METHOD OF OBTAINING 5(6)-AMINO-2-(4-AMINOPHENYL) BENZIMIDAZOLE Russian patent published in 2009 - IPC C07D235/18 

FIELD: chemistry.

SUBSTANCE: present invention pertains to organic chemistry and method of obtaining 5(6)-amino-2-(4-aminophenyl)benzimidazole, which is a monomer for producing heat resistant and high-strength fibres. Description is given of a method of obtaining 5(6)-amino-2-(4-aminophenyl)benzimidazole, involving reduction of 2¹,4,4¹-trinitrobenzanilide to 2¹,4,4¹-triaminobenzanilide in the presence of a catalyst in an aqueous medium, cyclodehydration in an aqua acid medium and separation of the target product. The reaction mass obtained from the reduction process after separation of catalyst is processed with sulphuric acid. 2¹,4,4¹-triaminobenzanilide is separated in form of mono-sulphate salt, which is subjected to cyclodehydration through heating in an aqueous sulphuric acid with formation of a hydrate of mono-sulphate salt 5(6)-amino-2-(4-aminophenyl)benzidazole and the base is separated by further neutralisation.

EFFECT: perfection of the method with the aim of efficient low-waste production of a product with high degree of purity.

6 cl, 1 dwg, 1 tbl, 6 ex