席夫碱-铝配合物的合成及对丙交酯的立体选择性聚合

Synthesis of Aluminum-Schiff Base Catalyst and Their Stereoselective Polymerization of Lactides

设计、合成了一系列不对称席夫碱配体,得到了相应的金属铝配合物.研究了配合物在外消旋丙交酯的开环聚合反应中的催化性能.结果表明,系列配合物对外消旋丙交酯(rac-LA)的聚合催化活性明显提高,并具有立体选择性.

A series of asymmetric Schiff-base ligands and their aluminum Al （Ⅲ） complexes that contained different steric substituent were designed and synthesized. The structures of ligands and their complexes were characterized. One crystal of Schiff-base aluminum complex was obtained. X-Ray diffraction analyses showed that the central aluminum atoms of the complex adopt twisted four pyramid geometry. They were chiral but ra-cemic complexes with two enantiomers in solid state. Their catalytic properties in the solution polymerization of racemic lactides（ rac-LA） in the presence of 2-propanol were investigated in detail. All of the complexes had poor stereoselectivity for ring-opening polymerization（ROP） of rac-LA（Pm about 0.55）, the polymerization rate of asymmetric complex was much faster than symmetric complex in ROP of rac-LA. The results evaluate that the substituent of ligands has great influence on the catalytic properties of the complex.