Electrocarboxylation of benzalacetophenone: Synthesis of 2,4-diphenyl-4-oxobutanoic acid

Electrocarboxylation of benzalacetophenone was studied in the presence of an atmospheric pressure of CO₂. The only carboxylic product obtained was 2,4-diphenyl-4-oxobutanoic acid in a one-compartment electrochemical cell equipped with magnesium as the sacrificial anode, copper (Cu), nickel (Ni), titanium (Ti), graphite (C) and stainless steel as the cathode and Ag/AgI as the reference electrode under the controlled potential conditions. Influences of solvents, electrolytes, the cathode materials, electrolysis potentials, the concentrations of substrate and temperatures were studied to improve the electrolysis yield. The results show that the electrolysis conditions have an important influence on the yield. The maximal yield reached 88% when the electrolysis was carried out in MeCN-0.1 mol·L^-1 TEABF ₄ on Mg-stainless steel under a controlled potential of -1.75 V vs. Ag/AgI until 2 F·mol^-1 of charge had passed through the cell at 0°C. The electrochemical behavior of benzalacetophenone has been studied in MeCN. The mechanism of the electrocarboxylation process involves a one-electron reduction and a chemical reaction followed by another one-electron reduction and a chemical reaction.