Hydrogen sulfide Hydrolysis

The hydrolysis of phosphoms sulfides has been studied quantitatively. A number of products are formed (Table 6). Whereas phosphoms(V) sulfide reacts slowly with cold water, the reaction is more rapid upon heating, producing mainly hydrogen sulfide and orthophosphoric acid, H2PO4. At high pH, P4S Q hydroly2es to a mixture of products containing thiophosphates and sulfides. 

Alternative means for removal of carbonyl sulfide for gas streams iavolve hydrogenation. For example, the Beavon process for removal of sulfur compounds remaining ia Claus unit tail gases iavolves hydrolysis and hydrogenation over cobalt molybdate catalyst resulting ia the conversion of carbonyl sulfide, carbon disulfide, and other sulfur compounds to hydrogen sulfide (25). 

Commercial-scale processes have been developed for the production of hydrogen sulfide from heavy fuel oils and sulfur as well as from methane, water vapor, and sulfur. The latter process can be carried out in two steps reaction of methane with sulfur to form carbon disulfide and hydrogen sulfide followed by hydrolysis of carbon disulfide (116). 

Further hydrolysis of the carbon disulfide and the trithiocarbonate produces hydrogen sulfide, etc (33). In another study of the decomposition of sodium ethyl xanthate [140-90-9] in flotation solutions, eleven components of breakdown were studied. The dependence of concentration of those components vs time was examined by solving a set of differential equations (34). 

Carbon disulfide is essentially unreactive with water at room temperature, but above about 150°C in the vapor phase some reaction occurs forming carbonyl sulfide (carbon oxysulfide) [463-58-1] and hydrogen sulfide [7783-06-4]. Carbonyl sulfide is an intermediate in the hydrolysis reaction ... 

Hydrochloric acid digestion takes place at elevated temperatures and produces a solution of the mixed chlorides of cesium, aluminum, and other alkah metals separated from the sUiceous residue by filtration. The impure cesium chloride can be purified as cesium chloride double salts such as cesium antimony chloride [14590-08-0] 4CsCl SbCl, cesium iodine chloride [15605 2-2], CS2CI2I, or cesium hexachlorocerate [19153 4-7] Cs2[CeClg] (26). Such salts are recrystaUized and the purified double salts decomposed to cesium chloride by hydrolysis, or precipitated with hydrogen sulfide. Alternatively, solvent extraction of cesium chloride direct from the hydrochloric acid leach Hquor can be used. 

A thioamide of isonicotinic acid has also shown tuberculostatic activity in the clinic. The additional substitution on the pyridine ring precludes its preparation from simple starting materials. Reaction of ethyl methyl ketone with ethyl oxalate leads to the ester-diketone, 12 (shown as its enol). Condensation of this with cyanoacetamide gives the substituted pyridone, 13, which contains both the ethyl and carboxyl groups in the desired position. The nitrile group is then excised by means of decarboxylative hydrolysis. Treatment of the pyridone (14) with phosphorus oxychloride converts that compound (after exposure to ethanol to take the acid chloride to the ester) to the chloro-pyridine, 15. The halogen is then removed by catalytic reduction (16). The ester at the 4 position is converted to the desired functionality by successive conversion to the amide (17), dehydration to the nitrile (18), and finally addition of hydrogen sulfide. There is thus obtained ethionamide (19)... 

Hydrogen cyanide (anhydrous), 15, 89 Hydrogen peroxide, 13, 94 16, 31 16, 4 Hydrogen sulfide, 16, 81 Hydrolysis... 

The alkyl chain distribution of the base alcohol in alcohol sulfates is easily determined by gas chromatography. However, alcohol sulfates and alcohol ether sulfates are not volatile and require a previous hydrolysis to yield the free alcohol. The extracted free alcohol can be injected directly [306] or converted to its trimethylsilyl derivative before injection [307]. Alternatively, the alcohol sulfate can be decomposed by hydroiodic acid to yield the alkyl iodides of the starting alcohols [308]. A preferred method forms the alkyl iodides after hydrolysis of the alcohol sulfate which are analyzed after further extraction of the free alcohol, thus avoiding the formation of hydrogen sulfide. This latter method is commonly used to determine the alkyl chain distribution of alcohol ether sulfates. 

The 2- and 3-halogenoquinoxalines may be converted into the corresponding quinoxalinethiones by treatment with sodium hydrogen sulfide, sodium thiosulfate, thioacetic acid (with concomitant decarboxylation), or (indirectly) by treatment with thiourea followed by alkaline hydrolysis of the thiouronio intermediate (usually as a one-pot procedure). The same substrates furnish corresponding alkylthio-, arylthio-, or arylsulfonylquinoxalines by treatment with a salt of the appropriate alkanethiol, thiophenol, or benzenesulfinic acid. The following classified examples illustrate such processes. 

Yellow insoluble substances of similar composition are obtained on reaction of hydrogen sulfide with either SO2, SOCI2, or SO2CI2 and on hydrolysis of S2CI2 [87], e.g. ... 

Hydrogen sulfide vapor reagent 86 Hydrolysis 62 ff -, acid 62... 

The products of hydrolysis and dissociation depend on the pH. In an acid medium, hydrogen sulfide, which has no depressing action, evolves. It is, therefore, necessary to use alkaline circuits in which HS, predominates. These sulfide ions are adsorbed on the copper sulfide mineral surface and react with the surface previously coated with cuprous xanthate. The reaction causes desorption of the collector, and as a result of this desorption the copper sulfide minerals generally become hydrophilic. There is, however, no action of the sulfide ions on molybdenite, and so molybdenite retains its hydrophobic character. 

The genus Thiobacillus, especially the species T. denitrificans catalyzed the oxidation reactions of hydrogen sulfide yielding soluble hydrosulfide compounds, elemental sulfur, and sulfuric acid. Carbonyl sulfide and carbon disulfide are converted to hydrogen sulfide by hydrolysis. Additionally, they are oxidized to SOx and sulfates via microbial action. The reported oxidation reactions of thiosulfate using nitrate as electron acceptor are ... 

The final method for constructing epidithiodiketopiperazine motifs relied on the nucleophilic thiolation of /V-acyliminium ions. Access to alpha-oxidized diketopi-perazine structures was central to this approach, and key developments were made in this regard. Schmidt first demonstrated the feasibility of this ionization approach in 1973 by conversion of proline anhydride to its diacetate using Pb(OAc)4 [42], Hydrolysis of the acetates, ionization of the hemiaminals with zinc chloride in the presence of hydrogen sulfide, and oxidation with iodine provided the epidisulfide of interest. In 1975, Matsunari reported access to alpha-methoxy diketopiperazines,... 

COMBISULF A process for removing sulfur compounds from the gases from combined-cycle power plants with integrated coal gasification. Carbonyl sulfide is removed by catalytic hydrolysis hydrogen sulfide is removed by selective absorbtion in aqueous MEDA and the sulfur is recovered from both processes by a modified Claus unit. Developed by Krupp Koppers and first operated in Spain in 1996. See PRENFLO. 

Organic sulfur compounds such as certain proteins and amino acids will produce hydrogen sulfide when degraded. The following hydrolysis of cysteine, an amino acid, exemplifies this ... 

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