Reaction Pathways for the Electrochemical Synthesis of KA Oil from Cyclohexane

Abstract

Recent decreases in the cost of electricity from both renewable and non-renewable sources and limitations of fossil fuel resources have bolstered interest in producing commodity chemicals using electrochemistry. Electrosynthesis offers promising alternatives to thermochemical processes, because they do not typically require extreme temperature and pressure. In addition, electric current can be used to replace dangerous reducing and oxidizing agents used in traditional organic chemistry. Electrosynthesis has been demonstrated as a possible pathway for partial oxidation of alkanes, which contain extremely inert C-H bonds.A major challenge in nylon 6,6 manufacturing is cyclohexane conversion to KA oil, a mixture of cyclohexanone and cyclohexanol. In the current industry, this process suffers from low cyclohexane conversion and pressure requirements. Although cyclohexane electrochemical oxidation to KA oil has been demonstrated in literature, the mechanism by which this occurs is still poorly understood.In this work, we demonstrate KA oil production through cyclohexane electrochemical oxidation in organic electrolytes. Using chronoamperometry, we identify the oxygen source (oxygen gas vs. water) for this reaction. In addition, we show that the cathodic counter reaction can influence cyclohexane conversion to KA oil and should be accounted for in mechanistic experiments. Based on literature, side product analysis, and electroanalytical methods, we propose a reaction pathway for electrochemical cyclohexane conversion to KA oil.