5-Chloro 2-nitro acetanilide sepn. from isomer mixt. obtd. by nitration - by dissolving in boiling ethanol, cooling and filtering, for anthelmintic synthesis

摘要

The process concerns sepn. of 5-chloro-2-nitroacetanilide (IA) from a mixt. of isomeric chloronitroacetanilides (I) contg. (IA) and 3-chloro-4-nitroacetanilide (IB) and obtd. by nitration of 3-chloroacetanilide. The novel features are that (a) the crude (I) is dissolved in a boiling solvent (II), consisting of EtOH contg. up to 10% water, in an amt. of at least 2 vol. pts. (II)/pt. dry (I); then (b) the homogeneous mixt. is cooled, pref. below room temp., and the (IA) crystals formed are filtered. USE/ADVANTAGE - (IA) is an important intermediate in the synthesis of benzimidazole and phenylguanidine derivs. used as anthelmintics for treating humans and animals. Over 93% of (IA) in (I) (which contains ca. 58% (IA)), is sepd. with a purity of up to 98%, which is suitable for almost all syntheses. The (II) consumption is much less than usual (not greater than 5 dm3EtOH/kg dry (I))