Preparation Of Functionalized Chiral Catalysts And Their Applications In The Synthesis Of Chiral Cyclic Carbonates

The transformation of carbon dioxides has attracted the most attention of the researchers. This article mainly discussed the cycloaddition reaction of carbon dioxide and the epoxides for the synthesis of cyclic carbonates, and the research progress. Meanwhile, we designed and synthesized an efficient, simple, recyclable and reusable catalytic system. While considering about the current research focuses, a new chiral bifunctional catalyst system based on the ionic liquid was synthesized. The content was divided into three parts:Chatper1:The catalysts, which catalyzed the cycloaddition reaction of carbon dioxide and epoxides, was divided into the homogeneous catalysts and the heterogeneous catalysts. As there were various of homogeneous catalysts, it approximately included organic metal complexes (Schiff base, porphyrin), ionic liquid, the compounds with Lewis acid meter center and Lewis base center, and the heterogeneous catalysts contained the metal oxides, the immobilized homogeneous catalysts. The reports about organic metal complexes were extremely various, so we compared the kinds of metals, the ligands. In summary, this content simply concluded the research progess and the new achievement in recent these years.Chapter2:Based on our research, combined the concept of ionic liquid, we designed and synthesized a new chiral bifunctional catalyst with alkylimmidazole ionic liquids. This catalyst combined the Lewis acid metal center and the Lewis base center, without any co-catalysts, any solvents, was applied for the synthesis of cyclic carbonates. This article demonstrated the effect of counter-ions, anion, and the alkyl chain length in this reaction. Under the optimized conditions, the chiral cyclic carbonates were obtained in high yield and the moderated enantioselectivity.Chapter3:In order to immobilize on the supports, the chiral homogeneous catalysts was designed to support on the cation resin. Because the cation resin possed the advantages such as stable, low cost, economic applicability, easily supported and unsoluble in the most solvents, the Salen Co(Ⅱ) complexes was supported on the cation resin with the valence bond. So the catalyst was avoided run off in the reaction, meanwhile the suppoted catalyst was stable, easily separated with the products through simply filter for the next use. The effect of the various co-catalysts such as tetrabutyl ammonium halogenide, was discussed. Various epoxides was synthesized to corresponding cyclic carbonates under this catalyst system. At last, this new catalyst can be reused for five times, without the catalytic activity loss, and the chiral cyclic carbonates’s enantioselectivity was increased, while it obtained the highest value at the fourth time.