Electrochemical Activation of Benzoic Acids

The study of the electrochemical and chemical behavior of electrochemically generated benzoyloxy radicals will be undertaken through this project. Literature reports very few ways to generate these radicals. For instance, the main ones are the thermal decomposition of the unstable benzoyl peroxide  and the CuCl-catalyzed decomposition of copper benzoate.  As a result, benzoyloxy radicals have been rarely used as a chemical reagent but most of the time as a radical-chain initiator.
Generation of benzoyloxy radicals by electrolysis of the corresponding carboxylate would be an appreciable alternative since neither metal or potentially explosive materials like peroxides, will be used in the process.

Even though aromatic carboxylates have been reported to not undergo Kolbe reaction,  electrolysis of benzoic acid, in presence of an excess of aliphatic acid, leads cleanly to the formation of the ester which presumably results from a recombination between a benzoyloxy radical and a radical formed by the Kolbe decarboxylation of an aliphatic acid.  Such a process would allow the formation of esters under very mild conditions. In fact, the reaction could be performed in basic, neutral or slightly acidic medium. Therefore, such conditions would be suitable for compounds that are usually unstable or easily epimerized under acidic conditions. Another interesting application would be the electrolysis in presence of pivaloic acid. This should give an easy way to form t-butyl esters that are usually difficult to prepare under standard chemical conditions.

The scope and limitations of this new methodology are now being investigated.