Reducing agents sodium hydrosulphite

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). 

Various hyposulphite compounds are used for industrial purposes including stable aldehyde compounds. Of these the formaldehyde compound (Formosul) is tie most important, since it is the reducing agent almost universally employed in applying vat dyes by printing methods to textile materials. The less stable sodium hydrosulphite is used in dyeing with vat dyes. Stable zinc compounds (Rongalite) are also on the market. 

Extraction of the elemental form of bromine is used to separate short-lived bromine activities from fission products. Potassium chlorate in 8 N nitric acid solution (255)s potassium permanganate in nitric acid solution (106,248), and a bromlde-bromate-hypofchlorite mixture in acidic solution (247) have been used as the oxidizing agent. The bromine is extracted into carbon tetrachloride and can be back-extracted into the aqueous solution by reducing agents, such as potassium nitrate (255)> hydrazine hydrochloride (106,248), or sodium hydrosulphite (106). 

Is a blend of alkalis - it buffers sodium hydrosulphite and other reducing agents. Does not have the same negative hazardous aspects of sodium hydrosulphite, but if used properly, it will produce the same results. 

Chemical nature stabilized blend of sodium hydrosulphite and other useful reducing agents... 

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... 

The 8204 ion exists in sodium dithionite, the reducing agent, hydrosulphite . This salt is prepared from the Zn salt, which results from the reduction of SO2 by Zn dust in aqueous suspension. In solution it rapidly decomposes to disulphite and thiosulphate 2S2O4" -> 8205 + 8203 The structure of this ion is rather extraordinary (Fig. 16.6(a)). It has an eclipsed configuration with the planes of... 

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. 

The sulphur dyes resemble the vat dyes in that they are insoluble in water but reduce to a soluble form which readily reverts to the original state on oxidation. In many cases this reversible change is accompanied by an alteration of colour. Sodium sulphide is the reducing agent commonly used, but in some cases sodium hydrosulphite maybe substituted, making it possible to dye selected vat and sulphur dyes together. 

D Thiosulphonic acid derivatives. The dye is pasted with cold water and dissolved by boiling, after the addition of sufficient water to ensure solution. The recommended quantity of reducing agent is then added and this may be either sodium sulphide or sometimes sodium hydrosulphite together with sufficient sodium carbonate to ensure stability of the liquor. Electrolyte is added when necessary for satisfactory exhaustion. 

Hydrosulphites are used to bleach the juice, particularly when the object is to manufacture sugars for direct consumption. The sodium salt is known under the name of Blankit and the calcium salt as Redos. These salts act as powerful reducing agents on the colouring matters of the... 

The aminochromes are reduced readily by a wide variety of reducing agents [26-29] the most widely used being sodium hydrosulphite (i.e. sodium dithionite Na2S204) ascorbic acid sodium borohydride and zinc and acetic acid. 

The hydrosulphites (dithionites), studied by Schiitzenberger from 1869, were closely connected with the application of commercial dyes. Following the isolation of hydrosulphurous acid , an unstable chemical, Schiitzenberger began to understand, and to explain, phenomena observed by colourists. These studies led to the control of certain industrial operations in which it was necessary to use a reducing agent. At the same time he developed a method for the determination of the quantity of dissolved oxygen in various liquids with sodium hydrosulphite (sodium dithionite). ... 

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