Preparation Of Magnetic PMO Supported Catalyst And Its Asymmetric Catalysis

Traditional inoganic silica coating magnetic nano material have gained muchattention for the application in vairous fields. However, integration of periodicmesoporous organosilica (PMO) with magnetic particles have been less explorated.As expected, ograno-silica coating magetic material also have many advantages，suchas facile preparation，remarkable thermal and mechanical stability, and terminated bya silanol group that can react with various coupling agents to covalently attachfunctional groups to the surfaces of these magnetic nanoparticles.What’s more,thesuperior hydrophobicity of this backbone layer can be benefit for the transmission ofreactant which may enhances significantly the catalytic activity, and in particular, thismagnetic catalyst can be recovered easily by using an outer small magnet. Neitherfiltration nor extraction was necessary. Asymmetric catalysis can be divided into twokind of typical types (except for enzyme).Based on those backgrounds, we designmagnetic organo-silica materials as carrier to support transition metal catalyst andorgano-molecule catalyst，respectively.(1)A phenylene-coated magnetic nanoparticle boosts aqueous asymmetrictransfer hydrogenation reaction: we utilize the salient hydrophobiciyt of periodicmesoporous organosilica and design a magnet-sepatated phenylene-coatedhetergeneous catalyst. The phenylene-coated layer onto Fe304was then formed viatheco-condensationof4-(trimethoxysilyl)ethyl)phenylsulfonyl-1,2-diphenylethylene-diamineand1,4-bis(triethyoxysilyl)benzene using cetyltrimethylammonium bromide as a templateto afford TsDPEN-functionalized PMO. Finally, the magnetic catalyst was obtainedsuccessfully by the direct complexation of (Cp*RhC12)2with TsDPEN-functionalizedPMO followed by further Soxhlet extraction for clearness of the nanochannels.Fromthe characterization of13C MAS NMR spectra, SEM, TEM, we konw that magneticheterogeneous catalysts have been successfully synthesed.The high hydrophobicity ofthe phenylene coating significantly enhances the catalytic activity for the reaciton ofasymmetric transfer hydrogenation reaction of aromatic ketones while retaining highenantiomeric excess (ee) values. After reaciton, catalyst can be recovered easily byusing a small magnet; neither filtration nor extraction is necessary. Furthermore, the catalyst can be reused for at least10times without loss of its catalytic activity.(2)Solid periodic mesoporous organosilica as carrier: Preparation ofheterogeneous catalyst and its catalytic performence research. We synthesized an kindof heterogeneous catalyst based on rhodium metal complex which are futrhercharacterized by many instruments, such as13C MAS NMR spectra, SEM, TEM，XPS，ICP and TG curves. From the result of catalysis for the reaciton of asymmetrictransfer hydrogenation reaction of aromatic ketonesjieterogeneous catalyst have anice catalytic activity and retain a high enantiomeric excess (ee) values. Atfer reaciton，catalyst can be recovered easily by using centrifugation, and the catalyst can be reusedfor at least6times without loss of its catalytic activity.(3)Magneticallyrecoverable nanoparticles: highly efficient catalysts for michaeladdition reaction of1,3-dicarbonyls to p-nitroolefins. We synthesized functionalorganocatalyst silica through thiol-ene click method, and prepared ethane-coatedorganocatlyst-functionalized magnetic heterogeneous catalyst by cocondensationmethod. Magnetic catalysts have been successfully synthesed through thecharacteirzation of13C MAS NMR spectra, SEM, TEM, XPS.Ands we performedsupported catalyst for michael addition reaction of1,3-dicarbonyls top-nitroolefins.The catalyst can be recovered easily by using a small magnet, neitherfiltration nor extraction is necessary. Furthermore, the catalyst can be reused for atleast9times without loss of its catalytic activity.