Sodium Hydroxide → 3-Chloro-4-methylbenzenesulfinic acid

Participants

Reaction Conditions

Reaction Steps

2350 ml of water and 420 g (3.3 mol) of sodium sulfite (=15.1% strength Na2SO3 solution) are introduced into a stirrer apparatus equipped with 2 dropping funnels and a pH electrode, and the mixture is heated to 50-55° C. In the course of about 2 h, 677 g (3 mol) of 2-chloro-p-toluenesulfonyl chloride are run in and simultaneously 690 g of NaOH (35% strength) are added dropwise so that a pH of 8-10 is maintained. The temperature is allowed to rise to 65° C. The reaction is completed when the pH remains constant at 8-10. The sodium sulfinate is in solution at 60-65° C., and crystallizes out from about 55° C.

Provenance & Evidence