sites, in contrast to conventional polystyrene bead technology where slow diffusion can often reduce the reaction rate. Additionally, the polyethylene fiber is extremely robust and is not degraded by stirring, again in contrast to polystyrene beads. Johnson Matthey has tested these catalysts in a number of representative cross-coupling, hydrogenation, oxidation and hydrosilylation reactions There are currently 4 series of FibreCat® catalysts grouped according to the reactions they are used in: 1000 series:
Cross-coupling reactions
2000 series:
Hydrogenation reactions
3000 series:
Oxidation reactions
4000 series:
Hydrosilylation reactions
The full list of products is shown in Section 6.
Comparison of FibreCat® Catalysts with Homogeneous Catalysts:
originating within the European Union must also be classified and labeled for supply in accordance with
1000 series – Cross-coupling reactions
Directive 93/21/EEC (as amended).
Suzuki Reaction To ensure safe treatment of the residues and to meet local regulations, Johnson Matthey requires a Material Safety Data Sheet for each residue returned.
Suzuki (or Suzuki-Miyaura) reactions involve the coupling of organoboron compounds with aryl, alkenyl and alkynyl halides or triflates. This reaction is a very useful and
The refining service is described in Section 3.8.
generally high yielding method for cross-coupling of aromatic and heterocyclic aromatics.
2.3 F IBRE C AT ®
O
O Br + B(OH) 2
2.3.1 General Description1 FibreCat® is a new range of polymer-anchored homogeneous catalysts offering the selectivity benefits of
Catalyst, toluene K 2 CO 3 (2 equivalents), N 2 , 70C, 2h
FibreCat® technology offers a more active catalyst than the homogeneous equivalent.
homogeneous catalysts with the filtration/ separation benefits of heterogeneous catalysts. The active metal species are covalently bound to a
FibreCat® 1001
[Pd(OAc)2]3 + 12 PPh3
Pd: 4-bromoacetophenone molar ratio
1 : 120
1 : 100
polymer chain. This active polymer is further linked to an inert polyolefin fiber, which is insoluble in all common
% Yield
99.9
76.5
organic solvents. The fiber can be prepared in a variety of 1 S Collard et al, Catalysis of Organic Reactions (proceedings of 19th ORCS conference) 2002, 49-60
© 2008 Johnson Matthey Plc
19
2000 series - Hydrogenation Reactions
2.
The hydrogenation of carbon-carbon double bonds using
Oxidation of alcohols to aldehydes FibreCat® catalyst can selectively oxidize alcohols to
organometallic complexes of rhodium is widely used in
aldehydes without over-oxidation to carboxylic acid.
organic synthesis. By anchoring coordination complexes to polymer supports, it should be feasible to combine the high selectivity and mild reaction conditions of the
For example, FibreCat® 3002 gives 70% conversion of benzyl alcohol to benzaldehyde with no over-oxidation to benzoic acid:
analogous homogeneous system with the ease of separation and recyclability of heterogeneous catalysts.
OH
O 10 mol% Ru as FibreCat 3002 Toluene
The fiber supports can also exert an influence on the selectivity and activity of the catalyst.
3 bar 60 C, 6 hours
In the selective hydrogenation of geraniol to citronellol1 and the selective hydrogenation of carvone to 7,8dihydrocarvone2, Rh FibreCat® catalysts exhibit similar
4000 series - Hydrosilylation Reactions
selectivities to their homogeneous counterparts. Platinum complexes are commonly used in hydrosilylation reactions as the exceptional activity of the catalyst allows the Pt to be used at very low levels. There can be issues,
OH
OH 1
though, with Pt being left in the product. This often needs to be removed, depending on the end application. These issues are overcome by using a supported homogeneous catalyst. O
O
In the reaction of trichlorosilane with tetradecene, the FibreCat® catalyst gives 85% conversion to product and a
2
colorless product, indicating that there is no Pt in the product. The hydrogenation of the least hindered double bond in these substrates is faster with homogeneous and C12 H 25
FibreCat® systems than other double bonds in the
+
Cl 3 SiH
C12 H 25
molecule meaning that the selective hydrogenation can be SiCl
achieved.
3000 series - Oxidation Reactions 1.
2.3.2 Catalyst Leaching and Recycle
The catalytic cis-dihydroxylation of olefins has traditionally been achieved with the use of osmium
Covalent linking of the metal catalyst to the polymer
complexes such as OsO4 and K2OsO2(OH)4. The use
support ensures that there is only very low leaching of
of homogeneous OsO4 is limited due to the hazards
metal into solution during the course of the reaction.
®
associated with its volatility and toxicity. FibreCat
As an example, analysis of the reaction liquor from the
lowers the volitility of the OsO4.
Suzuki coupling of 4–bromoanisole with phenyl boronic acid indicated that only ca 0.2% of the palladium was lost
In the cis-dihydroxylation of 1,2-cyclooctene to cis-1,2cyclooctane diol, FibreCat® 3003 gives 85%
to solution (less than 1 ppm palladium in solution).
conversion to product and Rh > Pt >> Ru Palladium is the most selective metal for the conversion The ease of hydrogenation decreases with increasing
of alkynes to alkenes without further hydrogenation to
substitution at the double bond. In molecules containing
the corresponding alkane. Modifiers such as amines or
more than one double bond, the least hindered will be
sulfur-containing compounds can be added to the reaction
hydrogenated preferentially, and exocyclic double bonds
system to improve the selectivity to the alkene.
more easily hydrogenated than endocyclic double bonds.
Alternatively, Pd catalysts can be modified with a second metal such as Pb, Cu or Zn. The best known and most
A complication in the hydrogenation of alkenes can be
widely used catalyst of this type is Lindlar’s catalyst which
double bond migration and cis–trans isomerisation. The
is a mixed Pd/Pb catalyst on a calcium carbonate support.
tendency of the PGMs to promote these reactions is
Selectivity to the alkene can also be improved by limiting
generally in the order
the hydrogen availability.
Pd > Rh > Ru > Pt = Ir Hence platinum catalysts are useful when double bond migration is to be avoided. Homogeneous (Rh and Ir) catalysts are particularly useful for selective alkene hydrogenations. For example in the rhodium-catalyzed hydrogenation of carvone to dihydrocarvone:
O Br + B(OH) 2
Neither the carbon–carbon double bond in the ring nor the ketone function is hydrogenated. Similarly, in the manufacture of the pharmaceutical Ivermectin, only one of several carbon-carbon double bonds is hydrogenated in the presence of Wilkinson’s catalyst, Rh-100 RhCl(PPh3)3. Rh-100 is normally selective for the least substituted double bond. Arene, carboxylic acid, ester, amide, nitrile, ether, chloro, hydroxy, nitro and sulfur groups are all tolerated. Catalysts such as Ir-90 [Ir(COD)(py)PCy3]PF6, Ir-93 [IrCl(COD)]2, Rh-93 [RhCl(COD)]2 or Rh-97 [Rh(nbd)2]BF4 are used for hydrogenating highly 24
© 2008 Johnson Matthey Plc
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
-C≡C- → -CH2.CH2-
50–100
1–10
None or alcohols
Pd/C A402002-5, A405028-5, Pd/c A503023-5, A102023-5, Pd/c A470085-5, A470129-5
-C≡C- → -CH=CH-
5–50
1–3
Alcohols, acetic acid, ethyl acetate or vapor phase
Pd/C A102038-5, Ni A-5000d/C Ni/Mo A7063 Pd(S)/C A103038-5 Pd/CaCO3 A303060-5 Pd,Pb/CaCO3 A305060-5, A306060-5
-CH=CH- → -CH2.CH2-
5–100
3–10
None, alcohols, acetic acid or ethyl acetate
Pd/C A402002-5,A405028-5, Pd/c A503023-5, A102023-5, Pd/c A470085-5, A470129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5
Selective hydrogenation of least substituted alkene
25–75
1–5
Methanol, ethanol, acetone, THF or toluene
Rh-100 FibreCat® 2003, 2006
Hydrogenation of substituted double bonds
25–75
1–5
Dichloromethane, toluene or ethanol
Ir-90, Ir-93, Rh-93 or Rh-97
4.1.2 Aromatic ring compounds
For the hydrogenation of alkyl-substituted polycyclic aromatics Rh and Pt catalysts are generally less selective
The activity of the catalysts, both heterogeneous and
than Ru unless the aromatic ring is highly substituted.
homogeneous, for the hydrogenation of aromatic rings are Benzene is readily hydrogenated to cyclohexane.
in the order
Industrially this reaction is performed in the vapor phase Rh > Ru > Pt > Pd
with a Pt/alumina fixed bed catalyst.
The rate of hydrogenation of the aromatic ring with PGM
Partial hydrogenation of benzene to cyclohexene can be
catalysts varies with the nature, number and position of
effected at 25–200°C and 10–70 bar with a heterogeneous
the substituents.
Ru catalyst.
Typical operating conditions for heterogeneous Rh
Ru is often recommended if C–O or C–N bond
catalysts would be 20–60°C and 1–4 bar hydrogen
hydrogenolysis is to be avoided. Basic additives may be
pressure. In general, homogeneous catalysts offer no
used to suppress unwanted hydrogenolysis or coupling
advantages and are very rarely used for ring
reactions and to increase the hydrogenation rate.
hydrogenations. There is considerable interest in the ring hydrogenation of
Carbocycles Rhodium is the most active catalyst, but cost may count against its large scale use in some cases. Pt and Ru catalysts usually require more extreme operating conditions but the performance of Ru catalysts can often be improved by the addition of small amounts of water.
© 2008 Johnson Matthey Plc
4-t-butylphenol to the cis-isomer (as opposed to the transisomer). Choice of a specific Rh/carbon catalyst together with the use of a non-polar solvent (e.g. hexane) can yield >90% of the desired cis-isomer. Increased solvent polarity (e.g. isopropanol) results in the production of increasing quantities of the trans product.
25
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Carbocyclic ring
5–150
3–50
None or alcohols
Rh/C C101023-5,C101038-5 Rh/AI2O3 C301011-5 Ru/C D101023-5,D101038-5, Rh/c D170201-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5 Pd/C A503023-5, A102023-5, Pd/c A102038-5, A470085-5 Ni A-5000
Phenol →Cyclohexanone
30–200
1–10
In summary, selectivity is affected by:• choice of catalyst (including bimetallics) • solvent polarity and pH • reaction conditions (temperature and pressure).
None
Pd/C A102023-5, A105023-5
Rh is the most active catalyst under mild conditions and is recommended when hydrogenolysis is to be avoided. Pd is an effective catalyst especially for the hydrogenation of acyl- or acyloxy- pyridines. Generally, Pd is the preferred catalyst for selective hydrogenation of nitrogen-containing heterocyclic rings in the presence of carbocylic rings.
A reaction of considerable commercial importance is the one step Pd-catalyzed conversion of phenol to cyclohexanone (a precursor of Nylon 6), with minimal over hydrogenation to cyclohexanol. This reaction can be performed in either the liquid or vapor phase at 30–200°C and 1–10 bar hydrogen pressure.
Heterocycles In general, heterocycles are easier to hydrogenate than carbocycles. Heterocyclic compounds such as pyridines, quinolines, isoquinolines, pyrroles, indoles, acridines and carbazoles can be hydrogenated over Pd,
Ru is an excellent catalyst at elevated temperatures and pressures where N–dealkylation or deamination is to be avoided.
Pt, Rh and Ru catalysts. Hydrogenation of furans and other oxygen-containing Acidic solvents, such as acetic acid, and aqueous HCl solutions are often used to facilitate hydrogenation. Pt catalysts have been successfully used in the
heterocycles becomes more complex due to hydrogenolysis and ring cleavage possibilities. Hydrogenolysis is generally promoted by high temperature and acidic solvents.
hydrogenation of many nitrogen containing heterocycles at 25–50°C and 3–4 bar hydrogen pressure, e.g.
Specific requirements should be examined on a case by case basis.
26
© 2008 Johnson Matthey Plc
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Pyridines
30-150
3-50
None or alcohols
Pt/C B102022-5, B103032-5, Pt/c B501032-5, B170147-5 Ni A-5000 Rh/C C101023-5, C101038-5
Furans
30-100
5-60
None, alcohol or water
Pd/C A503023-5, A102023-5 Pd/c A102038-5, A570147-5 Pd/c A570129-5 Rh/C C101023-5, C101038-5 Ru/C D101023-5, D101038-5
Pyrroles
30-100
3-50
Acetic acid or alcohol/acid
Pd/C A503023-5, A102023-5, Pd/c A570129-5 Pt/C B102022-5, B103032-5, Pt/c B501032-5, B170147-5 Rh/C C101023-5, C101038-5
1
4.1.3 Carbonyl compounds
Ether formation, which may occur as an alcohol dehydration product, can be reduced using a Ru catalyst.
Aldehydes
Pd is the preferred catalytic metal for the hydrogenation
In general, saturated aliphatic aldehydes can be
of aromatic aldehydes. Typical reaction conditions are
hydrogenated over Pt, Ru or Ir catalysts to the
5–100°C and 1–10 bar hydrogen pressure.
corresponding primary alcohols at 5–150°C and 1–10 bar hydrogen pressure. Pd tends to be an ineffective catalyst for aliphatic aldehydes but is the metal of choice for aromatic aldehydes.
Pd will also catalyze the production of hydrocarbon formed from the hydrogenolysis of the alcohol intermediate. Acidic conditions and polar solvents promote the formation of the hydrocarbon by-product.
Ru is the catalytic metal of choice for hydrogenation of aliphatic aldehydes. A well known example is the hydrogenation of glucose to sorbitol in aqueous solution. This reaction is traditionally performed industrially with a Ni catalyst, but there are advantages to be gained by using a Ru catalyst.
Although Pt and Ru can be considered for this application, there is the possibility of simultaneous ring hydrogenation. To some extent, this side reaction can be inhibited by the addition of either salts of Zn, Ag or Fe (typically Cl > F
The hydrogenation of halonitroaromatics to the
and its position on the aromatic ring with respect to the
corresponding haloaminoaromatic is a reaction of
nitro group being hydrogenated:-
considerable industrial importance. Traditionally, Fe/HCl catalyst has been used to obtain the desired yield of the haloamine (Béchamp Process) but it is increasingly being replaced by Pt catalysts because of several
ortho > para > meta Acidity in the form of acid addition or an acidic catalyst will tend to inhibit hydrodehalogenation.
inherent disadvantages:Typical operating conditions are 90–150°C and 8–12 bar • a steam distillation step is needed to separate the product haloamine from the iron oxide sludge –
hydrogen pressure, as more severe conditions promote hydrodehalogenation.
an operation which is energy intensive and therefore expensive
The reaction can be effectively carried out with or without the use of a solvent. A solvent, while facilitating
• environmental problems with the disposal of the iron sludge. These problems can be successfully overcome using a Pt supported catalyst; Pd catalysts cause high levels of hydrodehalogenation. The ease of halogen removal (as the
temperature control (acting as a heat sink for the exotherm) may have a marked influence on the rate and selectivity to the haloamine. Generally, aprotic solvents inhibit hydrodehalogenation whereas protic solvents tend to increase reaction rates.
hydrohalic acid) depends on the particular halogen:© 2008 Johnson Matthey Plc
31
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Halonitro → haloamine
90-150
8-12
Alcohols or cyclohexane
Pt/C B101032-3, B103032-3, Pt/c B102032-1, B101038-1, Pt/c B105047-1, B170147-1 Pt/c
4.1.6 Reductive Alkylation
R1 R
NH2
+
O
C
R
N
C
2
R
R1 R2
+
H2O
Pt H2 or Pd R1 R NH CH R2 Reductive alkylation involves the reaction of a primary or
In some cases, the amine may be produced in situ from
secondary amine with an aldehyde or ketone to form a
the corresponding nitro or nitroso compound. Similarly the
secondary or tertiary amine respectively.
carbonyl may, in some circumstances, be produced in situ from the appropriate acetal, ketal, phenol or alcohol.
Formation of the imine intermediate is favored by acidic conditions. The imine intermediate is seldom isolated in
Aldehydes are generally more reactive than ketones
such cases.
because they tend to be less sterically hindered. Pt or Pd catalysts are preferred for reductive alkylations. Typical
The amines formed are also suitable substrates for further
reaction conditions are 50–300°C and 1–50 bar pressure.
alkylation. A catalyst of high selectivity is required to minimize Thus, when wanting to produce a secondary amine (with a
hydrogenation of the carbonyl compound to the alcohol
minimum of tertiary amine) from a primary amine
prior to imine formation via condensation. Sulfided
feedstock, the primary amine to carbonyl molar ratio
platinum catalysts can be used to minimize alcohol
should not exceed one.
formation but generally require more severe operating conditions. Non-sulfided Pt catalysts are effective under mild reaction conditions (10 bar, 100°C).
R NH CH
32
R2
R1
R1
R1
+
O
+ H2
C R2
R
N CH
+ H2O
R2 2
© 2008 Johnson Matthey Plc
CH3 NH
NH2
CH CH2
+
CH3
C
O
CH3
NH
CH2
NH CH
CH
CH3 CH3
CH3 The manufacture of the rubber antioxidant 6-PPD
A reductive alkylation of commercial significance in the
Typical operating conditions are 25–50°C and 1–80 bar
rubber chemicals industry is the reaction of
pressure. A wide variety of solvents can be used – such as
4–aminodiphenylamine with MIBK (methyl isobutylketone)
dichloromethane, alcohol, toluene and tetrahydrofuran
to produce 6PPD.
(THF).
Homogeneous Ir catalysts (exemplified by Ir–93,
For example N–cyclohexylaniline can be formed in 98%
[IrCl(COD)]2 plus ligand) are effective for reductive
yield at atmospheric pressure in methanol.
alkylations (as well as imine hydrogenations – see section 4.1.8).
Ir O
+ H2N
+ H2
N H
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
from aldehyde
20–100
1–50
Alcohol or the aldehyde
Pd/C A109047-5, A503032-5, Pd/c A503023-5, A102023-5, Pd/c B570147-5, A570129-5 Ni A-5000 Ni/Mo A-7000 Pt/C B102032-3, B104032-3, Pt/c B170147-3, B105032-3, Pt/c B106032-3, B171147-3
from ketone
50–150
1–50
Alcohol or the ketone
Pd/C A109047-5, A503032-5 Pd/c A503023-5, A102023-5, Pd/c B570147-5, A570129-5 Ni A-5000 Ni/Mo A-7000 Pt/C B102032-3, B104032-3, Pt/c B170147-3, B105032-3, Pt/c B106032-3, B171147-3
© 2008 Johnson Matthey Plc
33
4.1.7 Reductive Aminations
R1
R1 C
O
+
NH3
R2
R2
Pd
R1 R2
C
N
H
+
H2O
H2
CH NH2
This reaction is essentially the same as a reductive alkylation except that the “amine” feedstock employed is ammonia. The catalyst of choice is almost invariably Pd. Excess ammonia is employed to suppress hydrogenation of the carbonyl to the corresponding alcohol.
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
from aldehyde
50–300
1–50
None or alcohol
Pd/C A109047-5, A503032-5, Pd/c A503023-5, A102023-5, Pd/c A570147-5, A570129-5
from ketone
50–300
10–50
None or alcohol
Pd/C A109047-5, A503032-5, Pd/c A503023-5, A102023-5, Pd/c A570147-5, A570129-5
4.1.8 Imines Me
Reductive alkylations/aminations involve the condensation of a carbonyl compound with an amine to form an imine
Me
Me N
HN
intermediate, which undergoes hydrogenation to the
HN
+
amine. In some cases, the imine is the feedstock for hydrogenation. Pd and Pt heterogeneous catalysts are
Ph
Ph
Ph
typically used although homogeneous Ir catalysts are also effective, particularly for enantioselective hydrogenations. Pd and Pt catalysts can be used under relatively mild operating conditions of 20–100°C and 1–10 bar pressure. Alcohols are usually the solvents of choice and acidic conditions often promote the reaction.
34
© 2008 Johnson Matthey Plc
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Imine → amine
20–100
1–10
Alcohol or toluene
Pd/C A109047-5, A503023-5, Pd/c A503032-5, A102023-5, Pd/c A570147-5, A570129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5
4.1.9 Nitriles
In neutral media, Pd is also effective for the production of tertiary amines.
Hydrogenation of nitriles can be carried out over Rh, Pt or Pd catalysts at 5–150°C and 1–100 bar hydrogen pressure.
For aliphatic nitriles, with proper selection of conditions,
Primary, secondary or tertiary amines can be formed via
either Rh, Pt or Pd may be effective for the formation of
the intermediate imine
primary amines, whereas Rh catalysts yield secondary amines as the predominant product and Pt or Pd catalysts RCH2NH2
favor the formation of tertiary amines – especially in the hydrogenation of short chain aliphatic nitriles.
R
C
N
RCH
NH
(RCH2)2NH Dinitriles, either aliphatic or aromatic, usually need (RCH2)3N
considerably higher operating pressures (100–220 bar) to effect the hydrogenation.
For example, veratrylnitrile can be readily hydrogenated to the corresponding primary amine with a Pd catalyst
In acidic aqueous media, nitriles can undergo reductive hydrolysis to aldehydes and/or alcohols by hydrolysis of
at 10–50°C and 3–5 bar
the imine intermediate.
CH3O
CN
CH3O
CH2 NH2
Pd CH3O
H 2O R
C
N
R CH
NH
RCHO
+
NH3
CH3O
Pd is the catalyst of choice for this reaction which can be For the formation of the primary amines, either acidic solvent conditions (at least 2–3 moles of acid/mole of nitrile) or excess ammonia (>2 moles/mole nitrile) are required. Formation of secondary amines is facilitated by neutral conditions while tertiary amines are usually produced predominantly only in the presence of a low molecular weight secondary amine. For aromatic nitriles in ammonia or acidic media, Pd and Pt are preferred for the production of primary amines. Pt and Rh are preferred for the formation of secondary amines in neutral solvents.
effected at 30–100°C and 1–5 bar. The aqueous solvent is made acidic with H2SO4, HCl or CH3COOH. The acid promotes the hydrolysis of the imine and acts as a scavenger for the ammonia. In order to force the reaction to the desired aldehyde, phenylhydrazine or semicarbazide can be added. The aldehyde forms the respective condensation phenylhydrazone or semicarbazone product. At least 1–2 moles of additive/mole of aldehyde needs to be added. Reductive cyclization may also be an important reaction pathway when a suitable second reactive functional group is available.
© 2008 Johnson Matthey Plc
35
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
5–100
1–10
Alcohol/ammonia or alcohol/min. acid or acetic anhydride
Pd/C A503023-5, A503032-5, Pd/c A102023-5, A570147-5, Pd/c A570129-5
to Aliphatic Amine 1°–amine RNH2
Pt/C B103032-5, B501032-5, Pt/c B570147-5 Rh/C C101023-5, C101038-5 Ni A4000, A5000, Ni A7000, A7063 AMCAT 5 AMCAT 7 2°–amine R2NH
50–100
2–5
Alcohols. neutral conditions
Rh/C C101023-5, C101038-5 Pd/C A503023-5, A503032-5 Pd/c A102023-5, A570147-5, Pd/c A570129-5
3°–amine R3N
50–100
2–5
Alcohols, or DMF with 2°–amine
Pd/C A503023-5, A503032-5 Pd/c A102023-5, A570147-5, Pd/c A570129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5
to Aromatic Amine 1°–amine ArNH2
50–100
1–10
Alcohol/ammonia or alcohol/min. acid or acetic anhydride
Pd/C A503023-5, A503032-5 Pd/c A102023-5, A570147-5, Pd/c A570129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5
2°–amine Ar2NH
5–100
2–5
Alcohol/water
Pt/C B103032-5, B501032-5, Pt/c B170147-5
3°–amine Ar3N
50-100
2–5
Alcohol or DMF with 2°–amine
Pd/C A503023-5, A503032-5 Pd/c A102023-5, A570147-5, Pd/c A570129-5 Pt/C B103032-5, B501032-5, Pt/c B170147-5
to Aldehyde 30–100
36
1–5
Alcohol/acid or water/acid
Pd/C A402002-5, A109047-5, Pd/c A503023-5, A570129-5 Pd/c A570201-5
© 2008 Johnson Matthey Plc
4.1.10 Oximes
Rh is also the catalyst of choice if reductive coupling is to
Hydrogenation of oximes can give rise to primary,
solvents favor the formation of primary amines by
secondary or tertiary amines, hydroxylamines or imines.
suppressing reductive coupling side reactions. Acidic
The imines are rarely isolated as such, since condensation
conditions are recommended to minimize reaction rate
coupling can readily occur as well as the possibility of
inhibition caused by the amine products. With a Rh
reductive hydrolysis to the aldehyde.
catalyst, the amount of acid is not critical, but with a Pd
be minimized. Acidic (H3PO4 or H2SO4) or ammoniacal
catalyst, there should be at least 2–3 moles of acid per Acetylation of the oxime facilitates hydrogenation.
mole of oxime.
Rh is the preferred catalytic metal for the formation of
Pt or Pd catalysts are generally preferred for the partial
primary amines usually producing less secondary amine
hydrogenation of oximes to the corresponding
product than Pd.
hydroxylamine (or imine precursor).
+
RCH2NH2 RCH
N
OH
H2O
RCH2NHOH
RCH
RCHO
NH
+
+
H2O
NH3
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
oxime → amine
30–60
1–5
Alcohol/acid
Pd/C A109047-5, A503023-5, Pd/c A503032-5, A102023-5, Pd/c A570147-5, A570129-5 Rh/C C101023-5, C101038-5
© 2008 Johnson Matthey Plc
37
4.1.11 Hydrogenolysis
(b) N–Debenzylation
Debenzylations
For N–debenzylations exemplified by the general scheme
Benzyl groups and related structures (e.g. carbobenzyloxy) are often used to protect amine and hydroxyl functional
CH2NR1R2
CH3
Pd
+
R1R2NH
groups. Catalytic hydrogenolysis for the removal of these protecting groups occurs under mild conditions. Typical operating conditions are 5–100°C and 1–10 bar hydrogen pressure.
both reduced and unreduced Pd/C can be effective.
Hydrogenolysis is promoted by high temperatures and low
Acidic solvents such as acetic acid, ketones with acid
pressures. In most cases Pd/carbon is the catalyst of
addition, or even acid buffered solvents are desirable to
choice, but there are differences between O–debenzylation
prevent inhibition of the catalyst by the amine products.
(cleavage of carbon–oxygen bonds) and N–debenzylation
The amine adsorption characteristics are pH dependent.
(cleavage of carbon–nitrogen bonds).
Typically, N-debenzylations are more difficult to perform than O-debenzylations. The slower N-debenzylation reaction rate can often be improved by using higher
(a) O–Debenzylation
palladium content in the catalysis design. The classical Pd/C catalyst used for this reaction is Pearlman’s catalyst (a 20% palladium hydroxide on carbon
(c) Removal of Carbobenzyloxy Group
catalyst), but in most cases it is possible to use a catalyst with a much lower Pd content. Best results are invariably
In practical terms, operating conditions are very similar to
obtained with an unreduced (oxidic) Pd/carbon catalyst.
those of N–debenzylation described above.
The best solvent for this reaction is THF (tetrahydrofuran)
Acidic conditions are desirable, not only to avoid amine
although acetic acid or alcohol have also been used
inhibition of the catalyst, but also to avoid poisoning by the
successfully.
liberated CO2.
CH2 CH2OR
OCONR1R2
CH3
CH3
Pd
+
+ R1R2NH + CO2 ROH
Pd
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Debenzylation
5–100
1–10
Alcohols, THF, acetic acid or alcohol/mineral acid
Pd/C A402002-5, A405028-5, Pd/c A405032-5, A503023-5, Pd/c A503032-5, A470129-5, Pd/c A402028-10, A402032-10, Pd/c A501023-10, A501032-10,
Pd/c A470129-10
38
Carbon–oxygen cleavage
50–150
3–50
Alcohol/mineral acid, THF or acetic acid
Pd/C A402002-5, A405028-5, Pd/c A405032-5, A503023-5, Pd/c A503032-5, A470129-5, Pd/c A402028-10, A402032-10, Pd/c A501023-10, A501032-10, Pd/c A470129-10, A401002-20, Pd/c A470129-20
Carbon–nitrogen cleavage
50–150
3–50
Alcohol/mineral acid or acetic acid
Pd/C A402002-5, A405028-5, Pd/c A405032-5, A503023-5, Pd/c A503032-5, A470129-5, Pd/c A402028-10, A402032-10, Pd/c A501023-10, A501032-10, Pd/c A470129-10
© 2008 Johnson Matthey Plc
Hydrodehalogenations
Rosenmund Reductions
Hydrodehalogenation occurs under relatively mild
The Rosenmund Reduction is the Pd catalyzed hydrogenation
conditions (5–100°C and 1–10 bar) but is favored by
of an acyl chloride to the corresponding aldehyde
increasing temperature rather than pressure. RX + H2 ➝ RH + HX COCl
X = F, Cl, Br, I Pd is the most active and preferred catalytic metal. The
CHO
Pd
+ R
HCl
R
ease of hydrogenolysis is in the order I > Br > Cl > F
The classical catalyst for this reaction is Pd/BaSO4, but in most cases Pd/carbon powders can be substituted with
Selective hydrodehalogenation is possible in some cases
advantage.
e.g. removal of chlorine (as HCl) with fluorine retention. This is demonstrated by the fixed bed vapor phase
The operating conditions must be mild (temperatures of
conversion of CFC (chlorofluorocarbon) to HFC
5–50°C and pressures of 1–3 bar), otherwise over-
(hydrofluorocarbon).
hydrogenation to the primary alcohol will occur. In order to preserve the selectivity to the aldehyde, nitrogen or sulfur-containing compounds are often added to modify the catalyst. Typical additives include thiourea or thioquinanthrene. These well-defined compounds have largely eclipsed the use of the variable “quinoline/sulfur” reagent. The reaction
The reaction rate also depends on molecular structure and
must be carried out in the absence of water, otherwise
neighboring functional groups. Cleavage of aryl halides is
hydrolysis of the feedstock to the corresponding carboxylic
more facile than alkyl halides.
acid will occur. Dry powder Pd/C catalyst must therefore be used (as opposed to water-wet pastes) to maintain the
The reaction rate is often adversely affected by the release
anhydrous conditions.
of halide ion, therefore an addition of basic halide acceptors is often made. Typical additives include aliphatic
As with other hydrodechlorinations, a basic chloride
amines (e.g. triethylamine), sodium carbonate, magnesium
acceptor is often utilized. Examples include 1,2-butylene
oxide etc. At least 2 equivalents of base per equivalent of
oxide, aliphatic amines, sodium carbonate, magnesium
halide should be added. Suitable choice of solvent can also
oxide, 2,6–dimethylpyridine etc. (again at least 2
help minimize the effect of catalyst inhibition by halide.
equivalents per equivalent of halide).
Alcohols or esters (such as ethyl acetate) can be used
Sometimes, due to the ease of acid chloride
as solvents, often with the addition of up to about 10%
hydrodechlorinations, it is possible to remove the liberated
water, which can help to maintain catalyst activity.
HCl with a nitrogen sparge or by operating at subatmospheric pressures so that the addition of specific chloride acceptors is not necessary.
© 2008 Johnson Matthey Plc
39
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Hydrodehalogenation
5–100
1–10
Alcohols, ethyl acetate or vapor phase
Pd/C A402002-5, A405028-5 Pd/c A503023-5, A503038-5, Pd/c A102023-5, A570129-5, Pd/c A570201-5
Rosenmund Reduction (acyl chloride → aldehyde)
5–50
1–3
Toluene, xylene, acetone or THF
Pd/C A302023-5, A302038-5, Pd/c A701023-5 Pd/BaSO4 A308053-5, A201053-5, A201053-10
4.1.12 Transfer Hydrogenations1
Transfer hydrogenation can be accomplished using homogeneous catalysts. For example, tetralone has been
When hydrogen gas and/or hydrogenation plant is not
hydrogenated with Rh-120 with an amine ligand in the
readily available, then the hydrogenation may be achieved
presence of a hydrogen donor, propan-2-ol.
using a chemical hydrogen donor. In effect the catalyst dehydrogenates the donor molecule to generate hydrogen to carry out the hydrogenation. The donor molecule and catalyst should be selected with care so that the rate of hydrogen release is comparable to the rate of hydrogenation of the feedstock. Typical donor molecules include cyclohexene, formates, phosphinates, propan–2–ol and indolene.
Examples of PGM precursors of homogeneous catalysts used for transfer hydrogenations in the literature are Iridium (Ir-93 [IrCl(COD)]2), Rhodium (Rh-93 [RhCl(COD)]2), (Rh-120 [RhCl2(CP*)]2) and Ruthenium (Ru-120 [RuCl2(pcymene)]2). Please refer to section 4.13 for information on asymmetric hydrogenation.
Pd and Pt are the heterogeneous catalysts of choice. Transfer hydrogenations are often performed under reflux but it is possible to operate at lower temperatures when required. Different selectivities are sometimes achieved by transfer hydrogenation rather than H2 gas.
O
OH
+
(CH3)2CHOH
+
(CH3)2CO
1 R.A.W. Johnstone et al. Chem. Rev. (1985) 85 129–170 40
© 2008 Johnson Matthey Plc
Reactant
Product
Donor
Solvent
Temperature
Catalyst
Nitro
Amine
Formic acid, phosphinic acid, sodium formate, sodium phosphinate, tetraethyl ammonium formate
Methanol, ethanol or THF
50–80
Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5
Halonitro
Haloamine
Formic acid, phosphinic acid, sodium phosphite
Methanol, ethanol or water
60–80
Pt/C B101032-3, B103032-3, Pt/c B170147-3, B102032-1, Pt/c B101038-1, B105047-1, Pt/c B170147-1
Imine
Amine
Formic acid & Et3N, propan–2–ol
None or acetonitrile
0–60
Ir–93 Rh–93, Rh–120
Alkene
Alkane
Cyclohexene, indolene, triethyl ammonium formate
None
Reflux
Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5
Carbonyl
Alcohol
Cyclohexene, phosphinic acid, sodium phosphinate
Ethanol or THF
Reflux
Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5
Ketone
Alcohol
Formic acid & Et3N, propan–2–ol
None or acetonitrile
0–60
Ir–93 Rh–93, Rh–120
Formic acid, sodium formate
Ethanol, methanol or THF
50–80
Pd/C A503023-5, A503032-5, Pd/c A470129-5, A402028-10, Pd/c A501023-10, A501032-10, Pd/c A470129-10
Debenzylation
4.2 DEHYDROGENATION Dehydrogenation is an endothermic process, and hence high operating temperatures (up to 250°C) and high catalyst loadings (3–10% with respect to feedstock) are often necessary. At such high temperatures, most PGM complexes decompose, so homogeneously catalyzed dehydrogenations in the liquid phase are usually not feasible. Traditionally, nitrogen has been used to purge the liberated
(˚C)
Hydrogen Acceptor
Product
Nitrotoluene
Toluidine (+ water)
Nitrobenzene
Aniline (+ water)
Maleic acid
Succinic acid
Dimethylmaleate
Dimethylsuccinate
α–methylstyrene
Cumene
trans–stilbene
Dibenzyl
Tetralin
Decalin
Indene
Indane
hydrogen from the reaction, but increasingly the use of hydrogen acceptors is finding favor.
© 2008 Johnson Matthey Plc
41
Hydrogen acceptors should be used in 0.5–2.0 molar
Very small additions (2–10 ppm with respect to the
quantities with respect to the liberated hydrogen. Where
feedstock) of organic sulfur compounds such as diphenyl
the products include water, care should be taken, because
sulfide can promote some dehydrogenation reactions.
the steam which is liberated can cause bumping of the
Such additions have to be very carefully optimized.
reactor contents in liquid phase reactions. A particular dehydrogenation of industrial importance is For the same reason it is desirable to use dry powder
the formation of iminostilbene from iminodibenzyl
catalysts for liquid phase reactions and dry pelleted catalysts for gas phase reactions. Pd/C
It is highly desirable to use a hydrogen acceptor if at all possible, thus permitting lower temperature operation than
nitrotoluene
N H
N H
would be possible without a hydrogen acceptor. The operating temperature should be as low as possible,
The product is an intermediate in the preparation of
consistent with acceptable product yields in order to
Carbamazepine – a treatment for epilepsy.
minimize:• metal crystallite sintering – see section 2.1.7
For the dehydrogenation of cyclohexanols and cyclohexanones, the favored hydrogen acceptors are
• product decomposition and/or by–product formation
olefins e.g. α−methylstyrene.
Typical high boiling point solvents used include biphenyl and polyglycol ethers. It is possible sometimes to use the OH
hydrogen acceptor as the solvent.
Pd/C
The ease of dehydrogenation is dependent on the substrate and operating conditions. However, the following general comments can be made:-
OH
R
α-methyl styrene R
• easier if at least one double bond is close to the dehydrogenation site A common problem with operating catalysts at high • easier if the end product is a fully aromatic compound
that coking may occur (see section 2.1.7). This has the
• 6 and 7-membered or larger ring systems are easier to dehydrogenate than 5-membered
temperatures in the vapor phase for extended periods is
rings1.
effect of masking individual metal crystallites. One way of reducing this effect on the Pd or Pt pelleted catalysts is to introduce a small quantity of hydrogen into the feedstock.
The catalysts of choice for liquid phase dehydrogenations are Pd > Pt > Rh Catalyst performance can be enhanced by the addition of inorganic bases such as Na2CO3, MgO (up to about 5% by weight with respect to the catalyst). Addition of base neutralizes any acidic sites on the catalyst, which if left untreated, could cause by–product formation.
1 M. Bartok Stereochemistry of Heterogeneous Metal Catalysis 1 Wiley Interscience (1985) 35–37 42
© 2008 Johnson Matthey Plc
Reaction
Temperature (°C)
Solvent
H2 Acceptor
Catalyst
Cyclohexanones/anols to Phenols
180–275
biphenyl
Olefinic (e.g. α−methylstyrene, tetralin)
Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5, A501023-10, Pd/c A501038-10, A101023-10, Pd/c A101038-10
Alkane to Alkene
180–250
Glycol, PEG
Nitrotoluene, nitrobenzene
Pd/C A503023-5, A503038-5, Pd/c A102023-5, A102038-5, Pd/c A570129-5, A501023-10, Pd/c A501038-10, A101023-10, Pd/c A101038-10
Alcohol to Carbonyl
>200
None (vapor phase)
None
Pt/C B103032-5, B103018-5, Pt/c B501032-5 Ni/Mo A-7000 Ni/Mo A-7200
4.3 HYDROFORMYLATION
The butyraldehyde is either reduced directly to n-butanol, or
Hydroformylation is the largest and oldest homogeneously
reduced to 2-ethylhexanol – a well known plasticizer alcohol.
catalyzed industrial process, in which the simultaneous
For terminal alkene hydroformylation, the Rh
addition of one mole of CO and H2 is made across a
homogeneous catalyst is used together with a large
carbon–carbon double bond to produce an aldehyde.
excess (50-100 x molar with respect to the catalyst) of a
aldolized and dehydrated to 2-ethylhexenal and then
tertiary phosphine such as triphenylphosphine. Many Industrially, the most important alkene feedstock is propene.
different Rh catalysts (or precursors) can be used. Typical Rh compounds include Rh-40 Rh(PPh3)2(CO)Cl, Rh-42
CH 3 +
CO +
CHO +
H2
straight chain
CHO
RhH(CO)(PPh3)3, Rh-43 Rh(acac)(CO)(PPh3) and Rh-50 Rh(acac)(CO)2.
branched chain
Provided the Rh compound selected can enter into the The original cobalt-catalyzed high pressure process was
catalytic cycle, the precise form of the precursor is of little
discovered in Germany over 60 years ago. The replacement
importance. The factors affecting the choice of a particular
of Co by Rh in the mid 1960’s provided a major
precursor usually involves such “practical” properties as:-
breakthrough in the history of homogeneous catalysts. The main advantages are:-
• absence of halogen (important for long term stability in steel reactors – but not in glass equipment)
• higher straight chain: branched chain product ratios (the straight chain product usually being the more
• ease of storage/handling in air
commercially desirable)
• minimal health hazards
• lower operating pressures, hence lower plant
• solubility in the reaction medium
capital costs • cost of conversion of the Rh metal to the • lower operating temperatures, hence less
particular complex
formation of oligomeric by-products • lower feedstock consumption per tonne of product, hence increased yield
The propene hydroformylation process operated by Hoechst (Ruhrchemie) is interesting in that the reaction medium is a two phase aqueous/organic system in which
These more than compensate for the higher cost of Rh.
the Rh catalyst is solubilized in the aqueous phase using a sodium sulfonate substituted triphenylphosphine as the
A consortium of three companies (Davy McKee/Johnson
ligand. Since the Rh is confined to the aqueous phase,
Matthey/Union Carbide) commercialized the Rh catalyzed
product/catalyst separation is straightforward with minimal
process, now known as the L.P. (Low Pressure) Oxo
loss of Rh into the organic phase.
Process and licensed it world-wide. Well over 1 million tonnes of n–butanol is now made annually from propene using the L.P. Oxo Process.
© 2008 Johnson Matthey Plc
43
RhH(CO)L3 L
C3H7CHO
CH2
CHCH3
RhH(CO)L2 H L2Rh H
H
O C
L2Rh CO
C3H7
CHCH3 CH2
CO
H2 O L2Rh
C
CH2CH2CH3 C3H7
L2Rh
CO
CO
L2Rh
CO C3H7
CO CO The catalytic cycle for the rhodium catalyzed hydroformylation of propene (L = triphenylphosphine)
There have been many studies of the mechanism of
The vast majority of (and certainly all of the industrially
hydroformylation. Suitable choice of operating conditions
important) processes use Rh as the catalytic metal of
and ligand can drive the reaction to form the straight chain
choice. The literature indicates that Pt has some activity as
aldehyde, or the branched chain product. Thus the tailor-
a hydroformylation catalyst, often used together with a
making of ligands to favor the formation of a particular
SnCl2 promoter.
product has become a practical proposition. For example, Union Carbide has developed a phosphite ligand to give very high straight chain to branched chain ratios. Other industrial processes incorporating a Rh catalyzed hydroformylation step include:• production of vitamin A The BASF process involves the hydroformylation of a terminal alkene, whereas the Hoffmann–La Roche process hydroformylates an internal alkene • production of 1,4-butanediol The Kuraray process (operated by Lyondell) involves the hydroformylation of allyl alcohol
44
© 2008 Johnson Matthey Plc
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Hydroformylation
50–150
10–50
Toluene or ethyl acetate
Rh–40, Rh–42, Rh–43, Rh–50, Rh–112 Rh 2–ethylhexanoate
4.4 CARBONYLATION
Methyl methacrylate can thus be obtained from the
The carbonylation of methanol to acetic acid is one of the
thereby avoiding the classical cyanohydrin route.
carbonylation of methyl acetylene in a methanol solvent,
largest industrial processes using homogeneous catalysis. By analogy, when water is used as the solvent, acids are formed (hydrocarboxylation). For example one step in a DuPont/DSM route to adipic acid involves the Rh/I CH3OH +
CO
CH3COOH
hydrocarboxylation of butadiene with an Ir catalyst.
Ir
+ CO
+
H2O
COOH
HOOC
The original process, developed by Monsanto and subsequently purchased by BP, used an iodide-promoted Rh catalyst. More recent work by BP Chemicals has
Under different conditions, Shell and others have shown
shown that an iodide-promoted Ir homogeneous catalyst
that polyketones can be formed from the carbonylation of
(Cativa™ process) can be used with
advantage.1
Over 60%
alkenes in the presence of cationic Pd complexes derived
of the world’s acetic acid is now made by methanol
from palladium acetate or PdCl2.2 Chelating diphosphines,
carbonylation.
such as diphenylphosphinopropane or 1,1’-bis(diphenylphosphino)ferrocene have been shown to be very effective
Pd is the catalytic metal of choice for the carbonylation of
ligands for this type of reaction.
alkynes and alkenes. In alcohol solvents esters are formed. O CH2
CH
CR
+ CO
+ R’OH
CH2
C
COOR’
CH2
+
CO n
O
O
n
R CH2
CHR +
CO
+ R’OH
RCH2CH2COOR’
These polymers find use as engineering thermoplastics.
1 J.H. Jones Platinum Metals Rev. (2000) 44(3) 94 2 E. Drent and P.H.M. Budzelaar Chem. Rev. (1996) 96 663
© 2008 Johnson Matthey Plc
45
Pd is also the catalyst of choice for the base-catalyzed hydrocarboxylation of aryl or benzyl halides. Base acts as a scavenger for the liberated HX.
ArX
+
CO
+
H2O
+
ArCOOH
HX
(X = halide) ®
Anchored homogeneous catalysts (FibreCat ) are under development for carbonylation reactions (see section 2.3).
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Alkene, alkyne or secondary alcohol carbonylation
50–150
10–50
Toluene or alcohol
Pd–62, Pd–100, Pd–103, Pd–111, PdCl2
Primary alcohol carbonylation
25–200
1–50
None
Rh–110, Rh–112, RhCl3.xH2O, RhI3
4.5 DECARBONYLATION
The decarbonylation reaction can be used to advantage in
Both Pd and Rh catalysts have been used to decarbonylate
one–step synthesis of arabinitol from glucose.
classical carbohydrate chemistry, exemplified by the
aldehydes (to produce alkanes) and acyl chlorides (to produce chloroalkanes or chloroarenes).
CHO H HO
RCOX
RX
+
CO
(X = H, Cl)
H H
CH2OH
OH H
HO
OH
H
OH
H
H
Glucose
CO
OH CH2OH
CH2OH
There are also reports of the effective decarbonylation of
+
OH
Arabinitol
carboxylic anhydrides, ketones and ketenes. Dihydrocinnamaldehyde can be decarbonylated with Rh
Yields of 90% can be achieved with Rh-100 in
(Rh–40 [RhCl(CO)(PPh3)2] or Rh–100 [RhCl(PPh3)3]) to form
N–methylpyrrolidone at 130°C in 30 minutes.2
ethylbenzene1
in 96% yield.
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Decarbonylation of aldehydes, acyl chlorides, carboxylic acid anhydrides, ketones and ketenes
110–145
1
N–methylpyrrolidone, toluene, benzonitrile or xylene
Rh–100, Rh–40, Rh–93 + chelating diphosphine
1 J.M. O’Connor and J. Ma J. Org. Chem. (1992) 57 5075 2 M.A. Andrews and S.A. Klaeren Chem. Comm. (1988) 1266 46
© 2008 Johnson Matthey Plc
4.6 HYDROSILYLATION
Rh catalysts can selectively hydrosilylate alkynes to the
Hydrosilylation (often referred to as hydrosilation) is the
solvent used.2
alkene, but the regiochemistry is very dependent on the
addition of an H–Si bond across a carbon-carbon double bond. RC
CH
+
Et3SiH
Rh-100
SiEt3
R H
CH2
CHR’
+
R3SiH
R3Si
R
H
H
SiEt3
+ H cis
CH2CH2R’
trans
The reaction finds practical application in the “curing” or hardening of silicone polymers effected by the cross
Solvent
% cis
% trans
others
Benzene
86
12
2
Acetonitrile
3
95
2
coupling of different silicone fragments.
O
R
R’
+
Si O
H
CH2
O Si CH O
O
R Si
O
CH2
R’
O Si CH2 O
Platinum compounds are extremely active catalysts for
Rh catalysts can also catalyze some hydrosilylation
this reaction.1 The catalyst can be used at such low levels
reactions that cannot be catalyzed by Pt complexes3. Rh
that it is not necessary to separate it from the silicone
catalysts have also been used to prepare chiral silanes.4
product. Originally, chloroplatinic acid (Speier’s catalyst) was used as the most readily available and cheapest hydrosilylation catalyst. However there are two problems:• chloroplatinic acid is a potent sensitizer and hazardous to health, so great care must be taken during its handling • chloroplatinic acid contains platinum in oxidation state IV which must be reduced to Pt(0) before it becomes catalytically active. This results in a variable induction period. A more reliable/reproducible catalyst is Karstedt’s catalyst which is made from chloroplatinic acid by the addition of an appropriate siloxane and reducing agent. The Pt is in the Pt(0) oxidation state when used. Johnson Matthey supplies a variety of custom Karstedt’s catalyst. In some cases, specific Pt(II) precursors are used rather than Karstedt’s catalyst. Compounds which have been used in this way include Pt-92 [PtCl2(cyclohexene)]2, Pt-96 [PtCl2(COD)] and Pt-112 [PtCl2(SEt2)2]. Although homogeneous catalysts are commonly used, heterogeneous Pt/C catalysts are effective in some cases.
1 L.N. Lewis et al. Platinum Metals Rev. (1997) 41 6 2 R. Takenchi and N. Tanonchi J. Chem. Soc. Perkin Trans. (1994) 2909 3 A.G. Bessmertnykh et al. J. Org. Chem. (1997) 62 6069 4 K. Tamao et al. J. Am. Chem. Soc. (1996) 118 12469
© 2008 Johnson Matthey Plc
47
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Hydrosilylation of alkenes
25–75
1
None or hydrocarbons
Chloroplatinic acid, Pt–92, Pt–96, Pt–112, Pt–114, Pt/AI2O3 B301013-5, B301099-5
Hydrosilylation of alkyne to cis-alkene
25
1
Ethanol or propan-2-ol
Rh–93, Rh–100
Hydrosilylation of alkyne to trans-alkene
25
1
Acetonitrile
Rh–93 + PPh3 or Rh–100
4.7 CROSS-COUPLING REACTIONS
The ease of C-X bond cleavage is in the order I > Br > Cl.
Cross-coupling reactions are among the most important
The relative reactivities of Ar-X can be correlated to their
chemical processes in the fine chemical and
respective bond dissociation energy:
pharmaceutical industries. These reactions represent the key steps in building complex molecules from simple
Ph-Cl: 96 kcal/mol
precursors. Recently, there has been a burgeoning of
Ph-Br: 81 kcal/mol
interests in this area, mainly due to interest in coupling
Ph-I:
65 kcal/mol
challenging substrates, such as electron rich aryl chlorides, triflates, nitriles, etc. Steric effect as well as the presence
In some cases, the iodide system is active enough for
of sulfur on the substrate can play an adverse role in
coupling to occur in the absence of a ligand. Typically, a
coupling reactions. One of the key mechanistic steps in
Ph3P-based Pd complex is suited for Ar-Br coupling, while
coupling reactions is the oxidative addition of the aryl
Ar-Cl coupling is practically impossible, although there has
halide, Ar-X to Pd(0) (see below).
been some success with activated aryl chlorides. Electron withdrawing substituents on the Ar ring activates the Ar-X
reductive elimination Ar-R
LnPd
oxidative addition
0
bond, while electron donating groups have a deactivation
ArX
effect on the Ar-X bond. During the late 1990’s several academic groups (eg: Koie,
Ar
LnPd
LnPd
Fu, Buchwald, Hartwig, Beller, etc.) found that electron-
X
R M B Sn Si Zn Mg
Ar
rich phosphines (aliphatic) in the presence of a Pd precursor favor the Ar-Cl addition to Pd(0). The bulkiness of the ligand (cone angle measures bulkiness) is also
transmetallation MX
important, as it facilitates the reductive elimination step. In this regard, t-Bu3P acts as an excellent electron rich, bulky
MR
General Mechanism of Coupling
oxidative addition
LnPd 0
base-HX
ArX base LnPd
H LnPd
X β- hydrogen elimination R
Ar X
R
Ar R
LnPd
H X
Ar Mechanism of Heck Coupling
Mehanism of Heck Coupling
48
© 2008 Johnson Matthey Plc
P(t-Bu)2
monodentate ligand. However, t-Bu3P is a pyrophoric waxy solid and therefore difficult to handle in a conventional production environment.
Fe
Ph
Our research indicates that bidentate ligands are equally
Ph
effective in coupling chemistry. It is well documented that the large bite angle of a bidentate ligand enhances the
Ph
reductive elimination step. From a handling perspective, a
Ph
fully formed, relatively air-stable yet active catalyst is a
Ph
preferred choice.
Q-Phos Johnson Matthey offers advanced technology for coupling reactions. Several examples of these electron rich bulky
These catalysts have been successfully scaled up and tested in commercial processes.
monodentate and bidentate phosphine based “third generation” catalysts are given below.
4.7.1 Heck Reaction A Japanese scientist, Mizoroki (1971) and an American scientist, Heck (1972) developed independently a protocol to couple an aryl or alkenyl halide with an olefin in the
P
Pd
P
presence of a Pd based catalyst. These reactions can occur both inter- and intra-molecularly.
The application of
this chemistry includes the synthesis of hydrocarbons,
Pd(t-Bu 3 P)2
conducting polymers, light emitting electrodes, dyes and enantioselective synthesis of natural products. An
Pd-116
example of classical Heck reaction is demonstrated for the synthesis of anti-inflammatory agent- LTD4 antagonists1,2.
Br Pd
P
O
P
Pd
CO2 Me
Br + Cl
3 mol% Pd(OAc) 2 9 mol% P(o -Tol) 3 Et 3 N / DMF / 100°C / 1.5 hr (91%)
N
Br [Pd(μ-Br)t-Bu3P]2
Cl
Pd-113
N
O
>95% trans -isomer
Me Cl
Cl
P
P
Cl
P
Pd
Fe
Pd Cl
CO 2Me
CO 2 Me
L-699,392 (Merck-Frosst)
These reactions are promoted by a base, which neutralizes Cl
P
N
CO 2 H
the liberated acid. Pd(0), stabilized with an aromatic phosphine ligand, is the active catalytic species (LnPd) and the favored reaction media are dipolar aprotic solvents such as acetonitrile, DMF, DMSO and DMA.
di-t-bpfPdCl2
Pd-118
FibreCat 1032
Recently Heck coupling has been applied to challenging substrates with the aid of the next generation catalysts. An example of such reaction for the synthesis of an API intermediate (actual substrate is disguised) is demonstrated below, where Pd(0) catalyst, Pd(t-Bu3P)2 is the best catalyst of choice. 1 V. Snieckus, Cross Coupling Strategies and methods in Aromatic and Heteroaromatic Synthesis (Scientific Update Course), New Orleans, November 12-14, 2002 2 A.O. King et.al. (Merck), J. Org. Chem., 1993, 58, 3731-3735
© 2008 Johnson Matthey Plc
49
R'' Cl
For challenging aryl chloride conversions several of Johnson Matthey’s third generation catalysts, including
R
R
Pd-cat +
R''
Pd-116, Pd-118 and Pd 119, provide significant advantages.
DMF/ 120 oC/Et3N
R
R
The di-tert-butylphosphinoferrocene palladium dichloride (Pd-118) is an air stable, yet highly active catalyst, which
Pd-catalyst
Conversion
Selectivity
Pd(Ph3P)2Cl2
0
-
Pd(OAc)2/TPP
0
-
has been proven to be effective in Suzuki coupling. The following table illustrates the generality of the catalyst in Suzuki coupling towards a wide variety of substrates.3
Pd(t-Bu3P)2
100
95
Pd2dba3/(o-tolyl)3P
95
2.5
Pd(PPh3)4
0
-
Pd(PCy3)2Cl2
0
-
Pd2dba3/t-Bu3P
100
82
ArX
Pd(0) (t-Bu3P)2 can be also used for indole and azaindole syntheses by direct annulation.1 In the following example, enamine formation followed by intra molecular Heck coupling of an aryl chloride is speculated, rather than alpha ketone arylation followed by enamine.
R1
R4
R4
Cl
Pd(t-Bu 3P)2 , K 3PO4
+ O
NH
HOAc, MgSO4, DMA
R3
R1
R3
N
R2
+
Pd-118/ 120oC
PhB(OH)2
Ar-Ph
K2CO3/DMF
Entry Substrate
Catalyst loading
yield (%)
1 2
4-chlorotoluene 4-bromoanisole
0.01 equiv 0.01 equiv
98 100
3 4
4-chloroanisole 4-bromo-3-methylanisole
0.01 equiv 0.01 equiv
100 96
5 6 7
2-chlorothiophene 2-bromo-4-fluoroanisole 2-chloro-4-fluoroanisole
0.01 equiv 0.01 equiv 0.01 equiv
84 95 95
8
2-chloro-3-methylpyridine
0.01 equiv
89
9
2-chloro-4, 6-dimethoxytriazine Bromomesitylene
0.01 equiv
100
0.01equiv
85
R2
10
4.7.2 Suzuki-Miyaura Coupling For moderately challenging substrates, such as Currently, Suzuki coupling is the most widely utilized Pd
bromothiophenes, chloropyridines, etc., the polymer
catalyzed coupling reaction in the Pharmaceutical and Fine
supported Pd catalyst, FibreCat 1032 has shown good
Chemical industries. The coupling reaction involves the
results. Following our preliminary report4, additional
reaction of a substituted aryl boronic acid (nucleophile)
research from Abbott Laboratories 5, indicates that these
with a substituted aryl halide, diazonium salt or triflate
are practical catalysts for conventional and microwave
(electrophile) to produce biaryls. In general, Suzuki
assisted Suzuki coupling. An example of the microwave
coupling reactions require milder conditions than the Heck
assisted Suzuki coupling reaction is given below.
reactions and are favored due to the non toxicity of the boron reagents. B(OH)2
Commercial examples include antihypertensive drug Valsartan (Novartis) and the fungicide Boscalid
3 % FibreCat 1032
+
K 2 CO3, EtOH, MW
(BASF)2.
N
Cl
N
Me Me
O N N
Yield: 89% (100%)
Cl
COOH O NH
N N
NH N
Valsartan (Novartis)
Cl Boscalid (BASF)
1 Nazare, et.al., Angew. Chem. Int. Ed., 2004, 43, 4526-4528. 2 Rouhi, Chemical and Engineering News, 2004, 82, 49-58 3 Colacot & Shea, Org. Lett., 2004, 21, 3731. 50
4 Colacot et. al., Organometallics, 2002, 21, 3301. 5 Sauer et.al., Org. Lett., 2004, 6, 2793.
© 2008 Johnson Matthey Plc
4.7.3 Alpha-ketone Arylation Alpha-ketone arylation is a relatively new type of carboncarbon coupling reaction, where an aryl halide is added to the alpha position of a carbonyl group by activating the
Simple Pd(0) compounds such as Pd-101 Pd(PPh3)4 or
CH. Early studies indicate that catalyst choice is critical in
catalysts made from precursors such as Pd-111
accomplishing this type of coupling. Initial results show
[Pd(OAc)2]3, Pd-110 [Pd(allyl)Cl]2 and Pd-94 Pd2(dba)3 with
that Pd-118 is a very good catalyst for such
suitable phosphine ligands can also be used, depending on the substrate.
transformations. An example is given below. X
X +
Ar-X
4.7.5 Organometallic Reactions
di-tbpfPdCl 2 alcoxide base Toluene
Ar O
O
Yield 70-95%
4.7.4 Carbon-heteroatom Coupling – e.g. Buchwald-Hartwig Amination Carbon–heteroatom coupling can be effected by a Pd-
In some reactions, a prerequisite is the production of an organometallic intermediate containing metals such as magnesium, tin, zinc or lithium. These organometallic compounds can react with an aryl halide with the elimination of the metal halide and the subsequent formation of a coupled product. The best known general example of this type of reaction is probably the Grignard reaction.
catalyzed reaction. This can include forming C-N, C-O, C-S ArX + Ar1MgX
and C-P bonds. The C-N bond forming process (amination)
Ar
Ar1
+ MgX2
is often referred to as the Buchwald–Hartwig, although initial work was carried out by Koie and co workers in
In some cases these reactions proceed satisfactorily.
Japan.
However, in other cases, the presence of a homogeneous
A general scheme of amination and ether formation is shown below. As there is an acid by-product, a base is
palladium catalyst may dramatically improve the yield of the coupled product.
used, often a strong organic base such as NaOtBu to drive
The relative positions of the substituents on the aromatic
the reaction.
rings determine the point at which coupling occurs, i.e. Br MgBr
Pd
+ MgBr2
+ R
R
Heterocyclic ring coupling is also possible, e.g. A wide variety of homogeneous Pd(0) catalysts can be used for the above reactions.
CH3
CH3
Br ZnCl
Pd
+ ZnClBr
+
The new range of highly active Pd-catalysts are very
S
S
suitable for this difficult coupling reaction. Pd-113 and Pd-
The organometallic reagent may in some cases be
116 have been shown to catalyze a wide range of
completely aliphatic, but coupling can still occur, e.g.
substrates including aryl chlorides and triflates. Air stable catalysts such as Pd-118 (Pd(dtbpf)Cl2) and Pd-107 (Pd(dppf)Cl2) show good activity for aryl chlorides and
CH2Br
Pd
CH2CH
CH2
+ Bu3SnBr
+ CH2 CHSnBu3
bromides, respectively.
Bu = butyl
The following example show the fast rates achieved with
Palladium-catalyzed reactions of this type, involving the
Pd-113 (strong base)6 and the stable turnover available
use of tin-based reagents, are often referred to as Stille
with Pd-116 (cheaper base)7.
coupling reactions. Similar reactions involving zinc-based reagents are referred to as Negishi couplings.
6 J. Hartwig et al, Angew. Chem. Int. Ed., 2002, 41, 4746 7 J. Hartwig et al, J. Org. Chem., 2002, 67, 6479
© 2008 Johnson Matthey Plc
51
4.7.6 Sonogashira Reaction
The generic structure of such species is
X = halide, acetate L = P or N
Palladium catalysts can also be employed in the coupling of terminal alkynes with aryl or alkyl halides. The reaction,
C
known as the Sonogashira reaction, generally involves the
L
X Pd
use of a palladium catalyst in conjunction with copper iodide, the copper reacting with the alkyne to form an
Pd X
L
C
alkynylcuprate. Mild conditions are usually used for this reaction, often
Many of these complexes show not only increased activity
room temperature, allowing a large number of functional
over the more traditional catalysts, but also exhibit very
groups to be tolerated.
good thermal and air stability. In the case of the phosphite catalysts developed by Bedford1 (see below) these reactions can be performed in air without the drying of
R
Pd/CuI X +
R
R’
R’
base
solvents or reagents – a major advance over the more conventional catalysts.
about the double bond is usually preserved, making this
Their main advantage is activity – catalyst loadings as low as 10-4 mol % have been successfully used in reactions of
an extremely useful reaction for the synthesis of ene-yne
aryl bromides.
If the reaction is performed on an alkene, the geometry
molecules with specific geometry.
The Bedford bridging chloro palladacycle containing the tris (2,4-di-t-butyl phenyl) phosphite ligand – Pd 109.
R' X
Pd/CuI
+
t-Bu
R' base
R
R
ArO O
4.7.7 Palladacycles
OAr P
Cl
t-Bu
Cl
The use and versatility of coupling reactions has increased
t-Bu
Pd
Pd
O
P ArO
OAr
recently with the advent of new Pd catalysts known as palladacycles.
t-Bu
Reaction
Temperature (°C)
Solvent
Catalyst
Heck
25–100
Various (e.g. toluene, THF)
Pd–62, Pd–100, Pd–101, Pd–106, Pd–108, Pd–109, Pd–111, Pd-116, Pd-119 FibreCat®–1001, 1002 Pd/C A109047-5, A405028-5, A503023-5, A102023-5, A470085-5
Suzuki
25–100
Various
Pd–101, Pd–109, Pd–111, Pd-113 Pd-118 FibreCat®–1001, 1002, 1032
Buchwald–Hartwig
80–100
THF or toluene
Pd–106, Pd–107, Pd–113 Pd–111, Pd–116, Pd–118 FibreCat®–1001, 1002
Organometallic reactions
25–100
THF, dioxane, toluene or DMF
Pd-62, Pd-100, Pd–101, Pd-103, Pd-106
Sonogashira reaction
25–120
THF or DMF
Pd-100, Pd-101 FibreCat® 1032
1 D.A. Aldisson, R.B. Bedford, S.E. Lawrence and P.N. Scully 2 Chem. Comm. (1998) 2095 52
© 2008 Johnson Matthey Plc
One of the best known applications is in the synthesis of
4.8 CYCLOPROPANATION AND
chiral methylphenidate. The racemic form of
CARBENE REACTIONS
methylphenidate is sold as Ritalin™, widely prescribed for
The generation of carbenes from the decomposition of
the treatment of hyperactive children. However, the
diazo compounds can be catalyzed by metal complexes.
d-threo isomer is 13 times more active than its mirror
The carbene binds to the metal and can subsequently be
image.2
transferred to an alkene (cyclopropanation), to an alkyne
Dirhodium(II) tetrakis[methyl-2-pyrrolidone 5(S) carboxylate] Rh2(5S-MEPY)4
(cyclopropenation) or even inserted into a C–H bond depending on the choice of catalyst, substrate and conditions. RCH
CHR + CR1R2N2
RCH
CHR
+
N2
C
CH3OOC
N
R2
R1
N Rh
Rh RC
CR
1 2
+ CR R N2
RC
CR
+
N2
C R1
N
O
CH3OOC
COOCH 3
O
O
N
O
COOCH3
R2
The original catalysts were based on Cu complexes, but more recent work has involved the use of Rh catalysts. For non-stereoselective cyclopropanations or
The process involves a highly selective intermolecular
cyclopropenations, the catalysts of choice are based on
asymmetric insertion at the α position of N–Boc piperidine with methyl phenyldiazoacetate followed by removal of the
dimeric Rh(II) carboxylates e.g. Rh-110 [Rh(OAc)2]2
Boc protecting group. Pd catalysts such as Pd-111 [Pd(OAc)2]3 have been used, but their application seems to be restricted to reactions
O
involving terminal olefins and α,β unsaturated carbonyls.
OCH3 N2
O
NBoc
It is in the area of enantioselectivity that the Rh(II)
OCH3
Rh2(5S-MEPY)4
carboxamidate1 complexes really demonstrate their
Cyclohexane/ 500C/ 4h
NBoc
effectiveness. These catalysts are characterized by four bridging amide
69%
HCl
ligands bound to the di–rhodium core, with two oxygens and two nitrogens bonded to each Rh atom, and each pair
O
of nitrogen atoms adjacent to one another.
OCH3 NH.HCl
d-threo-methylphenidate
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Carbene insertion into terminal alkene or α,β unsaturated carbonyl
0-10
1
Ether or dichloromethane
Pd–70, Pd–111
Cyclopropanation, cyclopropenation, carbene insertions
0–50
1
Cyclohexane, pentane or dichloromethane
Rh–110, Rh–115
1 M.P. Doyle and D.C. Forbes Chem. Rev. (1998) 98 911-935 2 T. Colacot Proc. Indian Acad. Sci. (Chem. Sci.) (2000) 112 197
© 2008 Johnson Matthey Plc
53
4.9 ISOMERIZATION
Olefin isomerization processes can also be catalyzed by Pd
Isomerization of olefins can be carried out effectively using
application because of their stability to air and moisture.
homogeneous catalysts. Wilkinson’s catalyst (Rh-100
Here the trans-isomer is favored kinetically as well as
RhCl(PPh3)3) has been used in the synthesis of several
thermodynamically.
or Ru. The Pd(II) catalysts are well suited for industrial
natural products and can be used in the isomerization of
Pd
allyl alcohols to enols.
OH
1-pentene
Rh CH3
trans-2-pentene
OH Heterogeneous catalysts are also effective for olefin isomerization, with Pd/C being the best when used under acidic conditions at elevated temperatures. Rearrangements can also be performed with Pd catalysts. Optically active cyanohydrin can be stereoselectively isomerized to the α,β–unsaturated nitrile1 in 89% ee using Pd-62 PdCl2(CH3CN)2. OAc
OAc PdCl2(CH3CN)2 C5H11
Reaction Allylic rearrangements
Temperature
Pressure
(°C)
(bar)
25–90
1
* CN
83% yield
C5H11
*
Solvent
Catalyst
THF, xylene, benzene or no solvent
Pd–111 + PPh3, Pd–101, Pd–62 Pd/C A109047-5, A503023-5, Pd/c A503038-5, A570147-5, Pd/c A570129-5 Rh–100, RhCl3.xH2O
CN
1 H. Abe, H. Nitta, A. Mori and S. Inoue Chem. Lett. (1992) 2443 54
© 2008 Johnson Matthey Plc
4.10 OLIGOMERIZATION AND POLYMERIZATION Rh, Pd and Ru are the main metals used in PGM-catalyzed polymerization reactions. Low molecular weight oligomers These catalysts were first developed by Grubbs2 in
can be produced and are dependent on the type of
1993. Tricyclohexylphosphine is the preferred ligand as
catalyst used.
bulky groups make the catalyst more active. These catalysts are active without rigorous exclusion of water CH2
C CH2 allene
or oxygen, and are more tolerant of functional groups than Zeigler–Natta catalysts. Rh
Rh PPh3 CH2
CH2
CH2
ROMP reactions with norbornene derivatives can be catalyzed by vinylidine Ru complexes.3 These carbene
CH2
complexes can be prepared from Ru-100 RuCl2(PPh3)3 by reaction with terminal alkynes followed by phosphine
CH2 CH2
CH2
CH2
ligand exchange.
Polyketones can be made by the Pd-catalyzed
Cl
copolymerization of carbon monoxide and an olefin
Cl
(ethylene or propylene). The Pd(II) catalyst is made from
PCy3 Ru
palladium acetate or palladium chloride and a diphosphine ligand.1
C
PCy3
Bu H
Similar Ru(II) carbene catalysts can be prepared from
Polymerization of simple alkenes such as polyethylene is normally carried out using Ziegler–Natta catalysts (W, Ti, Ni). However, recent advances in Ru carbene chemistry
Ru–120 [RuCI2(p–cymene)]2 without using phosphine ligands. These catalysts enable high stereoregularity in the polymerization of substituted norbornadienes.
have lead to new interest in PGM-catalyzed polymerization. Ring Opening Metathesis Polymerization (ROMP) can be efficiently catalyzed by Ru carbene complexes of the type shown.
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Polymerization
25–100
1–10
Alcohols, toluene, biphasic systems (water/hexanol), or no solvent
Ru–100, RuCl3.xH2O + ligand, Ru–120 + ligand, Pd–101, Pd–111 + PPh3, RhCl3.xH2O, Rh–100
Copolymerization
25–150
1–150
CH2Cl2 or methanol
Pd–62, Pd–101, Pd–111 or PdCl2 + ligand
Telomerization
25–80
1
Acetonitrile or methanol
Pd–101, Pd–111 + PPh3 + nucleophile
1 K. Nozaki, N. Sato and H. Takaya J. Am. Chem. Soc. (1995) 117 9911 2 S.T. Nguyen, R.H. Grubbs and J.W. Ziller J. Am. Chem. Soc. (1993) 115 9858 3 H. Kitayama and F. Ozaura Chem. Lett. (1998) 67
© 2008 Johnson Matthey Plc
55
4.11
In contrast to hydrogenation systems, sulfur-containing
SELECTIVE OXIDATION
moieties do not appear to poison PGM catalysts under
Supported PGMs are very good oxidation catalysts and
oxidation conditions.
this property is used to effect the total oxidation of For example, 2-thienylmethanol can be readily oxidized to
pollutants to CO2 , H2O and N2 in industrial fume abatement and automotive anti–pollution applications.
the corresponding aldehyde in >90% yield with a Pt/C catalyst in toluene. Furthermore, the catalyst can be reused quite effectively.
Pt catalysts are used for the oxidation of the fuel (hydrogen, lower aliphatic alcohols and some other fuels)
1/
in fuel cells and other electrochemical devices. S
2
O2
+ H 2O
CH 2OH
CHO
S
In order to effect selective oxidations, it is necessary to operate under relatively mild conditions to minimize CO2 formation; typically 20–60°C and up to 5 bar air pressure. If flammable solvents are required then low O2 concentrations (typically 3%O2 or 5%O2 in N2) can be used as a safe replacement for air. The longer reaction times can be compensated for by increasing the pressure within the reactor. Johnson Matthey has also shown that H2O2 (typically 30%) is an effective oxidant. The PGM catalysts will rapidly decompose H2O2, therefore efficient use requires a continuous feed over the course of
4.11.1(b) Secondary Alcohol to Ketone For aliphatic alcohols, Pt-Bi catalysts exhibit the highest activity. The Pt-Bi catalysts can be run under neutral or basic conditions. For example, 2-octanol can be readily oxidized to the corresponding ketone in >90% yield with Pt-Bi/C in water with 0.5 molar equivalent of NaOH added. The catalyst can be used for at least three reaction cycles with negligible loss in activity.
reaction. When using H2O2 as oxidant it must be noted
OH
O
that water by-product is also being introduced, the presence of which can enhance the selectivity to the
1/
carboxylic acid.
2
O2
+ H 2O
For aromatic alcohols the mixed metal catalyst Pd-Pt-Bi/C has shown the highest activity followed by Pd/C and Ru/C.
4.11.1(a) Primary Alcohol to Aldehyde
These catalysts require the presence of base (as with primary aromatic alcohol oxidation).
The selective oxidation of primary alcohols to the aldehyde functionality can be performed in the liquid phase. For
The selective oxidation of secondary alcohols can be
aliphatic alcohols the Bi-promoted Pt catalysts have shown
conducted in the presence of water, such that H2O2 is a
the highest activity. Ru/C is more aldehyde-selective but
suitable oxidant in these reactions.
higher catalyst loadings are required to attain desirable conversions.
4.11.1(c) Primary Alcohol or Aldehyde to Carboxylic Acid
Selectivity to the aldehyde is enhanced by the use of organic solvents which are immiscible with water, e.g. toluene, xylene, dichloroethane etc. For example, geraniol
The selective oxidation of primary alcohols and aldehydes
can be converted to citral in toluene or xylene solvent at
to the carboxylic acid functionality can be achieved using
60ºC and 3 bar air using Pt-Bi/C, Pt/C or Ru/C catalysts.
Bi-promoted Pt catalysts and trimetallic Pd-Pt-Bi/C. Under neutral conditions Pt-Bi/C can give high carboxylic acid yields, whereas Pt-Pd-Bi/C catalyst requires basic
OH + 1/ 2 O 2
O
conditions to attain high activity (which can also lead to + H 2O
the formation of condensation by-products). Water is a good solvent for this reaction due its promotional effect on
For aromatic alcohols the Pd-Pt-Bi/C, Pd/C and Ru/C
the oxidation of aldehyde to carboxylic acid.
catalysts all display high activity under basic conditions. These conditions can be achieved by running the reaction in the presence of base such as an aqueous solution of NaOH or NaHCO3. 56
© 2008 Johnson Matthey Plc
Pd-Pt-Bi/C has been used in aqueous solutions at 40–60ºC
• careful control of the oxygen availability (often achieved
for the air oxidation of sugars to the corresponding mono-
by operating the reaction with partial oxygen pressures
acid, e.g. glucose ➝ gluconic acid. The reaction is favoured
as low as 10 mbar)
by alkaline conditions, typically pH 8–10. • pH optimization Premature poisoning of the Pt catalyst can occur by complete coverage of the surface by oxygen to form a Pt
• periodic regeneration of the catalyst by a washing/reduction treatment
oxide species. This effect can be minimized by: Reaction
Temperature (ºC)
Pressure (bar)
Solvent
Catalyst
Primary Alcohol to Aldehyde
30-60
1-3
Toluene, xylene, acetonitrile
Pt/C B103032-5, B103018-5 B501032-5, B101002-5, B112002-5, B170201-5 Ru/C D101023-5, D101038-5 D170201-5, D103002-5 Pd/C A503023-5, A102023-5 A570129-5, A102038-5 Pt, Bi/C B503032-5, B111022-5 FibreCat® 3002
Secondary Alcohol to Ketone
30-80
1-3
Water, water + base, toluene, stylene acetonitrile
Pt/C B103032-5, B103018-5 B501032-5, B101002-5, B112002-5, B170201-5 Ru/C D101023-5, D101038-5 D170201-5, D103002-5 Pd/C A503023-5, A102023-5 A570129-5, A102038-5 Pt, Bi/C B503032-5, B111022-5 FibreCat® 3002
Alcohol or Aldehyde to Acid
30-60
1-2
Water, water + base
Pt/C B103032-5, B103018-5 B501032-5, B101002-5 B112002-5, B170201-5 Pd/C A503023-5, A102023-5 A570129-5, A102038-5
Glucose to Gluconic Acid
40-50
1
Water + base
Pt/C B103032-5, B103018-5 B501032-5, B101002-5 B112002-5, B170201-5 Pd/C A503023-5, A102023-5 A570129-5, A102038-5 Pt, Bi/C B503032-5, B111022-5
4.11.2 Dihydroxylation of Alkenes
Osmium tetroxide is extremely hazardous and great care must be exercised when using this reagent.
The cis-dihydroxylation of alkenes has been traditionally catalyzed by osmium tetroxide in combination with a
There are two user-friendly alternatives to using the
variety of co-oxidants including hydrogen peroxide, sodium
tetroxide. The first consists of osmium tetroxide anchored
hypochlorite, air (oxygen), N-methylmorpholine-N-oxide and
onto a polymeric support (FibreCat 3003). Supporting the
t-butylhydroperoxide.
osmium in this manner renders it non-volatile and nonhazardous.
RCH
CHR'
+ 1/2O2 + H2O
Os
R
H
H
C
C
R'
OH OH
© 2008 Johnson Matthey Plc
57
Reaction
Temperature (°C)
Pressure (bar)
Solvent
Catalyst
Dihydroxylation
0–50 0-60
ca 1 ca 1
t–Butanol, water or THF t–Butanol/Water
OsO4 or K2[OsO2(OH)4] FibreCat™ 3003
This material is best used in conjunction with Nmethylmorpholine-N-oxide and at temperatures of 60°C or
CH2
+ CH3CHO + Pd(0) + 2H
CH2 + Pd(II) + H2O
less which ensures that minimal levels ( 98% ee
OH
R1
t-BuO2H
+
R1
OH
often > 95% ee
Cat* = diethyl tartrate + Ti(Oi-Pr)4
O
R3 O
R2
Cat*
(-)-Menthol
HO
HO
R3
CO2H NCH3 H
OH
H3CO Naproxen
Citronellol
Morphine
The osmium-catalyzed asymmetric dihydroxylation was subsequently discovered in 1987.7 Mechanistic investigations and ligand engineering allowed the
The asymmetric hydrogenation of simple, unfunctionalized ketones remained an unresolved problem until 1995. There Noyori et al. found a general solution based on the use of
application of this second Sharpless reaction to any given class of alkenes, making it a very useful technology in organic synthesis.
a [RuCl2(bisphosphine)(diamine)] complex in the presence
HO
of an alkaline base.5 The newly devised
O
and selective in the hydrogenation of a range of aromatic,
OH
OH
bisphosphine/diamine complex proved to be very active
OH AD-β
AE (+)-DET
heteroaromatic and olefinic ketones in 2-propanol containing t-BuOK or KOH.
OH Geraniol
This method has been applied to the asymmetric
AE (-)-DET
AD-α
synthesis of several drugs, including (R)-denopamine, the HO
O
antidepresant (R)-fluoxetine and the antipsychotic (S)-
OH
OH
duloxetine. OH
AE - asymmetric epoxydation AD - osmium-catalyzed asymmetric dihydroxylation
CF3
H.HCl N
OH
O HO denopamine hydrochloride
During the 1990s, Jacobsen and Katsuki independently
NHCH3.HCl
OCH3 OCH3
developed chiral manganese-salen ligands for the catalytic fluoxetine hydrochloride
precursor of α-damascone
OCH3
OH
OH
O S
NHCH3
OH
epoxidation of alkenes in combination with cheap oxygen sources (i.e. NaClO), enantioselectivities often reaching 98% ee.
precursor of α-tocopherol OCH3
duloxetine
precursor of anthracyclins
During the last decade many new enantioselective reactions have been discovered (aminohydroxylation, aziridination, hydroformylation). Catalysis by palladium
Following the first discoveries in asymmetric
complexes has been actively developed, particularly in the
hydrogenation, the search for new families of chiral
areas of enantioselective allylic substitution and
phosphorous ligands with improved stereo-electronic
asymmetric Heck reaction.
characteristics has become an on-going effort both in academia and industry. Dr. Knowles and Prof. Noyori were awarded the Nobel Prize in Chemistry in 2001 for their outstanding contributions in this subject.
5 6 6 7 7 64
Noyori, R.; Ohkuma, T., Angew. Chemie. Int. Ed., 2001, 40, 1 Katsuki, T.; Sharpless, K. B. J. Am. Chem. Soc. 1980, 102, 5974. Hanson, R. M.; Sharpless, K. B. J. Org. Chem. 1986, 51, 1922. Crispino, G. A.; Sharpless, K. B. Synthesis 1993, 8, 777. Johnson, R. A.; Sharpless, K. B. in Catalytic Asymmetric Synthesis, Ed. Ojima, I., VCH, Weinheim, 1993, p.101 and p. 227.
© 2008 Johnson Matthey Plc
4.13.1 Asymmetric Hydrogenation
R
CO2R'' NHR'
Rh-catalyzed hydrogenation of dehydroaminoacids
Homogeneous asymmetric hydrogenation is one of the most important chiral technologies Johnson Matthey offers to its customers in the Pharmaceutical and Fine Chemicals industry through its business unit, Catalysis and Chiral
O R
R N Fe PR2 PR2
CO2R'
Technologies (CCT). This portfolio has been developed by combining in-licensed asymmetric ligands from companies and academic institutions with in-house developed catalytic systems. A range of technologies has been assembled that allows, a priori, the coverage of all the known application of asymmetric hydrogenation (C=C, C=O and C=N bonds).
CO2R'
R
CO2R'
Rh-catalyzed hydrogenation of α-ketoesters
Rh-catalyzed hydrogenation of itaconates
Boaz, N. W.; Debenham, S. D.; Mackenzie, E. B.; Large, S. E. Org. Lett. 2002, 4, 2421. Boaz, N. W.; Debenham, S. D.; Large, S. E.; Moore, M. K. Tetrahedron: Asymmetry 2003, 14, 3575.
P-Phos and Xyl-P-Phos
ParaPhos® and PhanePhos
P-Phos, licensed from Prof A. Chan, is a biaryl phosphine
PhanePhos was first reported in 1997, and has since found
with the unique feature of incorporating two methoxy-
applications in rhodium-catalyzed hydrogenation of
substituted pyridine rings in the backbone.8 This
dehydroaminoacids, palladium catalyzed amination,
contributes to the balance of electronic and steric
ruthenium-catalyzed hydrogenation of ß-ketoesters, and
properties that make the P-Phos ligand very active and
ruthenium-catalyzed hydrogenation of non-functionalized
selective in a series of reactions such as ruthenium-
ketones. Johnson Matthey obtained a licence to
catalyzed hydrogenation of ß-ketoesters and
PhanePhos in 2002.
dehydroaminoacids, and ruthenium-catalyzed Investigations into the reactivity of the common precursor
hydrogenation of non-functionalized ketones.
4,12-dibromo[2.2]paracyclophane towards electrophilic aromatic substitution has recently led to the introduction
O R
CO2Me
of the new paracyclophane-based ligands, ParaPhos. This research has improved the efficiency of the ligand
Ru-catalyzed hydrogenation of β-ketoesters
synthesis and has expanded the range of available phosphines by introducing substituents with different
OMe O
Ru-catalyzed hydrogenation of unsaturated acids CO2H R
R'
N MeO MeO N OMe
electronic effects on the paracyclophane backbone while breaking with the requirement for C2 symmetry.
PAr 2 PAr 2 Ru-catalyzed hydrogenation of aromatic ketones
Ar = Ph, Xyl
Both rhodium and ruthenium catalysts bearing the PhanePhos and ParaPhos ligands show an exceptionally high activity in most homogeneous hydrogenation reactions and a surprising high “tunability” associated with the use of different derivatives.9
™ Bophoz™ Bophoz™ is a phosphine-aminophosphine ligand based on the ferrocene backbone. It presents exceptional reactivity
R1 R3HN
O
R2
R
CO2Me
Ru-catalyzed hydrogenation of β-ketoesters
in rhodium-catalysed hydrogenations. The Bophoz™ range of ligands display a rather unique combination of activity and selectivity in the hydrogenation of C=C and C=O bonds (such as in ␣-ketoesters). A commercial agreement with the Eastman Chemical Company for the use of Bophoz™ has been in place since November 2003.
CO2Me
Rh-catalyzed hydrogenation dehydroaminoacids
R
PAr 2 O PAr 2
Boc N N Ac
CO2Me
Ru-catalyzed hydrogenation of aromatic ketones
PhanePhos
R=H
ParaPhosTM
R = CH2OH, CH2OTrityl CH2OTIPS, OMe
8 Pai, C. -C.; Lin, C. -W.; Lin, C. -C.; Chen, C. -C.; Chan, A. S. C.; Wong, W. T. J. Am. Chem. Soc. 2000, 122, 11513. 9 Rossen, K.; Pye, P. J.; Reamer, R. A.; Tsou, N. N.; Volante, R. P.; Reider, P. J. J. Am. Chem. Soc. 1997, 119, 6207. 9 Domínguez, B.; Hems, W. P.; Zanotti-Gerosa, A. Org. Lett. 2004, 6,1927.
© 2008 Johnson Matthey Plc
65
BINAM-P and Spiro-P
suited to provide the best ligands for this catalysis when
These structurally diverse ligands have been developed by Professor Chan of Hong Kong Polytechnic University. Johnson Matthey obtained a licence in 2002. BINAM-P is
used in combination with diamine ligands such as DPEN, DACH and DAIPEN.
Transfer hydrogenation technology
an amino-phosphine ligand with axial chirality characterized by a larger than usual dihedral angle that is a consequence
Ruthenium transfer hydrogenation catalysts bearing
of the partially reduced binaphthyl backbone. Spiro-P is a
tosylated diamine ligands were developed by Noyori and
phosphinite ligand based on the concept of a spiro-bicyclic
Ikariya, and are included in the license agreement
backbone.10
between JST and Johnson Matthey.
Both ligands have found excellent applications in the
The reduction of C=O groups in presence of i-PrOH and a
rhodium-catalyzed hydrogenation of dehydroaminoacids.
base or in the presence of a mixture of formic acid and triethylamine must be considered complementary to hydrogenation technology.12 Transfer hydrogenation gives
Ar2P PAr 2 O O
NHPAr 2 NHPAr 2
excellent selectivity on “difficult” substrates such as cyclic ketones, acetylenic ketones and imines.
i-PrOH / t-BuOK or
O
Spiro-P
BINAM-P
R
OH R
HCO2H/Et3N, 5/2
Ts Ph
N
Ph
Ru N Cl H2
Typical products obtained
Asymmetric Ketone Reduction In i-PrOH / t-BuOK
Ketone hydrogenation technology
OH
Dynamic kinetic resolution in i-PrOH / t-BuOK OH
In HCO2H/Et3N OH
OH
OH
The discovery by Professor Noyori’s group that nonfunctionalized aromatic ketones can be efficiently reduced
NHCbz
by ruthenium catalysts was a dramatic leap forward in the
H3CO
OH
OH
field of asymmetric homogeneous hydrogenation. The
NH
H3CO
broad applicability of the technology and the exceptionally
R
high activity of these catalysts makes asymmetric ketone hydrogenation the route of choice to chiral alcohols.11
4.13.2 Enantioselective Hydroamination
The Japan Science and Technology Corporation (JST) licensed this technology to Johnson Matthey in 2003. Two families of ligands, P-Phos and ParaPhos, are perfectly
This technology has been exclusively in-licensed from Yale (Professor John Hartwig). Johnson Matthey is optimizing
Ar P
Ar Cl Ru
P O
Ar
Ar Cl
the system for each particular substrate.
NH2 NH2 OH
t-BuOK, H2
H2N
NH2
NHAr
R
R
Potential Intermediate
ee > 98%
[(R)-P-Phos)Pd(OTf) 2]
Typical products obtained
Diamines
arylamine, toluene, 25o C
OH
OH NH2
Pd H L L
Fe
F3C NH2
DPEN H2N
NH2
DACH
Me NHAr
OH O
OMe
F3C high yield and high ee
MeO OH
OMe Me2N OMe
10 10 11 11 12 66
DAIPEN
OH OH
Zhang, F.-Y.; Pai, C. -C.; Chan, A. S. C. J. Am. Chem. Soc. 1998, 120, 5808. Chan, A. S. C.; Hu, W.; Pai, C. -C.; Lau, C. -P.; Jiang, Y.; Mi, A.; Yan, M.; Sun, J.; Lou, R.; Deng, J. J. Am. Chem. Soc. 1997, 119, 9570. Noyori, R.; Ohkuma, T. Angew. Chem. Int. Ed. 2001, 40, 1. Noyori, R. Nobel Lecture, Angew. Chem. Int. Ed. 2002, 41, 2008. Haack, K. J.; Hashiguchi, S.; Fujii, A.; Ikariya, T.; Noyori, R. Angew. Chem. Int. Ed. 1997, 36, 285 and 288.
© 2008 Johnson Matthey Plc
4.13.3 Enantioselective Alkyne Addition
4.13.5 CATAXA™ Anchored Catalysts
Developed by Professor Erick Carreira of ETH (Zurich).
Rhodium CATAXATM catalysts
O H
H
HO
R2
The hydrogenation of prochiral carbon-carbon double
R1
bonds using enantioselective organometallic complexes of
H
R1
R2
(+)-N-methyl ephedrine Zn(OTf) 2, Et3N
R1 = H or alkyl/aryl
rhodium is widely used in chiral organic synthesis. However, extensive purification of the products is often necessary to remove the rhodium, and/or expensive
R1 can be aryl or alkyl - linear or branched sterically
phosphine ligands from the product.
crowded. Enantiomeric excesses are generally above 98%. This methodology can be applied to the synthesis of
Johnson Matthey has anchored a range of rhodium
1,4-diols
catalysts on alumina, CATAXATM/ Rh, which are easily collected by filtration after the reaction and show Ph O (+)-N-Methylephedrine
negligible amounts of leaching into the reaction mixtures.
O
Me
Me Me
Ph O
OH 99% ee 93:7 diastereoselectivity
O
O
Me
Me
H Ph
Me
Me
By attaching chiral homogeneous catalysts onto an alumina
Me
O Me (-)-N-Methylephedrine
via a heteropolyacid, the high enantioselectivity and mild reaction conditions of the analogous homogeneous system can be combined with the ease of separation and simple method of recycle which is observed with
O
heterogeneous catalysts. In addition, the support can add Me
Me
Me OH
99% ee 92:8 diastereoselectivity
an extra dimension by exerting a positive influence on the enantioselectivity of the catalyst. In many instances, CATAXATM catalysts can be reused. The ability of the catalyst to recycle will depend on a number of factors including:
4.13.4 Asymmetric Michael Addition The La-BINOL complex for asymmetric Michael reaction is a highly stable powder. It has application for a broad range of substrates: cyclic enones (5-9 membered ring), acyclic enones and ß-dicarbonyl compounds.13 The homogeneous asymmetric complex can easily be recovered (ee > 98%) even after 4 recycles).
• The conditions under which they are used (whether the catalyst is exposed to air, moisture etc before/during/after the reaction); • The solvent in which the catalyst is used (some solvents, particularly alcohols, can themselves help to stabilize low co-ordinate metal complexes).
O O
R=
CO2Et O CO2Et
O O La O HO
R
All the ligands and catalysts discussed in this review are available through Alfa Aesar, a Johnson Matthey Company.
13 Matsunaga, S.; Das, J.; Roels, J.; Vogl, E. M.; Yamamoto, N.; Lida, T.; Yamaguchi, K.; Shibasaki, M. J. Am. Chem. Soc. 2000, 122, 2252. Yoshikawa, N.; Yamada, Y. M. A.; Das, J.; Sasai, H.; Shibasaki, M. J. Am. Chem. Soc 1999, 121, 4168. Shibasaki, M.; Sasai, H.; Arai, T. Angew. Chemie Int. Ed. Engl. 1997, 36, 1236.
© 2008 Johnson Matthey Plc
67
A variety of CATAXATM supported rhodium catalysts are
A precursor version of CATAXATM/ Rh catalysts is also
available. These are based on the general structure shown
available, CATAXATM/ Rh(COD)2. This material will allow the
below. The complexes can be chiral or achiral. Each catalyst
in-situ preparation of supported Rh catalysts by a simple
will exhibit different rates dependent on the solvents and
ligand exchange reaction with the desired diphosphine
substrate used.
ligand. The resultant catalysts generally require a prehydrogenation step for the pre-formed CATAXATM/ Rh/
Examples of diphosphine ligands:
Phosphine catalysts.
-dppb (1,4-bis(diphenylphosphine)butane). -(S,S)-BDPP (SkewPhos). -(S,S)-DIPAMP. Examples of dienes: -Cyclooctadiene. -Norbornadiene.
CATAXA™/ Rh(COD)2
Choice of solvent CATAXATM/ Rh/ Phosphine catalysts Many different solvents can be used in conjunction with The CATAXATM/ Rh catalysts exhibit similar or often higher enantioselectivity or selectivity to their homogeneous counterparts in reactions such as hydrogenation of dimethylitaconate (DMIT), to acetamido cinnamate (below) and geraniol.
CATAXA™/ Rh catalysts. The choice of solvent will depend largely on the substrate and the type of supported catalyst being used. Solvents such as ethanol and toluene have been used successfully with this material. As the material is air and moisture sensitive, we also recommend the use of dried and degassed solvents. Note: - Like many organometallic complexes, CATAXATM/ Rh samples are prone to oxidation and hence deactivation. To increase the shelf life of these materials they must be stored and handled under an inert atmosphere.
H H +
S
68
R
© 2008 Johnson Matthey Plc
5.
Table: Heterogeneous Catalysts
Catalyst Type
Support Material
Metal Loading %
Typical Applications
A101023-10
Carbon Powder
10
Dehydrogenation
A101023-5
Carbon Powder
5
Hydrogenation of aliphatic nitro compounds
A101038-10
Carbon Powder
10
Dehydrogenation
A102023-5
Carbon Powder
5
Hydrogenation of alkynes, alkenes, aromatic rings, nitro and nitroso compounds, imines, nitriles, aromatic carbonyls, reductive alkylation, reductive amination, hydrogenolysis, debenzylation, selective oxidation, dehydrogenation, C-C coupling
A102038-5
Carbon Powder
5
Hydrogenation of alkynes, alkenes, aromatic rings, aromatic carbonyls, hydrogenolysis, debenzylation, selective oxidation, dehydrogenation
A103038-5
Carbon Powder
5
Selective hydrogenation where lower activity is required
A105023-5
Carbon Powder
5
Conversion of phenol to cyclohexanone
A109047-5
Carbon Powder
5
Hydrogenation of aromatic nitriles, imines, oximes, reductive amination, reductive alkylation, C-C coupling
A201053-10
Barium Sulfate
10
Selective hydrogenation where lower activity is required
A201053-5
Barium Sulfate
5
Selective hydrogenation where lower activity is required
A302023-5
Carbon Powder
5
Rosenmund Reduction
A302038-5
Carbon Powder
5
Rosenmund Reduction
A303060-5
Calcium Carbonate
5
Selective hydrogenation where lower activity is required
A305060-5
Calcium Carbonate
5
Selective hydrogenation of alkynes to alkenes
A306060-5
Calcium Carbonate
5
Selective hydrogenation of alkynes to alkenes
A308053-5
Barium Sulfate
5
Selective hydrogenation where lower activity is required
A401002-20
Carbon Powder
20
Hydrogenolysis, debenzylation
A401102-5
Carbon Powder
5
Hydrogenation of aromatic and aliphatic nitro compounds
A402002-5
Carbon Powder
5
Hydrogenation of alkynes, alkenes, hydrogenolysis, hydrodehalogenation, debenzylation
A402028-10
Carbon Powder
10
Hydrogenolysis, debenzylation
A402028-5
Carbon Powder
5
Hydrogenolysis, debenzylation
A402032-10
Carbon Powder
10
Hydrogenolysis, debenzylation
A405028-5
Carbon Powder
5
Hydrogenation of alkynes, alkenes, aromatic and aliphatic nitro compounds, hydrogenolysis, hydrodehalogenation, debenzylation, C-C coupling
A405032-5
Carbon Powder
5
Hydrogenolysis, debenzylation
A470085-5
Carbon Powder
5
Hydrogenation of alkynes, alkenes, aromatic rings, aromatic and aliphatic nitro compounds, aromatic carbonyls, hydrogenolysis, debenzylation, C-C coupling
A470129-10
Carbon Powder
10
Hydrogenolysis, debenzylation
A470129-20
Carbon Powder
20
Hydrogenolysis, debenzylation
A470129-5
Carbon Powder
5
Hydrogenation of alkynes, alkenes, aromatic and aliphatic nitro compounds, aromatic carbonyls, hydrogenolysis, debenzylation
A470201-5
Carbon Powder
5
Hydrogenation of aromatic and aliphatic nitro compounds, aromatic carbonyls
A501023-10
Carbon Powder
10
Hydrogenolysis, debenzylation, dehydrogenation
PALLADIUM
© 2008 Johnson Matthey Plc
69
Catalyst Type
Support Material
Metal Loading %
Typical Applications
A501032-10
Carbon Powder
10
Hydrogenolysis, debenzylation
A501038-10
Carbon Powder
10
Dehydrogenation
A503023-5
Carbon Powder
5
Hydrogenation of alkynes, alkenes, aromatic rings, nitro and nitroso compounds, imines, nitriles, aromatic carbonyls, reductive alkylation, reductive amination, hydrogenolysis, debenzylation, selective oxidation, dehydrogenation, C-C coupling, isomerization
A503032-5
Carbon Powder
5
Hydrogenation of nitro and nitroso compounds, imines, nitriles, oximes, reductive alkylation, reductive amination, hydrogenolysis, debenzylation
A503038-5
Carbon Powder
5
Hydrogenation of aromatic carbonyls, hydrogenolysis, hydrodehalogenation, isomerization
A505085-5
Carbon Powder
5
Hydrogenation of aromatic and aliphatic nitroso compounds
A570147-5
Carbon Powder
5
Hydrogenation of nitro and nitroso compounds, imines, nitriles, oximes, reductive alkylation, reductive amination, isomerization
A570129-5
Carbon Powder
5
Hydrogenation of alkynes, alkenes, aromatic rings, nitro and nitroso compounds, imines, oximes, aromatic carbonyls, nitriles, reductive alkylation, reductive amination, hydrogenolysis, hydrodehalogenation, selective oxidation, dehydrogenation, isomerization
A570201-5
Carbon Powder
5
Hydrogenation of aromatic carbonyls, nitriles, hydrogenolysis, hydrodehalogenation
A701023-5
Carbon Powder
5
Rosenmund Reduction
B101002-5
Carbon Powder
5
Selective oxidation
B101032-3
Carbon Powder
3
Hydrogenation of halonitroaromatics
B101038-1
Carbon Powder
1
Hydrogenation of halonitroaromatics
B102022-5
Carbon Powder
5
Hydrogenation of heterocyclic compounds
B102032-1
Carbon Powder
1
Hydrogenation of halonitroaromatics, p-aminophenol production
B102032-3
Carbon Powder
3
Reductive alkylation
B103018-5
Carbon Powder
5
Hydrogenation of aliphatic carbonyls, dehydrogenation, selective oxidation
B103032-3
Carbon Powder
3
Hydrogenation of halonitroaromatics
B103032-5
Carbon Powder
5
Hydrogenation of alkenes, aromatic rings, heterocyclic compounds, aromatic and aliphatic nitro and nitroso compounds, imines, nitriles, aliphatic carbonyls, dehydrogenation, selective oxidation
B104032-3
Carbon Powder
3
Reductive alkylation
B105032-3
Carbon Powder
3
Reductive alkylation
B105047-1
Carbon Powder
1
Hydrogenation of halonitroaromatics, p-aminophenol production
B106032-3
Carbon Powder
3
Reductive alkylation
B111022-5
Carbon Powder
5
Selective oxidation
B112002-5
Carbon Powder
5
Selective oxidation
B170058-1
Carbon Powder
1
p-Aminophenol production
B170147-1
Carbon Powder
1
Hydrogenation of halonitroaromatics
B170147-3
Carbon Powder
3
Hydrogenation of halonitroaromatics, reductive alkylation
PLATINUM
70
© 2008 Johnson Matthey Plc
Catalyst Type
Support Material
Metal Loading %
Typical Applications
PLATINUM – continued B170147-5
Carbon Powder
5
Hydrogenation of alkenes, aromatic rings, heterocyclic compounds, aromatic and aliphatic nitro and nitroso compounds, imines, nitriles, aliphatic carbonyls
B170201-5
Carbon Powder
5
Selective oxidation
B171147-3
Carbon Powder
3
Reductive alkylation
B301013-5
Alumina Powder
5
Hydrosilylation
B301099-5
Alumina Powder
5
Hydrosilylation
B501032-5
Carbon Powder
5
Hydrogenation of alkenes, aromatic rings, heterocyclic compounds, aromatic and aliphatic nitro and nitroso compounds, imines, nitriles, aliphatic carbonyls, dehydrogenation, selective oxidation
B503032-5
Carbon Powder
5
Selective oxidationIRIDIUM
C101023-5
Carbon Powder
5
Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic nitro compounds, aliphatic nitriles, alkenes
C101038-5
Carbon Powder
5
Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic nitro compounds, aliphatic nitriles, alkenes
C301011-5
Alumina Powder
5
Hydrogenation of aromatic rings
D101023-5
Carbon Powder
5
Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic carbonyls, sugar hydrogenation, selective oxidation
D101038-5
Carbon Powder
5
Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic carbonyls, sugar hydrogenation, selective oxidation
D103002-5
Carbon Powder
5
Selective oxidation
D170201-5
Carbon Powder
5
Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic carbonyls, sugar hydrogenation, selective oxidation
E101049-4/1
Carbon Powder
4% Pd 1% Pt
Hydrogenation of alkenes, nitro and nitroso compounds, imines, selective oxidation
E101023-4/1
Carbon Powder
4% Pd 1% Pt
Hydrogenation of alkenes, nitro and nitroso compounds, imines, selective oxidation
F101023-4.5/0.5
Carbon Powder
4.5% Pd 0.5% Rh Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic nitriles, oximes
F101038-4.5/0.5
Carbon Powder
4.5% Pd 0.5% Rh Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic nitriles, oximes
G101038-5/0.25
Carbon Powder
5% Ru 0.25% Pd Hydrogenation of aromatic rings, heterocyclic compounds, aliphatic carbonyls
RHODIUM
RUTHENIUM
MIXED METAL
NOTE Paste catalysts are free flowing, powder–like materials, usually containing approximately 50–60% w/w water.
© 2008 Johnson Matthey Plc
NOTE The foregoing lists of catalysts and applications are not exhaustive
71
PRICAT® Catalysts PRICAT
Metal
Support
Promotors
Powder
Tablet
%
Ni 52/35
x
x
50
Kieselguhr
x
Ni 55/5
x
x
55
Kieselguhr
x
Ni 56/5
x
55
Kieselguhr
x
Ni 62/15
x
60
Kieselguhr
x
x
Ni 60/15
x
x
60
Kieselguhr
x
x
Cu 51/8
MgO
x
51
Silica
Cu 60/35
x
x
62
Silica
x
Co 40/55
x
x
40
Kieselguhr
x
ZrO2
Cr2O3
Al2O3
MnO
x
x x
SPONGE METAL
72
Product
Primary Metal
Promoters
Particle Size, median (u)
Typical applications
A-5000 A-5B00 A-5200
Nickel Nickel Nickel
Non-promoted Non-promoted Non-promoted
35 50 175
General hydrogenation General hydrogenation General hydrogenation
A-4000
Nickel
Fe & Cr
35
Diamine hydrogenation
A-7000 A-7200
Nickel Nickel
Mo Mo
35 175
Polyol hydrogenation General hydrogenation
A-7063 A-7B63
Nickel Nickel
Mo Mo
35 50
Polyol hydrogenation Polyol hydrogenation
A-7B73
Nickel
Mo
50
Polyol hydrogenation
A-2000
Nickel
Fe
35
Nitro group hydrogenation
A-3B00
Copper
Non-promoted
50
Dehydrogenation
A-8000 A-8B46
Cobalt Cobalt
Non-promoted Cr & Ni
35 50
Selective hydrogenation Selective hydrogenation
AMCAT-5 AMCAT-5343 AMCAT-7 AMCAT-2
Nickel Nickel Nickel Nickel
Non-promoted Non-promoted Mo Fe
35 35 35 35
In In In In
primary fatty amine tertiary fatty amine primary fatty amine primary fatty amine
© 2008 Johnson Matthey Plc
6. Table: Homogeneous Catalysts Our range of PGM homogeneous catalysts and precursors is listed in the tables below. We have also listed some simple PGM chloride salts which are the starting materials for most co–ordination compounds.
An explanation of the European Union (E.U.) hazard codes is given below:
E.U. Code
Hazard
Nature of the Hazard
Xi
Irritant
–
Non-corrosive substances which, through immediate, prolonged or repeated contact with the skin or mucous membrane may cause inflammation.
C
Corrosive
–
Substances which may, on contact with living tissues, destroy them.
O
Oxidizing
–
Substances which give rise to a highly exothermic reaction in contact with other substances, particularly flammable substances.
F
Highly flammable
–
Solid substances which may readily catch fire after brief contact with a source of ignition and which continue to burn or to be consumed after removal of the source of ignition.
Xn
Harmful
–
Substances which may cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin.
T
Toxic
–
Substances which in low quantities cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin.
T+
Very toxic
–
Substances which in very low quantities cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin.
CSNYFT
Caution Substance not yet fully tested.
–
New substance – not the subject of a full notification.
N
Dangerous for the Environment
–
Chemicals that may present an immediate or delayed danger to one or more components of the environment.
Solubilities The relative solubilities of the co–ordination compounds in different solvents are indicated in the tables. For guidance, the following abbreviations have been used:– v.s.
very soluble
ca. 1000 g/l
s.
soluble
ca. 100 g/l
f.s.
fairly soluble
ca. 15 g/l
sl.s.
slightly soluble
ca. 10 g/l
v.sl.s.
very slightly soluble
ca. 1 g/l or less
i
insoluble
© 2008 Johnson Matthey Plc
73
IRIDIUM COMPOUNDS Catalog No.
Compound
Color & Form
Mol Wt
% Metal Content
Stability
Ir-40
Carbonylchloro bis (triphenylphosphine) iridium(l) [IrCl(CO) (PPh3)2]
lemon yellow crystals
780
24.6
air stable
Ir-42
Carbonylhydrido tris (triphenylphosphine) iridium(l) [IrCl(CO)H(PPh3)3]
pale yellow powder
1007
19.1
slowly decomposes in air
Ir–90
(Cycloocta–1,5–diene) pyridyl tricyclohexyl– phosphine iridium(I) hexafluorophosphate [Ir(COD)py(PCy3)]PF6
orange crystals
804
23.9
air stable
Ir–91
Di -mu-chloro bis(cyclooctene) iridium (I) [Ir(C8H14)2Cl]2
yellow solid
896
42.9
slowly decomposes in air & moisture
Ir–92
Bis(1,5-cyclooctadiene)di- mumethoxydiiridium(I) [Ir(C8H12)2OCH3]2
yellow solid
651
58.0
slowly decomposes in air & moisture
Ir–93
Di μ–chloro bis (η4–cycloocta–1,5– diene) di–iridium(I) [IrCl(COD)]2
red– orange solid
671
57.2
air stable
Ir–112
"Iridium(III) acetate" Hexa(acetato) μ3–oxo tris (aquo) tri–iridium acetate [Ir3(OAc)6μ3–O(H2O)3]OAc
dark green solid
50–54
air stable
Iridium(III) chloride hydrate [IrCl3].H2O
green/ black crystalline flakes
50–56
air stable hygroscopic
Chloroiridic acid; Hydrogen hexachloroiridate(IV) hydrate H2[IrCl6].H2O
black– brown crystals
38–45
air stable hygroscopic
FibreCat® 4000-D11
Ir(COD)Cl on triphenylphosphine fibers
orange fiber
4.0-5.0
air stable
FibreCat® 4000-D12
Ir(COD)Cl on pyridine fibers
yellow fiber
4.0-5.0
air stable
OSMIUM COMPOUNDS Catalog No. Compound
74
Color & Form
Mol Wt
% Metal Content
Stability
Osmium tetroxide Osmium (VIII) oxide [OsO4]
yellow crystals
254
75
m.pt 41°C
“Potassium osmate dihydrate” Dipotassium trans dioxo tetra (hydroxy) osmium (VI) K2[OsO2(OH)4]
purple solid
368
51.6
air stable
FibreCat® 3003
OsO4 on pyridine fibers
yellow fiber
7.5 nominal
store cold -20°C
FibreCat® 3004
K2[OsO2(OH)4] on triethylamine fibers
violet fiber
7.5 nominal
store cold -20°C
© 2008 Johnson Matthey Plc
IRIDIUM COMPOUNDS Solubilities
E.U. Hazard Code CAS No. (EINECS No.)
Use and Comments
Catalogue No.
sl.s Chloroform sl.s toluene
T
14871–4–1 (2389416)
Hydrogenation Vaska’s compound
Ir–40
s. chloroform s. toluene
Xn
17250–25–8
Hydrogenation
Ir–42
sl.s acetone, dichloromethane, diethyl ether, ethanol
Xn CSNYFT
64536–78–3 ( –– )
Hydrogenation Crabtree's catalyst
Ir–90
i.water
12246-51-4
Imine Hydrogenation Chiral Hydrogenation
Ir–91
i. water
12148-71-9
Imine Hydrogenation Chiral Hydrogenation
Ir–92
Ir–93
s. chloroform, toluene sl.s acetone, alcohol
Xi
12112–67–3 (2351707)
Hydrogenation
s. acetic acid, water
Xi CSNYFT
52705–52–9 ( –– )
Catalyst precursor Ir–112 Solid contains metal in more than one formal oxidation state Also available in solution in acetic acid
s. alcohol, water
Xn
14996–61–3 * (2330446)
Catalyst precursor
f.s alcohol, water
C
16941–92–7 (2410128)
Catalyst precursor Also available as solution
i. all known solvents
hydrosilylation and hydrogenation
FibreCat® 4000–D11
i. all known solvents
hydrosilylation and hydrogenation
FibreCat® 4000–D12
*CAS No. refers to a specific hydrate
OSMIUM COMPOUNDS Solubilities
E.U. Hazard Code
CAS No. (EINECS No.)
Use and Comments
v.s carbon tetrachloride s. water
T+, C
20816–12–0 (2440587)
Oxidation Can be readily sublimed. Should only be used in a well ventilated remote environment.
s. water
Xi
19718 – 36 – 6 (2432471)
Oxidation. A convenient substitute for OsO4
i. all known solvents
T+
Oxidation
FibreCat® 3003
i. all known solvents
Xi
Oxidation
FibreCat® 3004
© 2008 Johnson Matthey Plc
Catalog No.
75
PALLADIUM COMPOUNDS
76
Catalog No.
Compound
Color & Form
Mol Wt
% Metal Content
Stability
Pd–62
Dichloro bis(acetonitrile)palladium(II) [PdCl2(CH3CN)2]
dark yellow powder
263
40.4
air stable
Pd–63
Tetrakis(acetonitrile)palladium(II) tetrafluoroborate Pd(CH3CN)4(BF4)2
pale yellow powder
444
23.9
air, moisture & light sensitive
Pd–70
Bis(acetylacetonato)palladium(II) [Pd(acac)2]
yellow orange solid
304
35.0
air stable
Pd–93
Bis(dibenzylideneacetone)palladium(0) Pd(C17H14O)2
purple brown
575
18.5
slightly air & moisture sensitive
Pd–94
Tris(dibenzylideneacetone)dipalladium(0) Pd2(C17H14O)3
dark purple solid
916
23.2
slightly air & moisture sensitive
Pd–95
Tris(dibenzylideneacetone)dipalladium(0) chloroform adduct Pd2(C17H14O)3.CHCI3
purple powder 1035
20.6
slightly air & moisture sensitive
Pd–100
Dichloro bis(triphenylphosphine) palladium(II); [PdCl2(PPh3)2]
yellow solid
701
15.2
air stable
Pd–101
Tetrakis(triphenylphosphine)palladium(0) [Pd(PPh3)4]
yellow solid
1154
9.4
air, heat, light & moisture sensitive
Pd–102
Diacetato 1,3–bis(diphenylphosphino) propane palladium(II) [Pd(OAc)2(Ph2PCH2CH2CH2PPh2)]
cream solid
636
16.7
air stable moisture sensitive
Pd–103
Dichloro 1,2–bis(diphenylphosphino) ethane palladium(II) [PdCl2(Ph2PCH2CH2PPh2)]
off white powder
575
18.5
air stable
Pd–105
Dichloro 1,4–bis(diphenylphosphino) butane palladium(II) [PdCl2(Ph2PCH2CH2CH2PPh2)]
yellow solid
603
17.6
air stable
Pd–106
Dichloro 1,1-bis(diphenylphosphino)ferrocene orange/red palladium(II) dichloromethane adduct solid [Pd(dppf)Cl2]. CH2CI2
816
13.0
air stable
Pd–107
Dichloro 1,1-bis(diphenylphosphino) ferrocene palladium(II) acetone adduct [Pd(dppf)Cl2]. (CH3)2O
brick red solid
789
13.4
air stable
Pd–109
Di–μ–chloro–bis (tris(2,4–di–t–butylphenyl) phosphite–2–C,P) dipalladium(II)
white – off white powder
1576
13.5
air stable
Pd–110
Di-μ-chlorobis(eta 3-2 propenyl) dipalladium [Pd(C3H5)Cl]2 Allylpalladium chloride dimer
yellow powder
366
58.1
very slightly air & moisture sensitive
© 2008 Johnson Matthey Plc
PALLADIUM COMPOUNDS
Solubilities
E.U. Hazard Code
CAS No. (EINECS No.)
Use and Comments
s. acetone, chloroform
Xn
14592–56–4 (2386373)
Coupling precursor, rearrangements, Pd–62 debromination.
21797-13-7
Coupling
Pd–63
14024–61–4 (2378598)
Alkene dimerisation, cyclization, oxidation
Pd–70
sls. chloroform
32005-36-0
Coupling reactions
Pd-93
s. chloroform
51364-51-3 52409-22-0 60748-47-2
Coupling reactions
Pd-94
52522-40-4
Coupling reactions
Pd-95
s. water
s. chloroform, toluene
Xi
Catalog No.
v.sl.s acetone, chloroform
Xn
13965–03–2 (2377442)
Carbonylation. Coupling reactions
Pd–100
s. chloroform, toluene
Xn
14221–01–3 (2380869)
Coupling reactions. Store refrigerated
Pd–101
s. acetic acid, chloroform, methanol sl.s acetone v.sl.s toluene
Xn CSNYFT
149796–59–8 (–)
Coupling reactions. Carbonylation
Pd–102
Xn CSNYFT
19978–61–1 (–)
Coupling reactions
Pd–103
Xn CSNYFT
29964–62–3 (–)
Coupling reactions
Pd–105
95464-05-4
Coupling reactions
Pd-106
sl.s DMF v.sl.s. acetonitrile, water
i. water
s. chloroform sl. s. dichloromethane
Xn CSNYFT
851232-71-8 (–)
Coupling reactions Carbonylation
Pd–107
i. water s. toluene, chloroform
Xn CSNYFT
217189–40–7 (–)
Coupling reactions especially Suzuki and Stille couplings of aryl bromides and iodides
Pd–109
12012-95-2
Coupling reactions
Pd-110
i. water
© 2008 Johnson Matthey Plc
77
PALLADIUM COMPOUNDS
78
– (CONTINUED)
Catalog No.
Compound
Color & Form
Pd–111
Palladium(II) acetate trimer Hexakis(μ–acetato) tripalladium(II) [Pd(OAc)2]3
Pd-113
Mol Wt
% Metal Content
Stability
orange/brown 673 needles
47.4
air stable
Dibromo bis(tri-tert-butylphosphine) dipalladium (I) [Pd(μ-Br)t-Bu3P]2
dark green/ black crystals
777
27.4
air & moisture sensitive
Pd-114
Dichloro bis(tricyclohexylphosphine) palladium(II) PdCl2[(C6H11)3P]2
yellow powder
738
14.4
air stable
Pd-115
Dichloro bis(tri-ortho-tolylphosphine) palladium(II) PdCl2[P(o-tolyl)3]2
yellow/orange 786 solid
13.5
air stable
Pd-116
Bis(tri-tert-butylphosphine)palladium(0) Pd(t-Bu3P)2
off white solid
510
20.9
air & moisture sensitive
Pd-117
Dichloro bis(diphenylphosphinophenyl)ether palladium(II) DPEPhos PdCl2
light yellow solid
719
14.8
air stable
Pd-118
Dichloro 1,1-bis(di-tert-butylphosphino) ferrocene palladium(II) di-t-bpfPdCl2
dark red/brown 651 solid
16.3
air stable
Pd-119
Dichloro 1,1-bis(di-isopropylphosphino) ferrocene palladium di-isoppf PdCl2
orange red solid
595
17.8
air stable
Pd–120
Dibromo 1,1-bis(tri-ortho tolylphosphine)palladium(II) PdBr2[P(o-toly)3]2
orange/yellow 875 solid
12.0
Slowly decomposes in air & moisture
Pd–121
Dibromo 1,1-bis(diphenylphosphino) ferrocene palladium(II) dppfPdBr2
purple red solid
820
12.9
air stable
Pd-130
Dibromo bis(triphenylphosphine) palladium (II) [Pd(PPh3)2Br2]
orange solid
791
13.5
air stable
FibreCat® 1001
Pd(OAc)2 on triphenylphosphine fibers
yellow/brown fiber
2.7-4.0
air stable
FibreCat® 1026
PdCI2 on triphenylphosphine fibers
orange fiber
3.5-5.5
air stable
FibreCat® 1032
Pd(OAc)2/tri-tert-butylphosphine on tritertbutylphosphine fibers
yellow fiber
4.5-5.5
air stable
Q Phos
1,2,3,4,5-Pentaphenyl-1’-(di-tert butylphosphino)ferrocene CTC-Q-PHOS (Use in conjunction with Pd precursor)
pink-red solid
711
n/a
air & moisture stable
Palladium(II) chloride [PdCl2]
red– brown powder
177
59.6–60.0
air stable
© 2008 Johnson Matthey Plc
PALLADIUM COMPOUNDS
– (CONTINUED)
Solubilities
E.U. Hazard Code
CAS No. (EINECS No.)
Use and Comments
Catalog No.
s. acetic acid, toluene
Xi
3375–31–3 (2584249)
Carbonylation. Coupling precursor. Slowly decomposes in alcohol solutions
Pd–111
i. water
185812-86-6
Highly active for all coupling reactions especially amination and Suzuki couplings
Pd-113
i. water
29934-17-6
Coupling reactions
Pd-114
i. water
40691-33-6
Coupling reactions
Pd-115
i. water (but decomposes)
53199-31-8
Highly active for all coupling reactions especially amination and Heck couplings
Pd-116
i. water
205319-06-08
Coupling reactions
Pd-117
i. water
95408-45-0
Highly active for all coupling reactions especially Suzuki couplings
Pd-118
i. water
215788-65-1
Coupling reactions
Pd-119
i.water
24554-43-6
Coupling
Pd–120
s. chloroform, dichloromethane
124268-93-5
Coupling
Pd–121
v.sl. s. acetone, acetonitrile
25044-96-6 (-)
Coupling reactions
Pd-130
i. all known solvents
Bromo/iodo coupling reactions
FibreCat® 1001
i. all known solvents
Bromo/iodo coupling reactions
FibreCat® 1026
i. all known solvents
Highly active for all coupling reactions especially chloro coupling, amination
FibreCat® 1032
i. water
s. dil mineral acids and aqueous alkali metal halides
© 2008 Johnson Matthey Plc
Xi
312959-24-3
Highly active for all coupling reactions especially Negishi couplings
7647–10–1 (2315962)
Catalyst precursor. Also available as H2PdCl4 solution
79
PLATINUM COMPOUNDS Catalog No.
Compound
Color & form
Mol Wt
% Metal Content
Stability
Pt–62
trans–Bis(acetonitrile) dichloroplatinum(II) trans–[PtCl2(CH3CN)2]
pale yellow micro– crystals
348
56.0
air stable
Pt–70
Bis(acetylacetonato) platinum(II); [Pt(C5H7O2)2]
lemon needles
393
49.6
air stable
Pt–90
Dichloro (η4–norbornadiene) platinum(II) [PtCl2(nbd)]
cream micro– crystals
358
54.4
air stable
Pt–91
(η4–Cycloocta–1,5–diene) diiodoplatinum(II) [PtI2(COD)]
yellow powder
557
35.0
air stable
Pt–96
Dichloro (η4 cycloocta–1,5–diene) platinum(II) [PtCl2(COD)]
pale yellow solid
374
52.1
air stable
Pt–100
cis–Dichlorobis (triphenylphosphine) platinum(II) cis–[PtCl2(PPh3)2]
white crystals
790
24.7
air stable
Pt–112
trans–Dichlorobis(diethylsulfide) platinum(II) trans–[PtCl2(SEt2)2]
bright yellow crystals
446
43.7
air stable
Pt–114
Karstedt catalyst solution Approximate formula Pt2(divinyltetramethyldisiloxane)3
pale yellow solution
3–4
air stable, store less than 50°C
FibreCat® 4001
Chloroplatinic acid on pyridine fibers
orange fiber
3.5-6.0
air stable
Platinum(II) chloride [PtCl2]
olive green powder
72.8 –73.6
air stable
Chloroplatinic acid; Hydrogen hexachloroplatinate(IV) hydrate H2[PtCl6].H2O
orange –red crystals
39 –42
air stable hygroscopic
266
RHODIUM COMPOUNDS
80
Catalog No.
Compound
Color & Form
Mol Wt
% Metal Content
Stability
Rh–40
Carbonylchloro bis (triphenylphosphine) rhodium(I) [RhCl(CO)(PPh3)2]
yellow crystals
691
14.9
air stable
Rh–42
Carbonyl hydrido tris (triphenylphosphine) rhodium(I) [RhH(CO)(PPh3)3]
yellow crystals
918
11.2
air stable
Rh–43
Acetylacetonatocarbonyltriphenylphosphine rhodium(I) (ROPAC) [Rh(acac)(CO)(PPh3)]
yellow crystals
492
20.9
air stable
Rh–50
Acetylacetonatodicarbonyl rhodium(I) [Rh(acac)(CO)2]
green flakey crystals
258
39.9
air stable
Rh–70
Tris(acetylacetonato) rhodium(III) [Rh(acac3)]
yellow crystals
400
25.8
air stable
© 2008 Johnson Matthey Plc
PLATINUM COMPOUNDS Solubilities
E.U. Hazard Code CAS No. (EINECS No.)
v.sl.s acetone i. dichloromethane t.s. DMF
T
13869–38–0 (2376192)
Pt–62
v.s chloroform
Xn
15170–57–7 (2392235)
Pt–70
s. acetic acid
Xn
12152–26–0 (2352716)
Hydrosilylation
Pt–90
s. dichloromethane
Xn
12266–72–7 (2355387)
Hydrosilylation
Pt–91
sl.s. chloroform, dichloromethane v.sl.s. alcohols
Xn
12080–32–9 (2351445)
Hydrosilylation
Pt 96
v.sl.s. chloroform, hexane, toluene
Xn
15604-36-1 (2334959)
v.s acetone s. ethyl acetate
Xn
15337–84–5 (2393731)
Hydrosilylation
Pt–112
68478–92–2 (2708444)
Hydrosilylation. Usually supplied in propan–2–ol/ divinyltetramethyldisiloxane.
Pt 114
Hydrosilylation
FibreCat® 4001
Dictated by solvent used
Use and Comments
Catalog No.
Pt–100
i. all known solvents
C, T
v.sl.s acetone, alcohol, water
Xn
10025–65–7 (2330341)
Hydrosilylation
v.s acetone, alcohol, ether, ethyl acetate, water
C, T
16941–12–1 (2410107)
Hydrosilylation. A powerful sensitiser and allergen
RHODIUM COMPOUNDS Solubilities
E.U. Hazard Code
CAS No. (EINECS No.)
Use and Comments
Catalog No.
f.s chloroform, ethanol
T
13938–94–8 (2377128)
Decarbonylation
Rh–40
17185–29–4 (2412303)
Hydroformylation
Rh–42
f.s chloroform
s. chloroform f.s toluene
Xi
25470–96–6 (2470150)
Hydroformylation. ROPAC
Rh–43
s. acetone sl.s alcohol, chloroform, toluene
T, F
14874–82–9 (2389479)
Hydroformylation. Dichromic green–red crystals when crushed
Rh–50
v.s chloroform s. alcohol © 2008 Johnson Matthey Plc
14284–92–5 (2381925)
Rh–70 81
RHODIUM COMPOUNDS
82
– (CONTINUED)
Catalog No.
Compound
Color & Form
Mol Wt
% Metal Content
Stability
Rh–92
Di μ–chlorobis (η4–norbornadiene) dirhodium(I) [RhCl(nbd)]2
mustard yellow crystals
461
44.7
air stable
Rh–93
Di μ–chlorobis (η4–cycloocta–1,5– diene)dirhodium(I); [RhCl(COD)]2
orange crystals
493
41.8
air stable
Rh–95
Acetylacetonato(1,5-cyclooctadiene) rhodium(I) Rh(C8H12)(C5H7O2)
orange crystal
310
33.0
air stable
Rh-96
Bis(cyclooctadiene)rhodium(I) tetrafluoroborate[Rh(C8H12)2]BF4
red-brown solid
406
25.3
slightly air & moisture sensitive
Rh–97
Bis(norbornadiene)rhodium(I) tetrafluoroborate [Rh(nbd)2]BF4
dark red solid
374
27.5
slightly air & moisture sensitive
Rh–98
Bis(1,5-cyclooctadiene)rhodium(I) trifluoromethanesulfonate [Rh(C8H12)2]O3SCF3
dark red crystals
468
22.0
air sensitive
Rh–100
Chloro tris(triphenylphosphine) rhodium(I) [RhCl(PPh3)3] Wilkinson’s catalyst
magenta crystals
925
11.1
slowly decomposes in air
Rh–101
Bromo tris(triphenylphosphine) rhodium(l) [RhBr(PPh3)3]
orange crystals
969
10.6
air sensitive
Rh–105
Hydrido tetrakis(triphenylphosphine) rhodium(ll) [RhH(PPh3)4]
yellow powder
1152
8.9
air sensitive
Rh–110
Rhodium(II) acetate dimer [Rh(OAc)2]2
emerald green powder
442
46.6
air stable
Rh–112
"Rhodium(III) acetate" Hexa(acetato) μ3–oxo tris(aquo) trirhodium acetate [Rh3(OAc)6μ3–O(H2O)3]OAc
brown solid
34–39
air stable
Rh–115
Rhodium(II) octanoate dimer [Rh(C8H15O2)2]2
emerald green powder
778
26.4
air stable
Rh–120
Di μ–chloro dichloro bis (η5–pentamethylcyclopentadienyl) di–rhodium (I); [RhCl2(η5–Cp*)]2
burgundy solid
618
33.3
air stable
Rh–125
Bis(norbornadiene)rhodium trifluoromethanesulfonate [Rh(C7H8)2]BF4
orange solid
436
23.6
stable at 0 deg C
Rh–126
Bis(ethylene)(pentanedionato)rhodium yellow Rh(C2H4)2(C5H7O) solid
257
39.9
air stable
Rh–127
(norbornadiene)(pentanedionato) rhodium Rh(C7H8)(C5H7O)
yellow solid
294
34.9
air stable
FibreCat® 2003
Rh(nbd)2BF4 on triphenylphosphine fibers
orange fiber
3.0-4.0
air sensitive
FibreCat® 2006
Rh(nbd)CI on triphenylphosphine fibers
yellow fiber
2.0-3.5
air sensitive
Rhodium (2–ethylhexanoate) in 2–ethyl hexanol
red/ brown solution
3.0–4.0
air stable
Rhodium(III) chloride hydrate [RhCl3].nH2O
dark red flakes
39–43
air stable
Rhodium(III) iodide [RhI3]
black powder
21.3
air stable but hygroscopic
484
© 2008 Johnson Matthey Plc
RHODIUM COMPOUNDS
– (CONTINUED)
Solubilities
E.U. Hazard Code
CAS No. (EINECS No.)
Use and Comments
Catalog No.
v.sl.s most solvents
Xn
12257–42–0 (2355104)
Hydrogenation. Isomerisation Hydroformylation.
Rh–92
sl.s acetone, methanol
Xi
12092–47–6 (2351576)
Hydrogenation. Isomerisation Hydroformylation
Rh–93
s. chloroform
12245-39-5
Hydrogenation (Chiral and non-chiral)
Rh–95
sl s methyl ethyl ketone, dichloromethane
35138-22-8
Hydrogenation, Isomerisation
Rh-96
36620–11–8 (–)
Hydrogenation, Isomerisation
Rh–97
s. chloroform
99326-34-8
Hydrogenation (Chiral and non-chiral)
Rh–98
v.s chloroform sl.s acetone, alcohol v.sl.s diethyl ether, toluene
14694–95–2 (2387445)
Selective Hydrogenation. Decarbonylation. Store under inert gas
Rh–100
Hydrogenation
Rh–101
i. water
CSNYFT
v.s. chloroform sl.s acetone, alcohol v.sl.s diethyl ether, toluene
Xn
14973–89–8 (2390505)
s. chloroform, toluene
CSNYFT
18284–36–1 (—)
sl.s methanol v.sl.s acetone, acetic acid, chloroform, water
Rh–105
15956–28–2 (2400848)
Cyclopropanation Carbene reactions
Rh–110
s. acetic acid, water
Xi
42204–14–8 (2557079)
Alcohol carbonylation catalyst precursor Available also in solution in acetic acid
Rh–112
sl.s alcohol
CSNYFT
73482–96–9 ( –– )
Cyclopropanation Carbene reactions
Rh–115
s. chloroform, acetone sl.s. THF, methanol i. diethyl ether
CSNYFT
12354–85–7 ( –– )
Hydrogenation Chiral hydrogenation precursor
Rh–120
s. dichloromethane & chloroform
178397-71-2
Chiral Hydrogenation precursor
Rh–125
s. dichloromethane & chloroform
12082-47-2
Hydrogenation precursor
Rh–126
s. dichloromethane & chloroform
32354-50-0
Hydrogenation precursor
Rh–127
i. all known solvents
Selective Hydrogenation
FibreCat® 2003
i. all known solvents
Selective Hydrogenation
FibreCat® 2006
s. propan–2–ol, acetone
Xn
20845–92–5 (2440791)
Catalyst precursor
s. alcohol, water sl.s acetone
Xn
20765–98–4 * (2331654)
Catalyst precursor
15492–38–3 (2395215)
Alcohol carbonylation catalyst precursor
i. most solvents
© 2008 Johnson Matthey Plc
83
RUTHENIUM COMPOUNDS Catalog No.
Compound
Color & Form
Mol Wt
% Metal Content
Stability
Ru–41
Dicarbonyldichloro bis(triphenylphosphine) ruthenium(II) [RuCl2(CO)2(PPh3)2]
yellow white crystals
752
13.4
air stable
Ru–42
Carbonylchlorohydrido tris (triphenylphosphine) ruthenium(II) [RuClH(CO)(PPh3)3]
pale yellow crystals
952
10.6
air stable light sensitive
Ru–70
Tris(acetylacetonato) ruthenium(III) [Ru(acac)3]
dark red– brown crystals
398
25.4
air stable
Ru–90
Dichloro (η4–cycloocta–1,5– diene) ruthenium(II) polymer [RuCl2(COD)]n
dark brown powder
38.3
air stable
Ru–91
Bis(2-methylallyl)(1,5cyclooctadiene)ruthenium (II) Ru(C8H12)(C4H7)2
off-white crystals
319
31.6
slowly decomposes in air & moisture as well as at warm conditions
Ru–92
(1,5 cyclooctadiene) ruthenium trifloroacetate [Ru(C8H12) (CF3CO2)]2
yellow powder
870
23.2
air stable
Ru–93
(1,5-cyclooctadiene) ruthenium acetate Ru(C8H12) (CH3CO2)2
yellow powder
327
30.9
air stable
Ru–100
Dichloro tris (triphenylphosphine) ruthenium(II) [RuCl2(PPh3)3]
black solid
958
10.5
air stable
Ru–112
"Ruthenium(III) acetate" Hexa(acetato)μ3–oxo tris (aquo)triruthenium acetate [Ru3(OAc)6μ3–O(H2O)3]OAc
dark green solid
40 – 45
air stable
Ru–120
Tetrachloro bis (η6–p–cymene) diruthenium(II) [RuCl2(η6–C10H14)]2
dark red crystals
612
33.0
air stable
Ru–121
Tetraiodobis (η6 p-cymene) ruthenium(ll) dimer [Rul2(η6-C10H14)]2
brownishyellow solid
978
20.7
stable at room temperature
Ru–130
Tetra (n–propylammonium) perruthenate [NPr4][RuO4], TPAP
very dark green/brown solid
351
28.7
air stable but hygroscopic
38–43
air stable but hygroscopic
5 nominal
air stable
3.0-4.5
air stable
Ruthenium(III) chloride hydrate [RuCl3].xH2O
84
FibreCat® 3001
TPAP on triethylamine fibers
FibreCat® 3002
Na2RuO4 on triethylamine fibers
black crystals
grey black fiber
© 2008 Johnson Matthey Plc
RUTHENIUM COMPOUNDS
Solubilities
E.U. Hazard Code
CAS No. (EINECS No.)
v.sl.s acetone chloroform, toluene
Xn
14564–35–3 (2386059)
insoluble in most solvents
T
16971–33–8 (2410510)
Disproportionation and silyl transfer. Transfer hydrogenation
Ru–42
s. chloroform sl.s acetone, ethyl acetate, methanol, toluene, water
T
14284–93–6 (2381930)
Hydrogenation
Ru–70
i. most solvents
Xn
50982–13–3 (2568892)
Hydrogenation
Ru–90
i. water
12289-94-0
Chiral Hydrogenation Ru–91 Reduction of CO groups
s. chloroform
133873-70-8
Chiral Hydrogenation Ru–92 Reduction of CO groups
s. chloroform
133519-03-6
Chiral Hydrogenation Ru–93 Reduction of CO groups
v.sl.s acetone, alcohol, chloroform, ethyl acetate, toluene
15529–49–4 (2395697)
Hydrogenation Dehydrogenation Oxidation
Ru–100
55466–76–7 (2596537)
Available also in solution in acetic acid
Ru–112
s. alcohol, chloroform Xn CSNYFT
52462–29–0 ( –– )
Hydrogenation Ru–120 Transfer hydrogenation Chiral hydrogenation precursor
s. chloroform
90614-07-6
Chiral Hydrogenation Ru–121 Reduction of CO groups
114615–82–6 ( –– )
Selective Oxidation
14898–67–0 * (2331675)
Catalyst precursor Available in solution
vs. acetic acid, water sl.s. acetone
s. dichloromethane, acetonitrile i. water
Xi, N
O, Xi CSNYFT
v.s water s. acetone, alcohol sl.s ethyl acetate
Use and Comments
Catalog No. Ru–41
Ru–130
i. all known solvents
Oxidation
FibreCat® 3001
i. all known solvents
Oxidation
FibreCat® 3002
* CAS No. refers to a specific hydrate © 2008 Johnson Matthey Plc
85
7. Table: Smopex® Metal Scavenging Products Trade name
Product description
Color Dry cont. Pharma %
Dry cont. Tech %
Funct. Cap. (mmol/g)
Std. Fibre Length (mm)
SMOPEX® Smopex-101
Styrene sulfonic acid grafted polyolefin fiber
Beige to brown
na.
>20
>=2.5
0.3
Smopex-102
Acrylic acid grafted polyolefin fiber
White to beige
>95
>20
>=5
0.3
Smopex-103
Styryl trimethylamine grafted polyolefin fiber
White
na.
>20
>=1.5
0.3
Smopex-105
Vinyl pyridine grafted polyolefin fiber
White to beige to yellow
>95
>20
>=3
0.3
Smopex-110
Styryl-based isothiouronium grafted polyolefin fiber
White
na.
>20
>=1.5
0.3
Smopex-111
Styryl thiol grafted polyolefin fiber
White to beige to yellow
>95
>20
>=2
0.3
Smopex-112
Acrylate based “alpha“-hydroxyl thiol grafted polyoleifin fiber
Off-white to white
na.
>20
>=2.5
0.3
Smopex-234
Mercaptoethylacrylate grafted polyolefin fiber
White to beige
>95
>20
>=2
0.3
Smopex-301
Styryl diphenylphosphine grafted polyolefin fibre
White to beige to yellow
na.
>95
>=0.9
0.3
Note: Pharmaceutical grade Smopex® can be used in API product streams and is supplied dry to conform with limits on residual solvents. Technical grade Smopex® is supplied with variable dry content.
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8. Glossary of Terms API
The Active Pharmaceutical Ingredient in a drug formulation.
Asymmetric catalysis
A catalytic reaction that produces a chiral molecule by controlling the reaction directly to give single enantiomer yields approaching 100%.
Chemisorption
Adsorption which involves the formation of a chemical bond between the adsorbed atom/molecule and the catalyst surface.
Chemo-catalyst
A man-made material used for catalysis – often containing a PGM as the active component (see definition of PGM).
Chemoselectivity
A reaction is chemoselective when it converts exclusively or preferentially one functional group in the presence of other functional groups.
Chiral
A molecule is chiral if its image and mirror image are not superimposable.
Chiral auxiliary
Chiral compounds such as solvents, additives, reactants which transform prochiral precursors to one of the two enantiomers preferentially.
Chiral molecule
Molecules that are not superimposable with their mirror images (e.g. the right and left hand are mirror images which are not superimposable).
Chiral pool
Naturally occurring chiral molecules, such as carbohydrates, hydroxycarboxylic acids, amino acids, terpenes, alkaloids etc.
Co-catalyst
A substance which adds its own activity (or deactivation) for the considered reaction to the catalyst itself and increases the overall rate of reaction by a synergetic contribution to the basic activity of the main catalyst.
Diastereomers
Structures with more than one chiral center and are not enantiomers. e.g. an R,R structure and an R, S structure. The R centers are identical while the R and S centers are enantiomers.
Enantiomer
The two forms of a chiral molecule. One enantiomer is the mirror image of the other. Distinguished as (R)- and (S)-isomers.
Enantioselective
A reaction or catalyst is called enantioselective if one of the product enantiomers is produced preferentially from a prochiral substrate. Also known as asymmetric.
Enantioselectivity (ee)
The selectivity of an enantioselective reaction is expressed as enantiomeric excess(ee), and is defined as: ee = [R] – [S] x 100% [R] + [S] Also known as optical yield (oy).
Hüttig Temperature
Temperature at which surface atoms become significantly mobile (= 0.3Tm in Kelvin).
Hydrogenolysis
Cleavage of a bond by reaction with molecular hydrogen in the presence of a catalyst.
Intermediates
Chemical substances isolated along the synthesis route to the API (see definition of API).
Ligand
In the context of this handbook, the ligand is a chiral molecule that is attached to the metal atom (which is responsible for the catalytic activity). The presence of the ligand, mainly through its shape and bulk close to the active metal, induces chirality in the product of the catalytic reaction.
Organometellic compound
Molecules containing carbon-metal linkage; a compound containing an alkyl or aryl radical bonded to a metal, such as tetraethyllead, Pb(C2H5)4. However, the definition of organometallic is often broadened to include a variety of ligands such as phosphines, amines, and CO.
% Conversion
The % substrate which is reacted to form reaction products.
% Selectivity
The quantity of desired product expressed as a percentage of the total reaction products.
% Yield
The % conversion x % selectivity, e.g. 90% conversion at 90% selectivity gives 81% yield.
Platinum Group Metals (PGM)
Pd, Pt, Rh, Ru, Ir, Os
Precious Metals (PM)
Pd, Pt, Rh, Ru, Ir, Os, Ag, Au
Prochiral
A molecule is prochiral if it has one symmetry element (plane or inversion centre). Reactions that destroy this symmetry element lead to chiral molecules. Also known as achiral.
© 2008 Johnson Matthey Plc
87
Glossary of Terms – continued Promoter
Dopants added to catalysts to improve their action – activity, selectivity or stability.
Racemate
A 1:1 mixture of enantiomers.
Regioselectivity
A reaction is regioselective when it takes place at only one of two or more possible functional groups to form just one of two possible isomers.
Substrate
Starting material (or reactant or feedstock) for the catalytic reaction.
Smopex®
Unique scavenging system where metal binding functionality is grafted onto fibres allowing the effective recovery of a range of precious metals.
Tammann temperature
Temperature at which lattices begin to be appreciably mobile (=0.5Tm in Kelvin).
Tm
Melting point in Kelvin.
Turnover number (TON)
The number of molecular reactions or reaction cycles occurring at the reactive centre up to the decay of activity. Specifies the maximum use that can be made of a catalyst for a particular reaction under defined reaction conditions.
VOC
Volatile Organic Compound.
9. Other publications from Johnson Matthey Platinum Platinum is an annual review of world supply and demand for the PGMs, published each year in May. It is updated after 6 months by an Interim Review. The review contains a market summary and outlook, information on supplies, mining and exploration, discussions of the markets for platinum, palladium and other PGMs, information on prices and futures and a breakdown of supply and demand.
Platinum should be read by anyone involved in sourcing decisions involving PGMs. Copies are available free and can be obtained by contacting your local Johnson Matthey office (see section 10).
Platinum Metals Review Platinum Metals Review is a quarterly journal of scientific research on PGMs, published by Johnson Matthey. It covers all areas in which PGMs find application, and not just catalysis. It is freely available on the internet at: http://www.platinum.matthey.com
Those wishing to subscribe to Platinum Metals Review or to submit papers for publication should contact Johnson Matthey offices or the Editor, 40-42 Hatton Garden, London EC1N 8EE; E-mail:
[email protected]
Catalytic Reaction Guide The Catalytic Reaction Guide, available free from Johnson Matthey, is a pocket-sized slide chart setting out over 100 reaction types and giving, for each, recommendations covering catalyst type, catalytic metal and reaction conditions. It is very useful as a first point of reference.
New Catalyst Development for Cross-Coupling Reactions Includes examples of catalysts for application in C-C, C-N, C-O, C-S coupling reactions.
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© 2008 Johnson Matthey Plc
10. Addresses of Local Offices UNITED KINGDOM Johnson Matthey Plc Orchard Road Royston Hertfordshire SG8 5HE Tel: (44) 176 325 3000 Fax: (44) 176 325 3419 e-mail:
[email protected] Johnson Matthey Plc 33 Jeffreys Road Brimsdown Enfield Middlesex EN3 7PW Tel: (44) 208 804 8111 Fax: (44) 208 804 1918 Johnson Matthey Plc Technology Centre Blounts Court Sonning Common Reading Berkshire RG4 9NH Tel: (44) 118 924 2000 Fax: (44) 118 944 2254 Johnson Matthey Plc PO Box 88 Haverton Hill Road Billingham Cleveland TS23 1XN Tel: (44) 1642 525 343 Fax: (44) 1642 522 542 Johnson Matthey Plc 28 Cambridge Science Park Milton Road Cambridge CB4 0FP Tel: (44) 1223 226160 Fax: (44) 1223 438037 AUSTRALIA Johnson Matthey (Aust) Ltd 339 Settlement Road Thomastown Victoria 3074 Tel: (61) 3 9465 2111 Fax: (61) 3 9466 4932
© 2008 Johnson Matthey Plc
AUSTRIA Johnson Matthey & Co GmbH Steckhovengasse 12 A 1132 Vienna Tel: (43) 187 79890 Fax: (43) 187 798903 BELGIUM S.A. Johnson Matthey N.V. Avenue de Bâle 8 – Bazellaan 8 B – 1140 Brussels Tel: (32) 2 729 07 43 Fax: (32) 2 726 90 61 BRAZIL Johnson Matthey Brazil Rua Dr. Jesuino Maciel, 919 Campo Belo 04615-002 São Paulo – SP Tel: (55) 11 5561 3805 Fax: (55) 11 5561 3098 CHINA Johnson Matthey (Shanghai) Catalyst Co., Ltd. 88 Dong Xing Road Songjiang Industrial Zone Shanghai P.C. 201613 Tel: (86) 21 33528282-6210 Fax: (86) 21 33528728 email:
[email protected] CHINA – HONG KONG Johnson Matthey Hong Kong Ltd Suites 2101 CMG Asia Tower The Gateway 15 Canton Road Tsimshatsui Kowloon Tel: (852) 27380327 Fax: (852) 27362345 CZECH and SLOVAC REPUBLICS Johnson Matthey V sadech 4 – Bubenec 160 00 Prague 6 Tel: (420-2) 24321549 (420-2) 24320367 (420-2) 33332384 Fax: (420-2) 24320433 DENMARK Johnson Matthey A/S Frederikssundvej 274D Bronshoj 2700 Copenhagen Tel: (45) 3889 6200 Fax: (45) 3889 6201 89
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[email protected] ISRAEL N. Intrater & Associates 5 Lurie Street P O Box 21016 Tel Aviv 61210 Tel: (972) 3629 2965 Fax: (972) 3528 8008 ITALY Please contact our Royston, UK facility for all inquiries
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JAPAN Johnson Matthey Japan Inc The Imperial Tower 14th Floor 1-1-1 Uchisaiwai-cho Chiyoda-ku Tokyo 100-0011 Tel: (81) 3 5511 8551 Fax: (81) 3 5511 8561 email:
[email protected] KOREA Johnson Matthey Korea Ltd 6th Floor, Woonam Building 294 Chamsil-dong Songpa-ku Seoul Tel: (82) 2 3431 3816 Fax: (82) 2 3431 3819 PORTUGAL Lusomelt – Fornecimento de bens e Serviços, Lda Rua de Belém, 48 – 2˚ P-1300-085 Lisbon Tel: (351) 21 361 62 10 Fax: (351) 21 363 49 95 RUSSIA Johnson Matthey Moscow Ilyinka 3/8 Building 5, Office 301 Moscow 109012 Russia Tel: 7095 101 2100 Fax: 7095 101 2113 SOUTH AFRICA Johnson Matthey (Pty) Limited Henderson Road South Gerniston Ext 7 Gauteng 1401 Republic of South Africa Tel: (27) 1134 58 500 SPAIN C.J. Chambers Hispania S.L. Apartado 92 08840 Viladecans Barcelona Tel: (34) 607 811 550 Fax: (34) 936 376 913
© 2008 Johnson Matthey Plc
SWEDEN Please contact our Royston, UK facility for all inquiries SWITZERLAND Johnson Matthey & Brandenberger AG Glattalstrasse 18 CH-8052 Zurich Tel: (41) 1 307 19 19 Fax: (41) 1 307 19 20
USA Johnson Matthey Inc 2001 Nolte Drive West Deptford New Jersey 08066 1727 Tel: (1) 856 384 7000 Fax: (1) 856 384 7282 e-mail:
[email protected]
TAIWAN Johnson Matthey Pacific Ltd Taiwan Branch 9F-3, 51 Keelung Road Section 2 Taipei Tel: (886) 2 23786818 Fax: (886) 2 27366558
Information contained in this publication is given in good faith, but Johnson Matthey will accept no liability for any claims made against a customer for any infringement of patent rights, registered or unregistered trademarks (including any copyright therein) or of registered designs or copyright involved in the use, resale or offering for resale of the compound either as sold by Johnson Matthey or otherwise. While Johnson Matthey has taken all reasonable care to ensure the accuracy of the contents of this brochure, it is incumbent on the user to exercise due care and diligence when handling these materials. Johnson Matthey can therefore accept no liability for loss or damage arising from their use. Ref 01.04 / UK © 2008 Johnson Matthey Plc
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