温和条件下电活化CO_2合成碳酸二甲酯

Electrosynthesis of Dimethyl Carbonate under Mild Conditions

在含0.1mol/L四乙基铵四氟硼酸盐的乙腈和N,N-二甲基甲酰胺溶液中,研究了CO2在铜电极上的循环伏安行为。结果表明,CO2在电位E=-2.3V(vs.Ag/AgI)发生不可逆还原。在常压CO2气气氛下,含0.1mol/L四乙基铵四氟硼酸盐的乙腈溶液的一室型电解池中,以镁为牺牲阳极,铜为工作电极,Ag/AgI电极为参比电极,在一定电位下电解时,CO2可以被电活化并与甲醇反应,加入烷基化试剂碘甲烷后可得碳酸二甲酯(DMC)。该合成方法安全清洁、体系简单、实验条件温和。考察了电解电位、通电量、反应温度、支持电解质、溶剂、电极材料等对电解产率的影响。确定当E=-2.3V(vs.Ag/AgI),通电量为理论电量,以四乙基铵四氟硼酸盐为支持电解质,乙腈为溶剂,在25℃和常压下反应,DMC产率最高,为14.92%。表明以CO2和甲醇为原料在温和条件下(PCO2=1.0atm,T=25℃)电合成制备DMC具有一定的可行性。

Cyclic vohammetry of CO2 in MeCN solution containing 0. 1 mol/L TEABF4 and DMF solution containing 0. 1 mol/L TEABF4 were studied at Cu electrode and it was shown that CO2 will be reduced irreversibly at E = -2. 3 V（vs. Ag/AgI）. Dimethyl carbonate（DMC） was electrosynthesized from CO2 and CH3 OH in the relevant solvent-supporting electrolyte systems in a one-compartment cell with Mg as consuming anode and Cu as cathode, followed by addition of MeI as an alkylating agent. The procedure was safe, clean and carried out under very mild conditions. The effect of solvent, supporting electrolyte, electrodes and temperature was investigated to optimize the electrolytic conditions. The highest yield of 14. 92% was obtained when the reaction was carried out at E = - 2.3 V （ vs. Ag/AgI） in MeCN solution containing 0. 1 mol/L TEABF4 at temperature of 25 ℃ with 1 F/mol passed charge. It is a new electrochemical procedure for the synthesis of DMC from CO2 and CH3OH under mild conditions（PCO2 = 1.0 atm, T=25 ℃ ）.