ELECTROLYTIC CARBONYLATION OF METHANOL OVER THE CUCL2 ANODE IN THE GAS-PHASE

Electrolytic carbonylation of CH3OH in the presence of CO over a CuCl2 -added graphite anode was studied in the gas phase at <101 kPa and amb ient temperature. No reaction proceeded at applied voltages lower than 1.0 V across the cell (cathode: He). The formation of dimethyl carbon ate (DMC) and CO2 started at >1.0 V. The rates of these formations sho wed maxima at ca. 1.4 V. Electrolysis of CH3OH to dimethoxymethane (DM M) and methylformate (MF) started at >1.4 V, reducing the formation of DMC and CO2 markedly. Replacement of He in the cathode compartment wi th O-2 decreased the applied voltage needed for the formation of DMC b y ca. 0.6 V. The results of the electrolysis of CH3OH alone suggested that DMM and MF were formed directly from CH3OH. However, the formatio n of CO2 at an applied voltage less than or equal to 1.4 V (cathode: H e) originated from the same precursor of DMC. The anode potentials mea sured during the reaction suggested that the electrolytic carbonylatio n of CH3OH as well as the electrolysis of CH3OH occur on Cu(II) cation s. The reaction scheme assuming a methoxide radical and a carbomethoxi de species as the reaction intermediates is suggested on the basis of kinetic studies on the formation of each product.