Hydrogenation of para-chloronitrobenzene over nickel borides

✍ Scribed by Yin-Zu Chen; Yih-Chung Chen

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 672 KB
• Volume: 115
• Category: Article
• ISSN: 0926-860X
• DOI: 10.1016/0926-860x(94)80377-3

✦ Synopsis

The selective hydrogenation of para-chloronitrohenxene was investigated over P-2W and P-l nickel borides. The effects of solvents, additives and reaction conditions were examined. P-2W nickel horide was found to be more active than P-l nickel boride and the commercial catalyst of Raney nickel for the reduction of the nitro-group. The solvent not only affected the rate but also the dehalogenation and the formation of intermediates. The nickel horides were more active in the protic solvents than in the non-protic solvents according to the following order: ethanol > methanol > cyclohexane > methylacetate. Only a small amount of intermediate (axoxychlorobenzene) and dehalogenation product (aniline) formed in the protic solvents; however, these products did not form in the non-protic solvents. The addition of molybdenum effectively promoted the reduction of the nitro-group and repressed dehalogenation. This reaction was a structure-sensitive reaction, with its rate decreasing with the dispersion of horide catalysts. The reaction rate was expressed as r = koe-E*fRT. C, * Pi 'I2 at a lower concentration and r = constant at a higher concentration.