Ionic liquids as efficient catalysts for the synthesis of ethyl methyl carbonate viatransesterification of dimethyl carbonate and ethanol

The synthesis of ethyl methyl carbonate(EMC) through transesterification of dimethyl carbonate(DMC) and ethanol over several kinds of alkaline ionic liquids as the catalysts was studied.The results indicated that 1-butyl-3-methylimidazolium bromate(Br) exhibited better catalytic performance in transesterification among the investigated alkaline ionic liquids.Furthermore,the reaction conditions were also optimized by using Br as the catalysts.The results showed that DMC conversion of 71.1% and the selectivity to EMC of 81.8% were attained under the optimum reaction condition as follows:atmospheric pressure,reaction temperature 90 ℃,reaction time 12 h,n(DMC)∶ n(ethanol)=1∶ 1,and Br dosage 2% of DMC mass.The catalyst still kept good catalytic activity after being reused three times.