Fast reactions of halogens with 2,2′-azinobis-(3-ethylbenzothiazole-6-sulphonate) (ABTS) were investigated by the stopped-flow-spectrophotometric technique. Iodine was found to undergo a reversible reaction withK = l.43 × 102. The difference in redox potential, ΔE°, for the reaction was calculated and agreed very well with the theoretically calculated value. Bromine was found to form the stable radical cation (ABTS+) whereas chlorine generated a decomposed product via the radical cation and the dication (ABTS++). The individual rate constants for these reactions were measured. The reactivities of the halogens are compared and discussed.
