Dimethyl disulphide, oxidation

Smith NA, DP Kelly (1988) Isolation and physiological characterization of autotrophic sulphur bacteria oxidizing dimethyl disulphide as sole source of energy. J Gen Microbiol 134 1407-1417. 

Methane thiol oxidizes at a convenient rate at 200—275 °C, the reaction being mildly autocatalytic and accompanied by a pressure decrease [107]. The rate is enhanced by increased oxygen concentration, but retarded by excess thiol. The main products include sulphur dioxide, carbon monoxide, formaldehyde, acetaldehyde and methane but no hydrogen sulphide, carbonyl sulphide or free sulphur. Unless excess oxygen is present, these products do not account for all the sulphur consumed, and Cullis and Roselaar [107] attributed this to formation of dimethyl disulphide although later work [108] has shown that this explanation was unlikely. 

A series of cyclic 1,2-diketones have been prepared via the a-methylthioketbnes prepared by sulphenylation of the ketone enolate with dimethyl disulphide, by treatment with a mixture of copper(II) chloride and copper(II) oxide in aqueous acetone... 

In a study of sulphenylations and dehydrosulphenylations of esters and ketones it has been reported that quenching the enolate of (507) with dimethyl disulphide or diphenyl disulphide affords (508 R = Me or Ph). Oxidation with sodium... 

Trost has described in full yet another method for the introduction of a double bond adjacent to an ester function. Treatment of the ester enolate with diphenyl-(or dimethyl-) disulphide affords the a-thioester which may be smoothly converted to the a/3-unsaturated ester following oxidation (Nal04 or w-ClC H CO3H) to the sulphoxide and thermal elimination at 110 "C (for an alternative, cf. ref. 98) the method gives acceptable yields. 

The highest concentration of hydrogen sulphide in biogas is noted in the early stages of waste decomposition. The decrease in the concentration of H S is most likely caused by the precipitation of the sulphides in the reaction with heavy metals (such as Cu and Fe) or their oxides, which are present in the deposited material. Sulphides as water insoluble compounds remain in the mass of waste (Parker et al. 2002). The organic sulfur compounds in the greatest concentrations in landfill gas are dimethyl sulphide (DMS), carbon disulphide, methyl mercaptan, dimethyl disulphide (DMDS) at the concentrations of 0.007-180 mg m" 0.09-61.6 mg m" 0.084-17.94 mg m 0.0124-0.942 mg m" respectively (Kim et al. 2005, Shin et al. 2002). 

DMSO can be boiled under reflux for long periods largely unchanged (3.7% of volatile decomposition products after 72 h) but under air or O2 in a sealed tube, kept just below the boiling point (189 C) for 68 h, it is completely transformed into paraformaldehyde, dimethyl sulphide, and bis(methylthio)methane, water, and dimethyl disulphide." " Peroxides catalyse the decomposition, as does MeSOjH." " The formaldehyde formed in this way can be used for in situ methylene acetal formation with oxidation products of alcohols and diols." Reduction of DMSO with Br2+HBr gives MezS, MeSOsH, and paraformaldehyde, while diphenyl sulphoxide is unchanged." ... 

The anaerobic oxidation of phosphines to their oxides by hydroxide ion has been shown to involve the liberation of hydrogen, possibly from the intermediate (21). These oxidations were studied with water-soluble phosphines, since solubility was found to be the main factor controlling the rate of oxidation. The preparation, and detailed n.m.r. spectrum, of PP-dimethyl-P P -diphenyldiphosphine disulphide (22) is a relatively rare example of a study of a mixed disulphide. Many examples of routine oxidation of phosphines to their oxides have appeared. These include the preparation of polyhalogenoarylphosphine oxides using dichromate... 

Table 1.3 Products of the interaction of sulphide minerals with sodium dimethyl dithio carbamate (5.8 x 10" mol/L at pH =8) and the measured rest potential (reversible potential for oxidation to thiouram disulphide is 0.176 V) (Finkelstein andGoold, 1972)...

Other reactions include those with phenyl isothiocyanate or carbon disulphide to give a carbodiimide, and with sulphur dioxide to give an N-sulphinylaniline. Reactions of N-phenyltriphenylarsinimine with triphenylacetonitrile-AT-oxide provided an arsahetero-cycle, and with dimethyl acetylenedicarboxylate gave a product which was probably an... 

Sulphonic acids may normally be obtained in 65-75% yields upon oxidation of thiols, thiolates or disulphides with 30% hydrogen peroxide234-240. Higher yields are realized if a tertiary thiol is used. The same products may also be realized by reaction of either thiols or disulphides with aqueous dimethyl sulphoxide (equation 37), in the presence of a catalytic amount of bromine, iodine or a hydrogen halide241,242. In this latter oxidation, dimethyl sulphide is formed as a by-product, but is easily removed by aspiration. 

The disulphide (175), obtained by photo-oxidation of 6-mercapto-l,3-dimethyl-lumazine, undergoes photorearrangement to the dithiin derivatives (176) and (177) by way of initial sulphur-sulphur bond homolysis. The photodecomposition of 2,2 -dithiodibenzoic acid derivatives has also been examined. Irradiation of... 

Dimethyl-p-tolylphosphine, (CHgjgCyHy.P, isolated m a similar manner to the foregoing phosphine, is a colourless, pungent liquid, B.pt. 210° C., w hich is not oxidised in air, but yields dimethyl-p-tolyl-phosphine oxide on treatment with mercuric oxide. It reacts violently with methyl iodide to form the corresponding phosphomum compound. Benzyl chloride forms a non-crystalline product with the phosphine, this substance forming a platinichloride, M.pt. 226° C. The phosphine gives a carbon disulphide compound, yielding clear red plates, M.pt. 110° C. in an open tube, 116° C. in a closed tube. 

Trimethylstibine dichloride, (CH3)3SbCl2, is prepared (1) by treating trimethylstibine in carbon disulphide solution with chlorine (2) by the interaction of trimethylstibine oxide and hydrochloric acid, (8) by heating trimethylstibine and hydrochloric acid together in a sealed tube, (4) by allowing antimony trichloride and mercury dimethyl to react, when a double compound of trimethylstibine dichloride and methylmercuric chloride is isolated. The dichlonde crystallises from water in hexagonal crystals, which dissolve readily in hot alcohol. 

Details have been published of Boekelheide s synthesis of [2,2]metacyclophane-1,9-dienes methylation on sulphur of the bis-sulphide (44), Stevens rearrangement, methylation again, and Hoffmann elimination, gave the dimethyl[2,2]metacyclo-phane-1,9-diene (45), which could be isomerized reversibly to trans-15,16-dimethyl-dihydropyrene. [2,2]Metaparacyclophanes and [2,2]metaparacyclophane-l,9-dienes were prepared by similar methods. A second synthesis of [2,2]metaparacyclo-phanes involves preparation and reduction of bis-dithianes, e g. (46), and a third synthesis involved pyrolysis of bis-sulphones obtained by oxidation of disulphides analogous to (44). Ring flipping in substituted [2,2]metaparacyclophanes and... 

Studies of oxidation reactions of differing substrate types have been described. The nature of oxidant species in HCIO4 and H2SO4 media has been examined by investigation of catalysis of the Ce -Hg reaction. It is suggested that at 2.OM-HCIO4 the iridium(iv) is hydrolysed with protonation constant of 0.4 for [Ir(H20)s0H] +. Most kinetic studies, however, refer to reaction of the hexachloro and hexabromo ions. The oxidation of thiourea (tu), iV,iV -dimethyl-thiourea (dmtu), and 2-imidazolidinethione (it) follows a rate law second order in [substrate] and first in [Ir "]. The rate of oxidation follows the reactivity trend established previously for aquo-metal ions. The mechanism proposed involves rapid pre-equilibria followed by disulphide radical formation,... 

Yiannios and Karabinos reported that thiols were selectively oxidized by DMSO to the corresponding disulphides in high yield with the concomitant reduction of DMSO to dimethyl sulphide (equation 33). Further... 

Cyclic Disulphides and Cyclic Diselenides.—Formation. No fundamentally new methods of synthesis of this class of compounds have been reported in the past two years. For l,2>dithiolan the oxidation of l,3>dithiols remains a favoured method, the use of iodine in the presence of triethylamine leading smoothly to 1,2-dithiolans without attendant polymerization. cis- and tra/ -l,2-Dithiolan-3,5-dicarboxylic acids were prepared from a diastereo-isomeric mixture of dimethyl 2,4-dibromoglutarates by sequential treatment with potassium thioacetate and potassium hydroxide in the presence of iodine,and jyn-2,3-dithiabicyclo[3,2,l]octan-8-ol was formed from 2,6-dibromocyclohexanone by successive treatment with potassium thiocyanate, lithium aluminium hydride, and iodine. The stereoselective formation of the less thermodynamically stable alcohol in this case was attributed partly to the formation of chelates with sulphur-aluminium bonds. 2,2-Dimethyl-l,3-dibromopropane was converted into 4,4-dimethyl-l,2-diselenolan on treatment with potassium selenocyanate at 175 °C, but at 140 °C the product was 3,3-dimethylselenetan. Reductive debenzylation of 2-alkylamino-l,3-bis(benzylthio)propanes with lithium in liquid ammonia and oxidation of the resultant dithiols with air afforded 4-dialkylamino-l,2-dithiolans, whilst treatment of a-bromomethyl-chalcone with sodium hydrosulphide gave, as minor product, trans-3 phenyl-4-benzoyl-l,2-dithiolan. Among the many products of thermal decomposition of /ra/ -2,4-diphenylthietan was l,4,5,7-tetraphenyl-2,3-dithiabicyclo [2,2,2]octane. ... 

Diphenylguanidine was successfully used as starting material for the Willgerodt-Kindler reaction, giving polythioamides. Carbon disulphide reacted with triethylamine and DMF to give A /Z-diethyl- and i W-dimethyl-thioformamide. Under the same conditions, dithiocarbamates decompose to give iViV-dialkyl-thioformamide and sulphur. HMPT and sulphur have been shown to be a useful system for the oxidation of a variety of aromatic and heteroaromatic compounds to the corresponding A -methyl- and JVAT-dimethyl-thioamides in the case of phenyl benzyl ketone, /mn -stilbene and the heterocyclic compounds (114) and (115) have been obtained as by-products. Whereas the benzylic... 

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