Thiosulfurous acid

Thiosulfurous acid
Names
	IUPAC names sulfurothious S-acid; sulfurothious O,S-acid
	Systematic IUPAC name hydroxidooxidosulfanidosulfur
	Other names sulfurothionous acid ; Thiothionyl hydroxide (minor tautomer)
Identifiers
CAS Number	15060-43-2;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:35926;
ChemSpider	7827575;
Gmelin Reference	184467
PubChem CID	9548652;
CompTox Dashboard (EPA)	DTXSID401045691 ;
	InChI InChI=1S/H2O2S2/c1-4(2)3/h(H2,1,2,3) Key: QAMMXRHDATVZSO-UHFFFAOYSA-N;
	SMILES OS(S)=O;
Properties
Chemical formula	H2S2O2
Molar mass	98.14668
Conjugate base	Thiosulfite
Related compounds
Related compounds	thiosulfuric acid; SSO; thiosulfinic acid
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Thiosulfurous acid is a hypothetical chemical compound with the formula HS−S(=O)−OH or HO−S(=S)−OH. Attempted synthesis leads to polymers.^[3] It is a low oxidation state (+1) sulfur acid.^[4] It is the Arrhenius acid for disulfur monoxide. Salts derived from thiosulfurous acid, which are also unknown, are named "thiosulfites", "thionosulfites" or "sulfurothioites". The ion is S=SO²⁻
₂.

Structures

Other possible isomers are dihydroxydisulfane or hypodithionous acid HOSSOH, a linear chain, and thiothionyl hydroxide (S=S(OH)₂) a tautomer where the hydrogen has moved from a sulfur to an oxygen.^[5] HOSSOH can have two different rotamers with symmetry C₁ and C₂. The isomer with one hydrogen on sulfur and one on oxygen is the most stable according to calculations.^[6]

Dithiosulfurous acid

The sulfur analog of thiosulfuric acid (HS−S(=O)₂−OH), in which two sulfur atoms branch off of the central sulfur atom of a linear dihydrogen trisulfide structure (tetrathiosulfuric acid, (S=)₂S(−SH)₂ or (⁻S−)₂S²⁺(−SH)₂) has also been computationally studied.^[7]

Reactions

It apparently decomposes to polysulfane oxide or polythionic acids in water, which is termed Wakenroder's liquid.^[5]

In alkaline conditions thiosulfurous acid rapidly deteriorates forming a mixture of sulfide, sulfur, sulfite, and thiosulfate. In acidic conditions it will form hydrogen sulfide and sulfur dioxide as well. Some of these react to form pentathionate and other polythionates. Thiosulfurous acid reacts with sulfurous acid to give tetrathionate, and with thiosulfuric acid to make hexathionate.^[8]

Esters

Four isomers are possible for R₂S₂O₂, at least restricting sulfur to di- and tetravalency: (RO)₂S=S, ROSSOR, RS(O)₂SR, and RS(O)SOR. For the first two, the R groups are equivalent, and in the latter two they are nonequivalent. A simple example is diethylthiosulfite, (EtO)₂S=S. It is also known as diethylthionosulfite. It is a stereochemically rigid on the NMR timescale to about 140 °C, somewhat similar to diethylsulfoxide. Many derivatives have been prepared from glycols. From meso-hydrobenzoin (PhCH(OH)−CH(OH)Ph), one obtains two isomers; a third isomer results from d,l-PhCH(OH)−CH(OH)Ph.^[9]^[10]

The reaction with simple alkoxide sources with disulfur dichloride gives the unbranched ROSSOR. They are immiscible in water, but dissolve in benzene or carbon tetrachloride.^[8] These species are less rigid than the thiosulfite esters.

References

^ ^a ^b International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. p. 139. Electronic version.
^ ACD Chemsketch Name Free
^ Schmidt, Heinar; Ralf Steudel; Detlev Suelzle; Helmut Schwarz (1992). "Sulfur compounds. 148. Generation and characterization of dihydroxy disulfide, HOSSOH: the chainlike isomer of thiosulfurous acid". Inorganic Chemistry. 31 (6): 941–944. doi:10.1021/ic00032a004. ISSN 0020-1669.
^ +1 is the average oxidation state of the two structurally different sulfur atoms. The exterior atom has an oxidation number of −1 while the central sulfur atom has the oxidation state of +3.
^ ^a ^b Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry. Academic Press. p. 552. ISBN 9780123526519. Retrieved 3 November 2013.
^ Miaskiewicz, Karol; Ralf Steudel (1991). "Sulphur compounds. Part 140. Structures and relative stabilities of seven isomeric forms of H2S2O2". Journal of the Chemical Society, Dalton Transactions (9): 2395. doi:10.1039/DT9910002395. ISSN 0300-9246.
^ Nishimoto, Akiko; Zhang, Daisy Y. (2003). "Hypervalency in sulfur? Ab initio and DFT studies of the structures of thiosulfate and related sulfur oxyanions". Sulfur Letters. 26 (5/6): 171–180. doi:10.1080/02786110310001622767. S2CID 95470892.
^ ^a ^b Nair, C. G. Ramachandran; A. R. Vasudeva Murthy (19 June 1961). "Hydrolytic Reactions of Esters and Amides of Thiosulfurous Acid" (PDF). Proceedings of the Indian Academy of Sciences. 56 (3). Bangalore: 130–140. doi:10.1007/BF03045863. S2CID 35057986.
^ Eli Zysman-Colman David N. Harpp "Dialkoxy Disulfides And Their Branch-bonded Thionosulfite Isomers" J. Sulfur Chemistry 2004, vol. 25, pp. 155–182. doi:10.1080/1741599342000202176
^ Zysman-Colman, Eli; Charles B. Abrams; David N. Harpp (2003). "Synthesis of New Cyclic Thionosulfites". The Journal of Organic Chemistry. 68 (18): 7059–7062. doi:10.1021/jo0346306. ISSN 0022-3263. PMID 12946149.

[redbookname-1] International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. p. 139. Electronic version.

[2] ACD Chemsketch Name Free

[Schmidt1992-3] Schmidt, Heinar; Ralf Steudel; Detlev Suelzle; Helmut Schwarz (1992). "Sulfur compounds. 148. Generation and characterization of dihydroxy disulfide, HOSSOH: the chainlike isomer of thiosulfurous acid". Inorganic Chemistry. 31 (6): 941–944. doi:10.1021/ic00032a004. ISSN 0020-1669.

[4] +1 is the average oxidation state of the two structurally different sulfur atoms. The exterior atom has an oxidation number of −1 while the central sulfur atom has the oxidation state of +3.

[WibergWiberg2001-5] Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry. Academic Press. p. 552. ISBN 9780123526519. Retrieved 3 November 2013.

[Miaskiewicz1991-6] Miaskiewicz, Karol; Ralf Steudel (1991). "Sulphur compounds. Part 140. Structures and relative stabilities of seven isomeric forms of H2S2O2". Journal of the Chemical Society, Dalton Transactions (9): 2395. doi:10.1039/DT9910002395. ISSN 0300-9246.

[7] Nishimoto, Akiko; Zhang, Daisy Y. (2003). "Hypervalency in sulfur? Ab initio and DFT studies of the structures of thiosulfate and related sulfur oxyanions". Sulfur Letters. 26 (5/6): 171–180. doi:10.1080/02786110310001622767. S2CID 95470892.

[Nair-8] Nair, C. G. Ramachandran; A. R. Vasudeva Murthy (19 June 1961). "Hydrolytic Reactions of Esters and Amides of Thiosulfurous Acid" (PDF). Proceedings of the Indian Academy of Sciences. 56 (3). Bangalore: 130–140. doi:10.1007/BF03045863. S2CID 35057986.

[9] Eli Zysman-Colman David N. Harpp "Dialkoxy Disulfides And Their Branch-bonded Thionosulfite Isomers" J. Sulfur Chemistry 2004, vol. 25, pp. 155–182. doi:10.1080/1741599342000202176

[Zysman-Colman2003-10] Zysman-Colman, Eli; Charles B. Abrams; David N. Harpp (2003). "Synthesis of New Cyclic Thionosulfites". The Journal of Organic Chemistry. 68 (18): 7059–7062. doi:10.1021/jo0346306. ISSN 0022-3263. PMID 12946149.

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