Organic Compounds containing Nitrogen

Amines

Amines may be regarded as derivatives of ammonia in which one, two or

all three hydrogen atoms have been replaced by alkyl or aryl groups.

Amines are designated as primary (1°), secondary (2°) or tertiary (3°)

according as one, two or three hydrogen atoms in ammonia molecule have

been substituted by alkyl or aryl groups.

Nomenclature of Aliphatic Amines.

(i) Common System. Aliphatic amines are named by prefixing alkyl group

to amine. Mixed secondary or tertiary amines are named as N-substituted

derivatives of the largest group of primary amine. For example, CH3NH2 is

named as methylamine, (CH3)2NH is namzed as dimethylamine and

CH3NHC2H5 is named as methylethylamine.

(ii) IUPAC System. Aliphatic primary amines are named as alkanamines

by removing the final "e" of the name of parent alkane and adding the

suffix 'amine'.

Nomenclature of Aromatic Amines. The simplest aromatic amine is

aniline, IUPAC name is benzenamine. Most of the aryl amines are named

as derivatives of aniline although some of them are given special names

also.

3. Structure of Amines. Nitrogen orbitals in amines are sp3 hybridized

and amines have a pyramidal shape. Due to the presence of a lone pair of

electrons on N atom, C-N-E (where E is C or H) bond angle is slightly

lesser than 109.5°.

In aromatic amines, because of the electron pair, nitrogen can conjugate

with the benzene ring giving carbon nitrogen bond with double bond

character. Thus the C-N bond in aromatic amines is shorter than that in

aliphatic amines.Amines are derivatives of NH3.