An Improved Large-Scale Preparation of Benzimidazole-2-Sulfonic Acids and 2-Chlorobenzimidazoles.‡

Abstract

Abstract An improved method for the preparation of benzimidazole-2-sulfonic acids from 2-mercaptobenzimidazoles has been developed which utilizes aqueous sodium percarbonate. 2-Chlorobenzimidazoles were obtained in high yield from the corresponding sulfonic acids upon reaction with PCl5 in POCl3 on a gram-mole scale.