FInaL Report l Exp 2 l CHM143L

PRELIMINARY TESTS AND SOLUBILITY CLASSIFICATION OF ORGANIC COMPOUNDS 1

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Ayson, Jose Paolo L. , Gomez, Ricky Jay, C. , Loyzaga, Earah Llou B. 1

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Student (s), CHM143L/B11, School of Chemical Engineering, Chemistry and Biotechnology, Mapua Institute of Technology

ABSTRACT This experiment compromises of different purposes by which all of these must be satisfied. It enables us to examine various compounds using different preliminary tests, to identify the solubility class of various organic compounds, and to examine and to identify an unknown compound through preliminary tests and through its solubility classes. This experiment basically deals with the classification of organic compounds through the use of two major qualitative schemes in identifying an organic compound which are: characterization of the physical properties in identifying unknown organic compounds and the solubility classification of various organic compounds. The physical property of a compound involves its color, odor and ignition properties. For the preliminary test, copper nitrate, acetic acid and an unknown were used while butyl bromide, ethanol, sucrose, buteraldehyde, ethanoic acid, methylamine, nitro phenol, diethyl ether, benzoic acid and propanone were used in solubility classification tests. Preliminary tests help us to be familiar with different with organic compounds and knowing the solubility of the unknown with various compounds enables us to identify accurately its solubility class. Keywords: Keywords: Electrophilic Aromatic Substitution, Substituent, Temperature, Solvent, Rates of reaction

INTRODUCTION

Organic compounds are compounds derived from living organisms. These organic compounds can be formed into simpler or more complex compound through the functional groups attached into. Different classifications of organic compounds can be determined by the orientation of its structures. One basic way to differentiate an organic compound with the other is by taking into account its physical properties. The phase of a compound can be related to its relative solubility and relativity. The color of the compound may indicate the presence of impurities or it is due to the presence of large chromophoric groups of molecule. Regarding to the odor of each compounds, precise description may not be feasible. Ignition test is another way to classify an organic compound. The flame resulting from ignition of sample helps in identifying the nature of the compound. The oxygen content of a compound may be determined from the color of the flame it produces.

Organic compounds can be classified as alcohols, phenols, aldehydes, ketones, carboxylic acids and derivatives, and amines depending on the substituent attached to the compound. compound.  An alcohol is a compound that has a hydroxyl group (-OH) bonded to a saturated, sp3hybridized carbon atom. The general formula of alcohols is ROH in which the R is an aliphatic hydrocarbon group, so alcohols may be looked upon as a derivative of water, HOH. Phenols are closely related to alcohols because of the presence of the hydroxyl ( OH) group. In phenols, phenols, however, however, the hydroxyl group is directly bonded to an aromatic group, such as benzene.  Aldehydes are organic compounds with carbonyl functional group and have one hydrogen attached to the carbonyl carbon. While, ketones have also carbonyl functional group but have two carbons attached to the carbonyl carbon. Carboxylic acids and their derivatives are one of the abundant compounds in both laboratory and living organisms. With these derivatives of carboxylic acids the most common are acid halides, acid anhydrides,

esters, and amides. Compounds that are carboxylic acid have the general formula of RCO 2H. Acid halides are organic compounds that have a general formula of RCOX; the X being the halide group. For compounds with general formula of RCO 2COR’, it is classified as acid anhydrides; R being the alkyl group and R’ being different from that of the first alkyl group. In esters, the general formula for its structure is RCO2R’ and for amides its structure’s general formula is RCONH2.  Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. This lone pair of electrons on the nitrogen makes amines basic and nucleophilic. Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a liquid solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on temperature and pressure. The extent of the solubility of a substance in a specific solvent is measured as the saturation concentration where adding more solute does not increase the concentration of the solution. This experiment covers a wide range of topics in which the previous experiments will be very much useful in terms of the solubility tests that are accompany by different kinds of organic compounds. The different tests for the solubility will serve as the guide for the determination of the class in which the compounds belong to. In this experiment, there are several tests applied to each reagent to analyze, examine and differentiate the different kinds of an organic compound. In part I, the physical properties of a given sample will be analyzed to verify what kind of organic compound it is. In part II, different reagents will be reacted to the test compounds and by its solubility with the reagents; this will substantiate the class where the test compounds belong. MATERIALS AND METHODS

The reagents used for this experemint are copper nitratre, ethanol, ethanoic acid, diethyl ether, 5% and 15% HCl, 5% NaHCO3, acetic acid, sucrose, metyl amine, benzoic acid, concentrated H 2SO4, butyl bromide, buteraldehyde, nitro phenol, propanone, 5%NaOH and an unknown sample. The following reagents were accompanied by several laboratory equipments such as pipettes, clay triangle, iron stand, test tube rack, bunsen burner, micro test tubes with cork stopper, crucible and cover and nichrome wire. The experiment is subdivided into two different parts. The first is the preliminary tests and the second is solubility classification tests. PRELIMINARY TEST This test has been used to determine the physical state, the color and the odor of the three different compounds namely copper nitrate, acetic acid and an unknown sample. Ignition test for each compound is also taken into account. For the physical state, note whether the compound is a solid or a liquid. For the color, observed its original color and the change of its color upon reaction with other reagents. For the odor, examine the odor through smelling the compounds, but do not inhale it directly. Lastly, for the ignition test, place a small amount of the compound, approximately 0.10 grams if solid and 0.5 mL if liquid, in a porcelain crucible. Heat it by increasing the flame slowly until the ignition is complete. During the ignition, observe the flammability and the nature of the flame, if the compound is solid, note whether it melts and examine the manner by which it melts, the odor of vapor or gas that evolves and the residue left after ignition if any. If there is residue left, add a drop of distilled water and test the solution with litmus paper, then add a drop of 15% HCl and note if gas has evolved. Afterward, perform the flame test on the solution produced using the nichrome wire in order to determine the metal present. SOLUBILITITY CLASSIFICATION TEST This test will classify the group where the test compounds belong to. Place 1 mL of water in a micro

test tube then add a drop of butyl bromide to the solvent. Shake the test tube to ensure mixing. Observe whether a solution forms when butyl bromide is added to the solvent. Follow scheme 1.1 for identifying the solubility of butyl bromide and use scheme 1.2 to identify the possible compounds present in butyl bromide. The same procedure will be followed for the following compounds: ethanol, sucrose, buteraldehyde, ethanoic acid, metyl amine, nitrophenol, diethyl ether, benzoic acid and propanone. Note that few substance of the test compound must be reacted with water, if liquid or solid, add a drop or add a pinch respectively. RESULTS AND DISCUSSION

The first part of the experiment was to test and analyze copper nitrate, acetic acid and the two unknown compounds by conducting different preliminary tests. Compounds

Copper nitrate

 Acetic Acid

Unknown 1 (3a)

Unknown 2 (3b)

Physical State

Liquid

Liquid

Liquid

Liquid

Color

Blue

White/Colorl ess

Colorless

Colorless

Odor

Foul odor

Strong Sour Odor (Vinegar)

Odorless

Good scented

Ignition Test

Green residue, Produced green flame (with metal) and have foul smell

No residue, Orange flame ( no metal)

White crystalize d residue, Produced bright yellow flame (with metal)

No residue, Flammable , Orange flame ( no metal)

TABLE 1: Physical Properties of Known and Unknown Compounds In table 1, physical properties of copper nitrate, acetic acid and the two unknown compounds were listed. Copper nitrate contains the Cu+ metal that is why when it is subjected to fire it produces green color of flame because the metal present in the

solution reacted with the fire subjected into it. The presence of oxygen in the compound causes the change in color of the flame. Copper nitrate contains several oxygen that are highly reactive when subjected to fire. With regards to its odor before ignition it is faint foul odor but as the ignition test was performed it gives off a strong foul odor and the compound which is initially a blue liquid became a green ash like residue. Due to its physical properties, copper nitrate can be classified as a non-organic compound since it has no distinct odor and it contains metal that is not common to every organic compound. The acetic acid contains -OH group which is the functional group common to all of the alcohols and phenols that is why they are flammable. In relation to its flammability, when acetic acid is subjected to fire, the flame that is produced did not change into other color which indicates that there is no metal present in the compound. Also, the compound produces a vinegar-like odor which is very common to all of the carboxylic acid. With all the properties it possesses, acetic acid can be verified that it belongs to the carboxylic acid group. For the first unknown sample, the flame produced in the ignition test is a yellow flame indicating that the compound has a metal in it. Based on research, the metal that produces a yellow flame when subjected to fire is sodium metal. Therefore, the first unknown has a sodium metal. Also, the compound is odorless and colorless just like the test in copper nitrate which also has a metal. The first unknown compound can be classified as a nonorganic compound since the observed properties are similar to the properties of copper nitrate. For the second compound, the compound has a good fragrance that is common for esters, carboxylic acids and aromatic compounds which are all organic. Also, these organic compounds are characterized to be flammable. Therefore, comparing the result of the second unknown compound to acetic acid the second unknown compound is most probably an organic compound.

In part two of the experiment, several test compounds have been reacted with different solvents to determine its solubility for it to identify what kind of organic compound it is. Butyl bromide, ethanol, sucrose, buteraldehyde, ethanoic acid, methyl amine, nitro phenol, diethyl ether, benzoic acid and propane was used to react with several solvents. By the name of the compounds, it is possible to determine what kind of organic compound does each of these compounds belongs to, but even if it is already given, several tests will be applied to them to verify their classification. Compounds

Butyl bromide

Ethanol

Sucrose

Buteral  dehyde

Ethanoic acid

Water Ether HCl NaOH NaHCO3 H2SO4 Reaction to Litmus Reaction to Phenolp hthalein Solubility Class

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neutral

neutral

neutral

Acid

Acid

No reaction

No reaction

No reaction

No reaction

No reaction

N

Sn

S

X

Sa

Compou nds

Water Ether HCl NaOH NaHCO3 H2SO4 Reaction to litmus Reaction to Phenolp hthalein

Methy  Nitrop l henol amine

Diethy  Benz  Propa l ether oic ne  Acid

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Basic

acid

Basic

acid

neutra acidic Neutra l l No acid No reactio reactio n n

Solubility S Sa B Sn Class TABLE 2: Solubility Test of different Compounds in every Solvent In table 2, every test compounds have their own solubility for every solvent given. These solubility will determine the group where these test compounds fit in. Butyl bromide belongs to the alkyl halide group.  Alkyl halides have little solubility in water but good solubility with nonpolar solvents, such as hexane. Many of the low molecular weight alkyl halides are used as solvents in reactions that involve nonpolar reactants. Sucrose belongs to the carbohydrate group. Carbohydrates serve as an abundant, diverse, and reusable source of carbon, their derivation for industrial applications is still a challenging task because of the low solubility in solvents other than water. For the benzoic acid and ethanoic acid, these two compounds belong to the carboxylic acid. Basically, this can be confirmed due to its given name, but observing the results, ethanoic acid belongs to class Sa, which signifies that it is a monofunctional carboxylic acids with five carbons or fewer compared to the benzoic acid that falls to class  A1 that indicates a strong organic acids which is a carboxylic acids with more than six carbons. For the methyl amine, it can be seen in table 2 that it is soluble in water. Similar to alcohols, amines are highly polar due to the lone pair in the nitrogen atom. Thereby, amines of those with fewer than five carbon atoms are generally water-soluble. For nitrophenol and ethanol, both of these compounds are classified as an alcohol, but both of these compounds have different orientation with regards to their structures. The results in table 2 show that small alcohols are completely soluble in water for whatever proportions they would be mixed. Buteraldehyde can be classified as an aldehyde organic compound. Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water. Propanone belongs to the ketone organic compound. The carbonyl group is polar as a consequence of the fact that the electronegativity of the oxygen center is greater than that for carbonyl carbon. Thus, ketones are nucleophilic at oxygen and electrophilic at carbon.

Because the carbonyl group interacts with water by hydrogen bonding, ketones are typically more soluble in water than the related methylene compounds. Diethyl ether can be classified as ether, basically by its given name. Ethers are slightly polar, as the COC bond angle in the functional group is about 110 degrees. Ethers are more polar than alkenes but not as polar as alcohols, esters, or amides of comparable structure. However, the presence of two lone pairs of electrons on the oxygen atoms makes hydrogen bonding with water molecules possible. Unkno Wat  Eth H  NaO NaHC  H2S wn er er Cl H O3 O4       1 (3a)       2 (3b) Unknown 1 (3a) 1(3b) Reaction to No Reaction Acid limus Reaction to No Reaction Acid Phenolphthalei n Solubility S Sa Class Possible Salts of organic Monofunctional Compounds acids; amine carboxylic hydrochlorides; acids, aliphatic amino acids; and aromatic polyfunctional acids with five compounds with carbons or hydrophilic fewer; functional arylsulfonic groups: acids. carbohydrates, polyhydroxy compounds, polybasic acids. TABLE 3: Solubility Test of the Unknown Samples in a given Solvent

In table 3, the two unknowns were tested for their solubility. For the first unknown, the compound is soluble for water, HCl, NaOH, and H2SO4 while it is insoluble for ether and NaHCO3. Therefore, since the compound is soluble in water we can conclude that it is a polar compound and since in the preliminary test

the compound contains metal which is sodium metal the first sample compound can be classified as class S. Meanwhile, the second unknown compound was soluble for all the solvents accept H2SO4. Therefore, the compound is polar since it is soluble in water. Furthermore, in the preliminary test it was concluded that the compound is an organic compound that resembles the properties of ether or aromatic compounds. By the principle, that “like dissolves like” the second unknown compound was classified to be a class Sa since the compound was dissolved in ether. CONCLUSION In this experiment, determination of the unknown compounds was performed using the two major schemes in identifying organic compounds: preliminary tests and solubility classification tests was done. Also, different tests and reactions were used to differentiate organic compounds such as their physical property and by their solubility. Moreover, different solvents such as water, ether, HCl, NaOH, NaHCO3 and H2SO4  were used in determining the class of each compound.

Even though there are errors made during the experiment, corrections were considered and that the use of the preliminary tests and solubility classification thoroughly identified the different characteristics of organic compounds that resulted to incorrect classification. In the first part of the experiment, observation and analysis of the physical properties was done. Physical properties of a given organic compound are one of the factors in classifying its identity. All organic compounds have their own distinctive and unique characteristics that can be differentiated to one another. Like the carboxylic acids, they are characterized to have a vinegar-like odor while the amines are known by their fish-like odor. For further determination, the solubility classification test was done to both known and unknown compounds using various solvents in order to identify their solubility class and support it with the data obtained from the preliminary tests. The samples were most probably salts of organic acids since the first sample contains

sodium metal and a carboxylic acid or an aromatic acid since the second sample was classified as an Sa class. In this experiment, it is a must to carefully follow the procedures written in the manual, be clear about the changes that can be seen and take note of it as well, be careful in inhaling the gases released by the gases of the volatile organic compounds and also proper laboratory attire must be worn.

REFERENCES

1. Klein, D. Organic Chemstry. C&E Publishing, Inc. 2.

Bruice, P.Y. (2004). Organic Chemistry  (4th ed). Pearson Prentice Hall, North America.

3.

Baluyut, J.Y. G., and De Castro, K. A., Organic Chemistry Laboratory Manual For Chemical Engineering Students Part 2.