SO₂ formation and peroxy radical isomerization in the atmospheric reaction of OH radicals with dimethyl disulfide

Abstract

The OH + DMDS reaction mainly forms SO2 and CH3O2 with a yield close to two and to a lesser extent RO2 isomerization products.

Atmospheric Fate of the CH3SOO Radical from the CH3S + O2 Equilibrium

“…The reaction time was 7.9 s, and the relative humidity (RH) was <0.1%. , Chemical ionization atmospheric pressure interface time-of-flight (CI-API-TOF) mass spectrometry was applied for product analysis. For SO 2 detection, the SF 6 – based ionization scheme was utilized by using absolute signal calibration. , CH 3 O 2 radicals were indirectly followed via the formation of the accretion product CH 3 C­(O)­CH 2 OOCH 3 arising from the RO 2 cross reaction with the acetonyl peroxy radical, CH 3 C­(O)­CH 2 O 2 . CH 3 C­(O)­CH 2 O 2 radicals are produced as the byproduct of the OH radical formation via ozonolysis of tetramethylethylene (TME), which was used as the OH radical source in all experiments .…”

“…The ozone concentration used was 1.6 × 10 10 molecules cm –3 , and the TME concentration was varied in the range (1.22–25.3) × 10 11 molecules cm –3 to produce different OH concentrations. Detection of CH 3 C­(O)­CH 2 OOCH 3 was performed by means of C 2 H 5 NH 3 + ionization. , The CH 3 S radical was generated through H-abstraction in the reaction of OH radicals with CH 3 SH. The amount of converted CH 3 SH has been calculated by using a detailed reaction scheme as described in the previous work …”

“…A large number of reduced-sulfur compounds are emitted to the atmosphere, and their degradation products, such as SO 2 and subsequently formed sulfuric acid as well as methanesulfonic acid, play an important role in cloud formation, acid precipitation, and global warming. , Therefore, the atmospheric oxidation mechanisms of these sulfur-containing compounds have been of great interest for a long time. ,, The methylthiyl radical (CH 3 S) is regarded as an important intermediate in the atmospheric oxidation of dimethyl sulfide (DMS), dimethyl disulfide (DMDS), and methanethiol (CH 3 SH) . Under atmospheric conditions, the CH 3 S radical will predominantly form a methylsulfinyl peroxy radical (CH 3 SOO) through the reversible addition reaction with O 2 (Figure , pathway 1).…”

Spectroscopic characterization of two peroxyl radicals during the O2-oxidation of the methylthio radical

“…Recently, an alternative abstraction pathway for the •OH initiated oxidation of DMS to SO 2 through the intramolecular H-shift in the common peroxyl radical intermediate CH 3 SCH 2 OO• (→ •CH 2 SCH 2 OOH) has been proposed (Fig. 1), in which the formation of the key stable intermediate hydroperoxymethyl thioformate (HPMTF, HOOCH 2 SCHO) has been confirmed experimentally 8,[15][16][17][18][19] . On the other hand, the atmospheric oxidation of DMS can also proceed through the OH-addition pathway (Fig.…”

“…On the other hand, the atmospheric oxidation of DMS can also proceed through the OH-addition pathway (Fig. 1), resulting the stepwise formation of additional VOSCs dimethyl sulfoxide (DMSO, CH 3 S(O)CH 3 ), and methanesulfinic acid (CH 3 S(O) OH) [15][16][17][18][19][20][21][22] .…”