Effect of Water on Electrochemical β‐Hydrocarboxylation of Vinylphenol Derivatives With CO ₂

This paper reports the development of a method for synthesizing carboxylic acids via the electrochemical hydrocarboxylation of vinylphenol derivatives. The electrolysis was conducted in an undivided cell under a CO 2 flow in galvanostatic mode, using graphite electrodes as both cathode and anode. Optimization of the reaction conditions revealed that employing tetraethylammonium p ‐toluenesulfonate (Et 4 NOTs) as the electrolyte, adding 5.0 equiv of water, and applying a current density of 4.7 mA/cm 2 with a total charge of 4 F/mol afforded the desired carboxylic acid in up to 71% yield. This method demonstrates the highest yield among approaches for introducing CO 2 into vinylphenol derivatives to produce carboxylic acids.