hydrogen thioperoxide
{{Chembox
| Name =
| ImageFileL1 = Hydrogen thioperoxide.png
| ImageFileR1 = Hydrogen-thioperoxide-3D-vdW.png
| IUPACName = Sulfenic acid
| SystematicName = Thioperoxol
| OtherNames = Sulfenic acid
oxadisulfane
Sulfur hydride hydroxide
Sulfonol
Sulfanol
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|Section1={{Chembox Identifiers
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| CASNo = 62607-44-7
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| ChEBI = 37858
| PubChem = 447587
| ChemSpiderID = 394637
| SMILES = OS
| StdInChI = 1S/H2OS/c1-2/h1-2H
| StdInChIKey = RVEZZJVBDQCTEF-UHFFFAOYSA-N
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| EINECS =
| Gmelin = 672
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| RTECS = WP4100000
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|Section2={{Chembox Properties
| BoilingPt =
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| Density = 1.249
| RefractIndex = 1.484
| H=2 | O=1 | S=1
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|Section8={{Chembox Related
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| OtherCompounds = {{unbulleted list|Hydrogen peroxide HOOH|Hydrogen disulfide HSSH|Hydroxylamine NH2OH|Sulfoxylic acid HOSOH|1-oxatrisulfane HSSOH|thiooxonium ylide H2OS{{cite journal|last1=Iraqi|first1=Muhammad|last2=Schwarz|first2=Helmut|title=Experimental evidence for the gas phase existence of HSOH (hydrogen thioperoxide) and SOH2 (thiooxonium ylide)|journal=Chemical Physics Letters|date=April 1994|volume=221|issue=5–6|pages=359–362|doi=10.1016/0009-2614(94)00293-2|bibcode=1994CPL...221..359I}}}}
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Hydrogen thioperoxide, also called oxadisulfane or sulfanol, is the chemical with the structure H–S–O–H. It can be considered as the simple sulfur-substituted analog of the common hydrogen peroxide (H–O–O–H) chemical, and as the simplest hydrogen chalcogenide containing more than one type of chalcogen. The chemical has been described as the "missing link" between hydrogen peroxide and hydrogen disulfide (H–S–S–H), though it is substantially less stable than either of the other two. It is the inorganic parent structure of the sulfenic acid class of organic compounds (R–S–O–H) and also the oxadisulfide linkage (R1–S–O–R2), where "R" is any organic structure. Sulfur is present in oxidation state 0.
Formation
Hydrogen thioperoxide has been synthesized in labs by photolysis of a mixture of ozone and hydrogen sulfide frozen in argon at 8 K{{cite journal |title= Matrix reactions of oxygen atoms with H2S molecules |first1= R.R. |last1= Smardzewski1 |first2= M.C. |last2= Lin |journal= J. Chem. Phys. |volume= 66 |pages= 3197–3204 |year= 1977 |issue= 7 |doi= 10.1063/1.434294 |bibcode= 1977JChPh..66.3197S }} and by pyrolysis of di-tert-butyl sulfoxide.{{cite journal |title= Gas-Phase Detection of HSOH: Synthesis by Flash Vacuum Pyrolysis of Di-tert-butyl Sulfoxide and Rotational-Torsional Spectrum |first1= G. |last1= Winnewisser |first2= F. |last2= Lewen |first3= S. |last3= Thorwirth |first4= M. |last4= Behnke |first5= J. |last5= Hahn |first6= J. |last6= Gauss |first7= E. |last7= Herbst |doi= 10.1002/chem.200305192 |journal= Chem. Eur. J. |volume= 9 |issue= 22 |pages= 5501–5510 |year= 2003 |pmid= 14639633 |bibcode= 2003CEJ.....9.5501W }}{{cite journal |title= Low-Pressure Pyrolysis of tBu2SO: Synthesis and IR Spectroscopic Detection of HSOH |first1= H. |last1= Beckers |first2= S. |last2= Esser |first3= T. |last3= Metzroth |first4= M. |last4= Behnke |first5= H. |last5= Willner |first6= J. |last6= Gauss |first7= J. |last7= Hahn |doi= 10.1002/chem.200500104 |journal= Chem. Eur. J. |volume= 12 |issue= 3 |pages= 832–844 |year= 2006 |pmid= 16240313 }}
Yet another synthesis is by an electric discharge through water and sulfur.
In the interstellar medium there is a hypothesis that hydrogen thioperoxide is formed in a reaction of sulfur monoxide with the trihydrogen cation, dihydrogen and an electron. Another possible route, is sulfur monoxide reacting with atomic hydrogen to form HOS and HSO which in turn can add another hydrogen atom. However this mechanism probably needs a dust grain to take away excess energy.Baum 70-73
Properties
Hydrogen thioperoxide molecules have a gauche conformation.{{cite journal |title= The Internal Rotation of Hydrogen Thioperoxide: Energy, Chemical Potential, and Hardness Profiles |first1= G.I. |last1= Cárdenas-Jirón |first2= J.R. |last2= Letelier |first3= A. |last3= Toro-Labbé |journal= J. Phys. Chem. A |year= 1998 |volume= 102 |issue= 40 |pages= 7864–7871 |doi= 10.1021/jp981841j |bibcode= 1998JPCA..102.7864C }} They are unsymmetrical, but have a low barrier to convert from left-hand to right-hand forms, so that the molecule can tunnel between the forms.{{cite book|last1=Baum|first1=Oliver|title=HSOH: An Elusive Species with Many Different Traits|date=2008|publisher=Cuvillier Verlag|isbn=9783867277907|url=https://www.uni-kassel.de/fb10/fileadmin/datas/fb10/physik/laborastrophysik/Dokumente/Paper_TGi/Dissertation_Baum_Oliver_2008.pdf|language=en|pages=1–2|access-date=2017-03-11|archive-date=2017-03-12|archive-url=https://web.archive.org/web/20170312060711/https://www.uni-kassel.de/fb10/fileadmin/datas/fb10/physik/laborastrophysik/Dokumente/Paper_TGi/Dissertation_Baum_Oliver_2008.pdf|url-status=dead}}
The measurements of the bond-lengths in hydrogen thioperoxide are H–S 1.3420 Å, S–O 1.6616 Å, O–H 0.9606 Å. The bond angles are H–S–O 98.57°, S–O–H 107.19°. The H–S and O–H bonds are twisted at 90.41°.Baum 84
The half-life of hydrogen thioperoxide in water is 40 minutes, much longer than the expected half-life of less than seconds for a sulfenic acid.{{cite journal | last=Kumar | first=Murugaeson R. | last2=Farmer | first2=Patrick J. | title=Chemical trapping and characterization of small oxoacids of sulfur (SOS) generated in aqueous oxidations of H2S | journal=Redox Biology | volume=14 | date=2018 | pmid=29096321 | pmc=5680521 | doi=10.1016/j.redox.2017.10.012 | pages=485–491}}
Reactions
Two molecules of hydrogen thioperoxide can undergo cyclocondensation to form sulfinothioic acid HS(=O)SH and water.{{cite journal|last1=Freeman|first1=Fillmore|last2=Bui|first2=An|last3=Dinh|first3=Lauren|last4=Hehre|first4=Warren J.|title=Dehydrative Cyclocondensation Mechanisms of Hydrogen Thioperoxide and of Alkanesulfenic Acids|journal=The Journal of Physical Chemistry A|date=2 August 2012|volume=116|issue=30|pages=8031–8039|doi=10.1021/jp3024827|pmid=22724673|bibcode=2012JPCA..116.8031F}}
Hydrosulfide {{chem2|HS−}} can react with HSOH to yield disulfane HSSH.{{cite book|last1=Kolloru|first1=Gopi K.|title=Hydrogen Sulfide in Redox Biology|date=25 February 2015|publisher=Academic Press|isbn=9780128016237|page=274|url=https://books.google.com/books?id=xO6cBAAAQBAJ&pg=PA274|language=en}}
References
{{reflist}}
{{hydrogen compounds}}
{{Sulfur compounds}}