Thermochemical aerobic oxidation catalysis in water can be analysed as two coupled electrochemical half-reactions

Abstract

Heterogeneous aqueous-phase aerobic oxidations are important catalytic transformations; however, their mechanisms and the role of O-2 remain unclear. Here we show that thermochemical aerobic oxidations of organic small molecules can be analysed as two coupled electrochemical half-reactions for O-2 reduction and substrate oxidation. We find that the polarization curves of the two half-reactions closely predict the mixed potential of the catalyst measured during thermochemical catalysis across diverse reaction conditions, catalysts and reactant identity. Additionally, we find that driving the substrate oxidation electrochemically without O-2 at the mixed potential leads to similar rates and selectivities as for the corresponding thermochemical reactions. These findings indicate that O-2 acts as an electron scavenger to supply the electrochemical driving force for substrate oxidation. These studies provide a quantitative and predictive link between thermochemical and electrochemical catalysis, thereby enabling the design of new aerobic oxidation schemes by applying the principles of electrochemistry.