Free-radical-induced oxidation of hydroxymethanesulfonate in aqueous solution Part 1A pulse radiolysis study of the reactions of OHand SO 4-
Abstract
The rate constants for the reaction of OH and SO4- with hydroxymethanesulfonate (HMS) have been determined. The hydroxyl radical was found to react with HMS by hydrogen abstraction to form CH(OH)SO3-, reaction (5), with a rate constant of (3.0±0.3)×108 d mol-1 s-1. The spectrum of the product is dependent on pH due to equilibrium (6). This equilibrium has been investigated and has a pKa of 6.35±0.1. The forward and reverse rate constants for the dissociation, k6 and k-6, are (5.9±0.5)×104 s-1 and (4.4±1.0)×1010 d mol-1 s-1, respectively. The dissociation is subject to acid–base catalysis by phosphate buffer, reaction (7), with k7=(9.5±0.1)×108 d mol-1 s-1 and k-7=(1.32±0.02)×108 d mol-1 s-1
The sulfate radical reacts with HMS with a rate constant of (1.3±0.2)×106 d mol-1 s-1. The product of this reaction has not been identified.