Bonsoir  praline80 :

   Voici  la  troisième  ( chlorosulfonation ) .

   25 g of dry powdered acetanilide are added with occasional stirring, to 63 ml (or 110 g) of chlorosulfonic acid and the mixture is heated to 60-70° C for 2 hours. Then the reaction mixture is cooled to room temperature and poured carefully on to about 500 g of crushed ice. The crude N-acetylsulfanilyl chloride separates as a white solid, which is filtered, washed it thoroughly with water in order to remove inorganic acids. This crude N-acetylsulfanilyl chloride is sufficiently pure for most synthesis. However, to obtain pure N-acetylsulfanilyl chloride, crystallization from chloroform yields 38 g of colorless crystals, which melt at 149-150° C.

Practical organic chemistry, by F. G. Mann, 181, 1960

   Bonnes  salutations