CuBr/DMAP/DMA catalyzed oxidative carbonylation for diethyl carbonate synthesis

In order to improve the diethyl carbonate (DEC) synthesis using oxidative carbonylation of ethanol, the effects of ligands, catalyst composition and concentration, reaction temperature and time on the ethanol conversion rate and DEC selectivity were investigated. Gas chromatography-mass spectroscopy (GC-MS) and gas chromatography (GC) were used to identify and quantify the reaction products. The results show that when 4-dimethylaminopyridine (DMAP) is used as the ligand with the CuBr/DMAP molar ratio of 1/2, the ethanol conversion rate can reach 28.6% and the selectivity of DEC is 99.9% under suitable reaction conditions (catalyst concentration: 0.25 mol∙L^-1, pressure: 3.5 MPa, temperature: 100℃, 40 mL N, N-dimethylacetamide ). Reaction mechanism study shows that the CuBr/DMAP/DMA catalytic system prefers the insertion of CO (the rate-controlling step) and the formation of intermediate, which reduces the induction period. The reaction time decreases from 180 min to 90 min and the formation of the byproduct ethyl acetate intermediate is suppressed. The reaction selectivity is also enhanced.