Mallinckrodt, Inc.

Vojko B Jovanovic

Thomas J Dunn

A process for removing impurities from an aqueous feed mixture comprising a reaction solution produced by catalytic hydrogenation of nitrobenzene in an acid aqueous medium. An aqueous feed mixture comprising the reaction solution is contacted with an extractant comprising aniline for extraction from the feed mixture of 4,4'-diaminodiphenylether, thereby providing a primary raffinate that contains p-aminophenol and is contaminated with aniline. The primary raffinate is contacted at a pH of between about 5.5 and about 8.0 with a purifying solvent, the purifying solvent comprising an organic solvent effective for extraction of aniline from the primary raffinate, thereby producing a purified raffinate comprising p-aminophenol. Also described is a unified process for the preparation of N-acetyl-p-aminophenol in which p-aminophenol contained in the aforesaid purified raffinate is acetylated without prior separation of solid p-aminophenol from the raffinate.

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St. Charles County, MO, United States of America

Vojko B Jovanovic