Sodium hydrosulphite reduction

Reduction to hydroquinone. Dissolve, or suspend, 0-5 g. of the quinone in 5 ml. of ether or benzene and shake vigorously with a solution of 1 0 g. of sodium hydrosulphite (Na2S204) in 10 ml. of N sodium hydroxide until the colour of the quinone has disappeared. Separate the alkaline solution of the hydroquinone, cool it in ice, and acidify with concentrated hydrochloric acid. Collect the product (extract with ether, if necessary) and recrystalhse it from alcohol or water. 

In cold aqueous solution, sodium orthoarsenate reacts with sodium hydrosulphite to form sodium arsenohydrosulphite,6 NagAs(S204)3, a creamy white granular powder. In the presence of sodium sulphite this compound decomposes, forming sodium arsenothiosulphate, an unstable intermediate product, and finally arsenious sulphide.7 If the reduction by sodium hydrosulphite takes place in the presence of hydrochloric acid, some arsenic subsulphide, As3S, is also precipitated,8 and this product is also obtained when the orthoarsenate in aqueous solution is treated with phosphorus trichloride and the mixture saturated with sulphur dioxide.9... 

The anthraquinones may be reduced to the corresponding anthra-quinols (hydroxyanthranols) with alkaline sodium hydrosulphite this reaction has a wide application in the dye industry. These compounds are difficult to isolate pure, for they rapidly oxidise in air. The anthranols —y-monohydroxyanthracenes—however, are stable, and may be obtained by reducing anthraquinone with acid-reducing agents—tin and hydrochloric acid, zinc and glacial acetic acid, copper or aluminium, and sulphuric acid, etc. For the complete reduction of anthraquinone, see Reaction LYIII. (a). 

Many patents have been granted for processes to prepare sodium hydrosulphite by the electrolytic reduction of sodium sulphite. 

Reduction of quaternary pyridine salts with sodium amalgam afford the 1,2-dihydro whereas sodium hydrosulphite gives the 1,4-dihydro derivative, respectively362. From a preparative point of view, partial hydrogenation of quaternary pyridinium salts in alkaline media to give substituted 1-methyl-A2-piperideines is very important363,364. 

Many achiral or chiral substituted382 and bridged 1,4-dihydropyridines383 have been prepared by a reduction of quaternary pyridium salts with sodium hydrosulphite as NADH models for enantioselective reduction of some prochiral substrates. A lithium aluminium hydride reduction of Af-acylenamines has also been observed384-386. 

Sodium hydrosulphite blend BURCO REDUCT 1 Burlington... 

The di-trans isomer 206 was isolated from the products of the reaction of 190 with the bisphosphonium salt 205 in the presence of lithium ethoxide. The reaction of 207 (obtained by the oxidative coupling of 206, with dimethyl sulphate followed by reduction with sodium hydrosulphite) yielded the cyclic compound, containing the dihydropyridine nucleus, 208a. Lithium aluminium hydride reduction of 207 yielded... 

If S-nitro-2-methylphenylarsinic acid is heated with alkali at 90° C., subsequent treatment with acid yields a mixture of stilbenediarsinic acids, as detailed on p. 194. Reduction with sodium hydrosulphite transforms these into 5 5 -diamino-2 2 -stilbene-l I -diarsinic acid. Further reduction yields the corresponding arseno-compound. 4-Nitro-5-ehlorotolyl-2-arsinic add undergoes a similar series of reactions. o-Phenylenediarsinic acid, ... 

Amiao-2-methoxy-4-hydroxyphenylarsinic acid is obtained when the preceding nitro-add is reduced with sodium hydrosulphite. It crystallises in needles containing 2 molecules of water of crystallisation, which darken at 120° C., and decompose at higher temperatures without appearing to melt. On reduction it yields the corresponding arseno-compoxmd (p. 847). 

Reducing agents used for the foregoing reactions are phosphorous acid, hypophosphorous acid, sodium hydrosulphite, stannous chloride in hydrochloric acid, and sodium amalgam in methyl alcohol in some cases electrolytic methods have been employed. Many arseno-compounds of low molecular weight have been isolated, using phosphorous acid for reduction. In the case of arsenoxides the reduction takes place in... 

Reduction of tliis compoimd by sodium hydrosulphite in sodium hydroxide solution at 60 C. in a carbon dioxide atmosphere 5delds the diamino-derivative. The product is soluble in water or methyl alcohol, less soluble in ethyl alcohol, insoluble in ether and acetone. It forms a dihydrochloride w hen treated with concentrated hydrochloric acid. 

Another method consists of reducing the dinitroaminophenylarsinic acid with alcoholic hypophosphorous acid, 4 it -diamino-Z 5 8 5 -tetranitroarsenobenzene resulting, and this on treatment with stannous chloride in concentrated hydrochloric acid yields the hexamino-base. Reduction of the dinitro-compound has also been effected by treating it with sodium hydrosulphite, and by the action of ferrous chloride in alkaline solution. ... 

The foregoing reduction of the dyestuff may be carried out in two stages. The first consists in reducing the dyestuff to 4-amino-8-hydroxy-phenylarsinic acid (p. 304) by alkaline hydrosulphite or aluminimn powder and sodium hydroxide, the second in further reducing this arsinic acid at 60 to 65° C. with alkaline hydrosulphite. Another modification of the process is as follows The alkaline solution of the piuified j8-naphthol dye is treated at 0° to 6° C. with sufficient hydrosulphite to discharge the colour of the solution, which is then saturated witii carbon dioxide. After removing the l-amino-2-naphthol, the filtrate is reduced with a 50 per cent, excess of sodium hydrosulphite for two hours at 60° C. ... 

The acid forms glistening violet crystals, melting indefinitely about 265° C., giving violet solutions in ammonium hydroxide or 2N sodium carbonate, a reddish-violet solution in normal sodium hydroxide, a red solution in 2N sodium acetate, and a brownish-yellow solution in concentrated sulphuric acid. Magnesia mixture and ammonium hydroxide yield reddish-violet precipitates with the acid. When the acid is diazotised and coupled with R-salt, it gives a violet dye. Reduction with sodium hydrosulphite forms an orange-coloured vat, which imparts a violet stain to filter-paper. 

Mercuri-bis-4-aminophenol is obtained from the corresponding nitro compound by reduction in alkaline solution wuth sodium hydrosulphite. It forms heavy needles, insoluble in water, but readily soluble in alcohol. The hydrochloride crystallises in brilliant needles, soluble in water. The free base in alkaline solution is rapidly oxidised on exposure to air, and its acetyl derivative crystallises in slender needles, soluble in alkali, forming stable solutions. 

Electrolytic reduction in sulphuric acid with a lead cathode, reduction with sodium hydrosulphite or hydrazine [28], and reduction of the oxime [1], have all been reported to give codeine, but the sodium hydrosulphito and hydrazine reductions have been reinvestigated by Findlay and Small [3], who obtained only complex transformation products and suggest that Hill s starting material [28] (inuoh more... 

Speyer and Rosenfeld on reduction of 14-bromocodeinone [xxn] with sodium hydrosulphite obtained an amorphous halogen-free base that was converted by hot alkali to a crystalline, ketonic, tertiary base Cx8H2i03N that they suggested was dihydro-i/ -codeinone [40], but its properties do not agree with those of the latter [7] and its nature remains obscure. 

Reductive bleaching with non-stabilised sodium hydrosulphite [98], sodium hydrosulphite-based sulphoxylate formaldehyde [99] and sodium and zinc hydroxymethanesulphinate [100] have been shown to provide wool excellent whiteness, with a lower cystine content than in the case of bleaching wool with other reducing agents. The result obtained is permanent, in contrast to the unstable peroxide white. 

Reduction bleaching of silk is generally carried out with sodium hydrosulphite or appropriate stabilised commercial products on this basis. The silk fibrion is... 

For acrylic/wool blends, the acrylic portion is brightened in the normal way and then the wool is bleached with hydrogen peroxide and subsequent reduction bleaching is done in a bath containing suitable brightener (1-2%) and stabilised sodium hydrosulphite (3-5 g/1) at 85 C for 30 min. The fabric is then rinsed and dried. 

An interesting aspect is that moths only thrive on keratin which contains disulphide bonds. If these are ruptured by reduction with sodium hydrosulphite and thioglycoUic acid and new links are built by methods such as joining primary amino groups with glyoxal, the wool is immune from attack by moths. 

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