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Synthesis Of Polymer-Supported Chiral Quaternary Ammonium Salts Phase-Transfer Catalysts And Studies On Their Asymmetric Catalysis Properties

Posted on:2006-12-20Degree:MasterType:Thesis
Country:ChinaCandidate:Q L LiFull Text:PDF
GTID:2121360152490072Subject:Polymer Chemistry and Physics
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Polymer-Supported chiral catalysts have many merits which are easily removed at the end of the reaction and can possibly be re-used and overcome these problem such as the high cost and diffculty in reuseability of homogeneous catalysts. Adapt to the need of green chemical industry and sustainable development. In this paper, kinds of new chiral quaternary ammonium salts were synthesized and characterized and the application of chiral quaternary ammonium salts as phase-transfer catalysts in the alkylation of active methylene group was discussed. This thesis consists of three parts as follows.Part I:Reviewchiral compound's study methods ,new concept of chiral technology in recent ye ar, kinds of means of attaining chiral compound ,the application and recent developm -ent of polymer-supported cinchona alkaloid catalysts in asymmetric dihydroxylation reaction, the Michael addition reaction, the alkylation of active methylene group, asymmetric reduction reaction of prochiral ketone and asymmertric synthesis of chiral epoxides by catalyzing alkenes were reviewed.As a new catalysts, their prospect and the problems they faced were also discussed in this part.Part II: Synthesis and characterizing of polymer-supported chiral quaternary ammonium salts phase-transfer catalysts.Polyethylene glycol and its derivatives can be used as phase-transfer catalysts just like crown ether, polyethylene glycol with different molecular weight have been supported on chlormethylated polystyrene, after the polymer of chlormethylated polystyrene-polyethylene glycol was chlorinated and iodided, Cinchonine react with it and gained a kind of polymer-supported chiral quaternary ammonium salts.These catalysts can posses merits of quaternary ammonium salts and crown ether in the same time, moreover, it can demonstrated good catalysis kind of triphase chiral catalysts were prepared in the first time by using three kinds of Cinchonine, Matrine and Lappaconitine as raw material, cross-linked polystyrene supported polyethylene glycol and chlormethylated polystyrene as supporter . Theirstructures were characterized by FT-IR SEM XPS TG-DTA and elemental analysis.Part III: The application of polymer-supported chiral quaternary ammonium salts phase-transfer catalysts in asymmetric alkylation reactionN-(diphenylmethylene) aceethyl esters was synthesized and its structure was confirmed by UV, NMR, at the same time the catalystic product was characterized by elemental analysis and GC-MS, The enantiomeric excess was determined by chiral HPLC (chiralcel OD-H column) .Asymmetric alkylation under different condiction using the polymer-supported chiral quaternary ammonium salts which we have synthesized as catalysts was studied, The possible catalystic mechanism of the reaction was also discussed .Influences of catalysts structure, ratio between catalysts and substrates, different temperatures, different alkylated reagents and the reusability of catalysts were studied. It is demonstrated that the recovered catalyst can be reused without appreciable loss of activity...
Keywords/Search Tags:Polymer-supported, Chiral quaternary ammonium salts, Asymmetric alkylation, Asymmetric Catalysis, Cinchonine, Matrine and Lappaconitine
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