Synthesis of dimethyl carbonate from carbon dioxide and methanol in the presence of methyl iodide and base catalysts under mild conditions: effect of reaction conditions and reaction mechanism

The synthesis of dimethyl carbonate (DMC) from methanol and CO2 was studied in the presence of methyl iodide and various base catalysts. Among the catalysts used, potassium carbonate was found to be most active. Dimethyl ether (DME) is formed as a byproduct. When the reaction was carried out at various pressure of CO2, two maxima in DMC formation were observed at 4.5 and 8 MPa, while DME formation decreased monotonically with increasing the CO2 pressure. The effects of the amounts of methyl iodide and potassium carbonate on the DMC and DME formation were also investigated. Mechanistic studies suggest that DMC and DME are produced in parallel pathways and methyl iodide is involved in the formation of both DMC and DME. Other alcohols show less reactivity than methanol.