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系统地研究了聚乙二醇体系中纳米钯催化氯苯的Suzuki偶联反应。通过对温度、聚乙二醇(PEG)链长以及碱等条件的优化,得出了最优化反应条件。研究发现,在100℃下,以PEG2000为反应介质,以Pd(OAc)2为钯源,以Na2CO3或K3PO4为碱,氯苯尤其是活化氯苯均能顺利发生反应。同时也研究了苯硼酸上取代基的电子效应和位阻效应对反应的影响,结果表明,当苯硼酸上具有给电子效应的基团时,反应更容易发生,取代基的位阻效应对反应无影响。研究还发现,在此催化体系中溴苯除发生Suzuki偶联反应外,还可发生还原去卤反应。同时,对反应机理进行了研究,TEM显示,在氯苯反应过程中有纳米钯的生成。最后研究了该催化体系的循环使用情况,研究表明该催化体系可以循环使用3次。
The palladium-catalyzed Suzuki coupling reaction catalyzed by nano-Pd in polyethylene glycol system was systematically studied. Optimized reaction conditions were obtained by optimizing temperature, PEG chain length and alkali conditions. The results show that at 100 ℃, with PEG2000 as the reaction medium, Pd (OAc) 2 as the palladium source, Na2CO3 or K3PO4 as a base, chlorobenzene, especially activated chlorobenzene, can react smoothly. The effects of electronic and steric effects on the substituents of phenylboronic acid have also been studied. The results show that the reaction is more likely to occur when phenylboronic acid has an electron-donating group, and the steric hindrance of the substituent on the reaction no effect. The study also found that in this catalytic system in addition to Suzuki Suzuki coupling reaction occurs, but also can occur reduction dehalogenation reaction. At the same time, the reaction mechanism was studied, and TEM showed that during the reaction of chlorobenzene, nano-palladium was formed. Finally, the recycling of the catalytic system was studied. The results show that the catalytic system can be reused three times.