Study On Preparation And Activity Of Supported Chiral Rhodium Catalyst

Recently, immobilized catalysts become hot spots of scientific research, because they are easy prepared and environmentally friendly. However, they also have many shortcomings, such as awful catalytic activity and selectivity, perishable. So finding applicable supporters is important for preparing immobilized catalysts. Scientific research about immobilized catalysts concentrated on enhancing catalytic activity and selectivity and reusability by making the best of physical and chemical properties of the supporters.In this paper, we prepared two immobilized catalysts successfully by two novel supporters, then check their catalytic activity using asymmetric reaction. Firstly, To prepare Water-soluble thermoresponsive polymer-coated organorhodium functionalized Si O2-nanospheres, we immobilized homogeneous catalyst on silica nanospheres and coated a layer of water-soluble thermoresponsive polymer(poly(acrylamide-co-acrylonitrile)) outside, then coordinated with [Cp*Rh Cl2]2. Secondly, we created a new supporter using the π-π adsorption between carbon nano tubes(CNTS) and pyrene, then synthesized azobenze modified S,S-1,2-diphenylethanediamine(DPEN). After that, we immobilized the azobenze modified S,S-1,2-diphenylethanediamine on the new supporter. The main work is as follow, [1]In this study, first, Si O2-nanospheres wereobtained through the co-condensation of tetraethoxysilane according to the reported method.Continuous postgraftings of triethoxy(vinyl)silane and chiral Ar DPEN-derivated siloxane did then afford vinyl@Ar DPEN-functionalized nanospheres in the form of a white powder. Finally, free radical polymerization of vinyl@Ar DPEN-functionalized nanospheres with acrylamide and acrylonitrile followed by complexation with [Cp*Rh Cl2]2 led to the crude heterogeneous catalyst.Experimental results indicated that the catalyst can promote the reaction, especially for the ee value of products, and also control the reaction rate by changing tempreture. [2] we created a new supporter using the π-π adsorption between carbon nano tubes(CNTS) and pyrene, then synthesized azobenze modified S,S-1,2-diphenylethanediamine(DPEN). After that, we immobilized the azobenze modified S,S-1,2-diphenylethanediamine on the new supporter and then coordinated with [Cp*Rh Cl2]2. The catalytic results showed the catalyst can release the homogeneous catalyst under irradiation of UV before reaction and collected the homogeneous catalyst under irradiation of visible light.