Process for preparing 1,2-benzoisothiazoline-3-one

摘要

Sodium sulfide hydrate is at least partially dehydrated by heating with N-methyl 2-pyrrolidone. 2-chlorobenzamide is added to the mixture which is heated further. The mixture is cooled and treated with aqueous hydrogen peroxide to give the sodium salt of 1,2-benzoisothiazoline-3-one in good yield. Acidification if desired gives rise to the free 1,2-benzoisothiazoline-3-one.