Sulfoxide, dibenzyl

Natriumboranat/Kobalt(II)-chlorid (s.S. 115) reduziert aliphatische undaroma-tische Sulfoxide in Athanol mit guten Ausbeuten zu den entsprechenden Sulfanen. Mit dieser Methode erhalt man7 z.B. Dibutyl-sulfan (98% d.Th.), Diphenyl-sulfan (95% d. Th.) oder Thiuxanthen (100H/o d. Th.). Dibenzyl-sulfoxid und Tetrahydro-thiophen-1-oxid werden praktisch nicht angegriffen. 

Lower members of the series of salts formed between organic sulfoxides and perchloric acid are unstable and explosive when dry. That from dibenzyl sulfoxide explodes at 125°C [1], Dimethyl sulfoxide explodes on contact with 70% perchloric acid solution [2] one drop of acid added to 10 ml of sulfoxide at 20° C caused a violent explosion [3], and dibutyl sulfoxide behaves similarly [4]. A fatal explosion resulted from mistakenly connecting a DMSO reservoir to an autopipette previously used with perchloric acid [5], (The editor has met a procedure for methylthiolation of aromatics where DMSO was added to excess 70% perchloric acid he did not feel justified in trying to scale it up.) Explosions reported seem usually to result from addition to excess sulfoxide. Aryl sulfoxides condense uneventfully with phenols in 70% perchloric acid, but application of these conditions to the alkyl sulfoxide (without addition of the essential phosphoryl chloride) led to a violent explosion [4]. Subsequent investigation showed that mixtures of phenol and perchloric acid are thermally unstable (ester formation ) and may decompose violently, the temperature range depending on composition. DSC measurements showed that sulfoxides alone... 

Sulfur functions in low oxidation states have been oxidized to sulfoxides, sul-fones, and sulfonic acids, often in very good yields in spite of the fact that cpe was not employed. This is probably due to the resistance towards oxidation of the products, making control of the anode potential a less critical factor, and to the use of a potential-buffering SSE (Sect. 5.3). Illustrative examples include the preparation of 2,2 -bishydroxyethyl sulfone 1 24 > dibenzyl sulfoxide 125 ethanesulfonic acid 126 dibenzyl disulfoxide 125) and dimethyl sulfone 127 ... 

The forward look in the electrochemistry of corrosion inhibitors is the theoretical design of inhibitors. The cutting edge in this field is in such design work (Hackerman, 1995 Singh and Lin, 1997). Consider the theoretical interpretation of the action of an inhibitor, dibenzyl sulfoxide ... 

For dibenzyl sulfoxide on iron, it turns out that indeed it is the hydrogen evolution reaction, the partner reaction to the anodic dissolution reaction, which controls the corrosion rate. Because the inhibitor acts cathodically, it must interfere with and slow down the rds of this reaction, i.e., make it more difficult for the H to be desorbed. 

Fig. 12.51. Coadsorption of dibenzyl sulfoxide with hydrogen. (Reprinted from P. Kutej, J. Vosta, J. Pancir, J. Macak, and N. Hackerman, Electrochemical and Quantum Chemical Study of Dibenzylsuifoxide Adsorption on Iron J. Elec-trochem. Soc. 142(3) 834,1995. Reproduced by permission of The Electrochemical Society, Inc.)...

Malta, O.L., Brito, H.F., Menezes, J.F.S., etal (1998) Experimental and ttieoretical emission quantum yield in ttie compound Eu(ttienoyltrifluoroacetonate)3 2(dibenzyl sulfoxide). Chemical Physics letters, 282, 233—238. 

The reaction was carried out on numerous aromatic and aliphatic sulfides and sulfoxides. Among the compounds made in essentially quantitative yields were dibenzyl sulfoxide, dibenzyl sulfone, dimethyl sulfone, diphenyl sulfoxide, thionyldiglycolic acid, and carboxymethylthionylsuccinic acid (Table I). 

Thiophenol is oxidized with DCT or TBT to diphenyl disulfide. The latter reacts with DCT under more rigid conditions to give benzyl chloride. DCT oxidizes dibenzyl sulfide in methanol to dibenzyl sulfoxide (69ZC325) (Scheme 120). 

Dichloroiodobenzene reacts with isotopic asymmetric dibenzyl sulfoxides diastereoselec-tively,90. 

Beilstein Handbook Reference) AI3-62190 Benzene, 1,r-(sulfinylbis(methylene))bis- Benzyl sulfoxide BRN 2049262 Dibenzyl sulfoxide Dibenzyl sulphoxide EINECS 210-668-7 NSC 55 Preventol Cl 5 Sulfoxide, dibenzyl Tardiol D. An organic inhibitor for use in cleansing acids and in the surface treatment of metals. Leaflets mp = 134° bpn 210° (dec) Xm = 220, 253, 260, 266, 270 nm (MeOH) insoluble in H2O, soluble in EtzO,... 

Diatrizoic acid sodium salt 1118 Dibenzyl sulfoxide 1128... 

The absorption spectrum of the sulfoxide chromophore conjugated to aromatic nuclei has also been examined [6,7,9,15-17]. There are generally three bands for simple aryl alkyl sulfoxides between 200 and 300 ran. The middle band is most associated with the sulfoxide function because of the solvent effect, which parallels that of dialkyl sulfoxides. In some solvents, the central band, which is stronger than the benzene-like low energy absorption, overwhelms and hides the low energy band [10,17]. Figure 2 illustrates that an insulating CH2 decouples the benzene and SO chromophores save for the intensity of the sulfoxide absorption, dibenzyl sulfoxide appears as approximately the sum of bibenzyl and DMSO. 

The photochemistry of dibenzyl sulfoxide 10 was briefly reported in the mid 1960s [21,22]. It was said to decompose mainly to benzyl mercaptan (isolated as the disulfide 17) and benzaidehyde 16. Though no mechanism was suggested at the time, it is now clear that these products arise from a standard a-cleavage mechanism, followed by secondary photolysis of the sulfenic ester 13. The careful reader will note that the yield of bibenzyl (19) is very low in comparison to photolysis of dibenzyl ketone. Sulfinyl radicals rarely lose SO, though some net extrusions are discussed later. 

In addition to the product smdies, some direct physical evidence for a-cleavage was produced in the mid to late 1970s. First among these was a microsecond flash photolysis study that included dibenzyl sulfoxide, diphenyl sulfoxide, and di-p-tolyl sulfoxide [40]. The well-known benzyl absorption was observed on photolysis of dibenzyl sulfoxide, and new nearly identical transients (with maxima at 312 and 420 nm) were observed for the two diaryl sulfoxides. The new transients were sensitive to O2 and assigned to the corresponding sulfmyl radicals but not otherwise characterized. 

Photoextrusion of small stable molecules is a well-known phenomenon, with SO2 being one of the standard leaving groups for that type of reaction. Photochemical extrusion of SO is also known, though less conunon, and is reviewed here. Loss of SO appears to be an uncommon process of sulfinyl radicals, at least near room temperature. This was foreshadowed by the earliest photolysis of dibenzyl sulfoxide vide supra), in which sulfenate-derived products clearly dominate any loss of SO from the benzylsulfinyl radical, in marked contrast to the ketone case. The loss of SO from CH3SO- is estimated to be endothermic by 50 kcal/mol [62,63], so it is clear that near simultaneous formation of a stable structure in the carbon portion of the molecule is a critical component in the design of extrusion reactions. 

Deoxygenation of sulfoxides. Alkyl sulfoxides are reduced to sulfides on treatment with either bromo- or iodotrimethylsilane in CCI4 at room temperature for 30 minutes (yields generally around 80%). Some halogenated products are also formed in the case of diaryl or dibenzyl sulfoxides. 

The following compounds are used as inhibitors in acid solutions amines, amino-imidazolines, amino- and nitrophenols, aminotriazole, aldehydes, bezothiazol, dibenzyl sulfoxide, dithiophos-phoric acids, guanidine derivatives, ureas, phosphonium salts, sulfonium salts, sulfonic acids, thio-ethers, thioureas, and thiocarbanoyl disulfides. Amino alcohols, aminobenzimidazole, benzoates, quinoline derivatives, cinnamates, fatty amines, polyether amines, silicates, and triazoles are used as inhibitors in neutral or weakly alkaline solutions, while for strongly alkaline solutions, aldehydes and fatty amines are used. 

Dibenzyl sulfoxide treated at 25 with 3 moles nitrosyl chloride and 3 moles pyridine in chloroform -chlorodibenzyl sulfoxide. Y 89%. F. e. s. R. N. Loeppky and D. C. K. Chang, Tetrah. Let. 1968, 5415. 

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