SYNTHESIS OF POLYCARBONATES BY COPOLYMERIZATION OF CARBON DIOXIDE AND CYCLOHEXENE OXIDE USING SCHIFF BASE COMPLEX AS CATALYST

摘要

Chemical fixation of CO_2 is a very attractive subject not only from the viewpoint of carbon resource utilization, but also from increasing environmental concerns. One of the most promising green reactions in this area is the alternating copolymerization of CO_2 with epoxides to generate biodegradable polycarbonates, which was first reported by Inoue using ZnEt_2/H_2O catalyst in 1969. Since then, there have been many catalysts so far developed for the alternating copolymerization. Among all the catalysts reported, the Schiff base complexes catalysts are known to produce high molecular weight polycarbonate at mild conditions. Herein, we report the synthesis of a novel Schiff base Zn complex and its catalytic behavior for the coupling reactions of carbon dioxide and cyclohexene oxide. The ligand was prepared by the reaction of 2-thiophenecarboxaldehy and o-phenylenediamine, and the catalyst was synthesized by the coordination of the ligand and ZnEt_2. The catalytic behavior of the catalyst for the copolymerization of CO_2 with epoxides was investigated. TON of 421.1 and 1.85 ×10~4g·mol~(-1) for the copolymer were achieved. This work was supported by Foundation of He'nan Educational Committee (14A150016); This work was also supported by Doctoral Fund of Henan Polytechnic University (B2012-052).