Process for preparing 4-aminodiphenylamines

The invention pertains to a method of producing 4-aminodiphenylamine or substituted derivatives thereof comprising the steps of: (a) bringing an aniline or aniline derivative selected from the group consisting of formanilide, phenylurea, carbanilide and thiocarbanilide, or from the group consisting of 2-methoxyaniline, 4-methoxyaniline, chloroaniline, p-toluidine, 4-nitroaniline, 3-bromoaniline, 3-bromo-4-aminotoluene, p-aminobenzoic acid, 2, 4-diaminotoluene, 2,5-dichloroanitine, 1, 4-phenylene diamine, 4, 4'-methylene aniline, 1,3,5-triaminobenzene, and mixtures thereof, and nitrobenzene or nitrobenzene derivative selected from the group consisting of o-and m-methylnitrobenzene, o- and m-ethylnitrobenzene, o- and m-methoxynitrobenzene, and mixtures thereof into reactive contact; (b) obtaining a 4-aminodiphenylamine intermediate product by reacting the aniline or aniline derivative and nitrobenzene or nitrobenzene derivative in the presence of a mixture comprising an organic quaternary ammonium base, an inorganic salt or a metal organic salt, or mixtures thereof, and air, and (c) reducing the 4-aminodiphenylamine intermediate product of step (b) to produce 4-aminodiphenylamine thereof of step (c) to an alkylated derivative of the 4-aminodiphenylamine or substituted derivatives thereof; and (d) optionally, reductively alkylating the 4-aminodiphenylamine or substituted derivatives product of betaine and a strong inorganic base.