Redox chemistry and energetics of radical cations of substituted benzenes

Abstract

Publisher Summary This chapter focuses on redox chemistry and energetics of radical cations of substituted benzenes. In general, aromatic radical cations are formed upon ionization—for example, by direct photolysis or radiolysis or one-electron oxidation of aromatic compounds. Pulse radiolysis has proven to be a very useful and versatile method for studies of both the kinetics and the thermochemistry of substituted benzene radical cations in aqueous solution. The redox properties of substituted benzene radical cations in aqueous solution appear to stand on a solid ground. The structure-activity relationships derived from experimental data provide a useful tool for prediction of unknown one-electron reduction potentials and give a systematic picture of the effects of ring substituents on the one-electron reduction potentials of benzene radical cations. There are two main techniques used for measurement of one-electron reduction potentials in solution; pulse radiolysis and cyclic voltammetry. They both have their advantages and disadvantages. The acidity of substituted benzene radical cations has been studied mainly by pulse radiolysis, but a few measurements using laser flash photolysis have also been reported.