K. Sehested, J. Holcman
Mar 1, 1996
Citations
2
Influential Citations
28
Citations
Journal
Radiation Physics and Chemistry
Abstract
Abstract Methanesulfinic acid, CH 3 SO 2 H, reacts with OH radicals at pH 7 forming CH 3 SO 2 radicals with a rate constant k =(6.0±1.0)×10 9 M −1 s −1 . The CH 3 SO 2 radicals absorbs at 325 nm with an extinction coefficient of 900±100 M −1 cm −1 and disappears in a second order self-reaction with k =(1.0±0.2)×10 9 M −1 s −1 . This radical reacts with oxygen, k =(1.2±0.3)×10 9 M −1 s −1 , forming a peroxy radical which absorbs in the UV below 300 nm. The peroxy radical reacts in turn with methanesulfinic acid reforming the CH 3 SO 2 radical whereby a chain oxidation of sulfinic acid takes place. During the course of the chain oxidation a peroxyacid, presumably methaneperoxymonosulfonic acid, is formed and accumulated. This acid absorbs in the UV and eventually decays by reaction with excess methanesulfinic acid k =5×10 3 M −1 s −1 . The final product of the chain autoxidation is methanesulfonic acid. The chain is very efficient and proceeds until either oxygen or methanesulfinic acid is exhausted. The mechanism is compared to the chain autoxidation of sulfite.