Dimethyldisulfide, formation

DMSO or other sulfoxides react with trimethylchlorosilanes (TCS) 14 or trimefhylsilyl bromide 16, via 789, to give the Sila-Pummerer product 1275. Rearrangement of 789 and further reaction with TCS 14 affords, with elimination of HMDSO 7 and via 1276 and 1277, methanesulfenyl chloride 1278, which is also accessible by chlorination of dimethyldisulfide, by treatment of DMSO with Me2SiCl2 48, with formation of silicon oil 56, or by reaction of DMSO with oxalyl chloride, whereupon CO and CO2 is evolved (cf also Section 8.2.2). On heating equimolar amounts of primary or secondary alcohols with DMSO and TCS 14 in benzene, formaldehyde acetals are formed in 76-96% yield [67]. Thus reaction of -butanol with DMSO and TCS 14 gives, via intermediate 1275 and the mixed acetal 1279, formaldehyde di-n-butyl acetal 1280 in 81% yield and methyl mercaptan (Scheme 8.26). Most importantly, use of DMSO-Dg furnishes acetals in which the 0,0 -methylene group is deuter-ated. Benzyl alcohol, however, affords, under these reaction conditions, 93% diben-zyl ether 1817 and no acetal [67]. 

The reaction of white phosphorus with dimethyldisulfide, initiated by irradiation, is composed of two steps a) formation of red phosphorus with participation of the solvent b) formation of ( 1138)3 from red phosphorus. The radiation chemical yields are of the order of several 100 molecules/100 eV at room temperature which indicates a radical chain reaction ... 

Dimethyldisulfide is degraded by autotrophic sulfur bacteria with the formation of sulfate and C02 which then enters the Ben-son-Calvin cycle (Smith and Kelly 1988). On the other hand, dimethyl sulfide and dimethyl sulfoxide are degraded by a strain of Hyphomicrobium sp. by pathways involving the formation from both carbon atoms of formaldehyde which subsequently enters the serine pathway (Suylen et al. 1986) (Figure 6.121). The key enzyme is methyl mercaptan oxidase which converts methyl sulfide into formaldehyde, sulfide, and peroxide (Suylen et al. 1987). A strain... 

Alkylation seems characteristic of the support acidity. Over NigHY2>7, the alkylaromatics distribution reveals 62 % toluene and 38 % Cg when dimethyldisulfide is used as a sulfiding agent, and shifts to 22 % C7-78 % C8 when diethyldisulfide is injected in place of DMDS. Therefore the alkylation reaction is mainly due to the presence of an alkyldisulfide. The initial formation of toluene is immediately followed by disproportionation, yielding xylenes. But product analysis also reveals that with the (benzene + DMDS) mixture, more methane is produced with HY2-7 catalyst where alkylation goes on, than over HY45 where no benzene conversion occurs. Thus, some of the methane may arise from a deep degradation of benzene, and such a reaction may also be considered as a minor source of alkylaromatics. 

Goux et al. (1994) have proposed the alkylthiolation of phenol with dimethyldisulfide over zeolites. They observe that on faujasite-type zeolites the reaction leads to the formation of 2- and/or 4-(methyl-thio)phenol (o- and / -isomers), although the ratio of o-lp- isomers depends on the composition of zeolite. In this way, it has been observed that Ce,Na-Y catalyst favours the highest p-lo- ratio (76/24). 

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