10.1007/s00706-013-0925-7
This research presents the development of a heterogeneous palladium catalyst supported by a polymerized functional ionic liquid for the reductive homocoupling of aryl halides. The purpose of the study was to create a recyclable catalyst that could selectively catalyze the formation of biaryls, which are important building blocks in pharmaceuticals and agrochemicals, under mild conditions. The researchers synthesized a homopolymer of 3-(cyanomethyl)-1-vinylimidazolium hexafluorophosphate and used it to support Pd nanoparticles, resulting in the Pd@poly-CN-PF6 catalyst. This catalyst was found to efficiently catalyze the homocoupling reactions of aryl halides in water at 100°C with good yields. The catalyst could be recycled and reused multiple times with only a slight loss in activity, which was attributed to palladium leaching at high temperature and aggregation of palladium nanoparticles. Key chemicals used in the process included 1-vinylimidazole, 2-chloroacetonitrile, potassium hexafluorophosphate, azodiisobutyronitrile (AIBN), and sodium borohydride (NaBH4) for the synthesis of the polymer and the Pd nanoparticles, as well as aryl halides, NaOH, and ascorbic acid in the catalytic reactions.