Synthesis and Structural Determination of Zinc Complexes Supportedby Imino-Benzotriazole Phenoxide Ligands：Catalytic Studies for Ring-Opening Polymerization of Cyclic Esters

• Main Authors: Chin-Hsiang Chang, 張進翔
• Other Authors: Bao-Tsan Ko
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/69981729543520998155

碩士 === 中原大學 === 化學研究所 === 101 === Four imino-benzotriazole phenoxide ligands, C1DMeIBTP-H (A), C1DIPIBTP-H (B), C1PhIBTP-H (C) and C1BnIBTP-H (D) were prepared in good yield(≧70%) from the condensation of 3-(2H-benzotriazol-2-yl)-2-hydroxy- 5-methyl benzaldehyde (C1AldBTP-H) with benzylamine or arylamine (aniline, 2,6-dimethylaniline and 2,6-diisopropylaniline (1.1 equiv.)) in solvent (toluene or ether). Zinc catalysts supported by imino-benzotriazole phenoxide ligands were characterized by microanalyses as well as single-crystal X-ray structural determinations. Treatment of the ligand (C1DMeIBTP-H or C1DIPIBTP-H) with 1.0 mol equiv. of ZnEt2 in toluene under the same stoichiometric proportion afforded the dimeric zinc complexes ([(-C1DMeIBTP)ZnEt]2 (1); [(-C1DIPIBTP)ZnEt]2 (2)) in 50% and 53% yields, respectively. The reaction of diethyl zinc (ZnEt2) with C1PhIBTP-H or C1BnIBTP-H (2.0 equiv.) yields tetra-coordinated monomeric zinc complex [(C1PhIBTP)2Zn] (3) or [(C1BnIBTP)2Zn] (4). Catalysis for ring-opening polymerization (ROP) of -caprolactone (-CL), -butyrolactone (-BL), and L-lactide (L-LA) of complexes 1-2 are investigated. Zinc complexes 1 and 2 catalyze the ring-opening polymerization of -caprolactone (-CL) in the presence of 9-anthracenemethanol (9-AnOH) with efficient catalytic activities in a controlled fashion. Additionally, polymerizations of -butyrolactone (-BL) catalyzed by complex 1 and 2 are demonstrated in a “living” character with the expected molecular weights and narrow molecular weight distributions. To examine stereoselectivity of PHB, complex 1 and 2 were employed as catalysts toward ROP of -BL. Experimental results exhibit that complex 1 or complex 2 catalyzes -BL to produce atactic PHB (Pr = 0.48). Furthermore, complex 1 catalyzes rac-LA to yield heterotactic PLA (Pr = 0.66). We also investigate the reaction rate of ring-opening polymerization by complex 1 in the presence of 9-AnOH catalyzes -CL, -BL, and L-LA. In addition, complex 3 and complex 4 are demonstrated to catalyze the ROP of L-LA in the presence of 9-AnOH. However, the catalytic activity and reaction time of complex 3 are much better than complex 4.