METHOD FOR PREPARING CHLORO-SUBSTITUTED AROMATIC CARBOXYLIC ACID AMINOANILIDES Russian patent published in 2008 - IPC C07C233/80 C07C231/02 

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of aromatic carboxylic acid aminoanilides, such as 2¹-chloro-4,4¹-diaminobenzanilide or bis-(2-chloro-4-aminophenol)terephthalamide used in production of thermostable, refractory and highly strength fibers. Method is carried out by acylation of 2-chloro-4-nitroaniline with 4-nitrobenzoic acid chloroanhydride or terephthaloyl chloride, respectively, in organic solvent medium at heating followed by reduction of formed chloro-substituted nitroanilide of aromatic carboxylic acid in a solvent. The acylation process is carried out in the presence of ferric chloride as a catalyst, at chloroanhydride excess with respect to 2-chloro-4-nitroaniline at graduate increase of temperature up to boiling of reaction mass under atmosphere pressure. Ferric chloride is used as anhydrous FeCl₃ or crystal hydrate FeCl₃ x 6H₂O or an aqueous solution. In the reduction process a mixture of water and dipolar aprotonic solvent is used, and mother solutions after isolation of chloro-substituted nitroanilide and chloro-substituted aminoanilide are recovered to recycle at corresponding step of process. Before recovering to recycle at acylation or reduction step, respectively, mother solutions are treated with activated carbon. Invention provides preparing end products of high quality and decreasing amount of waste.

EFFECT: improved method of synthesis.

6 cl, 1 tbl, 22 ex