DiThionate, sodium

The crude dithionate solution is prepared in accordance with the instructions given for calcium dithionate. This solution is brought to a temperature of 35 to 40°. With continuous agitation, barium carbonate powder is added a little at a time until ftui,her addition does not cause immediate increase in carbon dioxide evolution. Agita- 

The slurry is filtered by suction and the filter cake washed with 50 ml. of water at room temperature. To the filtrate warmed to 35° and strongly agitated, about 65 g. of sodium carbonate is added in 1- to 2-g. portions. The temperature is brought up to 45°. The slurry is tested a few minutes after each addition with blue litmus paper. When a distinct, permanent but mildly alkaline condition is reached (red litmus changing to a pale, not a deep, blue), the addition of sodium carbonate is stopped. The warm slurry is filtered and the cake washed with 150 ml. of water at 50° made alkaline to litmus with sodium carbonate. The precipitate is sucked as dry as possible. The filter cake is slurried in 200 ml. of water, made slightly alkaline to litmus with sodium carbonate, and the slurry, heated to 45°, is filtered and washed with 50 ml. of shghtly alkalized water at 50°. If the combined filtrates do not react slightly alkaline to litmus, a httle more sodium carbonate is added and the solution refiltered. 

Sodium dithionate is recovered by concentrating the solution on a steam bath. Successive crops of crystals are obtained by cooling to about 10°. These crystals are filtered off, sucked as dry as possible, but not washed. A precipitate, which may come down in the first concentra- 

In a preparation starting with 80 g. of Java pyrolusite (90 per cent Mn02), 177 g. (88.5 per cent) of sodium dithionate, Na2S20e-2H20, was obtained. 

The solid dithionates are stable at ordinary temperatures but undergo dehydration and decomposition at high temperatures. Above 150° they lose sulfur dioxide, forming sulfates. 

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Heavy water, see Hydrogen[ H] oxide Heazlewoodite, see rn-Nickel disulfide Hematite, see Iron(III) oxide Hermannite, see Manganese silicate Hessite, see Silver telluride Hieratite, see Potassium hexafluorosilicate Hydroazoic acid, see Hydrogen azide Hydrophilite, see Calcium chloride Hydrosulfite, see Sodium dithionate(III)... 

Sodium hydrosulfite or sodium dithionate, Na2S204, under alkaline conditions are powerful reducing agents the oxidation potential is +1.12 V. The reduction of -phenylazobenzenesulfonic acid with sodium hydrosulfite in alkaline solutions is first order with respect to -phenylazobenzenesulfonate ion concentration and one-half order with respect to dithionate ion concentration (135). The SO 2 radical ion is a reaction intermediate for the reduction mechanisms. The reaction equation for this reduction is... 

Further examples of reductions with sodium dithionate are given in References 220-222. The stereoselective syntheses of 1,3- and 1,4-dienes and pheromones are described in Reference 223. 

Redox titrants (mainly in acetic acid) are bromine, iodine monochloride, chlorine dioxide, iodine (for Karl Fischer reagent based on a methanolic solution of iodine and S02 with pyridine, and the alternatives, methyl-Cellosolve instead of methanol, or sodium acetate instead of pyridine (see pp. 204-205), and other oxidants, mostly compounds of metals of high valency such as potassium permanganate, chromic acid, lead(IV) or mercury(II) acetate or cerium(IV) salts reductants include sodium dithionate, pyrocatechol and oxalic acid, and compounds of metals at low valency such as iron(II) perchlorate, tin(II) chloride, vanadyl acetate, arsenic(IV) or titanium(III) chloride and chromium(II) chloride. 

Reduction of A-arylmaleimides with sodium dithionate gives monomeric and dimeric products a mechanism has been proposed. ... 

There is one report of reductive cleavage of the imidazole ring. Treatment of 122 with sodium dithionate in aqueous ammonia yielded amidine 123, which on hydrolysis with acid gave 124. Compound 124 was obtained directly on reduction with sodium dithionate in aqueous ethanolic sodium bicarbonate (83JHC1003). 

Scheme 6.35 Benzoins obtained from the reduction of benzils in the presence of thiourea derivative rac-36 and sodium dithionate.

Sulfur dioxide reacts with manganese dioxide to form manganese dithion-ate, which is an intermediate in the production of sodium dithionate ... 

This scries is represented by the dithionate, [Cr(NH3)5(QH)]S206. 2H20, which is prepared from aquo-pentammino-chromic bromide by treating it with dilute aqueous ammonia till the colour changes from yellow to deep red a concentrated aqueous solution of sodium dithionate is then added, the liquid stirred and left to stand, when carmine-red crystals separate. These are washed with dilute alcohol and dried in air. The dithionate is slightly soluble in water, and is decomposed by dilute hydrochloric acid with formation of aquo-pentammino-chromic chloride, [Cr(NH3)5H20]Cl3. 

Trans -hydroxo - aquo -diethylenediamino -chromic Dithionate, [Cr en2(H20)(0H)]S206, is also formed from the bromide by treating it in concentrated aqueous solution with sodium dithionate it is slightly less red in colour than the bromide or iodide, but otherwise behaves similarly. 

The dithionate, [Cr en2Br2]2S206, crystallises in bluish-violet needles on the addition of sodium dithionate to an aqueous solution of the bromide. 

The bromide, [Co(NH3)5OH]Br,.H20, is prepared from the corresponding aquo-salt in the same manner as the chloride, and separates from alcohol and water as a violet powder. The iodide, [Co(NHs)5OH]I2, is obtained from the chloride by dissolving it in aqueous ammonia and adding solid potassium iodide. The dithionate, [Co(NH3)5OH]S206. H,0, obtained from the chloride by treating it with ammonia and sodium dithionate, crystallises in short red prisms or leaflets. 

The bromide may be obtained from the chloride by double decomposition with ammonium bromide, and by the action of sodium dithionate, the dithionate,... 

The dithionate, [Rh(NH3)5N03]S206.H20, is precipitated from a saturated solution of the nitrate or chloride on the addition of a solution of sodium dithionate. It crystallises in white silky needles resembling the corresponding cobalt salt, and is insoluble in water. 

Whilst the formation of thionyl chloride by the action of phosphorus pentachloride on an alkali sulphite favours a symmetrical structure for the latter, the interaction of an alkali sulphite with ethyl iodide, as mentioned already, is directly opposed to this evidence, as also is the production of sodium sulphite on reducing sodium dithionate with sodium.5 The remaining inorganic evidence is little more satisfactory. 

With sodium thiosulphate the arsenite forms oxythioarsenates (see p. 282), as it also does with tri- and tetra-thionates sodium dithionate does not react either in cold or boiling solution. Sodium tellurate causes oxidation to arsenate.1 An ammoniacal solution of silver azide is reduced to silver by sodium arsenite other metallic azides do not react. 

The sodium dithionate is recovered by evaporation on the steam bath to a final volume of about 10ml. Successive crops of crystals are isolated by cooling and filtering without washing, Any insoluble material that forms during the initial concentration is filtered off. 

A little of the insoluble dithionate of the series may be precipitated from the faintly-colored mother liquor with sodium dithionate. 

Dithionate. Sodium dithionate. sodium hyposulfate. [CAS 7775-14-6], Na2S2Of 2H20. white solid, soluble, formed from manganese dithionate solution and sodium carbonate solution, and then filtering and evaporating the filtrate. 

Besides these main waves, three other waves are observed in Fig. 12.9. Waves I and II are attributed to oxidation of reaction products formed in wave V. This was proved by cycling the potential between -0.3 and 0.6 V vs. AglAgCl where waves I and II were absent. By addition of sodium dithion-ite to the solution, waves I and II again appeared, indicating that the reaction product formed in wave V is dithionite. Waves I and II were also observed at a bare-carbon-fibre electrode after addition of sodium dithionite. Therefore, it is not clear whether these reactions are electrocatalysed by [Fe(II)TSPc]4. However, when cycling between -0.3 and 0.6 V vs. AglAgCl, wave III still occurred under these conditions, indicating that this wave can be attributed to a species in solution. 

Sodium dithionite ( Sodium hydrosulfite ) (Sodium dithionate) [7775-14-6]... 

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