Alkyne All

Chapter 8 8.1 Name the following compounds: (a) CH3

CH3 CH3CHC

CCHCH3

2,5-dimethyl-3-hexyne (b) CH3 HC

CCCH3 CH3

3,3-dimethyl-1-butyne (c) H3CHC

CHCH

CHC

CCH3

2,4-octadiene-6-yne (d) H 3C H3CH2CCC

CCH2CH2CH3

H 3C

3,3-dimethyl-4-octyne (e) H3C H3CH2CCC

CH3 CCHCH3

H3C

2,5,5-trimethyl-3-heptyne (f)

6-isopropyl-cyclodecyne 8.2 There are seven isomeric alkynes with the formula C6H10. Draw and name them. Solution:

1-Hexyne

2-Hexyne

3-Hexyne

3-methyl-1-pentyne

4-methyl-1-pentyne

4-methyl-2-pentyne

3,3-dimethyl-1-butyne

8.3 What products would you expect from the following reactions? (a) H2 C H3 C

C C H2

CH

+

Cl

H2 C H 3C

2Cl 2

C H2

Cl

C

CH

Cl

Cl

(b)

C

+

CH

C

HBr

CH2

Br

(c) H2 C

H2 C H 3C

C H2

C C

CH3

+

C 4H 9

HBr

8.4 What product would you obtain by hydration of the following alkynes?

C

Br

H C

CH3

(a)

hydration C 3H 7

C

C3H 7

C

C3H 7

H2 C

C

C3H 7

O (b)

3HC H3 C

CH

hydration H2 C

C

C

3HC

C 3H 7

H3 C

CH

H2 C

C O

8.5 What alkynes would you start with to prepare the following ketones? O

O

(a)

CH3CH2CH2CCH3

(b)

CH3CH2CCH2CH3

Solution: (a)

CH3CH2CH2C

CH (b)

CH3CH2C

CCH3

8.6 What alkyne would you start to prepare each of the following compounds by a hydroboration / oxidation reaction?

O

CH3

CH2 CH

O

CH3CHCH2CCHCH3 (a)

CH3

(b)

Solution: CH

CH3

C

CH3CHC (a)

(b)

CCHCH3 CH3

8.7 How would you prepare the following carbonyl compounds starting from an alkyne?

C C 3H 7 H2

Br

O

O solution: Br

Br

HgSO4, H3O O

O

1.BH3 2.H2O2 / NaOH 8.8 Using any alkyne needed, how would you prepare the following alkenes? (a) trans-2-Octene (b) cis-3-Heptene (c) 3-Methyl-1-pentene solution: (a)

Li,NH3 (b)

H2 Lindlar catalyst (c)

H2 Lindlar catalyst

8.9 Propose structures for alkynes that give the following products on oxidative cleavage by KMnO4: (a) CO2H

+

CO2

(b) 2CH3(CH2)7CO2H + HO2C(CH2)7CO2H Solution: The structure is: (a)

(b) CH3(CH2)7C≡C(CH2)7C≡C(CH2)7CH3

8.10 The pKa of acetone, CH3COCH3, is 19.3. Which of the following bases is strong enough to deprotonate acetone? (b) Na+ -C≡CH (pKa of C2H2 = 25)

(a) KOH (pKa of H2O = 15.7) (c) NaHCO3 (pKa of H2CO3 = 6.4)

(d) NaOCH3 (pKa of CH3OH = 15.6)

Solution: (b) Because pKa (C2H2) > pKa (CH3COCH3) 8.11 Show the terminal alkyne and alkyl halide from which the following products can be obtained. If two routes look feasible, list both. Answer: (a) H3CH2 CH2CC H3CH2CH2C

C

C

CH3

3HCC

CH CH

Br

CH3

Br

CH2CH2CH3

(b)

H3C

H3C H3CHC

C

C

CH2CH3

H3CHC

CCH3 C

C

CH

Br

CH2CH3

CH C

BrCH3 (c) 8.12 How would you prepare cis-2-butene starting from propyne, an alkyl halide, and any other reagents needed? This problem can’t be worked in a single step. You’ll have to carry out more than one

reaction. Answer: H3CC

CH

NaNH2 NH3

BrCH3 THF HC

H2 H3CC

CCH3

Lindar catalyst

H3CC

CCH3

CH

H3C

CH3

8.13 Beginning with 4-octyne as your only source of carbon and using any inorganic reagents necessary, how would you synthesize the following compounds? (a) Butanoic acid

(b) cis-4-Octene

(d) 4-Octanol (4-hydroxyoctane)

(c) 4-Bromooctane

(e) 4,5-Dichlorooctane

Solution: (a) O

KMnO4 H3O

2

OH

(b) H2 Lindler catalyst

(c) H2 Lindler catalyst

HBr, ether

Br

(d)

H2 Lindler catalyst

1.BF3 , THF 2.H2 O2 , OHOH

(e) H2 Lindler catalyst

X2 CH2Cl2 Cl

Cl

8.14 Beginning with acetylene and any alkyl halides needed, how would you synthesize the following

compounds? (a) Decane

(b) 2,2-Dimethylhexane

(c) Hexanal

(d) 2-Heptanone

Solution: (a)

NaNH2

Na C

CH

CH3 CH2 CH2CH2CH2CH2CH2CH2Br

2H2 Pd/C

(b)

NaNH2

Na C

(CH3)3CCH2CH2Br

CH

2H2 Pd/C

(c) NaNH2

Na C

CH

CH3CH2CH2CH2Br 1.BH3 2.H2O2

O

(d)

NaNH2

Na C

CH

CH3CH2CH2CH2CH2Br

H2 SO4, H2O HgSO4

O

8.15 Name the following alkynes, and predict the products of their reaction with (i) H2 in the presence

of a Lindlar catalyst and (ii) H3O+ in the presence of HgSO4:

(a) HC

(b)

CH3

H3C

H3C

C

C C H2

H2C

CH3

CH3

HC C H2

C

C

CH2 CH H3C

Solution:

CH3

t Ca /L in dl ar 2

H

SO Hg /H

4

+

O

3

O

H

i /L

rC la nd

at

2

H O gS /H

4

+

O

3

O

8.16 From what alkyne might each of the following substances have been made?

(b)

(a) CH3 H2 C

CH H3C

C H2

H2 C

O C H

H2 C

H2 C C H

CH3 H C

Cl C

C H2

CH3

Cl

Solution: (a) is from CH3

H2 C

CH H3C

H2C

C

CH

4-Methyl-pentyne

H2 C

H2 C C H

CH3 H C

C

CH

C H2

and (b) is from 1-Ethynyl-2-methyl-cyclohexane

8.17 How would you prepare the following substances, starting from any compounds having four

carbons or fewer? HO

HC

CH

(a)

H3 C

C H2

CH2 C H2

OH

HO H C

CH

Solution:

H3C

CH2

Zn(Cu) Ether H 3C

C H2

CH2

HC

CH

C H2

C H2

O H2 C

H2C

C

C

C H2

(b)

CH3

H

O H2 C

H2C

C

C

C H2

CH

HgSO4

H

Solution:

H2 C

H2SO4, H2O H2C

C

C C H2

CH3

H

8.18 The following cycloalkyne is too unstable to exist. Explain.

H2C

CH2 C H2

Solution: It’s not possible to form a small ring containing a triple bond because the angle strain that would result from bending the bonds of an SP-hybridized carbon to form a small ring is too great. 8.19 Give IUPAC names for the following compounds. CH3

CH3 CH2C

CCCH3 CH3

a. b.

CH3C

CCH2C CH3

c. CH3CH

CC

CCH2CH3 CH3

CCHCH3

CH3

HC

CCCH2C

CH

CH3

d. e. H2 C

CHCH

CHC

CH

CH2CH3

CH3CH2 CHC f.

CCHCHCH3

CH2CH3

CH3

Solution: a. 2,2-Dimethyl-3-hexyne b. 2,5-Octadiyne c. 3,6-Dimethyl-2-heptene-4-yne d. 3,3-Dimethyl-1,5-hexadiyne e. 1,3-Hexadiene-5-yne f. 3,6-Diethyl-2-methyl-4-octyne 8.20 Draw structures corresponding to the following names:

a. 3,3-Dimethyl-4-octyne b. 3-Ethyl-5-methyl-1,6,8-decatriyne c. 2,2,5,5-Tetramethyl-3-hexyne d. 3,4-Dimethylcyclodecyne e. 3,5-Heptadien-1-yne f. 3-Chloro-4,4-dimethyl-1-nonen-6-yne g. 3-sec-Butyl-1-heptyne h. 5-tert-Butyl-2-methyl-3-octyne

Solution:

a.

3,3-Dimethyl-4-octyne

b.

3-Ethyl-5-methyl-1,6,8-decatriyne

c. 3,6-Dimethyl-2-heptene-4-yne

d. 3,4-Dimethylcyclodecyne

e.

3,5-Heptadien-1-yne

Cl

f.

g.

3-Chloro-4,4-dimethyl-1-nonen-6-yne

3-sec-Butyl-1-heptyne

h. 5-tert-Butyl-2-methyl-3-octyne 8.21 The following two hydrocarbons have been isolated from various plants in the sunflower family.

Name them according to IUPAC rules. (a) H3C

C H

C H

C

C

C

C

C H

C H

C H

C H

C H

CH2

C

C

C

C

C

C

C

C

C

C

C H

CH2

(b) H3C

SOLUTION: (a)

(3E, 5E, 11E)-1,3,5,11-Tridecatetraen-7, 9-diyne.

(b)

1-Tridecene-3, 5, 7, 9, 11-pentayne

8.22. Predict the products of the following reactions. H

H2, Pd/C

H2/Lindlar SOLUTION: A: H2 C

H2 C C H2

B:

CH3

A

B

H C

H C C H

CH2

8.23 A hydrocarbon of unknown structure has the formula C8H10. On catalytic hydrogenation over the

Lindlar catalyst, 1 equivalent of H2 is absorbed. On hydrogenation over a palladium catalyst, 3 equivalents of H2 are absorbed. a) How many degrees of unsaturation are present in the unknown? b) How many triple bonds are present? c) How many double bonds are present? d) How many rings are present? e) Draw a structure that fits the data. Solution: a)

4 degrees of unsaturation are present.

b) 1 triple bond is present. c)

1 double bond is present.

d) 1 ring is present. e)

The possible structure can be:

etc... 8.24 Predict the products from reaction of 1-hexyne with the following reagents:

a) 1 equiv HBr

b) 1 equiv Cl2

c) H2, Lindlare catalyst

d) NaNH2, in NH3, the CH3Br

e) H2O, H2SO4, HgSO4

f)2 equiv HCl

Solution: HCl

a)

1-hexyne

Cl Cl

Cl2

b)

1-hexyne

Cl

H

H

H

H2 Lindlar Catalyst

c)

1-hexyne

NaNH2

d)

1-hexyne

NH3

CNa

CH3Br

O

H2SO4,H2O HgSO4 1-hexyne

e)

Cl

2HCl 1-hexyne

f)

Cl

8.25 Predict the products from reaction of 5-decyne with the following reagents:

(a) H2, Lindlar catalyst. (b) Li in NH3. (c) 1 equiv Br2. (d) BH3 in THF, then H2O2, OH-. (e) H2O, H2SO4, HgSO4. (f) Excess H2, Pd/C catalyst. Solution: H

(a)

H

C4H9 C4H9

H

C4H9. O

(b)

C4H9

C4H9.

(f)

C4H9

C4H9

H

Br

. (c)

O

C4H9

C4H9

. (d)

Br

C4H9

C4H9.

C4H9

(e)

8.26 Predict the products from reaction of 2-hexyne with following reagents:

(a) 2 equiv Br2. (b) 1 equiv HBr. (c) Excess HBr. (d) Li in NH3. (e) H2O, H2SO4, HgSO4 Solution: Br

Br H3C

H3C

(a)

Br

Br

H

Br

H3C

(d)

H

. (b)

H

H

etc.. .

H

H3C

H3C

(e)

Br

C3H7

C3H7

and

Br

C3H7.

Br

Br C3H7

H

C3H7

+

C3H7

H3C

(c)

H3C

H

Br

H

O

C3H7

H3C

and

O

C3H7

8.27 Predict the products of the following reactions:

(a)

CH3CH2CH2CH2 CH2C CH

1.BH3,THF 2.H2O2

O CH3CH2CH2 CH2CH2CH2 CH

Br CH2

(b)

C NaNH2,NH3

CH

Br

Br CH3

C

NaNH2,NH3

CH

(c) 8.28 Hydrocarbon A has the formula C9H12 and absorbs 3 equivalents of to yield B,C9H18 ,when hydrogenated over a Pd/C catalyst. On treatment of A with aqueous H2SO4 in the presence of mercury(II), two isomeric ketones, C and D, are produced. Oxidation of A with KMnO4 gives a

mixture of acetic acid (CH3CO2H) and the tricarboxylic acid E. Propose structure for compounds A-D, and write the reactions. Solution:

A

H2 C C C CH3

C

H2 H2 O C C C

E

(1)

CH3

B

H2 H2 H2 C C C CH3

D

H2 O H2 C C C CH3

H HOOCH2C C CH2COOH CH2COOH H2 C C C CH3

(2)

H2 C C C CH3

(3)

H2 C C C CH3

H2 H2 H2 C C C CH3

H2 Pd/C

H2 H2 O C C C

mercury(II) H2SO4

KMnO4

CH3

H HOOCH2C C CH2COOH CH2COOH

8.29 How would you carry out the following reactions?

H2 O H2 C C C CH3

+

+

CH3COOH

O

(a)

(b)

H3CH2CC

CH

H3CH2 CC

CH

C

(c)

H2SO4, H2O H3CH2C

HgSO4 1, BH3

CCH3

CH3CH2CH2CHO

2, H2O2 CH

C

C

CH3

NaNH2 CH3Br H C

(d)

CCH3

H

H2 Lindlar catalyst

(e)

H3CH2CC

(f)

CH

CH3CH2 CH2 CH2CH

KMnO4

CH2

CH3

CH3CH2CO2H

1. Br2 2. KOH, ethanol

CH3 CH2 CH2CH2C

CH

8.30 Occasionally, chemists need to invert the stereochemistry of an alkene, that is, to convert a cis

alkene to trans alkene, or vice versa. There is no one-step method for doing an alkene inversion, but the transformation can be carried out by combining several reactions in the proper sequence. How would you carry out the following reactions?

(a)

trans-5-Decene

(b)

cis-5-Decene

1. Br2 2. KOH, ethanol 3. H2 , Lindlar catalyst 1. Br2

cis-5-Decene

trans-5-Decene

2. KOH, ethanol 3. Li, NH3 8.31 Propose structures for hydrocarbons that give the following products on oxidative

cleavage by KmnO4 or O3 (a) CO2 + CH3(CH2)5CO2H CO 2H

CH3CO 2H (b)

+

(c) HO2(CH2)8CO2H (d) CH3CHO + CH3COCH2CH2CO2H + CO2 (e) OHCCH2CH2CH2CH2COCO2H + CO2 Solution:

(a)

(b)

(c)

(d)

(e)

8.32 Each of the following syntheses requires more than one step. How would you carry them out?

(a) CH3CH2 CH2C

CH3 CH2CH2CHO

CH

(B) H

(CH3)2CHCH2C

CH2CH3

CH (H3C)2 HCH2C

H

Solution: (a)

H2 Lindlar catalyst

1. O3 2. Zn/H3 O

O

(b) (CH3 )2CHCH2C

CH

(CH3)2 CHCH2C

NaNH2

(CH3)2CHCH2 C

H

Li

CCH2CH3

CH3CH2 Br

CNa

CH2CH3

NH3 (H3C) 2HCH2C

H

8.33 How would you carry out the following transformation? More than one step is needed. H

H C

H2C H3C

H

H CH3

C H2

CH2 H

H2

+

C CH3

H

H C

H

H2C H3C

H CH3

C H2

CH2

8.34 How could you carry out the follow conversion? More than one step is needed.

?

CHO

Solution: OH BH3

PCC

H2O2/OH-

CH2Cl2

8.35 How would you carry out the following transformation? More than one step is needed.

CHO

Br Br

Br2

KOH Ethenal

CH2Cl2

C

C CH

C

KNH2

K

CH3Br

Li NH3

8.36 Synthesize the following compounds using 1-butyne as the only source of carbon, along with any

inorganic reagents you need. More than one step may be needed. (a) 1, 1, 2, 2-Tetrachlorobutane Solution: Cl HC

C

CH2

CH3

Cl2 CH2Cl2

CH2CH3 C

Cl2 CH2Cl2

C

H

H

Cl

Cl

Cl

C

C

Cl

Cl

CH2

CH3

(b) 1, 1-Dichloro-2-ethylcyclopropane Solution: H HC

C

H2 C

CH3

H2 Lindlar catalyst

C H

(c) Butanal Solution：

H

Cl

CHCl3 KOH

C CH2CH3

Cl C

H2C

CH

CH2

CH3

H HC

C

CH2

H2

CH3

H C

Lindlar catalyst H

H

OH

H

C

C

H

H

CH2

1. BH3, THF

C

2. H2 O2, OHCH2CH3

CH3

8.37 How would you synthesize the following compounds from Acetylene and any alkyl halides with

four or fewer carbons? More than one step may be required. (a) CH3CH2CH2C CH (b) CH3CH2C CCH2CH3 (c) (CH3)2CHCH2CH CH2 (e) CH3CH2CH2CH2CH2CHO

HC CH

O (d) CH3CH2CH2CCH2CH2CH2CH3

NaNH2

Solution: (a)

CH3CH2CH2Br

HC C Na

NH3

THF

CH3CH2CH2C CH

(b) HC CH

NaNH2 NH3

HC C Na

CH3CH2Br THF

CH3CH2 C CH

CH3CH2Br NaNH2 CH3CH2C CCH2 CH3 CH3CH2C C Na NH3 THF

(c) HC CH

NaNH2 NH3

HC C Na

(CH3 )2CHCH2Br

(CH3)2CHCH2C CH

H2 (CH3)2CHCH2CH CH2 Lindlar catalyst

(d) NaNH2 NaNH2 CH2CH2CH2Br CH3CH2CH2Br HC C Na CH3CH2 CH2C C Na CH3CH2CH2C CH NH3 NH 3 THF THF O H2 SO4,H2O CH3CH2 CH2CCH2CH2CH2CH3 CH3CH2CH2 C CCH2CH2CH3 HgSO4 HC CH

(e) HC CH

NaNH2 CH3CH2CH2CH2Br 1.BH3 HC C Na CH3CH2 CH2CH2C CH NH3 2.H2O 2 THF

CH3CH2CH2 CH2CH2CHO

8.38 How would you carry out the following reactions to introduce deuterium into organic molecules?

(a) D

D H3CH2CC

?

CCH2CH3

C

C C2H5

C2H5

(b) ? H3CH2CC

CCH2CH3

C2H5

D C

C

C2 H5

D

(c) ? H3CH2CH2CC

(d)

CH

H3CH2CH2CC

CD

C

CH

DC

?

CD2

Solution:

D CH3CH2C

CH3CH2C

D

D2

CCH2CH3

Lindlar catalyst

C2H5

Li,ND3

CCH2CH3

C2H5

D

C2H5

C2H5

D

Na+NH2H3CH2CH2CC

H3CH2CH2CC

CH

Na+

C

D2O

H3CH2CH2CC

CD

NH3 CD

C

CH C

+

Na NH2

C

C

-

D2O

CD2 CD

D2 Lindlar catalyst

NH3

8.39 How would you prepare cyclodecyne starting from acetylene and any alkyl halide needed?

Solution: H

Na

H

Na

+ 2 NaNH2

+

NH3

I

I

THF

8.40 The sex attractant given off by the common housefly is an alkene named muscalure. Propose a

synthesis of muscalure starting from acetylene and any alkyl halides needed. What is the IUPAC name for muscalure?

cis- H3C(H2C)7HC

CH(CH2)12CH3

Solution: The IUPAC name for muscalure is cis-9-tricosene.

NaNH2 H

C

C

H3C(H2C)7

H H3 C(H2C)7

(CH2) 12CH3 C

H

C

C

H

Br

NaNH2

H3C(H2C)7

C

H2 Lindlar

H3C(H2C)12

H3C(H2C)7

C

Br

C

(CH2) 12CH3

H

8.41 Compound A (C9H12) absorbed 3 equivalents of H on catalytic reduction over a palladium catalyst

to give B (C9H18). On ozonolysis , compound A gave, among other things, a ketone that was identified as cyclohexanone. On treatment with, gave C (C10H14) .Give the structure of A, B, C. Solution:

A:

B:

C: 8.42 Hydrocarbon A has the formula C12H8. It absorbs 8 equivalents of H2 on catalytic reduction over

a palladium catalyst. On ozonolysis, only two products are formed: oxalic acid (HO2CCO2H) and succinic acid (HO2CCH2CH2CO2H). Write the reactions, and propose a structure for A. Slution:

8H2

Pd/C cyclododecane

O3

2 HO

O

O

C

C

O OH + 2 HO

C

8.43 Identify the reagents a-c in the following scheme: a

b

c

H

`

H

Solution: 1. NaNH2, NH3 2. CH3CH2Br H2 / Lindlar Cat

CH2I2 / Zn(Cu)

H

H

8.44 Organometallic reagents such as sodium acetylide undergo an addition reaction with ketones, give OH alcohols: O 1. Na+ C

C R

R

2. H3O

CH +

C R

C R

CH

How might you use this reaction to prepare 2-methyl-1,3-butadiene, the starting material used in the manufacture of synthetic rubber Solution：

O CH2CH2

C

O

1. Na+ C

OH

CH

H2 SO4, H2O

+

THF

2. H3 O

H2 Lindlar catalyst

8.45 Erythrogenic acid, C18H26O2, is an acetylenic fatty acid that turns a vivid red on exposure to

light. On catalytic hydrogenation over a palladium catalyst, 5 equivalents of H2 are absorbed, and stearic acid, CH3(CH2)16CO2H, is produced. Ozonolysis of erythrogenic acid gives four products: formaldehyde, CH2O; oxalic acid, HO2CCO2H; azelaic acid , HO2C (CH2)7CO2H; and the aldehyde acid OHC(CH2)4CO2H. Draw two possible structures for erythrogenic acid, and suggest a way to tell them apart by carrying out some simple reactions. Solution The problem can be described as following illustration:

O H

C

H

O

C18H26O2

5H2

H3C

C18H36O2 H2 C

O3 Zn H3+O

C

OH

C

OH

O 16

C

OH

O

O

O H2 C

HO

OH

7

O HO

O H2 C

OH 4

And first we can predict the unsaturated degree of starting material by the fact that it can absorb 5 H2 and form a carboxylic acid. So The molecular has 5 double bonds or 1 triple bond and 3 double bonds or 2 triple bonds and 1 double bond besides a C=O bond, and there is no rings in the molecular. Second we can think about the products after it is treated with problem.

O3

,and we can get the solultion t the

H O HO

C

C

C

H2 C

C

7

C

H2 C

C

4

H

C H

H O HO

C H2 C

C

7

C

C

C

H2 C

C

4

H

CH

You can see two possible starting materials according to the problem exactly. However, we can tell them apart from each other by following method. STEP1 Treat the SM with Lindlar catalyst, and then we can get the product only contains double bond but no triple bond. STEP2 Treat the product get from the step with O3 ,H3O+ and Zn and then we can get the products following. STEP3 Analyze the products and you can find the differences written following between the different SMs . At last we can tell them apart easily.

HCHO H O HO

C

O C

C H

C H

H2 C

C 7 H

C H

H2 C

4

H

Zn H3O

C O3

HC

O H2 C

4

O

H HC

HO

CH O

H2 C

7

CH

O

O

C

CH

HCHO O

H O HO

C

C H2 C

C 7H

C H

C H

H2 C

C H

4

H2 C

HC

H Zn H O 3

CH

O

O3

4

CH

O C

H2 C

O

O

C

C

HO

HO

O

7

CH

OH

8.46 Terminal alkynes react with Br2 and water to yield bromo ketones. For example: O

Br2 , H2O

CH2Br

Propose a mechanism for the reaction. To what reaction of alkenes is the process analogous? Solution: H

H Br

O

H

H

Br O

H

Br Br

H

O

H

H O

H

O Br

rearrangement

Br

The mechanism here is just like the halohydrin of alkene. 8.47 A cumulene is a compound with three adjacent double bonds. Draw an orbital picture of

cumulene. What kind of hydridization do the two central carbon atoms have? What is the geometric relationship of the substituents on one end to the substituents on the other end? What kind of isomerism

is possible?

R 2C

C

C

CR 2

Solution: (a) They are sp hybridized. R

C

C

C

R

C

R

R

(b) The geometric relationship of the substituents on one end to the substituents on the other end is cis and trans. (c) Stereoisomers. 8.48 Reaction of acetone with D3O+ yields hexadeuterioacetone. This is, all the hydrogens in acetone

are exchanged for deuterium. Review the mechanism of alkyne hydration, and then propose a mechanism for this deuterium incorporation. O H3C

C

O

D3O+

C

CH3

D3C

Acetone

CD3

Hexadeuterioacetone

Solution: O

O H

C H3C

CH2 H

OH C

C H3C

……

H3C

CH2 D3O+

CH2 D

O C D3C

CD3