Reductions with sodium sulfide equations

Sulfur Dyes (C.I. Sulphur). Two types of sulfur dyes exist amorphous powders, which are insoluble or partially soluble in water. They must be brought into solution by reduction with sodium sulfide, according to Equation (5). 

An approach to 2,6-di(bromomethyl)-l,4-selenazanes (175) requires the reaction of diallylamines (174 R = H or Et) and selenium tetrabromide, followed by reductive debromination with sodium sulfide (Equation (39)) <77KGS58>. This procedure parallels that used to prepare 1,4-dichalcogenanes (Section 6.24.3.2), and if A-arenesulfonyldiallylamines (174 R = S02Ar) are used, tellurium tetrabromide gives the corresponding 1,4-tellurazines as the dibromides <89KGS564>. 

The reduction of nitro compounds should initially produce nitroso compounds. This area has not been systematically explored because the nitroso group can be more easily introduced by alternative methods such as direct nitrosation, condensation and oxidative procedures. - In fact, there have been few instances in which nitroso compounds have been isolated as intermediates in reductions of nitro compounds. For example, it was initially believed that w-trifluoromethylnitrobenzene produced the corresponding nitroso compound upon reduction, but subsequently the product was shown to be w-trifluoromethylazox-ybenzene. - Low yields of an intramolecular dimeric, nitroso compound, benzo[c]cinnoline dioxide (1), can be obtained by reducing 2,2 -dinitrobiphenyl with zinc or sodium sulfide (equation I). - ... 

Octafluorotelluranthrene is formed when 3,4,5,6-tetrafluoro-1,2-diiodobenzene is heated with tellurium at 300 °C and the product is treated with bromine. This yields the 5,5,10,10-tetrabromide intermediate, subsequent reduction of which is achieved (although in only 20% yield) using sodium sulfide (Equation (27)) <80JFC(16)245>. 

Controlled reductions arc also possible with a variety of other reagents m-Trrfluoromethylnitrobenzene is converted to the azoxy derivative with hot potassium hydroxide-methanol [SS] but gives the arrune with hot sodium sulfide-sodium hydroxide solution [iS9] (equation 71)... 

Hence, about 1.5 moles of Na2S is needed for each nitro group to be reduced. (The reduction does not always follow exactly the reaction given. Hence, the optimum quantity of sodium sulfide may vary somewhat from the theoretical amount and must be determined by trial.) Frequency, the hydroxide formed in the reaction has a deleterious effect, and in this event better results are obtained with sodium hydrosulfide (NaSH), i.e., a solution of sodium sulfide saturated with hydrogen sulfide. The reaction then proceeds without forming hydroxide, according to the equation ... 

Disulfides, such as the diallyl disulfide shown in Rgure 8.24, can be obtained by the reaction of sodium disulfide (NaiSi), itself prepared by the dissolution of an equivalent of sulfur in a concenctrated sodium sulfide (Na2S) solution, with the corresponding alkyl halide. Reduction of the disulfide (e.g., with zinc dust in acetic acid) results in cleavage of the sulfur-sulfur bond and thiol formation (Scheme 8.105). Alternatively, as might be expected, thiols are rather easily oxidized (e.g., by hypohalites [NaOCl]) and the products are disulfides (Equation 8.60). 

Treatment of 2,3 Cpoxy-l-amines with Lewis acid induces a rearrangement to aziridinium ions that react efficiently with a nucleophiles to give functionalized hydroxy sulfides or hydroxy amines (Equation 23) <1997SL11>. Under the influence of ethylaluminium chloride, an epoxide tethered to an azide undergoes Lewis acid-assisted cyclization followed by an intramolecular Schmidt reaction and subsequent in situ reduction of the intermediate iminium species upon addition of sodium borohydride (Scheme 8). This protocol was used as a key step in a novel synthesis of indolizidine alkaloids of pharmaceutical interest <20030L583, 2004JOC3093>. 

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