Describe the method for the identification of primary, secondary and tertiary amines. Also write chemical equations of the reactions involved.
The three types of amines can be distinguished by Hinsberg method. The sample is treated with benzene sulphonyl chloride, C6H5SO2Cl (Hinsberg’s reagent) followed by treatment with aqueous KOH (5%) solution. Based upon the observations, the following conclusions may be drawn:
(i) If a clear solution is obtained , then it is a primary amine.
(ii) If the solution is turbid or ppt appears and remains unaffected by the addition of an acid, the given amine is a secondary amine.
(iii) If the sample remains insoluble in alkali and dissolves in an acid, then it is a tertiary amine.
The secondary amine forms dialkyl sulphonamide which is insoluble in alkali
Tertiary amine do not react with Hinsberg’s reagent. They do not dissolve in alkali, but dissolve in acid.
