Electrocarboxylation of 1,3-butadiene with CO2 to 3-hexenedioic acid: effect of operating parameters on product selectivity

The electrochemical carboxylation of alkenes using CO2 is a sustainable and promising approach for synthesizing a variety of organic compounds, especially carboxylic acid derivatives. These processes are of high scientific and commercial interest as only one or two electrons are required per CO2 molecule to produce value-added products. Here, we report on the electrochemical dicarboxylation of 1,3-butadiene with CO2 to obtain 3-hexenedioic acid, a key intermediate to produce adipic acid. The electrocarboxylation was performed in acetonitrile using a nickel cathode, an aluminium anode, and Ag/AgCl reference electrode in an undivided cell. We systematically explore how different operating conditions including the applied voltage, water content, and temperature affect the reaction performance and the product distribution. Importantly, we find that the water content significantly influences product formation, highlighting its critical role in optimizing the reaction conditions. Temperature was found to play a key role as a maximum Faradaic efficiency of 36% toward electrocarboxylation products was achieved under ambient conditions, which increased to 59% at 40 °C but decreased to 49% at 60 °C.