Mesoporous Structure Of Organic Metal Catalyst Synthesis And Catalytic Asymmetric Hydrogenation

Asymmetric catalysis is the forefront of the field of organic chemistry and the direction of development. In recent years, the search for high enantioselectivity and high catalytic activity of chiral ligands, by homogeneous catalyst load is the latest asymmetric catalyst on hot issues. Mesoporous structure of the SBA-15 nanomaterials as a new type of supported materials were widely used in chiral ligands and supported metal catalyst. The feasibility of the "postgrafting and postmodification" methods is demonstrated by its successful application in asymmetric hydrogen of aromatic ketones . Advantages of the these catalysts such as easy preparation, high efficiency and moderate enantioselectivities, facile recovery and reuse.ect. are also exemplified in this dissertation.1. Syntheses of the mesoporous silica-supported chiral Rh and Ru catalysts and application in asymmetric hydrogenation.Two mesoporous silica-supported chiral Rh and Ru catalysts with ordered two-dimensional hexagonal mesostructures were prepared by directly postgrafting homogeneous Rh and Ir catalysts on SBA-15. During the asymmetric hydrogenation of various aromatic ketones under 40 atm H₂, both catalysts exhibited high catalytic activities (more than 97% conversion) and moderate enantioselectivities (33-54% ee). Furthermore, the chiral Rh and Ir catalysts could be easily recovered and used repetitively five times without significantly affecting its catalytic activity and enantioselectivity.2. Syntheses of the mesoporous silica-supported chiral Ir catalysts and application in asymmetric hydrogenation.Mesoporous silica-supported chiral Ir catalysts was prepared by co- condensation-postgrafting organometallic complex on SBA-15. We study the influences of the surface properties,the mesostructures and the metals of chiral complex on the catalytic performance of the materials. During asymmetric hydrogenation of aromatic ketones,the mesoporous silica-supported chiral Ir catalyst exhibited high catalytic activity(more than 92% conversions)and moderate enantioselectivity(30-55%ee) under 40atm H₂. Such catalysts could be recovered easily and reused.