Telluropentathionate, sodium

Sodium telluropentathionate 2-hydrate, 4 88, 89 Sodium tetrametaphosphate 4-hydrate, Na4P40i2-4H20, purification of, for preparation of sodium tetraphosphate, 6 98 Sodium tetraphosphate, Na P Oi3, for preparation of hexaguani-donium tetraphosphate 1-hydrate, 5 99... 

Sodium telluropentathionate 2-hydrate crystallizes as small plates or flat needles. A mass of crystals appears yellow with an orange tint single crystals are yellow with a greenish tint. Dilute aqueous solutions are yellow concentrated solutions are orange red. The salt is readily soluble in water, though less soluble than the analogous selenium compound. It is insoluble in ethanol and insoluble or very sparingly soluble in methanol. Its water of hydration, like that associated with sodium selenopentathionate, is lost very slowly in vacuo over sulfuric acid. 

A solution of 0.025 mol of sodium or potassium xanthate or dithiocarbamate in 100 ml. of water is added, with stirring, to 3.5 g. of sodium selenopentathionate (0.01 mol) or 4.0 g. of sodium telluropentathionate (0.01 mol) (.synthesis 31) dissolved in 100 ml. of water. The product immediately precipitates, and after being stirred for several minutes, it coagulates, leaving a clear liquid. It is filtered, washed with water and methanol, and dried in vacuo over sulfuric acid. Conditions for crystallization of some of these compounds are outlined in Table I. Selenium ethyl-xanthate, which is an oil, is extracted from the aqueous layer with ether. The ether extract so obtained is dried over anhydrous sodium sulfate, after which the ether is removed by distillation. 

Telluropentathionic Acid, H2TeS406.—The sodium salt of this acid may be prepared by the action of tellurium dioxide on an aqueous solution of sodium thiosulphate in the presence of hydrochloric acid (c/. p. 340) ... 

Sodium selenopentathionate 3-hydrate, which was first isolated in 1949,1 is prepared by the reaction used by Norris and Fay2 for the iodometric analysis of selenious acid. Salts of telluropentathionic acid were also first isolated in 1949.3 The reaction utilized in their preparation was also discovered by Norris and Fay.2,4 Tellurous acid cannot be analyzed by a procedure analogous to that which Norris and Fay applied to the determination of selenious acid, because telluropentathionate is not indifferent to iodine but may be titrated directly with it 3... 

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