Preparation And Catalytic Activity Of Supported Rhodium Catalysts For Organic And Inorganic Hybrid Silicon Materials

Imidazolium-Based organic-inorganic hybrid silica(IBOIHS) has the advantage of simple preparation, easy modification. As a compound having a double support features, which itself has the role of phase transfer catalysis in the catalytic reaction, having a more favorable effect in heterogeneous catalytic reactions involved as well. In addition, the material also has high thermodynamic stability, while a large number of surface hydroxyl groups, a catalyst to facilitate the modification and immobilization. Hydroxy and mostly located in the surface of the material, the more extensive and uniform distribution of active sites on these characteristics of the prepared solid catalyst carrier, a material having an open lamellar microstructure conducive substrates to the catalytically active centers, while the product is also beneficial to enhance stereoselectivity. Periodic mesoporous organosilica(PMO) has a larger surface area and pore volume, pore size and arranged in an orderly and controllable pore size distribution, high thermodynamic and mechanical stability, PMO material has its specific properties suchas has high hydrophobicity, they significantly promote the conversion of the organic functional group in the inner surface of the silica. Advantages of these two materials based on various aspects, we designed and synthesized two types of supported catalysts and explored their respective catalytic properties.(1) Preparation and catalytic properties of rhodium imidazolium-Mixed organic-inorganic hybrid silica as a carrier immobilized chiral precursor a kind of heterogeneous catalysts(Cp*RhTs-DPEN-PMO) to give a kind of homogeneous catalysts and they exhibit similar catalytic activity and enantioselectivity. Systematic study of the catalyst for catalyzing the aromatic ketone and the like, one asymmetric hydrogen transfer reactions in the aqueous phase in the catalytic activity and stereoselectivity which has equal performance with a homogeneous catalyst or even better, more importantly, heterogeneous catalysts 5 can easily be recycled and catalyze asymmetric hydrogen transfer α-halogenated acetophenone and benzyl 8 times by centrifugation and remain good catalytic activity and stereoselectivity. Demonstrate its broad prospects and potential applications in catalysis synthesis.(2) Synthesis of a Periodic mesoporous organosilica PMO(1) as a carrier immobilized chiral precursors S/Olefin-Rh catalyst to obtain a heterogeneous catalyst S/Olefin-PMO(2), chelating metal rhodium catalysts to obtain a heterogeneous catalyst S/Olefin-Rh-PMO(3), showing a homogeneous catalyst with relatively high catalytic activity and enantioselectivity. And by characterizing proved homogeneous catalysts S/Olefin-Rh has been successfully immobilized on mesoporous PMO silica(1). More importantly, the more important is the heterogeneous catalyst S/Olefin-PMO(2), chelating metal rhodium catalysts to obtain a heterogeneous catalyst S/Olefin-Rh-PMO(3) in 1,2-addition reactions can be easily recovered by centrifugation and re-use of the heterogeneous catalyst was repeated eight times more practical, but also exhibits excellent activity and enantioselectivity, showing its broad prospects in the catalytic synthesis and potential applications.