Amines: Hinsberg's test

Hinsberg's test

This test can be used to distinguish between primary, secondary and tertiary amines.

Benzene sulphonyl chloride- C6H5So2Cl

Benzene sulphonyl chloride reacts with primary and secondary amines to form sulphonamides.

(1) when react with primary amines

The hydrogen attached to nitrogen in sulphonamide is strongly acidic due to the presence of strong electron withdrawing sulphonyl group. Hense, it is soluble in alkali.

(2) when react with secondary amines

Since, N,N-Diethylbenzenesulphonamide do not have Alpha-hydrogen attached to nitrogen. So, it is not acidic. Hence, insoluble in alkali.

(3)  Tertiary amines do not react with benzene sulphonyl chloride because they do not have hydrogen atom attached to nitrogen.