New method for the preparation of ortho-phenylene-diamine

Abstract

4-Chloro-2-nitro-aniline, advantageously obtainable from benzene, can be catalytically hydrogenated to ortho-phenylene-diamine. In this process the reduction of the nitro-group and the dehalogenation take place in competition. Results of our laboratory experiments, carried out to choose a catalyst, active for both reaction steps, as well as to limit the suitable operation conditions are presented in this paper. On the basis of our kinetic investigations, two new routes are proposed for manufacturing ortho-phenylene-diamine. One of them is a low pressure, batch-type catalytic hydrogenation of 4-Chloro-2-nitro-aniline, using Raney nickel catalyst and applying mechanical agitation. The other is a high pressure, continuous process with palladium catalyst supported on charcoal and mixing by the hydrogen gas.