Immobilization Of Ruthenium Organometallic Catalysts On Mesoporous Silica And Study On Their Catalytic Behaviors During Homoallylic Alcohol Isomerization Performed In Aqueous Media

Development of harmless and highly effective catalysts used in water phase is one of important goal of "Green Chemistry". Mesoporous silicate materials are of uniform and tailored pore size, stable framework, suitable wall thickness, high surface area and the plenty silanol groups on its inner surface, which are favourable for modification. Organic-metal catalysts supported on these mesoporous materials can exhibit comparable activity and selectivity with their corresponding homogeneous catalysts and are more preferable for industrial application because of easy separation and repeated use.In this paper, modified mesoporous silicate materials, such as NH₂-MCM-41, NH₂-SBA-15, PPh₂-SBA-15, PPh₂-SBA-16, PPh₂-KIT-6 and PPh₂-FDU-12, were synthesized by self-assembly of surfactant. Ru(II) catalysts supported these materils were prepared by covalent bonding method and characterized by XRD, TEM, N2 adsorption-desorption and Solid NMR etc. Their catalytic performance was evaluated with homoallylic isomerization reactions as the probe in water media instead of traditionally used organic solvents, which could be considered as an example in green chemistry. The relationship between their catalytic behaviors and structural characters of the as-prepared catalysts was discussed briefly, and the reaction mechanism was studied. The detail is as follows:1. By prehydrolysis of inorganic silica sources, NH2-SBA-15 with high contents of amine groups was synthesized. It was of well-ordered arrays of mesochannels and a typical two-dimensional p6mm hexagonal symmetry. While the method of co-condensation of organic and inorganic silicon sources at room temperature was employed to synthize NH₂-modified mesoporous NH2-MCM-41 materials, which has large surface area and narrow pore size distribution. Ru(II) catalysts supported these materials were prepared by coordination, which exhibited high selectivity and good activity for homoallylic isomerization reactions in water. For example, yields of 4-phenyl-3-buten-2-ol can reach 54% and selectivity to 4-phenyl-3-buten-2-ol exceed...