METHOD OF PREPARING SUBSTITUTED DIPHENYLAMINE Russian patent published in 2002 - IPC

FIELD: chemical industry, more particularly preparation of intermediate products for medicines. SUBSTANCE: method is useful for synthesis of 2-(phenylamino)phenylacetic acid derivatives which are useful as analgesic antiphlogistic and rheumatic agents. Described is method of preparing substituted diphenylamine of general formula I: wherein R₁ is lower alkyl or alkoxy group, halogen, trifluoromethyl group; R₂,R₃ are hydrogen, lower alkyl, halogen. Said method comprises condensation of the corresponding N-acetylaniline with bromobenzene in the presence of catalyst and base, hydrolysis of the resulting substituted N- acetyldiphenylamine. Base includes carboxyliic acid salts and salts of alkali and alkaline-earth metals and magnesium. Catalyst is copper powder or chip and/or copper halides, and/or copper salts of carloxylic acids, and condensation process is accompanied by removal of liberating carboxylic acid from reaction zone. Method makes it possible to prepare substituted diphenylamine with higher yield (up to 95%) as compared with prior art method (60%) and to improve quality. The resulting diphenylamine is useful for synthesis of many medicines/ clofeline and other medicines). EFFECT: more efficient preparation method. 5 cl, 2 ex, 2 tbl