AbstractThe acylation of N‐monosubstituted benzimidazoles with various acid chlorides in ethyl acetate — aqueous bicarbonate mixture was investigated. The reaction, which leads to the fission of the imidazole ring, was found to be strongly dependent on the substitution on both the benzimidazole and the acid chloride used. Electron withdrawing groups in the benzimidazoles were found to facilitate the reaction. Carbobenzoxy chloride and ort ho substituted benzoyl chloride gave the highest yields of the fission products. The carbobenzoxylation and benzoylation of unsubstituted, 2‐monosubstituted and 1,2‐disubstituted benzimidazoles were also inves