| abstract |
The solution relates to a method of preparation of 4-aminodiphenylamine through an intermediate preparation of 4-nitrodiphenylamine and/or 4-nitrosodiphenylamine and/or their salts by the reaction of aniline with nitrobenzene in a liquid medium at a temperature of 50 to 130 °C, under normal or reduced pressure, in an inert atmosphere or in the presence of air oxygen, with subsequent hydrogenation of an intermediate of 4-nitrodiphenylamine and/or nitrosodiphenylamine and side products, and by isolation of 4-aminodiphenylamine and the side products and recirculation of unconverted raw materials. The reaction of aniline with nitrobenzene, with selectivity of at least 50 % of 4-nitrodiphenylamine and nitrosodiphenylamine, is performed in a reaction system, consisting of a true zwitterion salt solution with hydroxides of a general formula HO?-/(R1R2R3)N+-CHR4-(CH¿2)x-Y-/Z+ where R?1 and R2¿ means methyl to dodecyl, R3 means methyl, ethyl, phenyl, benzyl, R4 means hydrogen or methyl, x means an integer of 0 to 5, Y- means CO¿2?-, SO3?- and Z+¿ means a cation of an alkali metal Li, Na, K, Cs or a tetrasubstituted quaternary ammonium cation, like tetramethylammonium, or their mutual combinations, wherein 4-nitrosophenylamine and/or 4-nitrodiphenylamine and/or their salts arise which yield, after hydrogenation, 4-ADFA, and after the reaction at least a half of the reaction system is used again for the next reaction and/or it is recycled. The reaction medium is formed separately and/or it will be formed in situ in the reaction system from raw materials. The liquid medium for the reaction of aniline with nitrobenzene is formed of water and/or at least one organic compound, chosen from among aniline, pyridine, toluene, xylene, cyclohexane and aliphatic alcohols having the number of carbons in the molecule of 1 to 4. |