Disulfides aromatic, reduction

This mechanism is analogous to that of mercury thiophenolate [135], but different from the reduction mechanism of aromatic disulfide(I). 

Both, aliphatic and aromatic disulfides such as diphenyl disulfide and di-M-butyldisulfide undergo rapid reduction to the thiol stage, each consuming 2 equiv of the hydride, 1 equiv for hydrogen evolution and 1 equiv for reduction. However, methylphenyl sulfide is inert toward Li 9-BBNH. Sulfoxides, sulfones, and sulfonic acids are inert to this reagent. 

Dithiol is the trivial name of 4-methyl-l,2-dimercaptobenzene (I). Its solution in alcohol or dilute alkali reacts with weakly acid solutions of sulfide-forming metal ions to yield yellow to black precipitates. The magenta stannous salt (II or Ila) is formed from strong hydrochloric acid solutions of either Sn or salts. Sn v salts are reduced by the dimercaptan to give the aromatic disulfide. Since this disulfide is not soluble in water, it is better to use thioglycolic acid as reductant in all cases it is oxidized to water-soluble dithioglycolic acid. 

The photochemistry and optical properties of three diarylethenes derived from benzoth-iophene have been reported. A photoactivated reduction of aromatic disulfides in the... 

Nitriles from aromatic aldehydes, diammonium hydrogen phosphate, and 1-nitropropane, 43, 59 w-Nitrobenzenesulfonyl chloride, reduction to m-nitrophenyl disulfide by hydriodic acid, 40, 80 2 Nitro-2,3-dimethylbutane, 43, 89... 

Thiols can be prepared by the reduction of sulfonyl halides652 with LiAIH4. Usually, the reaction is carried out on aromatic sulfonyl chlorides. Zinc and acetic acid, and HI. also give the reduction. Sulfonic acids have been reduced to thiols with a mixture of triphenyl-phosphine and either Ii or a diaryl disulfide.633 Disulfides RSSR can also be produced.634 For the reduction of sulfonyl chlorides to sulfinic acids, see 0-118. 

On the pages which follow, general methods are illustrated for the synthesis of a wide variety of classes of organic compounds including acyl isocyanates (from amides and oxalyl chloride p. 16), epoxides (from reductive coupling of aromatic aldehydes by hexamethylphosphorous triamide p. 31), a-fluoro acids (from 1-alkenes p. 37), 0-lactams (from olefins and chlorosulfonyl isocyanate p. 51), 1 y3,5-triketones (from dianions of 1,3-diketones and esters p. 57), sulfinate esters (from disulfides, alcohols, and lead tetraacetate p. 62), carboxylic acids (from carbonylation of alcohols or olefins via carbonium-ion intermediates p. 72), sulfoxides (from sulfides and sodium periodate p. 78), carbazoles... 

Most interest in reductive transformations of environmental chemicals involves dehalo-genation of chlorinated aliphatic or aromatic contaminants and the reduction of nitroar-omatic compounds. Other reductive transformations that may occur abiotically in the environment include reduction of azo compounds, quinones, disulfides, and sulfoxides (Table 16.2). See other reviews (2, 9, 11) for additional discussion of the mechanisms of these reactions. 

Perfluoroalkyl halides can be converted into phenyl sulfides by treatment with aromatic or aliphatic disulfides under reductive conditions involving the presence of various precursors of the SO/ radical anion. ... 

This reaction has found little application to mercaptan syntheses since the mercaptans are usually as readily available (by other methods) as the disulfides. The S-S linkage is reduced by zinc in acetic or sulfuric " acid, lithium aluminum hydride, or metallic sodium. y-Hydroxy-propyl disulfide is reduced electrolytically in 70% yield. Reduction by sodium disulfide does not reduce the nitro group in the preparation of p-nitrothiophenol (65%), whereas zinc and acetic acid converts o-nitro-phenyl disulfide to o-aminothiophenol (90%). Disulfides made by the action of ammonium hydrogen sulfide on aldehydes are sources for difficultly available aromatic and heterocyclic mercaptans. The disulfides are reduced by aluminum amalgam and water. ... 

The first thiete fused to an aromatic system 219 (and an anthracene derivative) was reported in 1965 and was prepared by reduction of a naphthothiete sulfone. An attempt to prepare benzothiete by desulfurization of benzo-l,2-dithiolane was unsuccessful. Photolysis of benzo-l,2-dithiolane 1,1-dioxide in an attempt to extrude sulfur dioxide to give benzothiete also was unsuccessful. The naphthothiete 205, however, was prepared by extrusion of sulfur dioxide from 220 and nitrogen from 221. Thiete 205 also is obtained in 6-8% yield by treatment of 1,8-dehydronaphthalene with carbon disulfide. The unstable thiolactone 211 was formed by a photochemical extrusion of benzaldehyde from 222 and from 222a at 350°C. The benzothietes 209, 223, " and 224 have been... 

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