Organic Chemistry

688 CHAPTER 17 Carbonyl Compounds I

PROBLEM 10 SOLVED

a. Two amides are obtained from the reaction of acetyl chloride with a mixture of ethyl-

amine and propylamine. Identify the amides.

b. Only one amide is obtained from the reaction of acetyl chloride with a mixture of ethyl-

amine and pyridine. Why is only one amide obtained?

SOLUTION TO 10a Either of the amines can react with acetyl chloride, so both

N-ethylacetamide and N-propylacetamide are formed.

SOLUTION TO 10b Initially two amides are formed. However, the amide formed by

pyridine (a tertiary amine) is very reactive because it has a positively charged nitrogen atom,

which makes it an excellent leaving group. Therefore, it will react immediately with unre-

acted ethylamine, causing N-ethylacetamide to be the only amide formed in the reaction.

PROBLEM 11

Although excess amine is necessary in the reaction of an acyl chloride with an amine, ex-

plain why it is not necessary to use excess alcohol in the reaction of an acyl chloride with

an alcohol.

PROBLEM 12

Write the mechanism for the following reactions:

a. the reaction of acetyl chloride with water to form acetic acid

b. the reaction of acetyl bromide with methylamine to form N-methylacetamide

PROBLEM 13

Starting with acetyl chloride, what nucleophile would you use to make each of the follow-

ing compounds?

a. c. e.

b. d. f. CH 3 CO

O

CH 3 COH NO 2

O

CH 3 CNHCH 2 CH 3

O

CH 3 COCCH 3

OO

CH 3 CN(CH 3 ) 2

O

CH 3 COCH 2 CH 2 CH 3

O

CH 3 Cl

CH 3 CH 2 NH 2 CH 3 CH 2 CH 2 NH 2

NHCH 2 CH 3

+ CH 3 CH 2 NH 3 Cl−

++

+

CH 3 CH 2 CH 2 NH 3 Cl−

+

CH 3 CH 3 NHCH 2 CH 2 CH 3

N-ethylacetamide N-propylacetamide

+

+

C

O

C

O

C

O

−

CH 3 Cl

CH 3 CH 2 NH 2

N

++

CH 3 NHCH 2 CH 3

+

+

+

CH 3

CH 3 CH 2 NH 2

N

+

−

−

CH 3 CN

NH

CH 2 CH 3

O

HB B

+

CH 3 CN

NH H

CH 2 CH 3

O

CH 3 C NHCH 2 CH 3

N-ethylacetamide

O

N N

HCl

+ −

HCl

C

O

C

O

C

O

+