Synergistic Catalysis By Active Hydrogen Compounds With Potassium Iodide For Cycloaddition Reaction Of Carbon Dioxide With Epoxides

Recently, carbon dioxide（CO₂） is a main greenhouse gas. It is also a cheap, nontoxic, and abundant C1 building block chemical. Fixation of CO₂ is one of the most effective method, and cycloaddition reaction of CO₂ and epoxide has attracted tremendous research interest. Many catalysts have been developed for the reactions of CO₂ and epoxides to produce cyclic carbonates. As a kind of abundant, simple and cheap catalyst, Alkali halides has been widely used. In this paper, we explored a simple and cheap catalyst containing active hydrogen compounds based on potassium iodide, and achieved ideal results. The results are as follows:（1） In this section, we choosed a better cocatalyst named acrylamide from five simple and cheap amide compounds which contained hydrogen compound, and explored the optimal reaction conditions of the KI/acrylamide（AM）, in the experiment, KI/acrylamide（AM） catalytic system 98% propylene carbonate（PC） yield and more than 98% selectivity could be achieved without any co-solvents, the reaction time was 4h, at 120 °C, the pressure of CO₂ was 4.0 MPa, and the molar ratio of KI to AM was 2:2, Moreover, we investigated the catalytic activity of KI/AM system to the other epoxides, the results show that it was also applicable to the other epoxides.（2） In this section, we choose a better cocatalyst mamed polyvinyl alcohol（PVA） 1788 from polyvinyl alcohol（PVA） which contained hydrogen compound, and explored the optimal reaction conditions of the KI/PVA1788. Then, we explored the optimal reaction conditions of KI/PVA1788, the reaction was without annexing agent at 120 °C, 4 h, the particle size of PVA1788 was 500 mesh, the presure of CO₂ was 4.0 MPa, the mass ratio of KI/PVA1788 was 1:2. 98% PC yield and more than 99% selectivity could be achieved of KI/PVA1788. As to other terminal epoxides, KI/PVA1788 was also applicable, when KI/PVA1788 was repeatedly used, we surprised to find the catalytic activity decreased with the degree of crystallinity.（3） As a natural, non-toxic, cheap catalyst, wool powder was explored to be a cocatalyst. The catalytic system with 98% PC yield and more than 99% selectivity could be achieved at 130 °C, the reaction time was 4h, the presure of CO₂ was 2.0 MPa and the mass ratio of KI to WP was 2:2, moreover, the catalyst activity was unchanged when the catalyst was reused for five times, and KI/WP was proved to be applicable to other terminal epoxides.