One-pot Synthesis Of Dimethyl Carbonate Under Low Pressure

One-pot synthesis of dimethyl carbonate (DMC) from epoxide, methanol and CO2 is an important method to the preparation of DMC. In this thesis, many efforts have been made on the optimization of the reaction conditions under low pressure for the one-pot synthesis of DMC. The main contents of this thesis include the following several aspects.Five hydroxyl-functionalized ionic liquids were prepared using a solvent free, catalyst free and aerobic protocol developed by our group recently. Three of the hydroxyl-functionalized ionic liquids haven't been reported by any literature. Their structures were confirmed by 1H NMR,13C NMR and high resolution mass spectrum. The other two hydroxyl-functionalized ionic liquids known in the literature were confirmed by 1H NMR.The as-prepared hydroxyl-functionalized ionic liquids were used as the catalysts for the one-pot synthesis of DMC. A highly efficient reaction system with a two-component catalyst containing a hydroxyl-functionalized ionic liquid and an alkali carbonate under low pressure for one-pot synthesis of DMC was developed. The effects of the reaction conditions including reaction pressure, catalyst loading of alkali, reaction temperature, ionic liquid catalyst loading, reaction time, methanol amount and the structure of ionic liquid on one-pot synthesis of DMC were investigated systematically using a model reaction between propylene oxide (PO), methanol and CO2. Under the optimized conditions of epoxide 14.3 mmol, CH3OH 214.4 mmol, hydroxyl-functionalized ionic liquid 2.0 mol%, Na2CO35.0 mol%,0.5 MPa,120 ?,6 h, the highest DMC yield could be reached up to 86.0% in the case of ethylene oxide. A mechanism portraying the probable sequence of the reaction was proposed.An effient and simple reaction system with a single component catalyst of alkali carbonate under low pressure for one-pot synthesis of DMC was developed. The effects of the reaction conditions of catalyst species, pressure, temperature, reaction time, catalyst loading and methanol amount on one-pot synthesis of DMC were investigated using a model reaction between PO, methanol and CO2. Under the optimized conditions of epoxide 14.3 mmol, CH3OH 214.4 mmol, Na2CO35.0 mol%,0.5 MPa,120 ?,6 h, the highest DMC yield could be reached up to 63.5% in the case of ethylene oxide. A probable mechanism of the reaction catalyzed by alkali carbonate was proposed.