Mechanistic Insights into the Electrochemical Oxidation of Cyclohexane

Abstract

The detrimental effects of CO2 emissions from fossil fuels and the decreasing cost of electricity have accelerated interest in electrochemical synthesis. Electro-organic synthesis offers a sustainable and cost-effective pathway for chemical manufacturing. This method has the potential to minimize greenhouse gas emissions, enhance reaction selectivity, and replace hazardous chemical reagents with electric current.Electrochemistry enables alternative mild temperature and pressure pathways to traditional thermochemical reactions. An intermediate step to producing nylon 6,6 is synthesis of KA oil, a mixture of cyclohexanone and cyclohexanol, from cyclohexane. This reaction is limited by low conversion and high pressures. An electrochemical approach can introduce a more selective reaction pathway at more benign conditions. Although electrochemical cyclohexane oxidation to KA oil has been demonstrated in literature, its mechanism remains poorly understood. In this work, we elucidate the mechanism of electrochemical cyclohexane oxidation. We report the oxygen source (water vs. oxygen) and the role of the counter electrode reaction cyclohexane oxidation. Through analysis of side products and electroanalytical methods, we suggest a reaction pathway. In addition, we use chronoamperometry to demonstrate that electrode material affects cyclohexane conversion and recommend the optimal catalyst for this reaction.