Sn~(4+)修饰的PEG-Pd催化氯代硝基苯选择性加氢反应

考察了PEG-Pd(PEG:聚乙二醇,Pd 0.2%)催化剂催化对氯硝基苯的加氢反应中,添加第二金属组分以及Sn4+含量对反应的影响。结果表明,添加一定量的Sn4+对反应选择性有着显著的影响。不添加Sn4+离子,会有严重的脱氯反应发生;加入Sn4+离子后,在Sn与Pd的摩尔比为0.8,温度60℃,氢压1.0 MPa的条件下,经过60 min反应,对氯硝基苯转化率为99.6%,而对氯苯胺选择性由不加Sn4+离子时的68.5%上升到96.1%。对取代位置不同的其它氯代硝基苯,该催化体系同样表现出很高的催化活性和氯代苯胺选择性。

Selective hydrogenation of chloronitrobenzenes catalyzed by Sn4+ modified PEG-Pd catalyst

Selective hydrogenation of chloronitrobenzenes catalyzed by Sn4+ modified PEG-Pd catalyst PEG:poly(ethylene glycol),Pd 0.2%] was studied.The influence of a second metal cations and the Sn4+ content on reaction was investigated.It was found that the selectivity to chloroaniline was obviously affected by addition of Sn4+.The dechlorination reaction was serious due to the hydrogenolysis of C—Cl when no Sn4+ was added.However,when Sn4+ was introduced into the reaction system,the dechlorination reaction was greatly suppressed.When p-chloronitrobenzene was used as substrate and the molar ratio of Sn4+ to Pd was 0.8,under the conditions of 60 ℃,PH2=1.0 MPa,reaction time 60 min,the conversion of p-chloronitrobenzene reached 99.6% and the selectivity to chloroaniline was raised from 68.5%(no Sn4+) to 96.1%.It was also found that the PEG-Pd-SnCl4 catalyst exhibited high activity and selectivity for the hydrogenation of other chloronitrobenzenes with different substituted positions.