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Studies On The Alternating Copolymerization Of Carbon Dioxide With Cyclohexene Oxide By Chiral Semi-azacrown Ether Ligand

Posted on:2012-06-20Degree:MasterType:Thesis
Country:ChinaCandidate:L J LuFull Text:PDF
GTID:2211330338457050Subject:Organic Chemistry
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The level of carbon dioxide in the atmosphere has grown rapidly since the Industrial Revolution, and today the total number is 1 teraton in the earth. The excessive emission of carbon dioxide toward global warming and result in a lot of troubles, for example, the severe changes of the climate, greenhouse effect and so on. Furthermore, carbon dioxide which is an abundant, nontoxic, nonflammable, renewable C1 feedstock, have the particular qualities that attract scientists to replace petroleum resources. The development of processes to active and make use of carbon dioxide to synthesize chemicals to meet the demand is a potential research goal. One of promising pathways is the copolymerization of carbon dioxide with epoxides. In 1969, Inoue et al. made the first example of the production of a copolymer from carbon dioxide and propylene oxide, inspiring the development of this important area of polymer science. Some problems are hindering the development of industry, such as low catalytic activity and recycle using, poor selectivity, the low Mn and broad PDI as well as harsh reaction conditions.In this thesis, there is a review focusing on the homogeneous catalysts for carbon dioxide-cyclohexene oxide copolymerization as well as the study on the reaction catalyzed by chiral semi-azacrown ether ligand under mild condition even under low temperature of 10℃and CO2 pressure of 1 atm. additives, the reaction time and temperature as well as the solvent effect on the CO2-cyclohexen oxide copolymerization reveal that the liagnd with ZnEt2 is an active catalyst for the altenating copolymerization of CO2 and cyclohexen oxide providing isotactic enriched polycyclohexene carbonate with 93.6% ee (measured by hydrolyzing the copolymer and analyzeing the resulting cyclohexanediol derivate using chiral LC) and a narrow polydispersity. Until now, it is the first catalyst system that keeps excellent polymer selectivy and stereoselectivy stimultaneously under such mild condition.
Keywords/Search Tags:chiral semi-azacrown ether ligand, carbon dixide, cyclohexene oxide, mild condition, asymmetricl catalyst, alternating copolymerization
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