CO_2-H_2O体系中硝基苯选择还原制备苯基羟胺

在环境友好的常压、CO2-H2O体系中,硝基苯(NB)选择还原制得了苯基羟胺(PHA),考察了搅拌转速、锌粉粒径、水重复使用次数对该还原反应的影响,且比较了CO2-H2O体系和氯化铵水溶液体系中此还原反应的情况,得到了适宜的反应条件。实验结果表明,在NB用量10 mmol、锌粉用量30 mmol、锌粉粒径1～10μm、水用量20 mL、反应温度25℃、搅拌转速1 500 r/min、反应时间1.0 h的条件下,PHA选择性达到92%。此反应过程中水重复使用20次后,PHA收率基本不变。CO2-H2O体系中,加快搅拌转速和降低锌粉粒径都有利于此还原反应的进行,PHA收率也较高。与氯化铵水溶液体系相比,在CO2-H2O体系中,不仅此还原反应易于控制、PHA收率高,且该体系可重复使用,反应后无含氯废水排放。

Selective Reduction of Nitrobenzene to N-Phenylhydroxylamine in a CO2-H2O System

In an environmentally friendly CO2-H2O system with atmospheric pressure,N-phenylhydroxylamine(PHA) was prepared by the reduction of nitrobenzene(NB).The effects of stir speed,the particle diameter of Zn powder and the reuse of H2O on the reduction were studied.The reduction conditions in the CO2-H2O system were compared with those in NH4Cl aqueous solution system.The experimental results showed that the selectivity to PHA reached 92% under the reduction conditions of reaction temperature 25 ℃,reaction time 1.0 h,Zn powder with particle diameter of 1-10 μm 30 mmol,NB 10 mmol and stir speed 1 500 r/min.The yield of PHA was steady after H2O was reused for 20 times.In the CO2-H2O system,the increase of stir speed and the decrease of the particle diameter of Zn powder favor the reduction.Compared with the NH4Cl aqueous solution system,the CO2-H2O system can be reused with easy operation and high PHA yield,and without waste water containing chloride.