METHOD FOR PREPARING 5(6)-AMINO-2-(4'-AMINOPHENYL)-BENZIMIDAZOLE Russian patent published in 2006 - IPC C07D235/18 

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of 5(6)-amino-2-(4'-aminophenyl)-benzimidazole. Method involves the acylation reaction of 2,4-dinitroaniline with 4-nitrobenzoyl chloride in the presence ferric chloride as a catalyst in a solvent medium chosen from chlorobenzene, para-xylene, technical mixture of xylenes, toluene or ethylbenzene at boiling the reaction mass followed by crystallization after cooling the reaction mixture and the following reduction of synthesized 2,4',4-trinitrobenzanilide with powder-like iron in dimethylacetamide or dimethylformamide aqueous solution at temperature 96-101°C and the cyclodehydration reaction of synthesized 2',4',4-triaminobenzanilide with sulfuric acid aqueous solution in the presence of ammonia aqueous solution at temperature 100-101°C, and the following isolation of formed 5(6)-amino-2-(4'-aminophenyl)-benzimidazole as crystallohydrate of monosulfate and its neutralization with ammonia. Invention provides the development of the technological process for synthesis of the end product that excludes using hydrogen and expensive catalysts, enhancing the yield of salt and preventing formation of acid waste, effective isolation of 5(6)-2-(4'-aminophenyl)-benzimidazole salt with only trace amounts of impurities.

EFFECT: improved and effective method of synthesis.

9 cl, 1 tbl, 10 ex