&Thiolbenzoic acid, m, m'-dithiodibenzoic acid, 3-thiolpropanoic acid, and 4, 4'dithiodibutanoic acid react with anhydrous chlorine to form chloromlfinylacyl chlorides of the type ClS (0)-R-COCl by a procesa which ia believed to involve the intramolecular solvolyais of an intermediate organoaulfur trichloride.