The Formation of Sodium Thiosulfate from the Oxidation of Sodium Sulfides by Means of an Aromatic Nitro Compound

Abstract

The oxidation of sulfide with the subsequent formation of thiosulfate has been recorded as early as 1798 by Berthollet.' Since that time many investigators have contributed to knowledge in this field, among whom may be mentioned Vauquelin, Thomas and Rule, Kiister and Heberlein, and most recently Pearson and Robinson.2 In the field of organic chemistry, especially in the case of aromatic nitro compounds, the use of sulfide ion as a reducing agent has had wide application. This phase of the subject has been studied by Zinin, Beilstein and Kurbatow, Lobry de Bruyn and Blanksma, Brand, Vesely, J. B. Cohen and Fliir~cheim.~We have restricted our work to the oxidation of sulfide, hydrosulfide, and polysulfide ions by aromatic nitro compounds. We have obtained information concerning the formation of thiosulfate ion.Previous workers in this field have used nitro compounds that were not appreciably soluble in aqueous solution and have employed higher temperatures and mixed solvents. By the use of sulfonated aromatic nitro compounds-in particular sodium nz-nitrobenzenesulfonate-we were able to work in aqueous solutions of 0.1 M concentration and a t room temperature. In this oxidation thiosulfate ion and sodium m-amidobenzenesulfonate are the only products formed-sulfite ion was not found in any of our oxidations, see page 236. This enabled us to study the course of the reaction, which is traditionally formulated as followsRKOz f Na& f HzO = Rh"2 + lhia2&03Purification of Materials.-The materials involved could all be obtained in a very pure state or could be purified easily. In the case of sodium hydroxide this was prepared from C. P. sticks made up to a saturated solution with water in a seasoned Pyrex flask. The impurities, chloride, carbonate, and silicate, which may be present settle out on standing quite completely but the small quantities which remained in solution were without effect on the reaction as was proved by a series of blank tests.Sulfur was purified by recrystallization from carbon disulfide. Hydrogen sulfide was prepared by heating $-toluidine and sulfur together a t 200-220°.4 The resulting gas which is very pure was washed through water to remove any entrained solid.

The Baker–nathan Effect Observed in the Relative Rates of Reduction of Several Para-Alkylatednitrobenzenes by Sodium Hydrosulphide

“…These relative rates are shown in Table I. TABLE I Relative initial rates of reduction b y sodium hydrosulphide of para-substituted nitrobenzenes Previous work (3,4) has shown that in the reduction of nitrobenzene by sodium sulphide an induction period exists wherein reduction of nitrobenzene by sulphide ion occurred very slo~vly with simultaneous production of disulphide ion. The much greater reducing ability of the disulphide species, compared with that of the monosulphide ion, caused a sharp acceleration of rate.…”