Sulfide converting

Sometimes, hydrogen sulfide converts an oxygen-containing heterocycle into a sulfur-containing one, and as furans and polycyclic furans are very common in nature such reactions may be the origin of the polycyclic thiophenes mentioned above. A typical example is the formation of the isothiazolin-3-thione (6) from the isoxazolin-3-thione (7) on treatment with hydrogen sulfide and hydrogen bromide.8... 

Groundwater. Groundwater under reducing conditions in the presence of hydrogen sulfide converted ethyl bromide to sulfur-containing products (Schwarzenbach et al., 1985). 

Lithium aluminum hydride reduced p-benzoquinone to hydroquinone (yield 70%) [576] and anthraquinone to anthrahydroquinone in 95% yield [576]. Tin reduced p-benzoquinone to hydroquinone in 88% yield [174] Procedure 35, p. 214). Stannous chloride converted tetrahydroxy-p-benzoquinone to hexa-hydroxybenzene in 70-77% yield [929], and 1,4-naphthoquinone to 1,4-di-hydroxynaphthalene in 96% yield [180]. Other reagents suitable for reduction of quinones are titanium trichloride [930], chromous chloride [187], hydrogen sulfide [248], sulfur dioxide [250] and others. Yields are usually good to excellent. Some of the reagents reduce the quinones selectively in the presence of other reducible functions. Thus hydrogen sulfide converted 2,7-dinitro-phenanthrene quinone to 9,10-dihydroxy-2,7-dinitrophenanthrene in 90% yield [248]. 

The structure of the leukotrienes receptor antagonist cinalukast (58-9) bears only the vaguest resemblance to its predecessor, or, for that matter, to a leukotriene. Reaction of the cyanomethylphosphonate (58-1) with hydrogen sulfide converts the nitrile to a thioamide (58-2). Treatment of that intermediate with the bromoketone... 

The presence of chloride, nitrate, sulfide, organic sulfonates, cyanates, organic amines, and particulate matters may interfere in the test. The two major interferences, chloride and nitrate, however, may be removed in the acid backwash steps. Sulfide reacts with methylene blue to form a colorless complex. Interference from sulfide may be removed by treating the sample with a few drops of 30% H2Oz, whereupon sulfide converted into sulfate. 

Oxidative Dissolution. This is a process highly applicable to metal-sulfides. In general, under reducing conditions metal sulfides are insoluble solids. However, sulfide converts to sulfate (S04) under oxidative conditions and the metal-sulfate salts formed are relatively soluble (Singer and Stumm, 1970). 

In the thiophene series, phosphorus sulfide converts 1,4-diketones and sodium salts of succinic and alkylsuccinic acids to the five-membered heterocyclic compounds. The yields are low, usually 20-30% from the succinates and 60% from the diketones. 

FIGURE 10.13 Long-term variation of oxygen and hydrogen sulfide concentrations in the central Baltic deepwater (hydrogen sulfide converted into negative oxygen equivalents after Fonselius, 1969). 

FIGURE 10.18 Long-term variations of oxygen and hydrogen sulfide (converted into negative oxygen equivalents) and their influence on the distribution of phosphate (upper panel), nitrate, and ammonium in the bottom layer of the Gotland Deep between 1992 and 2003 (lower panel) (from Nausch et al., 2003, supplemented). 

Heating of carbonates, hydroxides, and certain sulfides converts them to what type of compound ... 

Reduced chalcogens. Silver is tarnished to Ag2S by H2S (unless pure and diy), S , and many organic compounds containing snlfur. Alkali sulfides convert silver halides to Ag2S. 

Cysteine-U- C is taken up by the squid giant axon and metabolized to l C-cysteinesulfinate, C-cysteate, C-hypotaurine, C-taurine, and C02, but not to C-isethionate. When S-cysteine is taken up, S-isethionate is formed. S-Sulfide diffuses into the squid axon, probably as unionized H2 S, and is also converted to S-isethionate. These results are shown in Tables 1 and 2. While the amount of sulfide taken up by the squid axon is much less than the amount of cysteine taken up, the amount of sulfide converted to isethionate as a fraction of the uptake is much greater than the amount of sulfur from cysteine considered in the same way. This suggests that the sulfur of cysteine is metabolized to isethionate via sulfide, or that both may pass through another common intermediate. 

Upon combining with alkali metal bases, hydrogen sulfide converts to alkali hydrosulfides such as sodium hydrosulfide and sodium sulfide, which are used in the degradation of biopolymers. The depilation of hides and the delignification of pulp by the Kraft process both are effected by alkali sulfides. 

The conversion products, other than gas and hydrogen sulfide (H2S), are essentially a gasoline fraction that, after pretreatment, will be converted by catalytic reforming an average quality distillate fraction to be sent to the gas oil pool and an atmospheric residue or vacuum distillate and vacuum residue whose properties and impurity levels (S, N, Conr. 

The desired pyridylamine was obtained in 69 % overall yield by monomethylation of 2-(aminomethyl)pyridine following a literature procedure (Scheme 4.14). First amine 4.48 was converted into formamide 4.49, through reaction with the in situ prepared mixed anhydride of acetic acid and formic acid. Reduction of 4.49 with borane dimethyl sulfide complex produced diamine 4.50. This compound could be used successfully in the Mannich reaction with 4.39, affording crude 4.51 in 92 % yield (Scheme 4.15). Analogous to 4.44, 4.51 also coordinates to copper(II) in water, as indicated by a shift of the UV-absorption maximum from 296 nm to 308 nm. 

The cis thioboration of terminal alkynes with 9-(arylthio)-9-BBN is catalyzed by Pd(Pli3P)4 in the presence of styrene. The product 136 is converted into the vinyl sulfides 137 and 138 by the treatment with MeOH or by Pd-catalyzed cross-coupling with aryl or alkenyl halides using K3PO4 in DMF[68]. No thioboration takes place with internal alkynes. 

Peroxy acids usually in dichloromethane as the solvent are also reliable reagents for converting sulfides to sulfoxides... 

One equivalent of a peroxy acid or of hydrogen peroxide converts sulfides to sulf oxides two equivalents gives the corresponding sulfone... 

Polythiodipropionic acids and their esters are prepared from acryUc acid or an acrylate with sulfur, hydrogen sulfide, and ammonium polysulfide (32). These polythio compounds are converted to the dithio analogs by reaction with an inorganic sulfite or cyanide. 

Gaseous Effluents. Twenty percent of the carbon disulfide used in xanthation is converted into hydrogen sulfide (or equivalents) by the regeneration reactions. Ninety to 95% of this hydrogen sulfide is recoverable by scmbbers that yield sodium hydrogen sulfide for the tanning or pulp industries, or for conversion back to sulfur. Up to 60% of the carbon disulfide is recyclable by condensation from rich streams, but costly carbon-bed... 

Sulfuration. Hydiocaibons, such as cyclohexane and / -pentane have been converted to dicyclohexyl and dipentyl sulfides by monoclinic sulfur... 

Two undesirable aspects of FCC naphtha quaUty are that it may contain unacceptably high amounts of foul smelling mercaptans, and that its thermal stabiUty may be too low. Mercaptans are usually found in the light FCC naphtha and may be removed or converted to sulfides and disulfides by a sweetening process such as Merox, developed by UOP. Thermal stabiUty is improved in sweetening processes through removal of cresyUc and naphthenic acids. It may be further improved by clay treating and by addition of oxidation inhibitors such as phenylene diamine. 

The iodides of the alkaU metals and those of the heavier alkaline earths are resistant to oxygen on heating, but most others can be roasted to oxide in air and oxygen. The vapors of the most volatile iodides, such as those of aluminum and titanium(II) actually bum in air. The iodides resemble the sulfides in this respect, with the important difference that the iodine is volatilized, not as an oxide, but as the free element, which can be recovered as such. Chlorine and bromine readily displace iodine from the iodides, converting them to the corresponding chlorides and bromides. 

Molybdenite concentrate contains about 90% M0S2. The remainder is primarily siUca, with lesser amounts of Fe, Al, and Cu. The concentrate is roasted to convert the sulfide to technical molybdic oxide. Molybdenum is added to steel in the form of this oxide. In modem molybdenum conversion plants, the oxidized sulfur formed by roasting M0S2 is converted to sulfuric acid. 

---