Patent ID: 6403833
Filing Date: 2002-06-11
Classification: C07C

Abstract:
A process for the single step hydrogenation of nitrobenzene to p-aminophenol, said process comprising:(a) contacting a mixture of nitrobenzene and aqueous acid with a Ni-containing hydrogen mono or bimetallic catalyst at a pressure up to 700 psi, at a temperature of from 80-120Â° C. for a period of from 1-4 hrs, (b) terminating the reaction to obtain product mixture, (c) removing the reaction mixture from the autoclave, (d) separating the catalyst and resin from the reaction mixture by filtration, (e) extracting the filtrate with toluene, (f) analyzing the organic and aqueous layers for reactants and products using GC and PLC, (g) treating the aqueous layer with ammonia solution to adjust the pH of solution to 3-4 to partly precipitate PAP, (h) separating the solid thus obtained by filtration, (i) extracting the filtrate with toluene, (j) treating the aqueous layer with ammonia solution to pH 7-8 to substantially precipitate PAP, and (k) washing the total solid thus obtained after first and second extraction with distilled water, drying and weighing.