Impacts of the Regeneration Pathways of the Oxoammonium Cation on Electrochemical Nitroxyl Radical-Mediated Alcohol Oxidation

Recent studies investigating the electrocatalytic properties of nitroxyl radicals (e.g. 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)) for electrochemical alcohol oxidation have demonstrated that the thermodynamic equilibrium oxidation potential and the steric environments unique to each nitroxyl radical have significant implications for their electrocatalytic abilities for alcohol oxidation. However, as the catalytic cycle of the nitroxyl radical involves not only the production and use of the oxoammonium cation for alcohol oxidation but also the regeneration of the oxoammonium cation from the hydroxylamine, the mechanism and rate of the regeneration of the oxoammonium cation critically affect the overall rate of electrochemical nitroxyl radical-mediated alcohol oxidation. Currently, a detailed understanding of this important aspect is lacking. Herein, the factors that affect the regeneration pathways of the oxoammonium cation are systematically investigated, and the impact that the regeneration pathways ...