CATALYTIC HYDROGENATION OF NITROBENZENE TO 4-AMINODIPHENYLAMINE Russian patent published in 2003 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to one-step catalytic hydrogenation of nitrobenzene to yield 4-aminodiphenylamine that can be used for preparing alkylated 4-aminodiphenylamine. Synthesized compounds are used for preparing anti-aging agents for polymers, especially for rubber. Method for preparing 4-aminodiphenylamine involves charge of nitrobenzene and, possibly, aniline into reaction zone under hydrogen pressure in the presence of strong base and the hydrogenation catalyst. Usually nitrobenzene is added gradually to reaction zone for time from 0.1 h to 10 h. Precious-base catalyst is used as the hydrogenation catalyst usually. Strong base is taken among group including alkaline metals, alkaline metals hydrides, alkaline metal hydroxides, alkaline metal alkoxydes, catalysts of phase transfer with a base taken among tetra-substituted ammonium hydroxide wherein each substituent is taken among alkyl, aryl or arylalkyl, alkyl-substituted diammonium hydroxide, aryl ammonium salts in combination with a base and crown-ethers in combination with a base, amine bases and their mixtures. Tetramethyl ammonium hydroxide is used preferably as a base in the molar ratio of nitrobenzene to tetramethyl ammonium hydroxide less or about 1.0 and in the molar ratio of aniline to nitrobenzene about 4:1. Method provides expansion of assortment of technical agents used for preparing 4-aminodiphenylamine and under definite conditions to obtain additional advantages, for example, enhancement of selectivity and yield of products. EFFECT: improved preparing method. 10 cl, 6 tbl, 3 ex