Synt6hesis and Ring Opening-Closure Behavior of Polymers Containing a Five-Membered Lactone Unit

用溴三氯甲烷端粒化甲基乙酸丁酯和衣康酸二甲基二聚体，通过化学转化制备了双功能五元内酯单体。这些内酯单体与一些脂肪族和芳族二胺和二醇聚合，得到聚酰胺、聚酯、聚酰胺酸和聚酰亚胺。由脂肪族伯二胺制备的聚酰胺由于内酯部分水解裂解而具有较高的亲水性。（2R^<**>,4S^<**>） -4-氯甲酰-2-氯甲酰甲基-2,4-维-4-丁烷内酯与单胺和单醇缩合物的开环和闭环反应有助于阐明缩合聚合物的开环行为。用^1H-NMR方法跟踪了开环比随时间的变化。模型化合物的行为受pH、溶剂、底物结构等因素的影响较大。当这些开环和闭环反应最终达到平衡时，内酯部分的开环被认为是可逆反应。另一方面，脂肪族伯胺衍生的模型化合物内酯单元的开环完全在磷酸盐缓冲溶液中进行，并且不依赖于酶。标题聚酰胺的水解受开环比和芳香位点的影响，结果表明端型断裂。

Bifunctional five-membered lactone monomers were prepared by the chemical transformation of t-butyl methacylate and dimethyl itaconate dimers telomerized using bromotrichloromethane. Polymerizations of these lactone monomers with some aliphatic and aromatic diamines and diols afforded polyamides, polyesters, polyamic acids, and polyimides. The polyamides prepared using aliphatic primary diamines had a high hydrophilicity owing to partial hydrolytic cleavage of the lactone moiety.The ring-opening and -closure reactions of condensation compounds of (2R^<**>,4S^<**>) -4-chloroformyl-2-chloroformylmethyl-2,4-dimenthyl-4-butanolide with monoamines and monools served to elucidate the ring-opening behavior of the resulting condensation polymers. The variation of ring-opening ratio with the passage of time was traced by the ^1H-NMR method. The behavior of model compounds was affected considerably by such factors as pH,solvent, structure of substrate, and so on. As these ring-opening and -closure reactions finally attain equilibrium, the ring-opening of the lactone moiety is presumed to be a reversible reaction. On the other hand, the ring-opening of lactone unit in the model compound derived from aliphatic primary amine proceeded completely in a phosphate buffer solution and it was independent of enzyme.Hydrolysis of titled polyamides is affected by the ring-opening ratio and aromatic site, and the results suggest the scission of end-type.