Sulfur, divalent

Sulfonates, aliphatic la 388, 389 Sulfones lb 321,360 Sulfonic acids la 91 Sulfonylurea derivatives lb 204 Sulfoxides lb 321,358,360,372,373,374 Sulfur compounds lb 338 Sulfur-containing compounds lb 301,339 Sulfur dioxide vapor la 86 -, dipole moment la 97 Sulfur, divalent lb 302 Sulfuric acid la 87,195,333,411,426 Sulfur ions lb 302 Sulfutyl chloride vapor la 86 Sulpyrid lb 268 Sunflower seed oil lb 286 Surfactant-TLC plates la 89 Sweeteners la 44, 388-390 Swep la 108... 

Of a series of indanylthiocarbamates, to1 indate (2) had significant antifungal properties. It is prepared simply from 5-indanyl thionochloroformate (1) by reaction with N-methyl-m-toluidine. It presumably joins the fairly large family of organic compounds having sulfur divalently bound to carbon which are useful topical agents for dermatophytes. 

The biochemical basis for the toxicity of mercury and mercury compounds results from its ability to form covalent bonds readily with sulfur. Prior to reaction with sulfur, however, the mercury must be metabolized to the divalent cation. When the sulfur is in the form of a sulfhydryl (— SH) group, divalent mercury replaces the hydrogen atom to form mercaptides, X—Hg— SR and Hg(SR)2, where X is an electronegative radical and R is protein (36). Sulfhydryl compounds are called mercaptans because of their ability to capture mercury. Even in low concentrations divalent mercury is capable of inactivating sulfhydryl enzymes and thus causes interference with cellular metaboHsm and function (31—34). Mercury also combines with other ligands of physiological importance such as phosphoryl, carboxyl, amide, and amine groups. It is unclear whether these latter interactions contribute to its toxicity (31,36). 

Roasting ofSulRdes. Most nonferrous metals occur in nature mainly as sulfides. These cannot be easily reduced directly to the metal. Burning metallic sulfides in air transforms them into oxides or sulfates which are more easily reduced. The sulfur is released as sulfur dioxide, as shown by the foHowing typical reaction for a divalent metal, M ... 

Zinin Reduction. The method of reducing aromatic nitro compounds with divalent sulfur is known as the Zinin reduction (57). This reaction can be carried out in a basic media using sulfides, polysulfides, or hydrosulfides as the reducing agent. These reactions can be represented as follows when the counter ion is sodium ... 

Sodium ethyl thiosulfate [26264-37-9] is also known as Bunte s salt after the name of its discoverer. Bunte salts may be thought of as esters of thiosulfuric acid (94—96). In essentially all of their chemical reactions, the cleavage is between the divalent and hexavalent sulfur atom. For example, acid hydrolysis produces a thiol and the acid sulfate ... 

For vanadium solvent extraction, Hon powder can be added to reduce pentavalent vanadium to quadrivalent and trivalent Hon to divalent at a redox potential of —150 mV. The pH is adjusted to 2 by addition of NH, and an oxyvanadium cation is extracted in four countercurrent stages of mixer—settlers by a diesel oil solution of EHPA. Vanadium is stripped from the organic solvent with a 15 wt % sulfuric acid solution in four countercurrent stages. Addition of NH, steam, and sodium chlorate to the strip Hquor results in the precipitation of vanadium oxides, which are filtered, dried, fused, and flaked (22). Vanadium can also be extracted from oxidized uranium raffinate by solvent extraction with a tertiary amine, and ammonium metavanadate is produced from the soda-ash strip Hquor. Fused and flaked pentoxide is made from the ammonium metavanadate (23). 

Thermally induced homolytic decomposition of peroxides and hydroperoxides to free radicals (eqs. 2—4) increases the rate of oxidation. Decomposition to nonradical species removes hydroperoxides as potential sources of oxidation initiators. Most peroxide decomposers are derived from divalent sulfur and trivalent phosphoms. 

Divalent Sulfur Derivatives. A diaLkyl ester of thiodipropionic acid (16) is capable of decomposing at least 20 moles of hydroperoxide (17). Some of the reactions contributing to the antioxidant activity of these compounds are shown in Figure 3. 

Although 2H- and 4//-thiadiazines with divalent sulfur are virtually unknown, both isomers have been prepared as the 1-oxides and, more commonly, as the 1,1-dioxides 109 (X = SO2) and 110 (X = SO2). 

Divalent sulfur compounds are achiral, but trivalent sulfur compounds called sulfonium stilts (R3S+) can be chiral. Like phosphines, sulfonium salts undergo relatively slow inversion, so chiral sulfonium salts are configurationally stable and can be isolated. The best known example is the coenzyme 5-adenosylmethionine, the so-called biological methyl donor, which is involved in many metabolic pathways as a source of CH3 groups. (The S" in the name S-adenosylmethionine stands for sulfur and means that the adeno-syl group is attached to the sulfur atom of methionine.) The molecule has S stereochemistry at sulfur ana is configurationally stable for several days at room temperature. Jts R enantiomer is also known but has no biological activity. 

The final possible mode of action for an antioxidant is as a peroxide decomposer. In the sequences that lead to photodegradation of a polymer the ready fragmentation of the hydroperoxide groups to free radicals is the important step. If this step is interfered with because the peroxide has undergone an alternative decomposition this major source of initiation is removed. The additives which act by decomposing hydroperoxide groups include compounds containing either divalent sulfur or trivalent phosphorus. The mechanism involves... 

The S-S bond between two divalent sulfur atoms plays an important role as the main stabilizer of the tertiary structure of many proteins. The simplest chemically stable compounds of this class are HSSH and CH3SSCH3. The structures of these two disulfanes have been established by microwave spectroscopy and electron diffraction experiments. 

F. Tuinstra, Structural Aspects of the Allotropy of Sulfur and the Other Divalent Elements, Waltman, Delft, 1967... 

The tetrasulfides R R MS4 with M=Si, Ge, Sn, or Pb bearing bulky substituents on the group 14 element were synthesized by the reaction of the corresponding divalent species R R M, which are heavier analogues of the carbenes, with elemental sulfur (see Scheme 1) [11-20]. The divalent species... 

Thiols, thioethers, disulfides Sodium metaperiodate + benzidine Substances with divalent sulfur yield white chromatogram zones on a blue background. [36]... 

This reaction is catalyzed by the presence of divalent sulfur — e.g. sulfur ions, substances with S-S links, thioethers, thiazoles. If such substances are present in a chromatogram zone then the iodine applied with the reagent is consumed by reaction with sodium azide according to the above reaction. It is no longer available for the for-... 

Compounds having divalent sulfur and selenium atoms bound to more electronegative elements react with alkenes to give addition products. The mechanism is similar to that in halogenation and involves of bridged cationic intermediates. 

Several copper minerals, containing copper in the divalent state, are completely soluble in sulfuric acid according to the following reactions ... 

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