Electrochemical and Digital Simulation Analyses of Two‐Proton‐Coupled Electron Transfer Between Superoxide and Hydroquinone: Mechanistic Insights and Kinetic Parameters

Abstract Electrochemical reduction of dioxygen (O 2 ) in the presence of benzene‐1,4‐diol (hydroquinone) in N , N ‐dimethylformamide (DMF) was examined using cyclic voltammetry and digital simulation techniques. The presence of hydroquinone modified the quasi‐reversible cyclic voltammograms (CV) of O 2 , resulting in formation of a superoxide radical anion (O 2 •− ), which was scavenged by hydroquinone to form quinone radical anion and hydroperoxide. This reaction proceeded via a two‐proton‐coupled electron transfer (2PCET) mechanism with superior reaction kinetics. Digital simulations of the CVs elucidated the details of the 2PCET process, which involved heterogeneous electrochemical reactions and homogeneous solution reactions between the electrogenerated O 2 •− and hydroquinone. The thermodynamic and kinetic parameters of 2PCET were obtained from simulation analyses, which included three elementary steps: (i) formation of the prereactive complex from the free reactants, (ii) intracomplex 2PCET forming the product complex via a transition state, and (iii) dissociation of the product complex yielding free products. These parameters provide essential information for the development of artificial electron‐transfer catalysts and electron transfer carriers using hydroquinone derivatives.