title: Reactive sulfur species: kinetics and mechanism of the oxidation of aryl sulfinates with hypochlorous acid.
abstract: The mechanism of oxidation of ArSO(2)(-) (PhSO(2)(-) and 5-sulfinato-2-nitrobenzoic acid = TNBO(2)(1-/2-)) with HOCl/OCl(-) has been investigated using the kinetic method. In contrast to previous reports for PhSO(2)(-) (for which it was suggested that OCl(-) and not HOCl was the reactant), the reaction proceeds through a conventional pathway: nucleophilic attack by ArSO(2)(-) on HOCl with concomitant Cl(+) transfer to give a sulfonyl chloride intermediate (ArSO(2)Cl), which we have identified spectrophotometrically. Remarkably, the rate constant for the reaction of HOCl with ArSO(2)(-) is on the order of 10(9) M(-1) s(-1), larger than the rate constants for corresponding thiolates, and is nearly diffusion-controlled. In contrast, the rate constant for the reaction of OCl(-) with ArSO(2)(-) is approximately 7 orders of magnitude smaller.
authors.affiliation: Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA.
authors.forename: Hisanori
authors.initials: H
authors.lastname: Ueki
authors.forename: Garry
authors.initials: G
authors.lastname: Chapman
authors.forename: Michael T
authors.initials: MT
authors.lastname: Ashby