The reaction of benzenesulphonyl chloride with secondary amines yields N,N-diethylbenzenesulphonamide, which lacks acidic hydrogen and is insoluble in alkali due to the absence of a hydrogen atom attached to the nitrogen.
Describe the reaction of benzenesulphonyl chloride with secondary amines and explain the solubility behavior of the resulting sulphonamide in alkali.
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Benzenesulfonyl chloride (Hinsberg’s reagent) reacts with secondary amines to form sulphonamides. The reaction involves the substitution of a hydrogen atom on the nitrogen of the secondary amine with a benzenesulfonyl group (-SO₂Ph). Unlike primary amines, the resulting sulphonamide is soluble in alkali for secondary amines. This solubility difference arises from the presence of an acidic hydrogen on the nitrogen of secondary amines, allowing the formation of water-soluble salts in alkaline conditions. This reaction and solubility behavior serve as a practical method for distinguishing between primary and secondary amines in organic chemistry.