Technical Research On The Synthesis Of Bromoaniline By Liquid Catalysis Hydrogenation

The traditional synthesis method for preparing bromoaniline is chemical hydrogenation. To overcome its shortcomings, a new synthesizing way of liquidly hydrogenating bromonitrobenzene under catalysis was offered in this paper. The flow process for preparing bromoaniline from catalysis hydrogenating bromonitro- benzene was studied. In the experiments, the effects of the temperature, pressure, time and the ratio of materials, etc.,on the reaction, and the recycling way of W-4 Raney-Ni were reviewed. In the end, the optimum conditions were determined.On the condition of using methanol as solvent,W-4 Raney-Ni as catalyst, dicyandia-mide as activator, the optimum condition for preparing p-bromoaniline through the single -factor experiments is as follows: the amount of p-bromonitrobenzene, methanol, Raney-Ni and dicyandiamide are 40g, 185ml, 4.0g and 0.8g, respectively. The reaction temperature, pressure and time are 70℃, 1.2M- Pa and 7.0 hours, respectively. The yield can reach 85.0%, the purity can reach 99.0%, the conversion of p-bromonitrobenzene is 99.5%.On the condition of using methanol as solvent, W-4 Raney-Ni as catalyst, dicyandiamide as activator, the optimum condition for preparing o-bromoaniline through the orthogonal experiments is as follows: the amount of o-bromonitrobenzene, methanol, Raney-Ni and dicyandiamide are 35g, 185ml, 4.5g and 0.8g, respectively. The reaction temperature, pressure and time are 70℃, 1.2M-pa and 7.5 hours, respectively. The yield can reach 75.0%, the purity can reach 99.0%, the conversion of p-bromonitrobenzene is 94.5%.On the condition of using methanol as solvent, W-4 Raney-Ni as catalyst, Ca(OH)₂ as activator, the optimum condition for preparing m-bromoaniline through the orthogonal...