Sodium trithionate

Sodium trithionate, Na2Si06, can be made by oxidizing sodium thiosulfate with cooled hydrogen peroxide solution... 

Against this latter view is the fact that little or no sulphuric acid is formed unless the mixture is boiled for a long time. In alkaline solution, alkali sulphide and trithionate react to form thiosulphate,1 but alkaline solutions of sulphate and sulphide do not.2 It would appear, therefore, that the correct explanation lies in the reversible equation (6) (p. 195). This receives support from the fact that when lead thiosulphate is boiled with water it yields, in the first instance, lead sulphide and lead trithionate.3 Conversely, lead sulphide on digestion with potassium trithionate yields lead thiosulphate.4 Further, weakly alkaline solutions of sodium thiosulphate itself yield, on boiling, sodium sulphide and sodium trithionate, with only a trace of sulphate if boiled with sodium plumbite, lead sulphide is precipitated and sodium trithionate remains in solution. 

Anhydrous sodium trithionate is formed in about 80-85% yield when the sulfate-free oxidized filtrate is run slowly into 150ml of alcohol. The precipitated crystalline salt is washed on the filter with about 50ml of alcohol and dried in air. 

Hydrated sodium trithionate may be isolated by evaporating the liquid (plus any deposited crystals of product) in vacuo, and isolating the salt as described in (I). The yield is about the same. 

Sodium trithionate, Na2S306.—The trithionate can be prepared from sodium thiosulphate by oxidation with hydrogen peroxide,10 or by electrolysis in acid or alkaline solution.11 It is also formed by heating a solution of sodium mercuric thiosulphate 12... 

Sodium trithionate forms transparent plates, very soluble in water. The heat of formation in aqueous solution from the elements is given by Berthelot14 as 393-6 Cal. The heat of solution of the trihydrate is —10-1 Cal. 

Analogous to the action of oxygen is that of sulphur, which slowly converts a sulphite in hot aqueous solution into the corresponding thiosulphate, some trithionate being formed simultaneously.2 The reaction goes to completion with excess of sulphur, and is accelerated by the presence of sodium sulphide. 

By the gradual addition of hydrogen peroxide to an ice-cold aqueous solution of sodium thiosulphate, it is possible to convert the latter into trithionate, the changes... 

Certain double salts of thiosulphurie acid when heated with water undergo decomposition with production of trithionate 8 thus the sodium-mercurous salt decomposes according to the equation ... 

At one time it was believed that trithionate could be synthetically produced by the action of iodine on an aqueous mixture of sodium... 

Another competing reaction that generally hinders the condensation with C—H acids is the attack of the carbanion on the 5-methyl group with displacement of the trithione. This C-methylating power of the trithionium salts has been observed, e.g., in the reaction of sodium acetoacetate or the sodium salt of fluorene on 108.62,68... 

The 1,2-dithiafulvalenes of the type 150, which are obtained (if at all) only in extremely small yields by the reaction of the sodium salt of fluorene with 108 or 111, can be prepared in useful yields from fluorene and trithione by a pyrolytic reaction. Trithiones with substituents in position 4, however, do not condense with fluorene under these conditions, probably because of steric factors. Attempts to condense indene with 5-aryltrithiones have also met with failure.46... 

The tetrathionate is converted by the action of sodium sulphite into trithionate and thiosulphate 1... 

It is also said to react with sodium sulphite, yielding the trithionate and thiosulphate 3... 

Chemical. In addition to its intrinsic interest, sulfur serves as a starting point for the synthesis of many labeled molecules. Digestion of sulfur in aqueous sulfites yields thiosulfates, which when heated with iodine lead to tetra-thionates and trithionates. Digestion of sulfur in alcoholic cyanide solutions yields thiocyanates, thence thiocyanogen and thiourea with its derivatives and coordination complexes. Oxidation of sulfur to sulfur dioxide is a potential route to labeled sulfamic acid and its derivatives and to labeled sulfuryl chloride. The intermediate sodium sulfide readily yields hydrogen sulfide and metallic sulfides. 

Gay-Lussac and Welter discovered dithionic acid (H2S20e). The name thionic acids , and the modern name dithionous acid for hyposulphurous acid, were proposed by Berzelius. Trithionic acid was discovered by Lan-glois and investigated by Mathieu Plessy, who gave a better method of preparation. Sodium tetrathionate was discovered by Fordos and Gelis. Pentathionic acid was discovered by Wackenroder (see p. 904). 

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