Sulfur containing sulfonyl groups

The effect of sulfur-containing substituents on free radicals appears to be a topic of current interest, so we will discuss it briefly insofar as it concerns sulfinyl and sulfonyl groups. Our discussion will refer mainly to a few recent papers, which usually contain copious references to earlier work see also Block247. 

This chapter describes the chemical behavior of a-sulfinyl and a-sulfonyl carbanions. The stereoelectronic effects of these sulfur-containing groups have been the subject of much controversy for more than a decade which has now gradually settled down. Meanwhile, the special features of the chemical behavior of these groups have been utilized for syntheses of thousands of useful organic substances. This chapter deals with the... 

Sulfur-containing groups at an a-position stabilize carbanions. All these species, i.e., the a-sulfonyl 6281-102, a-sulfmyl 6346-80, a-sulfenyl 645,103,104 and a-sulfonio carbanions 65105-1 ancj those derived from sulfonates 66 and sulfonamides 6795 may retain their... 

In all of these additions to various types of multiple bonds one notes that only products containing a sulfonyl group are obtained. There is never any indication of a bond being formed between a sulfinate oxygen and the species to which the addition is occurring. The same is apparently also true in the addition of a sulfinate ion to a sulfine (Veenstra and Zwanenburg, 1976). There addition occurs to the sulfur atom of the sulfine to form a sulfinyl sulfone ... 

Sulfur-containing functions are especially prone to undergo reductive removal. Hydrogenolysis of the thio group proceeds easily in the presence of Raney nickel and this procedure is ideally suited for the reduction of functional groups like thiols, sulfides, or thioacetals. The sulfonyl group can be reductively removed under the action of agents like Na in liquid ammonia ... 

Polyolefins can be chemically modified with the purpose of changing some of their properties. For example, polyethylene can be chlorinated or chlorosulfonated. Chlorosulfonation can be done with a mixture of chlorine and sulfur dioxide, leading to a material partially chlorinated and partially containing sulfonyl chloride groups. This treatment imparts elastomer character and the capability to be crosslinked, for example, with metallic oxides. 

Sulfur-containing pyrimidines are frequent intermediates in substitution reactions. Several methods exist for exchange of the thiol group with hydrogen, either by hydrogenolysis, especially by the use of Raney Nickel, or by oxidative desulfurization which involves a sulfinic acid intermediate. Oxidation may also lead to a sulfonic acid. The 2- and 4-/6-thiones are considerably more stable to air oxidation than 5-thiol derivatives. Disulfides are conveniently formed by oxidation with bromine. Oxidation with chlorine at low temperature can be used to prepare sulfonyl chlorides. These reactions have been summarized [Pg.187]

The XPS results indicated that there were about 3-5 at. % sulfur and 27-47 at. % oxygen incorporated onto the sulfur dioxide plasma treated LDPE substrate surfaces (Table 1). The sulfur atomic concentration reached a maximum at about 50 A from the sample surface (0 = 30°) right after the plasma treatment (Figure 3). (The uncertainty of the XPS multiplex scan for atomic concentration analysis is believed to be 0.5-1.0 at. %.) The sulfur-containing species diffused into the bulk of the polymer (> 100 A) as shown from the XPS data collected eleven days after the plasma reaction. This phenomenon is due to the mobility of the polymer surface. s After the sulfur dioxide plasma modification, the hydrophilic sulfonyl groups on the LDPE backbone diffuse away from the polymer surface toward the bulk of the material so that a lower surface energy can be attained. Because the air/LDPE interface has a low surface tension, thermodynamic equilibrium favors a hydrophobic surface. As a result, the sulfur atomic concentrations in the top 100 A of the substrates decreased with time as the sulfonyl groups diffused away from this surface layer. 

Chlorosulfonated polyethylene is a saturated chlorohydrocarbon rubber produced from CI2, SO2, and a number of polyethylenes, and contains about 20 to 40 percent chlorine and 1 to 2 percent sulfur as sulfonyl chloride. Sulfonyl chloride groups are the curing or... 

Molecules of liquid crystals can be built from a variety of structural elements. For instance, in 1927 Vorlander synthesized the first liquid crystal twins, now called tail-to-tail twins. A Siamese twin mesogen is a compound in which two independently mesogenic parts are joined in a single molecule. While earlier twins were ligated by carbon-containing groups such as methylene, Dehne et aV have shown that sulfur, sulfinyl or sulfonyl groups can perform a similar role. Anatomy of MLCs from the point of view of possible structures was reviewed in detail by Demus. ... 

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