二(芳氧基)稀土(Ⅱ)配合物催化ε-己内酯开环聚合

RING OPENING POLYMERIZATION OF ε CAPROLACTONE BY BIS(ARYLOXO )LANTHANIDE(Ⅱ) COMPLEXES

系统地研究了二（２，６二叔丁基４甲基酚基）钐［（ＡｒＯ）２Ｓｍ（ＴＨＦ）４］催化ε己内酯的开环聚合，发现它具有很高的催化活性并显示“活性”聚合的特点，在甲苯中，当［Ｍ］／［Ｉ］＝２０００（摩尔比），６０℃，１ｈ，转化率可达９８％．并比较了不同的两价稀土化合物的催化活性．通过核磁分析末端基结构的方法，研究了（ＡｒＯ）２Ｓｍ催化己内酯开环聚合的引发机理，发现催化剂首先与己内酯反应，生成三价烯醇式稀土化合物，后者引发己内酯聚合．

Ring opening polymerization of ε caprolactone catalyzed by (ArO) 2Sm(THF) 4 (ArO=2,6 ditertbutyl 4 methyl phenoxo ) was systematically studied.The polymerization system has “living ” characteristic and shows high activity,the conversion is as high as 98% in toluene at 60℃ for 1h under /=2000.The central ions and ligands have effect on the activity of catalysts.The initiation mechanism by divalent lanthanide complexes has been studied through oligomer end group analysis by NMR.The results demonstrate that catalyst reacts first with ε caprolactone to give a trivalent lanthanide enolate which then catalyzes caprolactone polymerization.