PROCESS FOR PREPARATION OF ALBENDAZOLE

摘要

The present invention discloses a novel, cost-effective process for preparation of a benzimidazole carbamates compound. Specifically, it relates to the process for the preparation of anti-parasite bulk drug albendazole. The process comprises a) thiocyanating 2-nitroaniline of formula VI with ammonium thiocyanated in presence of a halogen to obtain 2-nitro-4-thiocyanoaniline of formula V; b)propylating 2-nitro-4-thiocyanoaniline of formula V with propylbromide in presence of n-propanol and a base in absence of a phase transfer catalyst to obtain 4-propylthio-2-nitroaniline of formula III; C) reducing the nitro group of 4-propylthio-2-nitroaniline prepared in step b) by reacting an aqueous alkali metal sulphide or an alkaline metal sulphide to obtain 4-propylthio-o-phenylenediamine of formula II; and d)condensing 4-propylthio-o-phenylenediamine of formula II with alkali or alkaline earth metal salt of methylcyano carbamate in presence of an acid to form Albendazole of formula I.