磁性纳米颗粒负载钯催化剂对Heck反应的催化活性

采用水热法合成了碳包埋磁性纳米复合颗粒C/(Au@Fe),并以之为载体制备了纳米钯催化剂,利用透射电镜、X射线光电子能谱和振动样品磁强计等手段对催化剂进行了表征,评价了催化剂对Heck反应的催化活性.结果表明,催化剂的平均粒径约为300nm,表面覆盖着一层粒径为12nm的钯颗粒,整个催化剂呈现超顺磁性.对于碘代苯与丙烯酸之间的Heck反应,在乙酸钠或三乙胺碱性条件下反应4h,碘代苯转化率可达95%以上.催化剂重复使用10次时仍可保持很高的催化活性(碘代苯转化率88%).对于其他不同反应底物之间的Heck反应,催化剂同样显示有较高的催化活性.催化剂可稳定分散于反应体系中,并可在外磁场作用下快速与反应体系分离.

Catalytic Activity of Palladium Supported on Magnetic Nanoparticles for Heck Reaction

Carbon-enclosed magnetic nanoparticles synthesized by the hydrothermal method were used as a support for the palladium nanoparticle catalyst.The catalyst samples were characterized by transmission electron microscopy,X-ray photoelectron spectroscopy,and a vibration sample magnetometer.Its catalytic activity for the Heck coupling reaction was measured.The results showed that the mean catalyst particle size was 300 nm,the surface was covered with a layer of palladium particles(12 nm),and the catalyst was of superparamagnetic property.In the Heck reaction of iodobenzene and acrylic acid catalyzed by the catalyst,high iodobenzene conversion(more than 95%)could be obtained under the base conditions of both CH3COONa and NEt3 after 4 h.The iodobenzene conversion over the catalyst was about 88% after 10 recycles,and the catalyst could be steadily dispersed in the reaction mixture and be separated by the magnetic field added.