Thiosulphate and polythionates

Takana et al. [344] used high performance liquid chromatography on an anion exchange column with differential pulse polarographic detection to determine thiosulphate and tri, tetra-, penta- and hexathionates in trade effluents. The method is accurate to within 10% at the 0.001 mM concentration range. 

Hannah [346] has described a high performance liquid chromatographic anion exclusion method for the determination of fluorides in complex trade effluents. Pharmaceutical industrial effluents were examined for fluoride using an Ion-100 anion exchange column coupled with a GA-100 

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From Salts.—(a) Sulphites, thiosulphates and polythionates readily liberate sulphur dioxide when treated with an acid, or, in the case of the salts of the heavier metals, when merely heated. Calcium sulphite mixed with plaster of Paris and moulded into cubes forms a suitable material for use with sulphuric acid in an automatic gas generator such as Kipp s apparatus.6... 

A sensitive colour test for sulphite ions consists in adding, drop by drop, a 0-01 per cent, solution of Fast Blue R crystals, shaking after each addition, until the violet coloration disappears and a yellow solution is produced the test is sensitive to one part of sulphurous acid in about 175,000. Thiosulphates and polythionates do not interfere, but sulphides and hydroxides must be absent.1... 

Further applications are described for sulfur (Fig. 2.6) and copper in water by reversed-phase or ion-exchange high-performance liquid chromatography . Also anions such as thiosulphate and polythionates were separated from environmental samples by HPLC (anion-exchange) . The sensitive detection was made possible by reaction with Ce(lV) after separation and fluorimetry of Ce(lII) ions. 

Analytical properties of thiosulphate and polythionate anions have been reviewed [85]. 

See also Foerster and Stuhmer (ibid., 1930,206,1) and Kurten cker and Czemotzky (ibid., 1928, 175, 367) on the catalytic influence of arsenious acid on the decomposition of thiosulphates to polythionates. 

In W. Feld s process, a mixture of hydrogen sulphide and ammonia is passed into aq. soln. of ammonium tri- and tetra-thionate whereby the polythionates are converted into thiosulphate (NH4)2S306+(NH4)2S=2(NH4)2S203 and... 

The decomposition of the polythionic acids (q.v.) in the presence of alkali, the decomposition of hydrosulphites (p. 227) and the hydrolysis of nitrogen sulphide2 by water or aqueous alkali are also processes in which salts of thiosulphuric acid are formed. Certain micro-organisms capable of converting sulphur to thiosulphate have been isolated from soil cultures.3... 

When acids act on thiosulphates, polythionic acids are formed.5 This is explained by reactions (b) and (c). The fact that the amount of hydrogen sulphide liberated is very small in proportion to the amount of polythionic acid formed is attributed 8 to the fact that reaction (a) is that which normally occurs to the greatest extent when acid acts upon thiosulphate the hydrogen sulphide is thus liberated in the presence of a large amount of sulphurous acid and hence rapidly destroyed. Trithionic acid is thus a primary product of thiosulphate decomposition, and in its turn decomposes as explained on p. 212. 

If gaseous sulphur dioxide is passed into a solution of thiosulphate, a yellow solution is formed which on keeping becomes colourless it then yields a precipitate of sulphur when treated with formaldehyde and sodium hydroxide, but no polythionate can be detected. When the colourless solution is neutralised with sodium hydroxide, it is found to contain sulphite and thiosulphate, but sulphur is not precipitated. These results may be due to the formation of an additive compound such as that mentioned in (ii) above.5... 

On the other hand, much stronger evidence is available in favour of the earlier formula,4 which accords well with the relationship between the acid and the polythionic acids.5 The formation of sodium thiosulphate by Spring s synthesis from sodium sulphide and sodium sulphite (p. 194) is definitely favourable to this constitution, as also especially is the fact that an alkali thiosulphate will react with only an equimoleeular proportion of an organic (alkyl) halide,6 the product... 

Thiosulphates, e.g. sodium thiosulphate, are oxidisable to polythion-ates by the addition of the requisite quantity of hydrogen peroxide. If the reaction mixture is allowed to become alkaline, dithionate, tetra-thionate and sulphate are produced 2... 

Whenever sulphur dioxide, water and nascent sulphur meet, for example in the action of water on sulphur chloride, of mineral acids on a thiosulphate, or of hydrogen sulphide on aqueous sulphur dioxide solution, formation of polythionic acids is likely to occur. Dalton 1 in 1812 demonstrated that the last-named reagents gave rise to an acid liquid, a result which was confirmed later by Thomson 2 in 1846 Wackenroder 3 proved the presence of pentathionic acid in the liquid, since which date the aqueous reaction product has been known as Wackenroder s Solution. ... 

A small quantity of arsenic is precipitated in each case. Sodium dihydrogen arsenite yields a considerable precipitate of arsenic and also of the red disulphide. The polythionates react similarly to thiosulphates, yielding sulphite, thioarsenate and arsenate.5 The per- 1 ites also cause oxidation to arsenate. Sodium hydrosulphite... 

Schoon, N.-H. (1962). Kinetics of the formation of thiosulphate, polythionates and sulphate by the thermal decomposition of sulphite cooking liquors. Sven. Papperstidn. 65, 729-754. 

Decomposition of acidified solutions of thiosulphate forms sulphur dioxide, colloidal sulphur (S8,Ss), polythionic acids and hydrogen sulphide. The reaction kinetics have been examined several times ° and profitable studies of the conditions under which colloidal sulphur is formed were made 3,714, 716-718. acceptable interpretation was first given by Davis , in terms of the steps (7)-(15). These involve successive steps of nucleophilic displacement by thiosulphate, viz. 

Alternatively, under less reducing conditions, conversion may involve the addition of sulphur (S) from intermediate sulphur species (e.g. polysulphides, polythionates or thiosulphate (S2( )i )), which are the products and reactants in microenvironmental sulphur redox cycling. The reaction involving S2O5- can be summarized as ... 

Further oxidation of elemental sulphur wiU lead to the formation of thiosulphate, polythionates, sulphite and finally sulphate ... 

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