Abstract: A process for the preparation of diaryl para-phenylenediamines from a crude para-aminophenol solution such as obtained by the catalytic hydrogenation of nitrobenzene in an aqueous acid reaction medium. The process comprises contacting the para-aminophenol containing acidic solution, after neutralization with ammonia, with an aromatic amine selected from the group consisting of aniline, mixed toluidines, ortho-toluidine, mixed xylidines, and mixtures thereof under conditions whereby the aromatic amine extracts the para-aminophenol from the crude feed solution and is separated therefrom. The separated solution comprised essentially of the aromatic amine extractant, para-aminophenol, and minor amounts of impurities is then contacted with an alkylation catalyst to produce the diaryl para-phenylenediamines.

Abstract: An improved method for the recovery of para-aminophenol from crude solutions thereof such as obtained by the catalytic hydrogenation of nitrobenzene in an aqueous acid reaction medium. The method comprises neutralizing the cold, acidic solution containing the crude para-aminophenol whereby a very fine fluffy para-aminophenol precipitates. When an aromatic amine selected from the group consisting of aniline, mixed toluidines, ortho-toluidine, mixed xylidines, and mixtures thereof is admixed therewith an upper layer containing the para-aminophenol suspended in the aromatic amine forms when allowed to settle. A clear lower layer containing about 70 to 90% of the ammonium sulfate solution is separated and discarded. The upper layer which contains the aromatic amine and the para-aminophenol can be used as a source of para-aminophenol for producing para-aminophenol derivatives such as diaryl para-phenylenediamines.