Benzoic Acid → Benzoic acid, 3-(chlorosulfonyl)-

Participants

Reaction Conditions

Reaction Steps

349.5 g=199.7 ml (3.0 mol) of chlorosulfuric acid and 20.0 g of 96% strength sulfuric acid are placed in a 2 l four-neck flask fitted with stirrer, internal thermometer, reflux condenser with gas outlet and dropping-funnel, at 25° C., and 1.0 g of sulfamic acid is added. Subsequently 122.1 g (1.0 mol) of benzoic acid are introduced into this mixture. The reaction mixture is heated to 120° C. over 3 hours and stirred further until evolution of HCl has ended (about 30 minutes). Then it is cooled to 70° C. and 119.0 g (1.0 mol) of thionyl chloride are added dropwise over 2 hours. The reaction solution is then heated to 80° C. and stirred further for about 30 minutes until gas evolution has ended. The mixture is added dropwise to 1000 g of ice-water at 10° C. over 2 hours. The precipitated product is filtered off with suction and washed with 500 g of ice-water. 321.2 g of crude 3-(chlorosulfonyl)benzoic acid (water content: 33.9%; chlorine: 10.8%) are obtained, corresponding to 212.3 g (0.96 mol) of 100% 3-(chlorosulfonyl)benzoic acid. 1115 g of mother liquor and 538 g of wash-water are produced.

Provenance & Evidence