METHOD OF PRODUCING 21,4,41 -TRINITROBENZANILIDE Russian patent published in 2010 - IPC C07C233/66 

FIELD: chemistry.

SUBSTANCE: invention relates to organic chemistry and a method of producing 2¹,4,4¹ -trinitrobenzanilide (TNBA), a semiproduct of 5(6)-amino-2-(4-aminophenyl)benzimidazole synthesis, used as monomer in production of heat resistant and high-strength fibre. TNBA is obtained through acylation of 2,4-dinitroaniline with 4-nitrobenzoyl chloride using iron chloride as a catalyst while heating in a medium of an organic solvent in the presence of anhydride of 4-nitrobenzoic acid with extraction of TNBA through crystallisation, filtration and subsequent neutralisation with ammonia in an aqueous suspension, where the reaction mother solution formed after crystallisation and filtration is returned for recycling in the next acylation process. Anhydride of 4-nitrobenzoic acid is obtained by pre-heating 4-nitrobenzoyl chloride which contains an admixture of 4-nitrobenzoic acid in an organic solvent medium. The acylation process is combined with distillation of a portion of the solvent. The reaction mother solution is treated with activated carbon before recycling.

EFFECT: method prevents intense release of hydrogen chloride during the initial period of the reaction, considerably cuts on amount of wastes, reduces consumption of raw material and increases TNBA output.

4 cl, 15 ex