Reduction with hydrogen sulfide

Alloxantin has been obtained by the oxidation of uric acid with nitric acid, followed by reduction with hydrogen sulfide 2 by oxidation of uric acid with potassium chlorate, followed by reduction with stannous chloride by condensation of alloxan with dialuric acid in aqueous solution and by oxidation of dialuric acid. ... 

Reduction with hydrogen sulfide and its salts is sometimes referred to as the Zinin reduction (Org. Reactions 1973, 20,455). 

Ketones are obtained from a-diketones by reduction with hydrogen sulfide in a pyridine-methanol solution [237], by refluxing with 47% hydriodic acid in acetic acid (yield 80%) [916], and by decomposition of monohydrazones with alkali [923]. Reduction of a-diketones to hydrocarbons is achieved by decomposition of bis-hydrazones by alkali [923]. 

Reduction with hydrogen sulfide or its salts (maiy examples are given in this book). 

Ferric ion in solution can be reduced to ferrous ion by treatment with metallic iron or by reduction with hydrogen sulfide or stannous ion. 

In the past 10 years other reductants of the C— Hg bond have been used, mainly thiols and sodium amalgam. Reduction with hydrogen sulfide, sodium dithionite, metals,alcohols, alkaline aqueous bases, aromatic amines, Wilkinson s catalyst and electrochemical reductions have also been described. Organomercurials react with thiols by free radical substitutions with an 5h2 mechanism (Scheme 34). The reaction between PhSH and A -hexenylmercury chloride initiated by light or AIBN gives a mixture of 1-hexene and methylcyclopentane. ... 

The reaction of alcohol (41) with TFAA, followed by treatment with sodium azide, gave (42) in 75% overall yield. The p-toluenesulfonate or methanesulfonate of (41) has also been demonstrated to react with sodium azide affording (42) but in lower yield. Deprotection and subsequent reduction with hydrogen sulfide gave amine (43 Scheme 19). ... 

A 90% sulfur dioxide stream, which is a high enough concentration for recycling, is then regained by a combination of heating in the absence of air and partial reduction with hydrogen sulfide, as already described in detail. 

The nickel sulfide is refined by conversion to a sulfate solution and reduction with hydrogen to produce a high purity nickel powder. 

Preparation. Thiophosgene forms from the reaction of carbon tetrachloride with hydrogen sulfide, sulfur, or various sulfides at elevated temperatures. Of more preparative value is the reduction of trichi oromethanesulfenyl chloride [594-42-3] by various reducing agents, eg, tin and hydrochloric acid, staimous chloride, iron and acetic acid, phosphoms, copper, sulfur dioxide with iodine catalyst, or hydrogen sulfide over charcoal or sihca gel catalyst (42,43). 

An explosion was experienced during isolation of supposed diamine produced by reduction of the diazide with hydrogen sulfide. This was attributed to incomplete reduction [1], An explosion, apparently during reduction, of a closely related compound by this method has earlier been reported [2],... 

Anon., Lab. Accid. Higher Educ. Item 32, HSE, Barking, 1987 During the reduction of the azide in ethanol with hydrogen sulfide (no regulation other than main cylinder valve) under reflux (with insufficient flow of condenser water), the mixture apparently overheated, then exploded violently. 

Carbon is able to bind sulfur to its surface. The reaction of sugar charcoal or wood charcoal with elementary sulfur at temperatures of 400-1000° was studied in detail by Wibaut (118-122). In this reaction some carbon disulfide was formed as well as hydrogen sulfide, if hydrogen was present in the samples. The solid reaction products contained considerable amounts of sulfur, up to 20% by weight. The maximum sulfur uptake was observed at 600°. The sulfur was not completely volatized even by heating in a vacuum to 1000° (122). The sulfur came off in elementary form and as carbon disulfide. Neither could the sulfur be removed from the samples by extraction. It was disposed of by powerful chemical attack, e.g., by oxidation or by reduction with hydrogen at 700°. The formation of hydrogen sulfide started at 460°. 

Co-precipitation of Re S with platinum sulfide from cone, hydrochloric acid solutions of microamounts of technetium and rhenium is suitable for the separation of technetium from rhenium , since technetium is only slightly co-precipitat-ed under these conditions (Fig. 7). At concentrations of 9 M HCl and above, virtually no technetium is co-precipitated with platinum sulfide at 90 °C, whereas rhenium is removed quantitatively even up to 10 M HCl. The reduction of pertechnetate at high chloride concentration may be the reason for this different behavior, because complete co-precipitation of technetiiun from sulfuric acid solutions up to 12 M has been observed. However, the separation of weighable amounts of technetium from rhenium by precipitation with hydrogen sulfide in a medium of 9-10 M HCl is not quantitative, since several percent of technetiiun coprecipitate with rhenium and measurable amounts of rhenium remain in solu-tion . Multiple reprecipitation of Re S is therefore necessary. 

The synthesis of TATB (14) from the reaction of 2,3,4,5,6-pentanitroaniline (31) with ammonia has been reported. " In one route, 2,3,4,5,6-pentanitroaniline (31) is synthesized from the nitration of 3,5-dinitroaniline (30) " the latter is obtained from the selective reduction of TNB ° or via a Schmidt reaction with 3,5-dinitrobenzoic acid. Another route to 2,3,4,5,6-pentanitroaniline (31) involves the selective reduction of TNT (1) with hydrogen sulfide in ammonia followed by nitration of the resulting 4-amino-2,6-dinitrotoluene (46), during which the methyl group is lost by oxidation-decarboxylation. 

Hexaruthenium carbonyl complexes have been used to prepare Ti02-supported mthenium catalysts for the sulfur dioxide reduction with hydrogen [112, 113], A catalyst derived from [Ru6C(CO)i6] showed higher activity in the production of elemental sulfur at low temperatures than that prepared from RUCI3 as precursor. This catalytic behavior is related with the formation of an amorphous ruthenium sulfide phase that takes place during the reaction over the ex-carbonyl catalyst [112]. 

Botta and coworkers recently developed an Oxone cleavage methodology for the solid-phase synthesis of substituted uracUs (equation 57) . Whereas some common methods of thioether cleavage, such as reduction with Na/NHs, acid catalyzed hydrolysis, heavy metal ions followed by treatment with hydrogen sulfide and iodofrimethylsilane proved to be unsuccessful for this reduction, Oxone was shown to be an efficient and selective reagent for cleavage of polymer bound thiouracUs. 

---