Dimethyldisulfide, reaction with

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 third compound studied is the 4-thio analog of mescaline, 4-methylthio-3,5-dimethoxyphenethylamine. This was prepared (see scheme II) by the reaction, of lithiated m-dimethoxybenzene with dimethyldisulfide to form 2,6-dimethoxythioanisole. This underwent bromination uniquely adjacent to the methoxy group, and the resulting bromodimethoxythioanisole underwent a smooth benzyne reaction with acetonitrile to form the benzyl cyanide shown, which was reduced to the desired end product (3) with aluminum hydride in THF. 

Subsequent reactions with dimethylformamide, dimethyldisulfide, methyl isothiocyanate, carbon dioxide, trimethylchlorosilane, paraformaldehyde, cyclohexyl bromide, and bromoacetaldehyde diethylacetal. 

Hydrotreating was carried out at 3.1 MPa (450 psig) and 613 K (340 °C) in a three-phase upflow fixed-bed reactor (Figure 1). The feed liquid was prepared by combining different quantities of 1.0 wt% tetralin (Aldrich, 99%), 0.02 wt% N as quinoline (Aldrich, 99%), 0.05 wt% S as 4,6-dimethyldibenzothiophene (4,6-DMDBT, Fisher, 95%), 0.3 wt% S as dimethyldisulfide (DMDS, Aldrich, 99%), n-octane (Aldrich, 99%), and balance n-tridecane (Alfa Aesar, 99%). Liquid product compositions were determined with a Hewlett-Packard 5890A chromatograph equipped with a 50 m dimethylsiloxane colunm (Chrompack, CPSil 5B) of 0.32 mm i.d. Reaction products were identified by matching retention times with commercially available standards. 

Multicomponent tandem addition reactions have been investigated by Russell and coworkers. Addition of t-butyl radical to the allyl acrylate 70 with termination from dimethyldisulfide furnishes butyrolactone 71 as a diastereomeric mixture (remote center). However, the ring junction stereochemistry is exclusively trans [95JA3645],... 

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... 

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. 

The kinetic experiments were carried out with VO-TPP and o-xylene as solvent in a 250 ml batch autoclave. Approximately 80 mg of catalyst (pellet diameter 63 -160 pm) was weighed and introduced in the reactor. The catalyst was sulfided in situ for two hours with dimethyldisulfide (623 K, 6.0 MPa Hj). After sulfiding, VO-TPP dissolved in o-xylene (total reaction volume 125 ml) was introduced. The reactor was filled to 0.34 MPa with a mixture of 15 mol % HjS in Hj. Next Hj was added to a total pressure of 5.0 MPa and the reactor was heated to a temperature of 553 K. 

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 ... 

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. 

Catalysts used in this work had a composition of 3 wt% nickel, 8 wt% molybdenum and 0 or 2 wt% phosphorus. They were prepared by incipient wetness impregnation, followed by drying at 393 K and calcination at 773 K. Details of the catalyst preparation can be found elsewhere [2], The HDN reactions were carried out in a continuous-flow microreactor. A sample of 0.1 g catalyst diluted with 9.5 g SiC was used for each reaction. The catalyst was sulfided in situ with a mixture of 10% (mol) H2S and H2 at 643 K and 1.5 MPa for 4 h. After sulfidation, the pressure was increased to 3.0 MPa and liquid reactant was fed to the reactor by means of a high pressure pump, with n-octane as the solvent. The catalyst was stabilised at 643 K and 3.0 MPa for 100 h before samples were taken. The initial reactant partial pressure (P°) of Q, THQ5 and OPA was usually 4.76 kPa, and that of H2S was 6.5 kPa by adding dimethyldisulfide to the liquid reactant. n-Nonane as well as n-dodecane were used as internal standards. 

Hatakeyama, S., and H. Akimoto (1983). Reactions of OH radicals with methanethiol, dimethylsulfide and dimethyldisulfide in air. J. Phys. Chem. 87, 2387-2395. 

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). 

However, for liquid phase reactions, it is very difficult to correlate the results wiHi BrOnsted or Lewis acidity as the reaction conditions used are different from those used for characterization. When the Diels-Alder reaction is conducted in a solvent, it appears that the maximum for the activity of HY zeolites is obtained for a Si/Al ratio of 15. This maximum was also observed for esterification of carboiQ lic acids (14), methylthiolation of phenol with dimethyldisulfide (15), acylation of toluene with benzoic acids (15) or dehydration of fhictose (15), and in solvents such as alcohols, water or hydrocarbons. If we assume that Lewis species are transformed to Brdnsted ones in the presence of water as solvent, this would thus mean that the Diels-Alder reaction is preferentially catalyzed by BrSnsted species, the maximum observed at Si/Al=15 for HY zeolites being a good balance between the niunber 6ind the strength of the protonic species. 

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. 

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... 

The influence of modifications brought about by using benzenesulfonic acid (CgHsSOsH), the influence of the solvent on the reaction ofTi(OPr )4 with H2S, plus the influence of the alkoxyl group and other sulfidizing agents (dimethyldisulfide and hexamethyldisilathiane) were fnrther investigated, in order to control the reaction rate and products. 

Although the first stage of this system was considered a thermal reactor, it was found that the addition of 2wt. % Fe203, with dimethyldisulfide (DMDS), to a bituminous coal feed resulted in a significantly increased yield. This is attributed to catalysis by the iron sulfides formed during the reaction. 

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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