Sulfides, Disulfides

The free-radical chemistry of fluoroalkanesulfenyl chlorides with hydrocarbons was also investigated [S, 9], Depending upon the structures of the sulfenyl chloride and the hydrocarbon, these reactions yield as major products up to three of the following four types of organic compounds thiols, disulfides, sulfides, and chlorohydrocarbons (equation 6), Perfluoroisobutanesulfenyl chloride is unique m that the only major products detected are the thiol and chlorohydrocarbon [ ] (equation 6) (Table 3). 

Sulfiir-anchored SAMs and thin films, mostly from organosulfiir precursors, have been discussed at length by a number of authors [10, 181]. SAMs of organosulfiir compounds (thiols, disulfides, sulfides) form on gold substrates by spontaneous adsorption from either the liquid or the vapor phase. A number of experimental factors can affect the formation and structure of SAMs such as choice of solvent, temperature, concentration, immersion time, purity of adsorbate, oxygen concentration in solution, cleanliness, and structure of the adsorbate. Interestingly, the... 

The proposed metabolic pathway in strawberries is shown in Figure 3. Five compounds mixed disulfide, sulfide, sulfenic acid, thiophosgene and the GSH-re-action product have not been identified as a strawberry metabolite but their involvement is very likely based on the formation of bis-(fluorodichloromethyl)... 

When 2,5-diphenylfuran was treated with potassium peroxydisulfate, 4-methylquinoline was obtained in quantitative yield. Peroxydisulfate was also found to be a very efficient reagent for the conversion of thiols to disulfides. Sulfides can be selectively converted into the corresponding sulfoxides in the presence of potassium peroxydisulfate in acetic acid. ... 

Disulfides. Sulfides are oxidized to disulfides usually in 85-95% yield by 1 equivalent of nickel peroxide. 

V All other molecules having neither active hydrogen atoms nor donor atoms Hydrocarbons, carbon disulfide, sulfides, mercaptans, and halohydrocarbons not in Class IV... 

Examples hydrocarbons, carbon disulfide, sulfides, mercaptan... 

Among the sulfur compounds, only dimethylsulfoxide is reduced at a moderate rate whereas disulfide, sulfide, sulfone, tosylate, and sulfonic acid are inert to 9-BBN under the conditions. These observations are similar to those realized with borane, thexylborane, and disiamylborane. 

Many commercial sulfonylureas contain an ortho ester, therefore, preparation of tied-back ester was of great interest. We could use the target intermediate monomethylamide 2 (Scheme X), as both a directing group for metallation and as the latent lactone group. The sulfonamide handle could be added via metallation and quenched with propyl disulfide. Sulfide 2Q can also be prepared via a nucleophilic displacement of the chlorobenzamide 21. A second metallation of 2Q gave the ethanol derivative 22. Base hydrolysis to the amide to the carboxylate, then lactonization under acidic conditions, gave the isocoumarin 22. Oxidative chlorination and amination proceeded without a problem. 

Percentage of sulfur by weight Poly- sulfides Mer- captans Disulfides Sulfides and carbon dilsulfide Free sulfur Thio- phenes... 

Organic sulfur compounds such as sulfurized spermaceti oil, terpene sulfides, and aromatic disulfides have been used. Encumbered phenols such as di-tertiary-butylphenols and amines of the phenyl-alphanaphthylamine type are effective stopping the kinetic oxidation chain by creating stable radicals. 

Organic compounds containing sulfur are very important. Calcium sulfur, ammonium sulfate, carbon disulfide, sulfur dioxide, and hydrogen sulfide are but a few of the many important compounds of sulfur. 

Carbon disulfide, hydrogen sulfide, and sulfur dioxide should be handled carefully. Hydrogen sulfide in small concentrations can be metabolized, but in higher concentrations it quickly can cause death by respiratory paralysis. 

The reaction of butadiene with sulfur gives the disulfide 112, cyclic sulfide 113, and macrocyclic mono- and trisulfides 114 and 1I5[105]. 

Originally, vulcanization implied heating natural rubber with sulfur, but the term is now also employed for curing polymers. When sulfur is employed, sulfide and disulfide cross-links form between polymer chains. This provides sufficient rigidity to prevent plastic flow. Plastic flow is a process in which coiled polymers slip past each other under an external deforming force when the force is released, the polymer chains do not completely return to their original positions. 

Butyrolactone with sodium sulfide or hydrosulftde forms 4,4 -thiodibutyric acid (168) with sodium disulfide, the product is 4,4 -dithiodibutyric acid... 

Sweetening. Another significant purification appHcation area for adsorption is sweetening. Hydrogen sulfide, mercaptans, organic sulfides and disulfides, and COS need to be removed to prevent corrosion and catalyst poisoning. They ate to be found in H2, natural gas, deethanizer overhead, and biogas. Often adsorption is attractive because it dries the stream as it sweetens. 

Carbon disulfide [75-15-0] is a clear colorless liquid that boils at 46°C, and should ideally be free of hydrogen sulfide and carbonyl sulfide. The reaction with alkaU cellulose is carried out either in a few large cylindrical vessels known as wet chums, or in many smaller hexagonal vessels known as dry chums. In the fully continuous viscose process, a Continuous Belt Xanthator, first developed by Du Pont, is used (15). 

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... 

Conversion of carbon in the coal to gas is very high. With low rank coal, such as lignite and subbituminous coal, conversion may border on 100%, and for highly volatile A coals, it is on the order of 90—95%. Unconverted carbon appears mainly in the overhead material. Sulfur removal is faciUtated in the process because typically 90% of it appears in the gas as hydrogen sulfide, H2S, and 10% as carbonyl sulfide, COS carbon disulfide, CS2, and/or methyl thiol, CH SH, are not usually formed. 

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. 

Direct splitting requires temperatures above 977°C. Yields of around 30% at 1127°C are possible by equiUbrium. The use of catalysts to promote the reaction can lower the temperature to around the 327—727°C range. A number of transition metal sulfides and disulfides are being studied as potential catalysts (185). Thermal decomposition of H2S at 1130°C over a Pt—Co catalyst with about 25% H2 recovery has been studied. 

The direct reaction of methane and hydrogen sulfide to yield hydrogen and carbon disulfide is being studied (189). 

There are two manganese(II) sulfides, MnS and MnS2. Manganese(II) disulfide contains a S—S bond and has a pyrite stmcture. When a solution of a manganous salt is treated with ammonium sulfide, a flesh-colored hydrated precipitate is formed which is comprised of MnS and Mn(II)S2. This mixture very slowly changes to the mote stable green-black MnS. 

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