The Foundations of Chemistry

Some of these substances are fundamental building blocks of animal tissue, and minute
amounts of others have dramatic physiological effects, both harmful and beneficial. Count-
less other biologically important substances, including many vitamins, antibiotics, and other
drugs, contain amino groups, XNR 2 (where R can represent an H, alkyl, or aryl group).

Structure and Nomenclature

There are three classes of amines, depending on whether one, two, or three hydrogen
atoms have been replaced by organic groups. They are called primary, secondary, and
tertiary amines, respectively.

The systematic names of amines are based on consideration of the compounds as deriv-
atives of ammonia. Amines of more complex structure are sometimes named as derivatives
of the parent hydrocarbon with the term amino- used as a prefix to describe XNH 2.

Aniline is the simplest aromatic amine. Many aromatic amines are named as deriva-
tives of aniline.

Heterocyclic aminescontain nitrogen as a part of the ring, bound to two carbon
atoms. Many of these amines are found in coal tar and a variety of natural products. Some
aromatic and heterocyclic amines are called by their common names.

N N

N

N

N

N N

N

H

N

H

pyrrole

(secondary)

quinoline

(tertiary)

pyridine

(tertiary)

purine pyrimidine

N

HH

Cl

p-chloroaniline

(primary)

N,N-dimethylaniline

(tertiary)

aniline

(primary)

N

HH

Br

Br

3,4-dibromo-N-methyl-

aniline (secondary)

N

HCH 3

N

H 3 C CH 3

H

HNH 2

NH 2

HH CH 2 CH 3

C C

HH

HH

C C H

2-aminobutane or sec-butylamine 1-amino-3-ethylcyclohexane

N

NH 3

H

H

ammonia

N

RNH 2

CH 3 H

H

methylamine

(a primary amine)

N

R 2 NH

CH 3 CH 3

H

dimethylamine

(a secondary amine)

N

R 3 N

CH 3 CH 3

CH 3

trimethylamine

(a tertiary amine)

H

N

N

CH 2

CH 2

CH

strychnine

O O

C

N

N

CH 3

nicotine

27-12 Amines 1075