ELECTRO-ORGANIC SYNTHESIS IN SUPERCRITICAL ORGANIC MIXTURES

Dimethyl carbonate (DMC), formed electrochemically from carbon monoxide and methanol, has been synthesized at 90°C in the mixture-critical region of carbon dioxide-methanol, near a methanol mole fraction of 0.35. By operating in the single-phase region, we have avoided interphase mass transport. In our experiments, the rate of carbonate formation depended on the concentration of dissolved CO. For a mole fraction of carbon monoxide of 0.05, current efficiencies near 100% were obtained. For these studies tetrabutylammonium bromide (TBAB) served as the electrolyte and as a source of bromide ions for a reactive intermediate. The selectivity for the carbonate relative to methyl formate and dimethoxymethane was sensitive to the composition of the CO2-CH3OH cosolvent as well as the concentration of TBAB.