Pd/SiC催化碘代芳烃和芳基硼酸羰化Suzuki偶联反应性能

以高比表面积碳化硅为载体,通过液相还原法制备出Pd/SiC催化剂,并用于催化碘代芳烃和芳基硼酸羰化Suzuki偶联反应.利用X射线衍射、电感耦合等离子体质谱和高分辨透射电子显微镜等对催化剂进行了表征.结果表明, SiC表面的Pd纳米颗粒分散均匀,平均粒径约为2.8 nm.在优化溶剂、碱、压力和温度等反应条件后,发现以3 mmol的K2CO3和10 mL苯甲醚分别为碱和溶剂,1.0 mmol碘苯和1.5 mmol苯硼酸在3 wt% Pd/SiC催化剂存在的条件下,在CO压力为1.0 MPa和100oC下反应8 h即可实现羰化偶联,碘苯转化率为90%,二苯甲酮选择性为99%.并且, Pd/SiC对含有不同官能团的碘代芳烃和芳基硼酸羰化Suzuki偶联反应具有较好的普适性.同时, Pd/SiC也具有较好的稳定性,经5次循环反应后,碘苯转化率从90%降至76%；催化剂活性降低的主要原因是活性组分Pd在有机反应体系中的流失.

Carbonylative Suzuki coupling reactions of aryl iodides with arylboronic acids over Pd/SiC

High surface area SiC has been used to prepare a Pd/SiC catalyst using the liquid reduction method, and the resulting catalyst was used for the carbonylative Suzuki coupling reaction of aryl iodides with arylboronic acids. The catalyst was also characterized by X‐ray diffraction, inductively coupled plasma‐mass spectroscopy and high‐resolution transmission electron microscopy. The results of these analyses showed that homogeneous Pd nanoparticles with a mean diameter of 2.8 nm were uniformly dispersed on the SiC surface. Optimization of the reaction conditions for the carbonyla‐tive Suzuki coupling reaction, including the solvent, base, pressure, temperature and reaction time, revealed that the model reaction of iodobenzene (1.0 mmol) with phenylboronic acid (1.5 mmol) could reach 90%conversion with a selectivity of 99%towards the diphenyl ketone using 3 wt%Pd/SiC under 1.0 MPa of CO pressure at 100 °C for 8 h with K2CO3 (3.0 mmol) as the base and ani‐sole as the solvent. The Pd/SiC catalyst exhibited broad substrate scope towards the carbonylative Suzuki coupling reaction of aryl iodides with arylboronic acids bearing a variety of different sub‐stituents. Furthermore, the Pd/SiC catalyst exhibited good recyclability properties and could be recovered and reused up to five times with the conversion of iodobenzene decreasing only slightly from 90%to 76%. The decrease in the catalytic activity after five rounds was attributed to the loss of active Pd during the organic reaction.