Synthesis Of Polymer Gel Supported-Pd Catalysts And Their Application In Catalysis

Pd-catalyzed Heck, Suzuki and Sonogashira coupling reactions are important methods for construction of C-C bond organic synthesis. The polymer supported-catalysts, with characteristics of high catalytic activity, good selectivity and reusability, have been widely used in the C-C coupling reaction.The polymer gel, with three-dimensional networks, can be used as an excellent support for Pd catalyst after being well designed. The using of polymer gel supported-Pd catalyst for C-C coupling reactions in water can be proceed in a green catalytic procedure, which exhibits the advantages of "quasi-homogeneous catalyst". Herein, the intelligent hydrogel-supported Pd catalyst and magnetic microgel-supported Pd catalyst are designed and prepared, and their catalytic activities are evaluated by catalyzing C-C coupling reactions in water. The main contents are summarized as follows:(1) The porous, quick responsive and chelating hydrogel (P (NIPAM-co-PAP)) and P (NIPAM-co-PAP)/Pd catalyst are prepared, and characterized by FT-IR, SEM and DR-UV etc. The catalytic activity of P (NIPAM-co-PAP)/Pd catalyst is evaluated by catalyzing Sonogashira reaction in aqueous media and the results show that it has high activity, stability and good reusability. The reactions proceeded well within hydrogel, which can be attributed to the good dispersion of Pd catalyst in the macroporous structure as well as the enrichment of reactants and catalyst within hydrogel under reaction conditions.(2) To further extend the scope of P (NIPAM-co-PAP)/Pd catalyst, it is used to catalyze Suzuki and Heck coupling reactions in water. The results show that the P (NIPAM-co-PAP)/Pd is still with high activity, stability and good reusability in both reactions.(3) A novel chelating magnetic microgel (Fe3O4@PUNP) and Fe3O4@PUNP-Pd catalyst are synthesized, and characterized by FT-IR, VSM and XRD etc. The Fe3O4@PUNP-Pd catalyst is applied to the Suzuki and Heck reaction in water for evaluating the catalytic activity. The results reveal that the Fe3O4@PUNP-Pd catalyst exhibits high activity, stability and good reusability. This can be attributed to that the Fe3O4@PUNP with nanoscale size can disperse in medium, and thus increases the probability of contact between the reactant with the active sites of catalyst and conduces to improving the catalytic activity of catalyst. Furthermore, the Fe3O4@PUNP-Pd catalyst can be easily separated and recovered by an additional magnet.