连续流动状态下纤维负载Pd(Ⅱ)催化Suzuki偶联反应的研究

Research on fiber supported-Pd(Ⅱ)catalyst for Suzuki coupling reaction under continuous flow conditions

以偕胺肟化聚丙烯腈纤维(AOFs)为载体,制备了纤维负载Pd(Ⅱ)催化剂AOFs-Pd(Ⅱ)。利用FTIR,SEM,EDS,XPS,ICP-OES等方法对AOFs-Pd(Ⅱ)进行结构表征;研究了连续流动状态下AOFs-Pd(Ⅱ)催化卤代芳烃与苯硼酸Suzuki偶联反应的性能,考察了反应温度、反应物流量、卤代芳烃浓度及不同取代基的卤代芳烃对偶联产物收率与产量的影响。实验结果表明,在连续流动状态下,AOFs-Pd(Ⅱ)具有良好的催化活性。偶联反应的最佳条件为:温度70℃、反应物流量3 mL/min(即最佳停留时间6.67 min)、卤代芳烃浓度60.0 mmol/L、乙醇-水(乙醇与水体积比为2∶1)为溶剂。在此条件下,AOFs-Pd(Ⅱ)催化碘苯与苯硼酸Suzuki偶联反应,碘苯的转化率高达97%,偶联产物的选择性为99%。催化剂表现出良好的稳定性,连续反应20 h,催化剂活性为694.29 mmol/(g·h);连续流动状态下,AOFs-Pd(Ⅱ)的催化效率是间歇式反应的2.6倍。

Pd(Ⅱ)complex supported by amidoxime polyacrylonitrile fibers(AOFs)(AOFs-Pd(Ⅱ))was synthesized.The structure of AOFs-Pd(Ⅱ)was characterized by FTIR,SEM,EDS,XPS and ICP-OES.The Suzuki coupling reaction of aryl halides and phenylboronic acid catalyzed by the AOFs-Pd(Ⅱ)was investigated under continuous flow conditions.The effects of reaction temperature,flow rate,concentration and scope of substrate on yield and production of coupling product were investigated.Under the optimal reaction conditions,namely flow rate of 3 mL/min(residence time is 6.67 min),aryl halides concentration of 60.0 mmol/L in a of co-solvent of EtOH/water(volume ratio 2∶1)at 70℃,the conversion of iodobenzene was up to 97%and the selectivity to the corresponding cross-coupling product can reach 99%.AOFs-Pd(Ⅱ)catalyst showed good stability after a continuous operation time of 20 h,and the catalytic efficiency of Pd was 694.29 mmol/(g·h),which was 2.6 times of that obtained with traditional batch reaction.