Kinetics of the formation and decomposition of hydroxymethanesulfonate

The kinetics of the formation and decomposition of hydroxymethanesulfonate (HMSA) have been examined at p H 4 and 5. The second‐order rate constant for the formation of HMSA at 25°C was measured to be 1.94 ± 0.11 and 12.60 ± 1.04 mol −1 s −1 at p H values of 4 and 5, respectively. The rate constant of HMSA decomposition to form formaldehyde (HCHO) and aqueous sulfur dioxide S(IV) at p H 4 and 5 was 4.8 ± 0.4 × 10 −7 and 3.5 ± 0.2 × 10 −6 s −1 , respectively. In addition, no reaction between hydrogen peroxide (H 2 O 2 ) and HMSA was observed when a tenfold molar excess of H 2 O 2 was present at p H values of 4 and 5.