Synthesis And Catalysis Of Organically Functionalized Mesoporous Molecular Sieves MCM-41 Immobilized Salen Mn/VO Complexes

A bis(3-(triethoxysilyl)propyl)amine functionalized mesoporous molecular sieves MCM-41 as a support for immobilization of salen metal complexes were synthesized by co-condensation method. A heterogenized Salen Mn(Ⅲ) complex with (1R,2R)-1,2-diaminocyclohexane was synthesized by a multi-step grafting method. The structure of the supported complex was characterized by FT-IR, DR UV-Vis, XRD,N2 adsorption and ICP. The immobilized complex was employed in the asymmetric epoxidation of several olefins. The effects of reaction temperature, reaction time, molar ratio of catalyst and oxidant on the enantioselective epoxidation of non-functional olefins were investigated. Compared to the correspondent homogeneous catalyst, it was found that both the catalytic activity and the enantiomeric excess of the heterogenized catalyst were obviously decreased. For example, the conversion of cis-β-methylstyrene was only 11.5%, the selectivity and ee were 53.5%and 13.5% respectively when m-CPBA was used as an oxidant.Two heterogenized Salen Mn(Ⅲ) complexes with (1S,2S)-1,2-diphenylethylene-diamine and different group at C5 of salicylaldehyde moiety were prepared by anchoring complexes onto a secondary amino modified MCM-41. The heterogenized catalysts were characterized by FT-IR,XRD,DR UV-Vis,N2 adsorption and ICP. Their catalysis and recyclability in the asymmetric epoxidation of unfuctionalized alkenes were studied. The results indicate that the group at C5, the mesoporous structure of the support and the Mn content all were the key factors effecting on the catalytic properties of the heterogenized Salen Mn(Ⅲ) complexes.A Salen VO/MCM-41 complex was synthesized from the salen ligand anchored onto the functionalized MCM-41 and V(Ⅳ). The structures of intermediates and the heterogenized complex were characterized by FT-IR,XRD,DR UV-Vis,N2 adsorption and ICP. The catalysis in the oxidation of cyclohexane with H2O2 as an oxidant was studied. It was found that the conversion of cyclohexane can go up to 45.5% with a 100.0% selectivity of cyclohexanone and cyclohexanol when the reaction was run at 60℃for 12 hours in the presence of cyclohexane (5mmol), 30% H2O2 (10mmol) and the catalyst (0.02mmol).