Question -
Answer -
Primary, secondary and tertiary amines canbe identified and distinguished by Hinsberg’s test. In this test, the aminesare allowed to react with Hinsberg’s reagent, benzenesulphonyl chloride (C6H5SO2Cl).The three types of amines react differently with Hinsberg’s reagent. Therefore,they can be easily identified using Hinsberg’s reagent.
Primary amines react with benzenesulphonyl chloride toform N-alkylbenzenesulphonyl amide which is soluble in alkali.Due to the presence of a strong electron-withdrawingsulphonyl group in the sulphonamide, the H−atom attached to nitrogen can beeasily released as proton. So, it is acidic and dissolves in alkali.
Secondary amines react with Hinsberg’s reagent to give asulphonamide which is insoluble in alkali.
There is no H−atom attached to the N-atom in thesulphonamide. Therefore, it is not acidic and insoluble in alkali.
On the other hand, tertiary amines do not react withHinsberg’s reagent at all.