Preparation Of Novel Ionic Liquids And Their Applications For The Synthesis Of Cyclic Carbonates From Carbon Dioxide And Expoxides

Despite blamed for global warming, CO2is a C1resource that is nontoxic,inexpensive and abundant. With increase of the consumption of fossil fuels, the “C1resource crisis” becomes serious. In recent years, the transformation of CO2into usefulchemicals attracts more and more attentions. The synthesis of cyclic carbonates viacycloaddition of CO2with epoxides is one of the few strategy for utilization of CO2, dueto the100%of atom utilization ratio, the concept of “green chemistry” as well as “atomeconomy”. Cyclic carbonates is an important chemical product that can be used aspolar aprotic solvents, as a raw material for the formation of phenolic resins,polycarbonates and thermosetting resin, as electrolytes in lithium secondary batteries, ascosmetic additives, and as intermediates in the production of pharmaceuticals and nechemicals. However, most of developed catalysts have inherit disadvantages, such aslow activity, need co-catalyst and/or solvent, and/or difficultly for separation ofproducts. Therefore, the novel, efficient and reusable cataltsts for synthesis of cycliccarbonate from expoxides and carbon dioxide are needed develped.1. A series of (carboxyl, hydroxyl, and amino) functional guanidinium-based ionicliquids (FGBILs) with acid-basic sites were prepared by a simple method, which showgood catalytic activity and selectivity for the synthesis of cyclic carbonates from CO2and epoxides in the absence of co-catalyst and co-solvent. Under mild conditions (130oC,2.5MPa), propylene oxide conversion was nearly completed within2h while using[TMGC2H4NH2]Br as catalyst. Furthermore, the effects of catalysts structure (length ofmethylene chain, functional groups, anions), as wel as reaction conditions (catalystloading, temperature, pressure and time) on the catalytic activity were investigated indetail.2. A series of (carboxyl, hydroxyl, and amino) functionalized phosphonium-basedionic liquids (FPBILs) were synthesized by a simple method, and evalutated as catalystsfor the cycloaddition reaction. In the absence of co-catalyst and solvent, FPBILsperform well for the synthesis of cyclic carbonates. Almost100%of propylene oxideconversion can be achieved under relative mild conditions over [Ph3PC2H4COOH]Brcatalyst. Furthermore, the effects of catalysts structure (length of methylene chain,functional groups, anions), as wel as reaction conditions (catalyst loading, temperature,pressure and time) on the catalytic activity were investigated in detail. 3. A novel cross-linked polymer bead grafted with asymmetrical dication ionic liquidwas fabricated (defined as [P-Im-C4H8Ph3P]Br2). In the absence of co-catalyst andco-solvent, the selectivity and yield of propylene carbonate was99.5%and96.8%,respectively at130oC,2.5MPa,4h and0.38mol%of catalyst relatively. Moreover, thecatalyst shows good stability and reusability. Base on the experimental results, aplausible reaction mechanism was proposed for the reaction.4. A series of polymers grafted with functionalized dication imidazolium-based ionicliquids (P-FDIILs) were fabricated and evaluated as efficient catalysts for the synthesisof cyclic carbonates from epoxides and CO2in the absence of co-catalyst and solvent.The P-FDIILs, especially the carboxyl-functionalized ones, perform well in thecycloaddition reaction at a low catalyst loading of0.3mol%. Furthermore, themethylene chain length between imidazolium cation and functional group, and thehalide anion species affect the activity of the catalysts. It is noted that the catalyst showsno significant loss of activity in a reusability test of five times. From the view point ofindustrial application, the catalyst is attractive due to its good stability and excellentcatalytic efficiency.