Sodium compounds dithionite

Common reducing agents are hydrogen in the presence of metallic or complex catalysts (e.g. Ni, Pd, Pt, Ru, Rh), hydrides (e.g. alanes, boranes, LIAIH, NaBHJ, reducing metals (e.g. Li, Na, Mg, Ca, Zn), and low-valent compounds of nitrogen (e.g. NjHj, NjHJ, phosphorus (e.g. triethyl phosphite, triphenyiphosphine), and sulfur (e.g. HO-CHj-SOjNa = SFS, sodium dithionite = Na S O. ... 

Sodium Tetrahydroborate, Na[BH ]. This air-stable white powder, commonly referred to as sodium borohydride, is the most widely commercialized boron hydride material. It is used in a variety of industrial processes including bleaching of paper pulp and clays, preparation and purification of organic chemicals and pharmaceuticals, textile dye reduction, recovery of valuable metals, wastewater treatment, and production of dithionite compounds. Sodium borohydride is produced in the United States by Morton International, Inc., the Alfa Division of Johnson Matthey, Inc., and Covan Limited, with Morton International supplying about 75% of market. More than six million pounds of this material suppHed as powder, pellets, and aqueous solution, were produced in 1990. 

In the benzene and naphthalene series there are few examples of quinone reductions other than that of hydroquinone itself. There are, however, many intermediate reaction sequences in the anthraquinone series that depend on the generation, usually by employing aqueous "hydros" (sodium dithionite) of the so-called leuco compound. The reaction with leuco quinizarin [122308-59-2] is shown because this provides the key route to the important 1,4-diaminoanthtaquinones. 

Diaminoanthraquinone and Related Compounds. Leuco-l,4-diaminoanthraquinone [81-63-0] (leucamine) (32) is an important precursor for 1,4 diaminoanthraquinone [128-95-0] (33) and is prepared by heating 1,4-dihydroxyanthraquinone (29) with sodium dithionite in aqueous ammonia under pressure. 

Ceric ammonium nitrate converts a 1,4-dimethoxy aromatic compound to the quinone, which is reduced with sodium dithionite to give a depro-tected hydroquinone. ... 

By contrast, alkylamination of naphthazarin (7) in the presence of sodium dithionite followed by oxidation gives l,4-bis(alkylamino)-5,8-naphthoquinone (31).18,19 However, Kikuchi and co-workers20 obtained isomeric l,5-bis(alkylamino)-4,8-naphthoquinone (32) from the reaction of leuco naphthazarin (33) with alkylamine They also isolated 5-alkylamino-leuco-naphthazarin (34) as an intermediate, which is further aminated at the 1-position to give 32. Bloom and Dudek21 have studied the structure of leuco aminonaphthoquinones and their tautomeric equilibria in solution. They concluded that the reaction of leuco naphthazarin (33) or the leuco compound (35) derived from l,5-diamino-4,8-naphthoquinone (36) with methylamine gives mixtures of l,4-bis(methylamino)-31 (R = Me) and 1,5-bis(methylamino)naphthoquinones 32 (R = Me) after oxidation of leuco aminonaphthoquinones (Scheme 10). Some of the structures of leuco aminonaphthoquinones are shown in Scheme ll.20... 

The redox behavior of aminonaphthoquinones has been investigated by Matsuoka and co-workers.11 Reduction of quinoxaline quinone (40) by sodium dithionite in aqueous sodium hydroxide gives the corresponding leuco dye (41) which absorbs at 445nm. Compound 40 shows quinone-... 

Hydroxyacetone (12.48), mentioned in section 12.8.1 in connection with sulphur dyes, is sulphur-free and biodegradable. This compound was originally proposed for use with vat dyes and continues to generate some interest. This agent can be used for the pad-steam application of vat dyes in the presence of high concentrations of sodium hydroxide (about 3.5-4.5 g/1). Hydroxyacetone does not cause over-reduction of indanthrone vat dyes but does give different shades with carbazole dyes, compared with sodium dithionite [218]. 

Crosslinking using diazonium compounds usually creates deeply colored products characteristic of the diazo bonds. Occasionally, the conjugated molecules may turn dark brown or even black. The diazo linkages are reversible by addition of 0.1 M sodium dithionite in 0.2 M sodium borate, pH 9.0. Upon cleavage, the color of the complex is lost. 

Figure 19.22 Phenolic compounds may be derivatized to contain reactive diazonium groups by nitration with tetranitromethane followed by reduction with sodium dithionite and diazotization with sodium nitrite in dilute HCI.

The key intermediate 124 was prepared starting with tryptophyl bromide alkylation of 3-acetylpyridine, to give 128 in 95% yield (Fig. 37) [87]. Reduction of 128 with sodium dithionite under buffered (sodium bicarbonate) conditions lead to dihydropyridine 129, which could be cyclized to 130 upon treatment with methanolic HC1. Alternatively, 128 could be converted directly to 130 by sodium dithionite if the sodium bicarbonate was omitted. Oxidation with palladium on carbon produced pyridinium salt 131, which could then be reduced to 124 (as a mixture of isomers) upon reaction with sodium boro-hydride. Alternatively, direct reduction of 128 with sodium borohydride gave a mixture of compounds, from which cyclized derivative 132 could be isolated in 30% yield after column chromatography [88]. Reduction of 132 with lithium tri-f-butoxyaluminum hydride then gave 124 (once again as a mixture of isomers) in 90% yield. 

A limited number of such reactions have been recently published, and the results are compiled in Table 5. The first example is the reduction of azido compound 76 by sodium dithionite to the corresponding amine 77. Furthermore, some nucleophilic substitutions of the chlorine substituents of heterocycles 78 and 80 have also been reported these compounds, when reacted with morpholine and w-bromoaniline, respectively, furnished the substitution products 79 and 81. 

Cl Sulphur Black 1, which is produced from the relatively simple intermediate 2,4-dinitrophenol and aqueous sodium polysulphide. A similar product (Cl Sulphur Black 2) is obtained from a mixture of 2,4-dinitrophenol and either picric acid (6.148 X = N02) or picramic acid (6.148 X = NH2). A black dye possessing superior fastness to chlorine when on the fibre (Cl Sulphur Black 11) can be made from the naphthalene intermediate 6.149 by heating it in a solution of sodium polysulphide in butanol. An equivalent reaction using the carbazole intermediate 6.150 gives rise to the reddish blue Cl Vat Blue 43 (Hydron blue). This important compound, which also possesses superior fastness properties, is classified as a sulphurised vat dye because it is normally applied from an alkaline sodium dithionite bath. Interestingly, inclusion of copper(II) sulphate in the sulphurisation of intermediate 6.150 leads to the formation of the bluish black Cl Sulphur Black 4. 

Reducing agents, such as zinc dust or sodium dithionite, convert heteropolyacids into deeply colored blue compounds consisting of heteropolyacids with four hydrogen atoms to be substituted. This makes it possible to precipitate more dye with the same heteropolyacid to produce an insoluble pigment. 

Sodium dithionite is well established [ 1 ] as a powerful reducing agent under alkaline conditions. Its redox potential is close to that of sodium borohydride [2] and, in several respects, there are advantages in the use of sodium dithionite as an alternative to the metal hydrides under phase-transfer catalytic conditions, particularly in the reduction of carbonyl compounds [3],... 

Viologen salts act as one-electron phase-transfer agents and, in conjunction with sodium dithionite which regenerates the bipyridinium radical cation, they have been used for the debromination of 1,2-dibromoalkanes to yield alkenes in variable yields [13-15]. Nitroarenes are reduced to anilines in high yield (>90%) under similar conditions [16], whereas conjugated nitroalkenes are converted into the oximes of the saturated ketones [17] saturated aliphatic nitro compounds are not reduced by this process. 

The compounds were received from T. G. Traylor s laboratory in the Fe(lII) chloride form. Approximately. 4 mg of this crystal was dissolved in absolute methanol, degassed, and brought back to atmospheric pressure with argon. Aqueous solutions of cetyltrimethylam-monium bromide (CTAB) were prepared, filtered and bubbled with carbon monoxide gas to saturate the system. Sodium dithionite was added for the reduction of Fe(lII) to Fe(ll) and the methanol solution of the heme was added to the CTAB to create an aqueous solution -5 -4... 

As previously reported, the radical addition of CF2Br2 on glycals (initiated by sodium dithionite) affords difluorobromomethylated compounds. These latter molecules are easily dehydrohalogenated in the presence of TBAF. Under such conditions, these difluorovinyl compounds can add a fluoride ion (from TBAF). The subsequent elimination of the acetate moiety yields trifluoromethyl unsaturated compounds. The double bond can then be reduced (Figure 6.37). The same kind of reaction occurs in the presence of DAST with gcm-difluor-omethylene compounds, which are obtained by addition of an ylide onto an ulose (Figure 6.37). 

In the case of giant wheel (molybdenum blue) compounds, the general synthetic strategy involves the acidification (pH 1) and reduction of an aqueous molybdate(VI) solution [possible reducing agents iron powder, tin(II) chloride, molybdenum(V) chloride, ascorbic acid, cysteine, hydroxylamine, hypophos-phorous acid, sodium dithionite, or hydrazine sulfate].On the other hand, an icosahedral ball-shaped cluster can be formed in an aqueous Mo(VI)... 

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