Application of the LFER in Organic Electrochemistry: Jnterpretation of the Hammett Reaction Constant (e) for Processes of Reversible Electroreduction in Aprotic Solvents

The paper is an overview of the application of the concept of linear free energy relationships (LFER), most notably through the Hammett equation, to investigations of reversible organic electrochemical reactions in aprotic solvents. In sequence the following topics are covered: the effect of solvent properties on the equilibrium, ion pairing effects, the direct application of Hammett's equation on polarographic data, entropic and enthalpic contributions to substituent effects, and the quantum chemical interpretatation of the reaction rate constant in aprotic media. The application of polarographic techniques is advocated as more sensitive and easier to interpret than the techniques of homogeneous kinetics.