Dimethylsulfide photochemical oxidation

Biogenic Sulfur Emissions from the Ocean. The ocean is a source of many reduced sulfur compounds to the atmosphere. These include dimethylsulfide (DMS) (2.4.51. carbon disulfide (CS2) (28). hydrogen sulfide (H2S) (291. carbonyl sulfide (OCS) (30.311. and methyl mercaptan (CH3SH) ( ). The oxidation of DMS leads to sulfate formation. CS2 and OCS are relatively unreactive in the troposphere and are transported to the stratosphere where they undergo photochemical oxidation (22). Marine H2S and CH3SH probably contribute to sulfate formation over the remote oceans, yet the sea-air transfer of these compounds is only a few percent that of DMS (2). 

E.J. Corey and co-workers synthesized the cdc25A protein phosphatase inhibitor dysidiolide enantioselectively. In the last phase of the total synthesis, the secondary alcohol functionality of the side-chain was established with a highly diastereoselective oxazaborolidine-catalyzed reduction using borane-dimethylsulfide complex in the presence of the (S)-6-methyl CBS catalyst. Finally, a photochemical oxidation generated the y-hydroxybutenolide functionality. This total synthesis confirmed the absolute stereochemistry of dysidiolide. 

Cloud condensation nuclei (CCN) concentrations in remote marine regions may be controlled by dimethylsulfide, CH3SCH3 (DMS), emissions from marine phytoplankton (Charlson et al., 1987). After DMS is emitted from the ocean, it undergoes photochemical oxidation via a series of gas-phase reactions (OH radical and NO, radical) to produce, as major sulfur-containing products, methanesulfonic acid, CH3S03H (MSA), and S02 (Yin et al., 1990a, b Jensen et al., 1991, 1992 Tyndal and Ravishankara, 1991). 

In principle, any one-electron oxidant with a high enough redox potential (> 1.5 V) [82], as well as electrochemical [83, 84] or photochemical methods [85, 86] may be used to generate such sulfur-centered radical cations directly. Their formation (monomer and dimer species) is not limited to aqueous solutions but seems possible in practically any environment, including hydrocarbon solutions [87], neat dimethylsulfide [88], or in the gas phase, including mass spectrometry conditions [89-93]. 

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