Dimethyldisulfide derivatives

The second, even more convenient, method to determine double-bond positions in unsaturated hydrocarbons is the use of dimethyldisulfide derivatives (Francis and Veland, 1981 Carlson et al, 1989 Howard, 1993). In this approach, alkenes are dissolved in a carbon disulfide and iodine solution and kept overnight. The reaction yields a derivative with methyl sulfide substituents on each of the carbons that comprised the double bond. If the double bonds are separated by four or more methylene groups, the reaction proceeds... 

FIGURE4.40 EI-MS spectrum of (Z)-9-octadecen-4-olide and its dimethyldisulfide derivative showing. Cleavage between thioether groups (from Cosse, A. A., et al, Journal of Chemical Ecology 27 (2001) 1841-1853.)... 

Some volatile compounds such as methanethiol, dimethylsulfide and dimethyldisulfide have been shown to yield methane when they were added to anaerobic cultures derived from aquatic sediments (70. 71V Kiene et al. (22) showed that methane bacteria and sulfate-reducers competed for dimethyldisulfide when it was added at low concentrations to anaerobic aquatic sediments. They also isolated a methanogen that metabolized dimethyldisulfide to methane and carbon dioxide (72). Recently Oremland et al (22) detected trace amounts of ethane released from anoxic sediment slurries. This could be stimulated by the addition of ethanethiol or diethylsulfide and inhibited by the addition of bromoethanesulfonic acid which specifically inhibits methane bacteria. These results indicated that methane bacteria co-metabolized these two OSC. 

A variety of nonprotic reagents, such as dimethyldisulfide, alkyl halides, trimethylsilyl derivatives, and halogens, also react with [Tp ]MgR, and some of these reactions are summarized in Scheme 3. 

Dimethyldisulfide was the only non-cyclic sulfur corrqwund identified in the WGH-G, DWGH-G, and AWGH-G model systems resulting fixrm the condensation of the two molecules of methanethiol, derived fixrm methionine. 

Dimethyldisulfide derivatization is the most common method used for double bond position determination. Reaction of the alkene in hexane with dimethyl disulfide (DMDS) and iodine under an inert atmosphere at 60°C produces the DMDS adduct. MS fragmentation of the DMDS derivatives occurs between the methylsulfide groups, thus locating the original double bond position (Figure 7). DMDS derivatization was used for the determination of the double bond position in (E)-8-dodecenyl acetate, the sex pheromone of the citrus fruit borer. 

We derive common names of simple disulfides by listing the names of the groups bonded to sulfur and adding the word disulfide, as, for example, CH3S—SCH3, which is named dimethyldisulfide. 

The monomeric product CHjSFe(CO)2CgHg is the first example of a methylthio derivative of a transition metal where the sulfur atom does not bridge between two metal atoms. This organosulfur derivative may also be obtained in 13% yield from CgHgFe(CO)2H (9) and dimethyldisulfide, Similar reactions of dimethyldisulfide with HMn(CO) and CgHgMo(CO) H have previously been shown to give the dimeric derivatives [CH SMn(CO) ]2 and... 

Treatment of C5H5M(CO)3H(M = Mo or W) with dimethyldisulfide gives the black to dark red crystalline methylthio derivatives [CsH5M(CO)2 SCH3]2(M = Mo or W) (137)... 

Trimethylchlorosilane, dimethyldisulfide, butyl bromide, butyl iodide, paraform, acetic and pivalic aldehydes, benzaldehyde, acetone, and cyclohexanone are used as electrophilic reagents relative to N-allenylpyrrole metalated with butyUithium. The conditions of the second stage of the reaction, electrophilic substitution, or addition (for aldehydes and ketones) depend upon the electrophile anployed. In all the cases, a-allenic derivatives are formed as a rule (Table 2.20). 

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