Electrochemical behaviour of syringaldazine, a colorimetric redox reagent

Abstract

Oxidation of syringaldazine ( 1H 2 ) was studied in acetonitrile and in an aqueous medium using various electrochemical methods and pulse radiolysis. In water and in buffered acetonitrile, a reversible two-electron—two-proton transfer leads to the formation of a deep purple compound 1. In acetonitrile various intermediates ( 1H 2 .+, 1H −, 1H ., 1H +, 1 2−, 1 .−) involved in this process can be formed reversibly, depending on the experimental conditions, thus allowing us to measure the thermodynamic parameters ( E° and p K a).