Hinsberg reagent/benzenesulphonyl chloride on reaction with secondary amine N,N-diethylbenzenesulphonamide. This compound is insoluble in alkali as it does not contain any reactive acidic hydrogen attached to the nitrogen atom.

The sulphonyl group attached to nitrogen atom is a strong electron withdrawing group but that is not the reason for insolubility of the sulphonamide, the absence of acidic hydrogen.