Production of C₃ -C₆ Acetate Esters via CO Electroreduction in a Membrane Electrode Assembly Cell

Electrocatalytic carbon monoxide reduction has been previously reported to yield a range of carbonaceous products including alcohols, hydrocarbons and carboxylic acids. However, esters, an important family of organic compounds, have not been formed. Herein, we report the electrosynthesis of C₃ to C₆ acetate esters (H₃ C-(C=O)-O-R) from carbon monoxide using copper catalysts in a membrane electrode assembly cell. Ethyl acetate and propyl acetate could be produced with an unprecedented total Faradaic efficiency (FE) of ∼22 % and with a current density of up to -55 mA cm^-2 , alongside minor quantities of methyl acetate and butyl acetate. The esters are produced via the addition reaction of ethenone (H₂ C=C=O) and alcohols produced during CO reduction. We show that the near water-free reaction conditions and the high local pH play key roles in the formation of the esters.