Sulfur-containing compounds, effect

The physical properties of the principal constituents of natural gas are Hsted in Table 5. These gases are odorless, but for safety reasons, natural gas is odorized before distribution to provide a distinct odor to warn users of possible gas leaks in equipment. Sulfur-containing compounds such as organic mercaptans, aUphatic sulfides, and cycHc sulfur compounds are effective odorants at low concentrations and are added to natural gas at levels ranging from 4 to 24mg/m. ... 

Homogeneous catalysts may also be effective in the hydrogenation of sulfur-containing compounds. (Z)-2-Benzamide(acetamido)-3-(2-thienyl)-2-propenoic acid was reduced in 100% yield and 78% enantiomeric excesses over Rh(I)-DlOP catalysts (25),... 

Activities of ALA-S and Haem-S were decreased after exposure to hydrogen sulfide. However, the changes in heme metabolism are not specific for hydrogen sulfide, and other sulfur-containing compounds such as methyl mercaptan can produce similar effects. 

Mazumder TK, Nishio N, Fukazaki S, et al. 1986. Effect of sulfur-containing compounds on growth of Methanosarcina barkeri in defined medium. Appl Environ Microbiol 10 617-622. 

Walash et al. [14] described a kinetic spectrophotometric method for determination of several sulfur containing compounds including penicillamine. The method is based on the catalytic effect on the reaction between sodium azide and iodine in aqueous solution, and entails measuring the decrease in the absorbance of iodine at 348 nm by a fixed time method. Regression analysis of the Beer s law plot showed a linear graph over the range of 0.01 0.1 pg/mL for penicillamine with a detection limit of 0.0094 pg/mL. 

Element-specific detection combined with capillary GC has become a key technique in the chemical communication studies of our laboratory. An effective detector of this type is based on the microwave plasma emission (Wylie and Quimby 1989), with a tunable selectivity for several elements and a prominent sensitivity for sulfur-containing compounds, which is significantly greater than... 

The elevated urinary acidity in the chicken period may have resulted from, among other factors, the distinct sulfur amino acid ratios. The ratio of Met/Cys (mg/g N) in chicken is 150/80 whereas in soybeans it is 80/100, or in more comparable terms 150/100 suggesting that in relation to methionine, soybeans have twice as much cysteine as chicken. Sherman and Gettler (23) noted the importance of both phosphorus and sulfur. That sulfur containing compounds in the diet have an important effect on urinary acidity was confirmed by Lemann et al. (39) who demonstrated that elevated urinary acidity accompanied methionine feeding in humans. 

The biosynthesis 237,5381 involves enzymatic dehydration of serine and threonine residues in a manner similar to the formation of thiazoles and dihydrothiazoles vide supra) with or without subsequent oxidation to yield the 2-(l-aminoalkyl)oxazole-4-carboxylic acid and 2-(l-aminoalkyl)dihydrooxazole-4-carboxylic acid shown in Scheme 38. These cyclic peptides display interesting physiological properties such as cytotoxicity/541, 569,5831 antitumor activities, or antineoplastic effects/523,5291 but as for the sulfur-containing compounds the mechanism of action is not yet understood despite extensive SAR studies. 515,521,540,5431... 

Spanier, A.M. and Drumm Boylston, T. 1994. Effect of temperature on the analysis of beef flavor volatiles Focus on carbonyl and sulfur-containing compounds. Food Chem. 50 251-259. 

It is of note that alkaline and acid phosphatase exhibit no silikatase activity. Divalent sulfur-containing compounds, such as sulfide, methionine, cysteine and glutathione have a positive effect on silica uptake536) also water temperature and silica concentration in the aqueous phase control the Si-cycle in cellular systems529-531, 53 ). 

If each type of sulfur compound is removed by a reaction that was first-order with respect to sulfur concentration, the first-order reaction rate would gradually, and continually, decrease as the more reactive sulfur compounds in the mix became depleted. The more stable sulfur species would remain and the residuum would contain the more difficult-to-remove sulfur compounds. This sequence of events will, presumably lead to an apparent second-order rate equation which is, in fact, a compilation of many consecutive first-order reactions of continually decreasing rate constant. Indeed, the desulfurization of model sulfur-containing compounds exhibits first-order kinetics, and the concept that the residuum consists of a series of first-order reactions of decreasing rate constant leading to an overall second-order effect has been found to be acceptable. 

The chain terminating additives are usually aromatic amines, phenols, or sulfides. Those that inhibit the catalytic effect of metallic ions such as Cu, Fe, Pb, Mn, and Co are generally organic sulfides, phosphites, or thiophosphates. Although oxidation or corrosion inhibitors are frequently referred to separately, many of the phosphorus and sulfur containing compounds are effective in both applications. The entire matter of oxidation is affected by many things, including the temperature of the lubricant and the material of construction of the equipment in which the lubricant is used. It is also materially affected by inherent resistance of the base oil to oxidation. 

In hydrogenation conditions the effect of sulfur adsorption is the result of interactions between the metal, the hydrocarbon, and the sulfur-containing compound. As a consequence, for a given metal, the sulfur coverage, and its effect on the activity and selectivity of the unpoisoned metallic surface area, will be defined by the nature of the hydrocarbon. 

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