Thiosulfate (IUPAC-recommended spelling; sometimes thiosulphate in British English) is an oxyanion of sulfur with the chemical formula S2O2−3. Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid, such as sodium thiosulfateNa2S2O3 and ammonium thiosulfate(NH4)2S2O3. Thiosulfate salts occur naturally. It rapidly dechlorinates water and is notable for its use to halt bleaching in the paper-making industry. Thiosulfate salts are mainly used in dying in textiles and the bleaching of natural substances.[2]
Thiosulfate is tetrahedral at the central S atom. Thiosulfate ion has C3v symmetry. The external sulfur atom has a valence of 2 while the central sulfur atom has a valence of 6. The oxygen atoms have a valence of 2. The S-S distance is appropriate for a single bond. The S-O distances are slightly shorter than the S-O distances in sulfate.
Also reflecting its affinity for metals, thiosulfate ion rapidly corrodes metals in acidic conditions. Steel and stainless steel are particularly sensitive to pitting corrosion induced by thiosulfate ions. Molybdenum improves the resistance of stainless steel toward pitting (AISI 316L hMo). In alkaline aqueous conditions and medium temperature (60 °C), carbon steel and stainless steel (AISI 304L, 316L) are not attacked, even at high concentration of base (30%w KOH), thiosulfate ion (10%w) and in presence of fluoride ion (5%w KF).[citation needed]
In the era of silver-based photography, thiosulfate salts were consumed on a large scale as a "fixer" reagent. This application exploits thiosulfate ion's ability to dissolve silver halides. Sodium thiosulfate, commonly called hypo (from "hyposulfite"), was widely used in photography to fix black and white negatives and prints after the developing stage; modern "rapid" fixers use ammonium thiosulfate as a fixing salt because it acts three to four times faster.[4]
Thiosulfate salts have been used to extract or leach gold and silver from their ores as a less toxic alternative to cyanide ion.[2]
The enzyme rhodanase (thiosulfate sulfurtransferase) catalyzes the detoxification of cyanide ion by thiosulfate ion by transforming them into thiocyanate ion and sulfite ion:
CN− + S2O2−3 → SCN− + SO2−3
Sodium thiosulfate has been considered as an empirical treatment for cyanide poisoning, along with hydroxocobalamin. It is most effective in a pre-hospital setting, since immediate administration by emergency personnel is necessary to reverse rapid intracellular hypoxia caused by the inhibition of cellular respiration, at complex IV.[5][6][7][8]
Thiosulfate ion is a component of the very rare mineralsidpietersitePb4(S2O3)O2(OH)2.[13] The presence of this anion in the mineral bazhenovite was disputed.[14]
Thiosulfate is an acceptable common name and used almost always
The functional replacement IUPAC name is sulfurothioate; the systematic additive IUPAC name is trioxidosulfidosulfate(2−)ortrioxido-1κ3O-disulfate(S—S)(2−).[1]
^Sowerby, A. L. M., ed. (1961). Dictionary of Photography: A Reference Book for Amateur and Professional Photographers (19th ed.). London: Illife Books Ltd.[page needed]
^Hall, Alan H.; Dart, Richard; Bogdan, Gregory (2007). "Sodium Thiosulfate or Hydroxocobalamin for the Empiric Treatment of Cyanide Poisoning?". Annals of Emergency Medicine. 49 (6): 806–13. doi:10.1016/j.annemergmed.2006.09.021. PMID17098327.
^Miles, Bryant (February 24, 2003). "Inhibitors & Uncouplers"(PDF). Texas A&M University. Archived from the original(PDF) on 4 March 2016. Retrieved 25 November 2015.
^Stylianou, I. M.; et al. (2005). "Microarray gene expression analysis of the Fob3b obesity QTL identifies positional candidate gene Sqle and perturbed cholesterol and glycolysis pathways". Physiological Genomics. 20 (3): 224–232. CiteSeerX10.1.1.520.5898. doi:10.1152/physiolgenomics.00183.2004. PMID15598878.
^handbookofmineralogy.org, Mineral Handbook, citing Roberts, A.C.; Cooper, M.A.; Hawthorne, F.C.; Stanley, C.J.; Key, C.L.; Jambor, J.L. (1999). "Sidpietersite, Pb4(S6+O3S2-)O2(OH)2, a new thiosulfate-bearing mineral species from Tsumeh, Namibia". The Canadian Mineralogist. 37: 1269-1273. and Cooper, M.A.; Hawthorne, F.C. (1999). "The structure and topology of sidpietersite,Pb4(S6+O3S2-)O2(OH)2". The Canadian Mineralogist. 37: 1275-1283.
