Electrochemical Synthesis Of Dimethyl Carbonate With Carbon Dioxide/Ch₃OH In1-butyl-3-Methylimidazoliumtetrafluoborate

The increasing amount of CO2from the large-scale use of energy fuels like oil and coal has caused many environmental problems. Carbon dioxide (CO2) becomes one of the main gases leading to the green house effect, however, CO2is recognized to be a naturally abundant, nontoxic and recyclable carbon source. Thus, the conversion and utilization of CO2becomes more and more significant from the ecological and economic point of view.Dialkyl carbonates are an important class of compounds. Their versatility allows their application in several fields of chemical and pharmaceutical industry. Dimethyl carbonate(DMC), as an environm-entally building block, can be used as carbonylating reagents, fuel additives, alkylating reagents and polar solvents to replace toxic reagents like phosgene, dimethyl sulfate. Therefore, synthesis of DMC should been extensively studied.Electrochemical fixation of CO2was considered to be an effective route of chemical fixation, which can carry out under mild condition. Ionic liquids, with wide electrochemical potential window, high ionic conductivity, good solvating ability and low vapour pressure, have been used as green reaction media in organic synthesis.Synthesis carbonates from the electrochemical reduction of CO2in Ionic liquids has a very important practical significance.What the paper studied may be summarized as follows:1. In this paper, the research progress of both current status of CO2emission and strategies for CO2conversion and utilization were reviewed, the composition and nature of ionic liquid and the applications of DMC were also explained.2. The electrochemical reduction behavior of CO2in both ionic liquid,1-butyl-3-methylimidazoliumtetrafluoborate(BMIMBF4) and organic solution were studied by cyclic voltammetry. The effect of temperature and scan rate was also investigated. The reduction process of CO2was mostly controlled by diffusion.3. The electrolysis experiments were carried out by constant-potential electrolysis in an undivided cell under mild conditions on In electrode in ionic liquid1-butyl-3-methylimidazoliumtetrafluoborate (BMIMBF4), affording the dimethyl carbonate in a moderate yield (76%) at a potential of-1.7V (vs Ag) at the temperature of40℃. We also obtained a moderate yield (69%) on Cu electrode at the temperature of55℃under the potential of-1.8V. The results showed that the yields were affected by temperature, working potential and charge passed. The mechanism for DMC synthesis was discussed.