苯并噁唑取代氨基酚氧基锌氯化物催化外消旋丙交酯开环聚合研究  

Ring-opening Polymerization of rac-Lactide Catalyzed by Zinc Chloride Complexes Supported by Aminophenolate Ligands Bearing a Benzoxazolyl Group

作　　者：王玉娜 王超[1] 马海燕[1] Wang Yuna;Wang Chao;Ma Haiyan(Laboratory of Organometallic Chemistry,School of Chemistry and Molecular Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学、化学与分子工程学院、金属有机化学研究室,上海200237

出　　处：《化学学报》2025年第1期25-35,共11页Acta Chimica Sinica

基　　金：国家自然科学基金(No.21871082)资助.

摘　　要：合成了4个苯并噁唑取代的氨基酚氧基锌氯化物1~4,通过1H NMR、13C NMR和元素分析对其结构进行表征.对配合物1通过X-ray单晶衍射分析确定了其晶体结构.该系列锌氯化物稳定性较高,可以催化工业级外消旋丙交酯(rac-LA)开环聚合,并具有较好的催化活性,主要得到环状聚合物和部分线性聚合物;在添加苄醇的条件下,得到苄氧基和羟基封端的线性聚合物,同时有较多环状聚合物生成.骨架氮原子上取代基对配合物催化性能有较大影响,具直链烷基取代的配合物1催化活性最高,在80℃下,以环氧环己烷为溶剂,催化50000倍物质的量工业级rac-LA开环聚合,转化频率(TOF)值达到2716 h^(−1),得到分子量为M_(n)=2.03×10^(4) g/mol的聚合物.骨架氮上环己基取代的配合物3对rac-LA聚合的等规选择性最高,在80℃聚合时达到P_(m)=0.67;降低聚合温度至室温,等规选择性提高至P_(m)=0.70.通过改变单体浓度,利用配合物1实现了分子量最高达到M_(n)=3.10×10^(4) g/mol的环状聚丙交酯的合成.基于低聚物的基质辅助激光解吸电离飞行时间(MALDI-TOF)质谱分析,认为该系列配合物通过先引发环氧环己烷开环得到金属烷氧基物种,进而通过配位插入机理催化外消旋丙交酯开环聚合,并通过端对端环化以及非选择性环化得到环状聚丙交酯.Four zinc chloride complexes supported by aminophenolate ligands bearing a benzoxazolyl group were synthe-sized via the reactions of the corresponding sodium salts of the proligands HL1-4 with one equiv.of zinc dichloride at room temperature respectively,and their structures were well-characterized by 1H NMR,13C NMR and elemental analysis(EA)methods.The molecular structure of complex 1 was further determined by X-ray single crystal diffraction analysis,where the phenoxy oxygen atom,the skeleton N atom,and the benzoxazolyl N atom of the ligand all coordinate with the metal center,forming a disordered tetrahedral coordination geometry around the metal center together with the chloride ligand.This series of zinc chloride complexes showed high stability,and could be applied to catalyze the ring-opening polymerization(ROP)of industrial grade racemic lactide(rac-LA)with good activities.The substituent on the skeleton N atom exhibited a significant impact on the catalytic performance of the complex.Complex 1 with a linear n-butyl group on the skeleton N atom displayed the highest catalytic activity.At 80℃,50000 equiv.of industrial grade rac-LA could be polymerized by complex 1 using cyclohexane oxide(CHO)as a solvent,and a high turnover frequency(TOF)value of 2716 h^(−1) was reached,resulting in a cyclic polymer with a molecular weight of M_(n)=2.03×10^(4) g/mol.Complex 3 with a cyclohexyl group on the skeleton N at-om showed the highest isotactic selectivity among these zinc chloride complexes toward the ROP of rac-LA,at 80℃,P_(m)=0.67,which could be increased to P_(m)=0.70 when the polymerization was carried out at 25℃.By adopting a high monomer concentration of 14 mol/L in the polymerization,cyclic polylactide with a molecular weight of M_(n)=3.10×10^(4) g/mol was achieved using complex 1.Based on the matrix-assisted laser desorption ionization time-of-flight(MALDI-TOF)mass spec-troscopic analysis of oligomers,it was found that in the absence of benzyl alcohol,the polymer formed was mainly cyclic,containing

关 键 词：苯并噁唑取代氨基酚配体 锌氯化物 外消旋丙交酯 开环聚合 环状聚丙交酯 

分 类 号：TQ316.314[化学工程—高聚物工业]