Sodium hydrosulphite, production

Silicic acid, purification of, 51. Sodium hydrosulphite, production of, 35. 

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... 

Sodium hydrosulphite reduces arsenates and arsenites, yielding precipitates containing sulphides the composition of which varies with conditions. In strongly acid solutions arsenic trisulphide is the main product.2 Sodium thiosulphate also precipitates arsenic as the trisulphide from acid solutions,3 but the amount of precipitation depends on the nature and concentration of the acid present. Thus, with hydrochloric, perchloric or sulphuric acid, the precipitation reaches a maximum of 50 to 80 per cent, for 0-1N acid,4 and above this concentration the amount of precipitation falls to zero with hydrochloric acid but passes through a minimum with perchloric acid at N concentration and with sulphuric acid at 2 to 3N concentration. At still higher acid concentrations precipitation becomes almost quantitative. 

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). 

Short-lived iodine fission products have also been separated by a similar method. In this case, an oxidant such as nitrite ion in acidic aqueous solution has been used (50,255) the iodine extracted into carbon tetrachloride, and then back-extracted into an aqueous solution containing sodium hydrosulphite (50). 

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... 

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. 

Chloromercurithiophene or mercury 2 2 -dithienyl is treated with arsenious chloride and the product warmed on the water-bath. The filtrate from this mixture is treated with aqueous sodium hydroxide, then with hydrogen peroxide. Addition of barium chloride then helps to remove any inorganic arsenic which has not crystallised out as sodium arsenate. The whole is filtered, the filtrate freed from barium and sulphuric acid and evaporated down after the addition of concentrated hydrochloric acid. The residue is dissolved in alcohol, boiled with charcoal, and treated with sodium hydroxide. The sodium salt of the arsinic acid crystallises out in transparent, colourless, non-deliquescent, rhombic plates, which are very soluble in water. The free acid forms tufts of needles, M.pt. 185 5° C., fairly soluble in water or alcohol. At 106° to 108° C. it is converted into the corresponding anhydride. Sulphurous acid in the presence of a trace of hydriodic acid reduces it to thienyl-2-arsenoxide, whilst with sodium hydrosulphite it yields 2 2 -arsenothiophe-ne,... 

This derivative results when 14 grams of phenylglycinc-p-arsinic acid in 200 C.C. of water and 100 c.c. of normal sodium hydroxide arc mixed with 15-2 grams of 4-acetylaminophenylstibinic acid in 300 c.c. of water and 50 c.c. of sodium hydroxide and the whole reduced with sodium hydrosulphite. The product is brownish-black, soluble in aqueous alkalis or aqueous pyridine, but insoluble in water, alcohol, or acetone. 

Solutions containing, respectively, 12 grams of sodium 4-hydroxyphenyI-arsinate in 240 c.c. of water, and 13 2 grams of 4-hydroxyplu nylstibinie. acid in 30 c.c. of water aird 50 c.c. of normal sodium hydroxide, are mixed together and diluted with 1260 c.c. of water. To this solution, 260 grams of sodium hydrosulphite are added and the whole stirred until no further precipitate separates (for about two hours). The product is then filtered off, washed with water, and dried in x acuo. It is a brownish-black powder, insoluble in water, soluble in alcohols, acetone, pyridine, and aqueous sodimn hydroxide. 

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... 

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

Blacks present some difficulty because they cannot be produced satisfactorily by most conventional methods. The best results are obtained by a modified azoic process. A dyebath is made up with 2 per cent (of the weight of the goods) of Cibacet Diazo Black HI), and 3 per cent of Ciba-naphthrd RTO (C.I. azoic coupling component 18). The material is dyed with these products at the boil for 45 minutes and then rinsed. A cold liquor is made up containing 8 per cent of sodium nitrite and 14 pet cent of hydrochloric acid (32 per cent), and the temperature is raised gradually to 83°C (185°F) at which it is maintained for 30 minutes. The cellulose will only be stained, and may be cleared with sodium hydrosulphite and formic acid, after which it is dyed with a copper after-treated direct black. 

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