Precise Synthesis of Functional Polymers Utilizing Cl Resources.

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Aiming at the synthesis of functionalized polymers with precise control of structure and molecular weight, introduction of functional groups into the polymers have been examined, especially utilizing the easily available Cl resources, such as carbon monoxide and carbon dioxide. The two major subjects are, (i) asymmetric alternating copolymerization of olefins and carbon monoxide ; and (ii) asymmetric alternating copolymerization of meso-epoxide and carbon dioxide. The achievements are summarized as follows.(i) Asymmetric alternating copolymerization of olefins and carbon monoxideUsing a palladium complex of chiral phosphine-phosphite ligand BINAPHOS, alternating copolymerization of CO with perfluoroalkyl substituted olefins were examined. The isotactic copolymerthus obtained exhibited high water repellent property. Also, side-chain liquid crystalline polyketones were successfully produced.(ii) Asymmetric alternating copolymerization of meso-epoxide and carbon dioxideCompletely alternating copolymerization of cyclohexene oxide with carbon dioxide was achieved using a zinc complex of chiral amino alcohols. The polymerization proceeded in a highly enantioselective manner and thus, highly enantioselective alternating copolymerization has been performed for the first time. One of the unique features of the current study is that the enantiomeric excess of each of the chiral unit could be determined unambiguously. Because the polycarbonate can be hydrolyzed under alkali conditions, degradation of the polymer gave us the chiral diol unit whose enantiomeric excess was determined to be 70 % by chiral GLC analysis. Further studies on the catalyst revealed that the active species is a dimeric zinc complex. Isolation of the pure dimeric complex enabled us to disclose the reaction mechanism as well as elevate the enantiomeric excess finally up to 80 %.