Chlorosulfonic acid → 4-(Chlorosulfonyl)-1,3-dimethyl-1H-pyrazole-5-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

Into 200 ml of chlorosulfonic acid, there was added dropwise 50.4 g (0.3 mol) of Ethyl 1,3-dimethyl-5-pyrazole carboxylate under cooling at 5° C. or lower. After heating at 120° C. under stirring for 10 hours, the reaction mixture was poured into ice-water and extracted with ether. After washing with water and drying, evaporation of the solvent gave 49 g of crude 1,3-dimethyl-4-chlorosulfonyl-5-pyrazole carboxylic acid as a solid.

Provenance & Evidence