Dimethyl sulphide, oxidation

A convenient route to both saturated and unsaturated acylsilanes lies in the hydroboration-oxidation of alkynylsilanes (Chapter 7). Recent improvements (6) to this method involve the use of the borane-dimethyl sulphide complex for hydroboration, and of anhydrous trimethylamine A-oxide for the oxidation of the intermediate vinyl boranes. 

The photolysis of dimethyl sulphoxide (at 253.7 nm) in a wide range of solvents has been studied in detail176. Three primary reactions occur, namely (i) fragmentation into methyl radicals and methanesulphinyl radicals, equation (60), (ii) disproportionation into dimethyl sulphone and dimethyl sulphide, equation (61) and (iii) deactivation of the excited state to ground state dimethyl sulphoxide. All chemical processes occur through the singlet state. Further chemical reactions of the initial photochemical products produce species that have been oxidized relative to dimethyl sulphoxide. 

ETHYLENE GLYCOL ETHYL MERCAPTAN DIMETHYL SULPHIDE ETHYL AMINE DIMETHYL AMIDE MONOETHANOLAMINE ETHYLENEDIAMINE ACRYLONITRILE PROPADIENE METHYL ACETYLENE ACROLEIN ACRYLIC ACID VINYL FORMATE ALLYL CHLORIDE 1 2 3-TRICHLOROPROPANE PROPIONITRILE CYCLOPROPANE PROPYLENE 1 2-DICHLOROPROPANE ACETONE ALLYL ALCOHOL PROPIONALDEHYDE PROPYLENE OXIDE VINYL METHYL ETHER PROPIONIC ACID ETHYL FORMATE METHYL ACETATE PROPYL CHLORIDE ISOPROPYL CHLORIDE PROPANE... 

Kocsis M, Hanson A (2000) Biochemical evidence for two novel enzymes in the biosynthesis of 3-dimethylsulfoniopropionate in Spartina altemiflora. Plant Physiol 123 1153-1161 Kocsis M, Nolte K, Rhoades D, Shen T-L, Gage D, Hanson A (1998) Dimethylsulfoniopropionate biosynthesis in Spartina altemiflora. Plant Physiol 117 273-281 Kowalewsky S, Dambach M, Bjorn M, Dehnhardt G (2006) High olfactory sensitivity for dimethyl sulphide in harbour seals. Biol Lett 2 106-109 Lamb C, Dixon R (1997) The oxidative burst in plant disease resistance. Annu Rev Plant Physiol Mol Biol 48 251-275... 

Barnes, I., K. H. Becker, and I. Patroescu, FTIR Product Study of the OH Initiated Oxidation of Dimethyl Sulphide Observation of Carbonyl Sulphide and Dimethyl Sulphoxide, Atmos. Environ., 30, 1805-1814(1996). 

Sulphur dioxide is both emitted into the troposphere and also formed during oxidation of dimethyl sulphide (DMS) and other sulphur containing species produced in the biosphere. Important sources of atmospheric S02 are volcanoes. However, the major single global source is probably the combustion of sulphur-containing fossil fuels. In the stratosphere there are two important sources of sulphur dioxide, i.e. injection by volcanic eruptions and oxidation of carbonyl sulphide (COS), which is transported from the troposphere. 

Reaction of borane (as a complex with dimethyl sulphide) with optically pure (+)-a-pinene (in 15% excess) results in the almost exclusive formation of di-isopinocampheylborane (Ipc2,BH)67 (Section 4.1.7, p.421). The use of this optically pure borane in the hydroboration of the prochiral (Z)-but-2-ene, followed by oxidation, yields (R)-(—)-butan-2-ol (ee 98.1%) (Expt 5.45). Interestingly, monoisopinocampheylborane (IpcBH2) with (Z)-but-2-ene gives (S)-(+)-butan-2-ol, and hence the importance of careful reagent preparation is emphasised.68... 

A most convenient procedure for the conversion of carboxylic acids to aldehydes results from their initial treatment with borane-dimethyl sulphide to give first, the triacyloxyborane (9), which is then reduced further to the intermediate (10) the trimer of (10) is the trialkyloxyboroxine (11). Oxidation of (11) with PCC then yields the aldehyde.110 The method is illustrated for the preparation of octanal (Expt 5.81), but it has been applied to cyclohexanecarboxylic acid and to various aromatic carboxylic acids (X-C6H4C02H, X = p-Cl, NOz, OMe, ni-CN). 

The Swem Oxidation of alcohols avoids the use of toxic metals such as chromium, and can be carried out under very mild conditions. This reaction allows the preparation of aldehydes and ketones from primary and secondary alcohols, resp. Aldehydes do not react further to give carboxylic acids. A drawback is the production of the malodorous side product dimethyl sulphide. 

Dimethyl sulphide (DMS) is produced in sea-water as a consequence of enzymatic action in phytoplankton and zooplankton grazing. Measurements of DMS indicate an average global sea-to-air flux of 40 Tg of sulphur per year (1.3). Instantaneous emission rates to the atmosphere, however, can vary considerably, and depend on the nature and concentration of the phytoplankton, the time of year and the prevailing meteorology. For example, nigh concentrations of Phaeocystis, a prolific producer of DMS, have been found in the North Sea and when it blooms, emissions of DMS may increase by a factor of 40-60 over those in the absence of blooms (4). The sea-to-air flux is also dependent on the depth at which the phytoplankton is found since DMS is slightly soluble in water and can be oxidized in aqueous solution. 

Chlorination not accompanied by oxidation occurred on treatment of aliphatic sulphides and phenylated dimethyl sulphide with 3-(dichloroiodo)pyridine in chloroform for example, methyl ethyl sulphide afforded a mixture of the two monochlorinated sulphides (CH2CISCH2CH3 and CH3SCHCICH3) in a ratio of 1 3 [25]. 

Pyridinium chlorochromate, described as a safe, stable, and readily prepared alternative to the chromium trioxide-pyridine complex, is a convenient oxidant for primary and secondary alcohols84 and should find use in steroid chemistry. Dimethyl sulphide ditriflate , prepared from DMSO and trifluoromethanesulphonic anhydride at —78°C, has been used to oxidize 3-hydroxy-steroids.85 The biological... 

Indolo-steroids have been obtained by -coupling of steroid dienamines with dia-zonium salts in dimethylformamide followed by Fischer-indole cyclization of the resulting hydrazone39 (Scheme 37). In methylene chloride the /Fcoupled product 75 was obtained, cyclization of which gave indazoles 74 and 762a. The oxidative role of dimethyl sulphoxide in the formation of 76 was attributed to nucleophilic attack by the solvent on 75 leading to intermediates 77 and 78, with elimination of dimethyl sulphide (Scheme 38). 

Of the other trace gases (e.g. N2O, dimethyl sulphide, CH3CI, etc.) many are, like methane, of dominantly biological origin and are transient disequilibrium components of the air eventually oxidized, whereas others are of volcanic origin, mostly eventually rained out in some form or other. 

Regiospecific oxidation of the 3-hydroxy-group of methyl fusidate has been accomplished by use of the Corey reagent (one equivalent of AT-chlorosuccinimide-dimethyl sulphide complex). 

Dimethyl sulphide (CH3SCH3, DMS) is the dominant natural sulphur eompound emitted from the world s oeeans (Berresheim et ai, 1995, Urbanski and Wine, 1999), accounting for about one quarter of global sulphur gas emissions. Oceanic DMS, through its oxidation products, is proposed to play a key role in climate regulation, especially in the remote marine atmosphere (Charlson et al, 1987). 

S,5-Dimethylsulphimides (readily prepared from the primary amine, dimethyl sulphide and AT-chlorosuccinimide) react with nitrile oxides (review [B-43]) under mild conditions to form a fused oxadiazine. 

DIMETHYL SULPHIDE (75-18-3) Forms explosive mixture with air (flash point — 36°F/—38°C). Reacts with water, steam, acids, acid fumes producing hydrogen sulfide fumes, which can explode in air. Reacts violently with strong oxidizers, chlorobenzenediazo-nium salts, mercurous chloride. Incompatible with zinc acetate. Flow or agitation of substance may generate electrostatic charges due to low conductivity. 

Borane-dimethyl sulphide solution (73 mmol, 2.74 m in THF) was added dropwise, with stirring, to the neat alkynylsilane (200mmol), keeping the reaction temperature below 20°C by use of an ice bath. The mixture was stirred for 2 h at 0-5 °C. At this time, the solution of the trialkenyl borane was diluted with THF (200 ml), and then anhydrous trimethylamine A/-oxide (240 mmol, dried by azeotropic distillation with toluene) was added over 5 min at ambient temperature. The resultant slurry was heated (bath temperature 75 °C) for 4h, and then cooled to ambient temperature. The enol borinate thus formed was hydrolysed by the addition of water (100 ml), followed by stirring for 5 min. The layers were separated, and the aqueous phase was extracted with ether (2x 100ml). The combined organic extracts were washed with brine and dried. Concentration and distillation gave the acylsilane (75-91%). 

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