Dibenzyl sulfide

Two efficient syntheses of strained cyclophanes indicate the synthetic potential of allyl or benzyl sulfide intermediates, in which the combined nucleophilicity and redox activity of the sulfur atom can be used. The dibenzylic sulfides from xylylene dihalides and -dithiols can be methylated with dimethoxycarbenium tetrafiuoroborate (H. Meerwein, 1960 R.F. Borch, 1968, 1969 from trimethyl orthoformate and BFj, 3 4). The sulfonium salts are deprotonated and rearrange to methyl sulfides (Stevens rearrangement). Repeated methylation and Hofmann elimination yields double bonds (R.H. Mitchell, 1974). 

Treatment of dibenzylic sulfides with triethylphosphite and UV-light also led to cyclophanes in high yield (H.A. Staab, 1979). 

Benzyl chloride reacts with alkaH hydrogen sulfides, sulfides, and polysulfides to yield benzenethiol, dibenzyl sulfide, and dibenzyl polysulfide, respectively. With sodium cyanate it forms benzyl isocyanate (20). 

Dibenzyl sulfide [538-74-9] M 214.3, m 48.5 , 50 . Crystd from EtOH/water (10 1), or repeatedly from Et20. Also chromatographed on AI2O3 (pentane as eluent), then recrystd from EtOH [Kice and Bowers J Am Chem Soc 84 2390 7962]. Vacuum dried at 30° over P2O5, fused under nitrogen and re-dried. 

Acetyl bromide cleaves dibenzyl sulfide, while diethyl or diisopropyl are resistant (27). 

When reactions with oxygen-containing acceptors were performed [3] in the 300-400°C region, the formation of adducts occurred with both Tetralin and mesitylene. This reaction was observed when benzyl radicals were generated from dibenzyl ether, dibenzyl sulfide, benzyl alcohol, and benzaldehyde. 

Dibenzyl sulfide, 50, 33 Diborane, 50, 90 52, 59 reduction of dinitrile with,... 

Despite the fact that dibenzothiophene can be readily oxidized with peracetic acid, it is generally resistant to milder oxidative conditions. It is, for example, stable to heating in an inert solvent at 150° in the presence of bronze and oxygen, conditions under which both biphenyl sulfide and dibenzyl sulfide gave insoluble precipitates. It is not surprising, therefore, that dibenzothiophene has been reported to have little or no antioxidant properties and more recent work has generally confirmed this. Octahydrodibenzothiophene has, however, been reported to be useful as an oil antioxidant. ... 

Examination of Table I reveals that the edge of dibenzothiophene is displaced from that of dibenzyl sulfide, the first inflection energy being some 0.6 eV higher for the former compound. From previous XANES data on dibenzothiophene and dibenzyl sulfide and physical mixtures of the two, it proved possible to identify each compound in the presence of the other (3b,8). Additionally by simply measuring the heights of the third derivative features at 2469.8 eV and 2470.4 eV relative to the base line in the model compound mixtures, a calibration was established which allowed an approximate estimate of the amounts of each component in hydrocarbon samples to be obtained. 

Reaction with chlorobenzene at elevated temperatures yields thiophenol as major product and dibenzyl sulfide in smaller amounts ... 

Similar behavior of other aromatic disulfides and thiols on gold electrodes has been described based on the SERS experiments [167]. Adsorption of benzenethiol, benzenemethanethiol, p-cyanobenzenemethanethiol, diphenyl sulfide, and dibenzyl sulfide was studied on the roughened gold electrode. All these species adsorb dissociatively as the corresponding thiolates. Monolayers formed from symmetric disulfides were exactly like those formed from the corresponding thiols. These monolayers were stable in a wide potential window from -1-800 to —1000 mV (versus SCE), which was limited by the oxidation of the Au surface from the positive side and hydrogen evolution at —1000 to —1200 mV at the negative side. 

Moreover, product formation was not the same. Dibenzyl ethylsulfonium salt 72 gave only benzyl ethyl sulfide (73) and benzyl thiocyanate 74, but no dibenzyl sulfide or ethyl thiocyanate. By contrast, the cyclic sulfonium salt 75 gave a mixture containing chiefly (80%) dihydroisothianaphthene (76) with an equivalent amount of ethyl thiocyanate (77) and a minor amount (20%) of the sulfide-thiocyanate 78. This work represents the first direct experimental information on the rate of bimolecular nucleophilic substitution and relative orientation of the benzene ring and the leaving group and it demonstrates clearly the importance of stereoelectronic effects in these reactions. 

Figure 2. Sulfur XANES spectra of mixed dibenzothiophene and dibenzyl sulfide. The left panel shows the absorption spectra, and the right panel the corresponding third derivatives, from top to bottom, pure dibenzothiophene, a 1 1 molar mixture of dibenzothiophene and dibenzylsulfide, and pure dibenzylsulfide...

Figure 3. Calibration plot for quantification of dibenzothiophene and dibenzyl sulfide mixtures, from mixtures of the pure compounds. Points denoted as "A" indicate the third derivative amplitude at 2469.8 eV, and those as "0" the third derivative amplitude at 2470.4 eV.

Symmetrical sulfides can be made from the alkyl halide and Na2S as the product from the first step is the monoanion needed to make the second C-S bond. The synthesis7 is just to combine the alkyl bromide with Na2S in ethanol dipropyl sulfide (R = Et) is formed in 91% yield from the bromide while dibenzyl sulfide (R = Ph) is made in 83% yield from benzyl chloride 25. 

X-ray Photoelectron Spectroscopy (XPS) tests were conducted on surfaces lubricated with a sulfur-containing extreme pressure additive, dibenzyl sulfide (Baldwin, 1976 Bird and Galvin, 1976). The films can arise from the use of additives that contain sulfur, phosphorus, chlorine, bromine, or boron and the differences in reactivity are affected by the formation of protective layers. Triboinduced electrons are said to activate the formation of iron halides, iron phosphates and iron sulfides (Dorison and Ludema, 1985 Grunberg, 1966 Kajdas, 2001 McFadden et al., 1998 ). When a chemical reaction takes place, e.g., oxygen interacts with aluminum to form aluminum oxide, a large oxygen peak is seen at approximately 500 eV in the Auger electron spectra (Benndorf et al., 1977 Nakayama et al., 1995). 

Benzotrichlorides have also been prepared via another sulfur derivative. Dibenzyl sulfides (RC6H4CH2)2S with R= o,m,p-Me, 0-Br,/ -NO2 are chlorinated in CC14 at 80 °C to give 27-91% of RC6H4CC13882 883. 

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