METHOD OF PRODUCING 2',4,4'-TRINITROBENZANILIDE FROM ANILINE AND 4-NITROBENZOIC ACID Russian patent published in 2015 - IPC C07C231/14 C07C233/66 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing 2',4,4'-trinitrobenzanilide, which is an intermediate product in the synthesis of 5(6)-amino-2-(4-aminophenyl)benzimidazole - a monomer for producing heat-resistant high-strength fibres. The method includes acylating aniline with 4-nitrobenzoic acid while heating with distillation of reaction water and separating 4-nitrobenzanilide, followed by nitration thereof with nitric acid in a sulphuric acid medium and separating the end product. The method is characterised by that acylation is carried out under pressure at molar ratio of aniline to 4-nitrobenzoic acid of (2-20):1. The 4-nitrobenzanilide is separated in powder form and after nitration thereof, the obtained 2',4,4'-trinitrobenzanilide is separated from the reaction solution by diluting to sulphuric acid concentration of 30-85 wt %. Further, the product is recrystallised from an aromatic solvent or from a mixture of an amide solvent with water.

EFFECT: method cuts the duration of acylation, improves the quality of the product and reduces the amount of wastes.

3 cl, 2 tbl, 8 ex