Sulfanes synthesis

The sulfenyl carboxylate is, on complete exclusion of moisture, a stable, colorless liquid, which on irradiation with UV light decomposes to FC(0)SCFs and CO2. The sulfane is a good starting material for the synthesis of additional perfluoro compounds By means of fluorine-chlorine substitution with BCI3 (20°C, 2 days), it is possible to obtain C1C(0)SCF3, whose existence previously could be shown only by mass spectrometric study of the products of irradiation of a mixture of CFsSCl and CO (237). As an acid chloride, ClC(0)SCFs can be esterified with alcohols, but hydrolysis to the free acid fails. 

The addition of equivalent quantities of a (dialkylamino)trifluoro-/l4-sulfane (see Section 8.4.) to a (dialkylamino)trimethylsilane results in the formation of a bis(dialkylamino)difluoro-/l4-sulfane.71 The dialkylamino moieties of the reactants can be different, resulting in the synthesis of unsymmetrical products. This class of compound is not stable to distillation and is generally utilized without prior purification. For small-scale fluorinations, the bis(dialkylamino)difluoro-/l4-sulfanes are generated in situ, for example, by the addition of one equivalent of commercial-grade DAST to a solution of an appropriate (dialkylamino)trimethylsilane at low temperature.72 73 Examples for the preparation of a bis(dialkylamino)difluoro-/l4-sulfane l71 and dif-luoro-/l4-sulfane 25,11 with different dialkylamino groups are given below. 

A more general synthetic procedure to prepare aryltrifluoro-l -sulfanes. e.g. 4, is the fluorination of an aryl disulfide, e.g. 3, with silver(ll) fluoride, although the cost of the silver(II) fluoride precludes large-scale synthesis.80... 

In general, the sulfanes have a less well-developed chemistry, partly because of the difficulty in isolating them pure, although they have been used for the synthesis of some organosulfur compounds see Sulfur Organic Polysulfanes). 

Not only fission, but also formation of sulfur-sulfur bonds may be regarded as a reaction at a sulfur center, e.g., the synthesis of sulfanes, chlorosulfanes, or sulfur allotropes ... 

Preparation of S12 from S2CI2 and a polysulfane mixture H2S sulfanes H2S and dichlorosulfanes S Cl2 react with each other with elimination of HCl forming new S-S bonds. Since piue sulfanes with more than two sulfur atoms are difficult to prepare, this synthesis uses a mixture of sulfanes, called crude sulfane oil , which can easily be prepared from aqueous sodium polysulfide and concentrated hydrochloric acid at 0 °C [39, 40] ... 

Amino(dimethylthiocarbamoyl)sulfane may be used for the synthesis of 1,4,2-dithiazines 3 from 2-substituted 4,5-diphenyl-l,3-dithiol-2-ium perchlorates. At room temperature in acetonitrile within a few days, the sulfenamide nitrogen is incorporated into the ring system, the other products being bis(thiocarbamoyl)disulfane and ammonium perchlorate.13... 

Sodium Prundecatungstosilicate (8-), (Na4P,-SiW 0 )). 27 90 Solid state synthesis, 26 377 X -Sulfane, (2-bromoetbenyl)-pentafluoro-, 27 330... 

The next logical step was the extension of this chemistry to SH derivatives. Attempts to oxidatively fluorinate CF3SSH with monofluoroxenonium hexafluorometalates failed, even at 195 K. Only decomposition into the already mentioned Sg + salts could be observed (24). On the other hand, the synthesis of the fluoro(trifluoromethyl)sulfonium- and fluoro(methyl)sulfonium cations from the SH acidic sulfanes CF3SH and CH3SH proceeded without difficulty at 213 K (Figure 1) (25). The elimination of HF at 213 K is expected to be preferred from a thermodynamic point of view, although HF elimination is probably kinetically inhibited in this case. However, at 233 K decomposition of all of these compoimds into the characteristic blue Sg2+ salts is observed. By reaction with chlorine... 

In comparison with the membranes with common aromatic skeletons such as poly-sulfane (PS), poly(ether ether ketone), poly(phthalazinon ether sulfone ketone), poly(etherimide), poly(benzimidazole), poly(phenylene oxide), polysiloxane, poly(oxyethylene) methacrylate, poly(arylene ether sulfone), and polyethersulfone Cardo, which are generally at high price and of complicated synthesis processes, the most important advantages of the aliphatic polymer materials as PEM membranes are their low cost, easy preparation, and simple structure. These aliphatic PEMs are particularly environmentally friendly (e.g., if the quatemization process is proceeded when these aromatic membranes are used for alkaline PEM fuel cells, the synthesis route uses chloromethyl ether for chloromethylation, which is very toxic and carcinogenic). However, the stability of the aliphatic PEMs is not very good. This is probably the biggest challenge when they are used in electrochemical devices. 

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