Well-defined Synthesis of Polyester by Living Anionic Alternating Copolymerization of Ketene and Aldehyde

研究了乙基苯乙烯酮与芳香醛的活性阴离子交替共聚反应。丁基锂和四氢呋喃分别用作引发剂和溶剂。氯化锂的加入对于获得具有窄多分散性的相应聚酯是必要的。各种芳族醛如甲氧基取代的和烯丙氧基取代的苯甲醛可用作单体。乙基苯基乙烯酮与取代苯甲醛的共聚也是成功的。定量得到了相应的聚合物，其分子量分布较窄。侧链甲硅烷氧基的脱甲硅烷基化导致成功形成在侧链中具有酚部分的相应聚酯。此外，还实现了立体选择性共聚。主链中重复单元的相对立体化学被发现是由用于聚合的溶剂和添加剂很好地控制。聚合物被还原降解为重复单元，其进一步衍生为分子，其单晶通过X射线分析以确定聚合物主链中的相对立体化学。利用光学活性添加剂导致光学活性聚酯的形成，其通过旋光计和配备有光学活性柱的HPLC进行分析。

Living anionic alternating copolymerization of ethylphenylketene with various aromatic aldehydes was achieved. Butyllithium and tetrahydrofuran were used as an initiator and a solvent, respectively. Addition of lithium chloride was essential to obtain the corresponding polyester having narrow polydispersity. Various aromatic aldehyde such as methoxy-substituted and allyloxy-substituted benzaldehydes can be used as monomers. Copolymerization of ethylphenylketene with siloxy-substituted benzaldehyde was also successful. The corresponding polimer was obtained quantitatively, and its molecular weight distribution was narrow. Desilylation of the side chain siloxy group resulted in successful formation of the corresponding polyester having phenol moiety in the side chain. In addition, stereo-selective copolymerization was also accomplished. The relative stereochemistry in the repeating unit in the main chain was found to be well-controlled by solvent and additive used for the polymerization. The polymer was reductively degradated into the repeating unit, which was further derivatized into the molecule, whose single crystal was analyzed by X-ray to determine the relative stereochemistry in the polymer main chain. Utilization of optically active additive resulted in formation of optically active polyester, which was analyzed by polarometer and HPLC equipped with optically active column.