Formation of Methane Sulfinic Acid in the Gas-Phase OH-Radical Initiated Oxidation of Dimethyl Sulfoxide

• Published in: Environmental science & technology Vol. 36; no. 23; pp. 5155 - 5163
• Main Authors: Arsene, Cecilia, Barnes, Ian, Becker, Karl H, Schneider, William F, Wallington, Timothy T, Mihalopoulos, Nikolaos, Patroescu-Klotz, Iulia V
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.12.2002
• Subjects: Acids; Applied sciences; Atmospheric pollution; Dimethyl Sulfoxide - chemistry; Exact sciences and technology; Hydroxyl Radical - chemistry; Methane; Oxidants - chemistry; Oxidation; Oxidation-Reduction; Photochemistry; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Solvents - chemistry; Sulfinic Acids - chemistry; Sulfur Organic compounds; Pollutant behavior; Reaction product; Photochemical reaction; Free radical reaction; Methyl sulfoxide; Atmospheric chemistry; Reaction mechanism; Sulfoxide; Air pollution; Oxidation; Photooxidation; Hydroxyl
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es020035u

Dimethyl sulfoxide (CH3S(O)CH3:  DMSO) is an important product of dimethyl sulfide (CH3SCH3:  DMS) photooxidation. The mechanism of the OH-radical initiated oxidation of DMSO is still highly uncertain and a major aim of recent studies has been to establish if methane sulfinic acid (CH3S(O)OH:  MSIA) is a major reaction product. In the present work the products of the OH-radical gas-phase oxidation of dimethyl sulfoxide have been investigated in the absence and presence of NO x . All experiments were performed in a 1080 L reaction chamber in 1000 mbar synthetic air at 284 ± 2 K using long-path FT-IR spectroscopy and ion chromatography to monitor and quantify reactants and reaction products. Formation of methane sulfinic acid in high yield (80−99%) was observed in both in the absence and presence of NO x , and the results support that it is the major primary reaction product. Other products observed included dimethyl sulfone (CH3S(O)2CH3:  DMSO2), sulfur dioxide (SO2), methane sulfonic acid (CH3S(O)2OH:  MSA), and methane sulfonyl peroxynitrate (CH3S(O)2OONO2:  MSPN). The formation behavior of these products is in line with their source being mainly secondary production via oxidation of a primary product, i.e. MSIA.