Amines

Notes

1. Amines

Amines are organic derivatives of ammonia (NH₃) in which one or more hydrogen atoms are replaced by alkyl/aryl groups.

Depending upon the number of alkyl/aryl groups attached directly to nitrogen, amines are classified as primary, secondary and tertiary amines.

Primary Amine (1°)

A primary amine contains one alkyl/aryl group directly attached to nitrogen.

General formula:

2. Nomenclature of Amines

The PDF discusses both common names and IUPAC names of amines.

IUPAC Naming

The parent alkane is named by replacing the final -e with -amine.

Examples from the notes include:

CH

3

​

CH

2

​

CH

2

​

NH

2

​

IUPAC: Propan-1-amine

Common name: Propylamine

For:

CH

3

​

NHCH

2

​

CH

3

IUPAC: N-methylethanamine

Common name: Ethylmethylamine

For:

(CH

3

​

)

3

​

N

IUPAC: N,N-dimethylmethanamine

Common name: Trimethylamine

When groups are directly attached to nitrogen, N- is used to indicate substitution on nitrogen.

Methyl chloride → Ethanenitrile → Ethanamine

Primary Amine

Primary amine forms:

N-alkylbenzenesulphonamide

The product contains acidic hydrogen on nitrogen and dissolves in KOH.

Secondary Amine

Secondary amine forms:

N,N-dialkylbenzenesulphonamide

The product does not contain acidic hydrogen on nitrogen and is insoluble in KOH.

Tertiary Amine

The PDF states that tertiary amine does not react under these conditions because it has no hydrogen attached to nitrogen.

21. Electrophilic Substitution Reaction of Aniline

The PDF identifies the –NH₂ group as a +M group.

The lone pair of nitrogen participates in resonance with the benzene ring.

As a result, electron density increases particularly at the ortho and para positions.

Therefore –NH₂ is strongly activating toward electrophilic substitution.

22. Acetylation of Aniline

The PDF shows conversion of aniline into acetanilide.

C

6

​

H

5

​

NH

2

​

CH

3

​

COCl/Py

​

C

6

​

H

5

​

NHCOCH

3

​

Acetic anhydride is also shown as an acetylating reagent.

On hydrolysis:

Acetanilide

H

3

​

O

+

​

Aniline

23.…