CONTINUOUS-FLOW COLUMN ELECTROLYTIC SPECTROELECTROCHEMISTRY FOR 2-STEP ONE-ELECTRON TRANSFER-REACTIONS

Mathematical treatments of continuous-flow column electrolytic spectro scopy for the two-step one-electron transfer reaction are presented. T he relationship between the absorbance and the apparent number of elec trons in electrolysis, which is independent of electrolytic efficiency , is useful for the analysis of quasi-reversible as well as reversible redox reactions. The theory has been applied to the analysis of the r edox reaction of 9,10-anthraquinone-2,7-disulfonate, which exhibits to tally reversible characteristics in continuous-flow column electrolysi s and also in cyclic voltammetry at a column electrode in stationary s olution. The redox potentials of the two successive electron transfers and the absorption spectra of the semiquinone intermediate in aqueous solution have been successfully determined. The redox reaction of 2,6 -dimethyl-1,4-benzoquinone, which is irreversible (or quasi-irreversib le) in cyclic voltammetry at a conventional solid electrode, has also been characterized from the thermodynamic aspects. (C) 1998 Elsevier S cience S.A. All rights reserved.