Understanding the oxidation mechanism of methanesulfinic acid by ozone in the atmosphere

Methanesulfinic acid (MSIA) is an important intermediate in the oxidation of dimethyl sulfide (DMS) in the marine boundary layer. The oxidation of MSIA by ozone in the gas phase to form methanesulfonic acid (MSA) was investigated using theoretical calculations in this paper. Three pathways can be found for the reaction of MSIA with ozone. The highest energy barrier is 13.02 kcal mol(-1) in the most favorable pathway. By comparing the reaction rate of MSIA + O-3 with that of MSIA + OH, it can be concluded that the oxidation of MSIA by O-3 to form MSA is of minor significance relative to its oxidation by OH radical in the gas phase. This study can provide some information for the theoretical and experimental studies in the significantly heterogeneous and aqueous-phase oxidation of MSIA by O-3.