Synthesis of Chlorosulfonyl-containing Pyrazolone Azo Compounds with Thionyl Chloride-DMF System

摘要

Chlorosulfonyl-containing pyrazolone azo compounds (2a, 2b) have been prepared by reaction of the corresponding sodium sulfonate (1a, 1b) with thionyl chloride in the presence of a catalytic quantity of N,Ndimethylformamide in dry benzene. The effects of reaction temperature, time, catalyst and solvent amount on the yield of 2a and 2b were investigated. The results show that chlorination of 1a and 1b under optimal conditions gives 2a and 2b in 95.5% and 99.2% yield respectively. The given method is facile and suitable for large-scale synthesis.