DISPROPORTIONATION AND ECE MECHANISMS .I. THEORETICAL ANALYSIS . RELATIONSHIPS FOR LINEAR SWEEP VOLTAMMETRY

A general mechanism involving two successive charge-transfer steps coupled with acid-base reactions is considered. It is shown that ECE reaction paths as well as disproportionation reactions must be taken into account in the general case. According to the value of the experimental parameters two limiting behaviours are to be considered (i) ECE mechanism without any kinetic interference of disproportionation reactions (ii) apparent disproportionation of the first charge-transfer product, the rate constant being dependent on the acidity of the medium. Theoretical relationships allowing the kinetic analysis of such reaction schemes by linear sweep voltammetry are established. Diagnostic criteria are developed whereby variation of peak current and peak potential with sweep rate and initial concentration can be used to characterize the mechanism. Rate-constant determination is discussed. © 1968.