The Study of Reactive Intermediates by Electrochemical Methods

Publisher Summary All organic reactive intermediates readily undergo electron transfer reactions; electrochemical methods play an important role in the study of their chemistry. The measurement of the electrode potential for the formation of the intermediate can lead directly to the standard free energy of the process. The kinetics of the reactions of intermediates, formed in exceedingly low concentrations can be deduced from the electrode response of the substrate from which the intermediate is derived by an electron transfer. This chapter describes the study of reactive intermediates by electrochemical methods. The study of reactive intermediates generated at electrodes is organic electrochemistry. In volume reactions, the electrode functions as an electron source or sink and specific interactions between the electrode and substrates or intermediates are weak or insignificant. In this case, the remaining possible influence of the electrode is because of the electric field in its immediate vicinity. During surface reactions the substrate, the intermediates, or both, interact strongly with the electrode and diffusion is restricted. The reactions of intermediates generated under these conditions differ substantially from those in homogeneous solution. Electrode potentials measured under such conditions cannot be equated to thermodynamic potentials for the formation of the intermediates. Electrode measurements involve low substrate concentrations; therefore, reactive impurities have to be held to a very low level. The measurement of an electrode potential is the most direct method of obtaining the free energy change or the equilibrium constant of a reaction.