AJ publishes a paper on chlorine mediated selective epoxidation of cyclohexene

AJ’s paper demonstrates a liquid diffusion electrode (LDE) reactor that enables greater than 90% selective electrochemically-driven oxidation of cyclohexene to cyclohexene oxide through a chlorine-mediated pathway. This system enables Faradaic efficiencies of ~80% and ~65% at 50 and 100 mA/cm² respectively, with >90% selectivity in both cases. The LDE reactor geometry utilizes an engineered, porous electrode that separates the aqueous electrolyte from the pure-phase organic reactant, thereby avoiding mass transfer limitations and use of solvent that are typical disadvantages for the more common, mixed phase organic / aqueous electrosynthetic approaches. We use a non-precious metal catalyst, cobalt oxide, to electrochemically oxidize chloride ions, another abundant element, to in situ generate active chlorine species which interact with the cyclohexene throughout the pores of the electrode. We explore the effects of pH, halide identity/concentration, and current density on product selectivity, separation in aqueous vs. organic phases, and Faradaic efficiency. We also provide evidence via differential electrochemical mass spectroscopy and ion chromatography with conductivity detection to identify Cl₂ as the active chlorine species responsible for oxidation. Congratulations AJ!