Organic Chemistry

Section 21.4 Reactions of Amines 887

PROBLEM 3

a. Draw the structure of 3-quinuclidinone.

b. What is the approximate of its conjugate acid?

c. Which has a lower the conjugate acid of 3-bromoquinuclidine or the conjugate

acid of 3-chloroquinuclidine?

21.4 Reactions of Amines

The lone pair on the nitrogen of an amine causes it to be nucleophilic as well as basic.
We have seen amines act as nucleophiles in a number of different kinds of reactions: in
nucleophilic substitution reactions—reactions that alkylatethe amine (Section 10.4)—
such as

in nucleophilic acyl substitution reactions—reactions that acylate the amine
(Sections 17.8, 17.9, and 17.10)—for example,

in nucleophilic addition–elimination reactions—the reactions of aldehydes and ke-
tones with primary amines to form imines and with secondary amines to form enam-
ines (Section 18.6)—such as

and in conjugate addition reactions (Section 18.13)—for instance,

CH 3 CCH 3 NH

CH 3

CH 3 O

CHCH

CH 3

NCH 3

CH 3

+ CH 3 C

O

CH 2 CH

O

ONHN

H 2 NCH 2 H 2 O

catalytic

H+

catalytic

H+

benzylamine

pyrrolidine

an imine

an enamine

+

++H 2 O

NCH 2 +

N

HH

NH +

+

an amide

piperidine an amide

methylamine

O

C

CH 3

O

N

C

CH 3

O

• OCCH
  3

O

CH 3

C

O

Cl

C 2 CH 3 NH 2 CH 3 NH 3 Cl–

CH 3 CH 2

O

+

++

NHCH 3

C

CH 3 CH 2

O

+

pKa,

pKa

CH 3 CH 2 Br CH 3 CH 2 NH 2 CH 3 CH 3 CH 2 NHCH 3 HBr

Br–

CH 3 NH 2

methylamine ethylmethylamine

+

++