超顺磁性介孔纳米颗粒嫁接肟Pd环络合物对Heck反应的催化活性

采用溶胶-凝胶法制备出介孔二氧化硅包裹四氧化三铁纳米复合颗粒,在其表面修饰巯基,并以此为载体通过-SCH2-化学键嫁接长链的肟钯环络合物.利用透射电镜(TEM)、高分辨透射电镜(HRTEM)、傅里叶变换红外(FT-IR)光谱、N2吸附-脱附、X光电子能谱(XPS)、振动样品磁强计(VSM)等手段对催化剂进行表征,通过Heck反应对催化剂的活性进行评价.实验结果表明:所制备的磁性颗粒直径约为150nm,比表面积为287.0m2·g-1,且具有大小为3.5nm呈不规则的孔道结构,整个催化剂呈现超顺磁性.对于碘代苯与丙烯酸乙酯之间的Heck反应,2.5h后碘代苯的转化率可达到99%,催化剂在重复使用6次后能保持很高的催化活性(碘代苯转化率为95%).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 an Oxime Carbapalladacycle Complex Grafted onto Superparamagnetically Mesoporous Nanoparticles for the Heck Reaction

A mesoporous SiO2@Fe3O4 nanocomposite was prepared by the sol-gel method. The nanocomposite was modified with a thiol and then a long carbon chain oxime carbapalladacycle complex as grafted by a—SCH2— linkage. The catalyst was characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), and vibration samplemagnetometry (VSM). Its catalytic activity for the Heck coupling reaction was measured. The BET surface area of the support with a diameter of 150 nm was about 287.0 m2·g-1 and the average pore size was about 3.5 nm. The catalyst had superparamagnetic properties. In the Heck reaction of iodobenzene with ethyl acrylate, a high conversation of 99%was obtained after 2.5 h. The catalyst was reused 6 times without significant loss of activity (95%after the sixth run). The catalyst was easily dispersed in the reaction mixture and was separated swiftly by an added magnetic field.