Study On Synthesis Of Immobilized Metal Complex Catalysts And Their Application In Asymmetric Catalytic Reaction

A major problem associated with homogeneous catalyst systems is the separationand recycling of the expensive chiral catalyst. Thus the development of a novelcatalysts with high activity and enantioselectivity without leaching of catalytic speciesis highly desirable. For this purpose, in this dissertation, we have designed andsynthesized two novel types of chiral phosphine-functionalized ligands by choosingC2-chiral diphosphine pyrphos ligand pyrphos as model molecule and employingN-methylimidazole and Fréchet polyether dendrimer as support. Their catalyticproperties have been studied by applicating these catalysts in asymmetrichydrogenation of2-(acetylamino)-3-phenyl-2-propenoic acid. On this basis,thecatalytic recycle of catalyst and structures of catalyst have been studied.1The study on synthesis of N-methylimidazole ionic liquids-tagged chiral pyrphosand their application in asymmetric catalytic reactionA type of chiral pyrphos-functionalized N-methylimidazole ionic liquids-taggedpyrphos have been synthesized, characterized, then applied their Rh-complex in theasymmetric hydrogenation of2-(acetylamino)-3-phenyl-2-propenoic acid. Theinfluence of reaction medium, reaction temperature, reaction time, structure ofcatalyst and halide impurities on the catalytic activity and stereoselective have beenresearched. The studies show that the properties of the catalyst is similar toN-acetyl-pyrphos. Under optimal conditions, the dehydrogenation has been applied toother potential chiral asymmetric hydrogenation of amino acids obtained better results.In the catalyst recovery test,[BMIM] BF4/MeOH=1/1as solvent and after the end ofthe reaction,diethyl ether is added. At this time, two phases have been separated withthe catalyst recovered.2The study on synthesis of the fourth generation of the core with the alkyl chainFréchet polyether dendrimer-tagged pyrphos and their application in asymmetriccatalytic reactionIt was found that the dendrimer catalyst almost “lost” its activity when goingfrom generation3to generation4. This was probably due to a transition change inshape of the dendritic macromolecule from an extended to a more globularconformation. Therefore, generation4of the core with an alkyl chain Fréchetpolyether dendrimer-tagged pyrphos have been synthesized, characterized, then applied their Rh-complex in the asymmetric hydrogenation of2-(acetylamino)-3-phenyl-2-prop-enoic acid. The influence of catalyst recovery and the structure ofcatalyst on the catalytic activity and stereoselective have been studied. The Studiesshow that the properties of the catalyst is similar to N-acetyl-pyrphos-Rh. In thecatalyst recovery test, methanol/toluene as solvent and after the end of the reaction,methanol has been added. At this time, two phase separation methods have achievedthe recycling and reuse of the catalyst.