Precursor sulfur containing

More recendy, molecular molybdenum-sulfur complexes and clusters have been used as soluble precursors for M0S2 in the formulation of lubricating oils for a variety of appHcations (70). Presumably, the oil-soluble molybdenum—sulfur-containing precursors decompose under shear, pressure, or temperature stress at the wear surface to give beneficial coatings. In several cases it has been shown that the soluble precursors are trifunctional in that they not only display antifriction properties, but have antiwear and antioxidant characteristics as weU. In most cases, the ligands for the Mo are of the 1,1-dithiolate type, including dithiocarbamates, dithiophosphates, and xanthates (55,71). 

Neoprene Type TW was shown to have low oral toxicity in rats. The LD q was found to be in excess of 20,000 mg/kg. Human patch tests with Types GN, W, WRT, and WHV showed no skin reactions (169). The FDA status of Du Pont Neoprene polymers is described (172). Although polychloroprene itself has not been shown to have potential health problems, it should be understood that many mbber chemicals that may be used with CR can be dangerous if not handled properly. This is particularly tme of ethylenethiourea curatives and, perhaps, secondary amine precursors often contained in sulfur modified polychloroprene types. Material safety data sheets should be consulted for specific information on products to be handled. 

Contrary to the expectation that a sulfur-containing substituent will be a catalyst poison, a phenylthio group serves as an effective selectivity control element in TMM cycloadditions. A single regioisomer (30) was obtained from the carbonate precursor (31) in good yield. The thermodynamically more stable sulfide (32) is readily accessible from (30) via a 1,3-sulfide shift catalyzed by PhSSPh. A wide array of synthetically useful intermediates could be prepared from the sulfides (30) and (32) with simple transformations (Scheme 2.10) [20]. 

Sulfur-containing amino acids, such as methionine and cystine, are probably the precursors of the mercaptans, sulfides, and disulfides.3 Dimethyl sulfide yields dimethyl sulfoxide and its oxidized product dimethyl... 

Fig. 11. Graphs of the Auger signals resulting from exposure to various sulfur containing precursors as a function of potentials. Adapted from ref. [279],...

Sulfur-containing amino acids, especially L-methionine, serve as precursors for MT and the many materials derived from this compound, such as DMS, DMDS, DMTS, methyl thioacetate, etc. The most direct route for the L-methionine MT conversion is by demethiolation (Equation 4) catalyzed by methionine y-lyase, EC 4.4.1.11 ... 

Nomura, R. Fujii, S. Kanaya, K. Matsuda, H. 1990. Oxygen- or sulfur-containing organoindium compounds for precursors of indium oxide and sulfide thin films. Polyhedron 9 361-366. 

Gruber AS, Zim D, Ebeling G, Monteiro AL Dupont (2000) Sulfur-containing palladacycles as catalyst precursors for the Heck reaction. J Org Lett 2 1287-1290... 

Catalysts used for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of heavy oil fractions are largely based on alumina-supported molybdenum or tungsten to which cobalt or nickel is added as a promoter [11]. As the catalysts are active in the sulfided state, activation is carried out by treating the oxidic catalyst precursor in a mixture of H2S and H2 (or by exposing the catalyst to the sulfur-containing feed). The function of hydrogen is to prevent the decomposition of the relatively unstable H2S to elemental sulfur, which would otherwise accumulate on the surface of the... 

Ni and Padwa developed an interesting method for the construction of sulfur-containing 1,3-dienes 116 using 115 as precursor of a palladium-catalyzed reaction, which was executed in the absence of an amine base (Scheme 14.26) [55]. 

Two types of sulfur-containing five-membered heterocycles are convenient precursors of thiocarbonyl ylides, namely, 2,5-dihydro-1,3,4-thiadiazoles (20) and l,3-oxathiolan-5-ones (21) (Scheme 5.5). The precursors 20 are accessible by two different methods. 

Similar data for sulfate have been reported in many studies. Figure 9.36, for example, shows overall average sulfate distributions measured in marine areas as well as at continental sites (Milford and Davidson, 1987). The marine data show two modes, a coarse mode associated with sea salt and a fine mode associated with gas-to-particle conversion. Sulfate in seawater, formed, for example, by the oxidation of sulfur-containing organics such as dimethyl sulfide, can be carried into the atmosphere during the formation of sea salt particles by processes described earlier and hence are found in larger particles. The continental data show only the fine particle mode, as expected for formation from the atmospheric oxidation of the S02 precursors. 

Scheme 7.3 Enzymatic production of sulfur-containing flavour compounds in Allium species from amino acid flavour precursors, a S-Alk(en)yl cysteine sulfoxides and b (+)-S-l-propenyl cysteine sulfoxide (isoalliin) P-5 -Ppyridoxal-5 -phosphate...

Owing to very low thresholds, volatile sulfur compounds (VSCs) usually have prime impact on food aromas they are found in lots of natural sources, including fermented foods (e.g. wine, beer, cheese), and act as both flavours and off-flavours [249, 250]. Although their biogenetic formation has been elucidated in detail, only few biotechnological processes with potential for commercial application have been reported. The sulfur-containing amino acids L-methionine and L-cysteine are the natural precursors of a wide variety of VSCs. Methanethiol is the most frequently found VSC in cheese and can be readily oxidised to other VSCs, such as dimethyl suMde and dimethyl disulfide, or... 

Sulfur Containing Heterocycles from Thioamide Precursors , M. Tisler, in Organic Sulfur Chemistry , ed. R. K. Freidlina and A. E. Skorova (invited lectures presented at the 9th International Symposium), Pergamon, Oxford, 1980, pp. 209-217. 

Inorganic Sulfate Provides precursors for sulfur-containing compounds Unknown... 

Gruber, A. S. Zim, D. Ebeling, G. Monteiro, A. L. Dupont, J. Sulfur-containing pallada-cycles as catalyst precursors for the Heck reaction. Org. Lett. 2000, 2, 1287-1290. 

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