Reduction by Sulfides

It is also possible to take advantage of studies dealing with the preparation of supported oxide precursors (namely, oxides to be further activated to produce active metals or sulfides by reduction or sulfidation, respectively). Although there is limited information in this field, some scattered information has been published, essentially for M0O3 and V2O5. Infrared and Raman spectroscopies have provided data concerning various steps in the transformation of precursor salts to oxides. 

Thiols and sulfides. Benzylic halides can be converted into either a thiol or a sulfide by reduction with suifurated sodium borohydride depending on conditions of hydrolysis. Aryl halides do not react with the reagent. Aliphatic... 

Most molybdenum is used for the production of alloys. Ferromolybdenum may also be produced directly from the sulfide by reduction with carbon in an arc or by a metallothermic procedure. 

Most important from a corrosion view point are those microorganisms that produce sulfides by reduction of sulfate ions or other oxidized sulfur compounds. These so-called sulfate reducing bacteria (SRB) grow under anaerobic conditions. The sulfides formed at the metal surface can have several effects they may interfere with the formation of a passive oxide film (Chapter 6), they may favor acid corrosion by locally creating conditions of lower pH or they may facilitate hydrogen ingress into the metal that leads to cracking (Chapter 11). 

The differences in the amino acid chemistry of the hide coUagen and the hair keratin are the basis of the lime-sulfide unhairing system. Hair contains the amino acid cystine. This sulfur-containing amino acid cross-links the polypeptide chains of mature hair proteins. In modem production of bovine leathers the quantity of sulfide, as Na2S or NaSH, is normally 2—4% based on the weight of the hides. The lime is essentially an unhmited supply of alkah buffered to pH 12—12.5. The sulfide breaks the polypeptide S—S cross-links by reduction. Unhairing without sulfide may take several days or weeks. The keratin can be easily hydrolyzed once there is a breakdown in the hair fiber stmcture and the hair can be removed mechanically. The coUagen hydrolysis is not affected by the presence of the sulfides (1—4,7). 

Zinc is produced by reduction of 2inc oxide, usually a calcine obtained by roasting 2inc sulfide concentrates. Carbon is used in the absence of air at 1200—1300°C, well above the boiling point of the metal (906°C). 

The compound can be prepared from 2,4,6-trinitrophenol (picric acid [88-89-1]) by reduction with sodium hydrosulfide (163), with ammonia —hydrogen sulfide followed by acetic acid neutralization of the ammonium salt (164), with ethanolic hydrazine and copper (165), or electrolyticaHy with vanadium sulfate in alcoholic sulfuric acid (159). Heating 4,6-dinitro-2-benzamidophenol in concentrated HQ. at 140°C also yields picramic acid (166). 

Cold methanol has proven to be an effective solvent for acid gas removal. Cold methanol is nonselective in terms of hydrogen sulfide and carbon dioxide. The carbon dioxide is released from solution easily by reduction in pressure. Steam heating is required to release the hydrogen sulfide. A cold methanol process is Hcensed by Lurgi as Rectisol and by the Institute Francaise du Petrole (IFP) as IFPEXOL. 

Arninobenzoyl-L-glutarnic acid (12) is obtained by condensation of -nitrobenzoyl chloride [122-04-3] (18) with L-glutamic acid [56-86-0] (19) under Schotten-Baumann conditions. This is followed by reduction of the nitro group with either sodium hydrogen sulfide (29) or by electrochemical methods (30). 

The SRC-II process, shown in Figure 2, was developed in order to minimise the production of soHds from the SRC-I coal processing scheme. The principal variation of the SRC-II process relative to SRC-I was incorporation of a recycle loop for the heavy ends of the primary Hquefaction process. It was quickly realized that minerals which were concentrated in this recycle stream served as heterogeneous hydrogenation catalysts which aided in the distillate production reactions. In particular, pyrrhotites, non stoichiometric iron sulfides, produced by reduction of iron pyrite were identified as being... 

This compound can be converted to l,5-diamino-4,8-dihydroxyanthraquiaone by reduction of nitro groups with sodium sulfide. 

The Msib group has been used for the protection of tyrosine. It is cleaved by reduction of the sulfoxide to the sulfide, which is then deprotected with acid. Reduction is achieved with DMF-SO3/HSCH2CH2SH or Bu4N I or with SiCWTFA. ... 

Sharpless and Masumune have applied the AE reaction on chiral allylic alcohols to prepare all 8 of the L-hexoses. ° AE reaction on allylic alcohol 52 provides the epoxy alcohol 53 in 92% yield and in >95% ee. Base catalyze Payne rearrangement followed by ring opening with phenyl thiolate provides diol 54. Protection of the diol is followed by oxidation of the sulfide to the sulfoxide via m-CPBA, Pummerer rearrangement to give the gm-acetoxy sulfide intermediate and finally reduction using Dibal to yield the desired aldehyde 56. Homer-Emmons olefination followed by reduction sets up the second substrate for the AE reaction. The AE reaction on optically active 57 is reagent... 

Thiophenethiols are prepared by reduction of the sulfonyl chlorides or, more conveniently, by the reaction of Grignard rea-gents or thienyllithium compounds with sulfur. They have also been obtained by cleavage or thienyl alkyl sulfides with sodium in liquid ammonia. 3-Thiophenethiol is a by-product in the commercial thiophene synthesis. Thiophenethiols have recently also been prepared by a synthesis involving Friedel-Crafts reaction of 2,4-dinitrobenzenesulfenyl chloride with thiophenes, followed by basic cleavage of the resulting sulfide. ... 

Compounds 15 can be prepared either by acylation of bis(o-aminophenyl) ditelluride (88KGS276 89KGS120) or by reduction of A -acyl-2-trichlorotelluro-benzenes with sodium sulfide (88MI1). 

Dibenzo[d,g][l,5]telluroazocines 65 are the only representatives of Te, N-containing eight-membered heterocycles known thus far. Treatment of bis(2-bromomethylphenyl)tellurium dibromide 66 with methylamine followed by reduction of the reaction mixture with sodium sulfide gives, instead of the expected... 

A heterocyclic ring may be used in place of one of the benzene rings without loss of biologic activity. The first step in the synthesis of such an agent starts by Friedel-Crafts-like acylation rather than displacement. Thus, reaction of sulfenyl chloride, 222, with 2-aminothiazole (223) in the presence of acetic anhydride affords the sulfide, 224. The amine is then protected as the amide (225). Oxidation with hydrogen peroxide leads to the corresponding sulfone (226) hydrolysis followed by reduction of the nitro group then affords thiazosulfone (227). ... 

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