Sulfur oxoacid

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The sulfur oxoacids are chemical compounds that contain sulfur, oxygen and hydrogen. The best known and most important industrially is sulfuric acid. Sulfur has a number of oxoacids; however, some of these are known only from their salts (these are shown in italics in the table below). The acids that have been characterised contain a variety of structural features, for example:

  • tetrahedral sulfur when coordinated to oxygen
  • terminal and bridging oxygen atoms
  • terminal peroxo groups
  • terminal S=S
  • chains of (-S-)n
Acid Formula Oxidation state(s) Structure Related anions Notes
Sulfuric acid H2SO4 VI Sulfate, SO42 and hydrogen sulfate commonly known as bisulfate, HSO4 Best known and industrially significant.
Polysulfuric acids including disulfuric acid or pyrosulfuric acid H2SO4.nSO3 VI Disulfate (commonly known as pyrosulfate), S2O72 and trisulfate, S3O102 Pure disulfuric acid melts at 36 °C.

Present in fuming sulfuric acid, oleum. Examples known for n=1,2.

Peroxymonosulfuric acid H2SO5 VI Peroxymonosulfate, OOSO32 "Caro's acid", a solid melting at 45 °C
Peroxydisulfuric acid H2S2O8 VI Peroxydisulfate, O3SOOSO32 A solid melting at 65 °C.
Dithionic acid H2S2O6 V Dithionate, O3SSO32 Not isolated in pure form, only concentrated solutions have been prepared
Thiosulfuric acid H2S2O3 0 (for the terminal S atom), IV (for the central S atom) Thiosulfate, S2O32
Hydrogenthiosulfate HS2O3 (ammonium salt prepared in anhydrous methanol at −80 °C[1])
Aqueous solutions decompose.
Disulfurous acid or pyrosulfurous acid H2S2O5 IV Disulfite commonly known as metabisulfite, S2O52 Not known.
Sulfurous acid H2SO3 IV Bisulfite, HSO3 and sulfite, SO32 Not known.
Dithionous acid H2S2O4 III Dithionite, O2SSO22 Not known.
Polythionic acids H2SxO6 0 (for the bridging S atoms), V (for the terminal central S atoms) Polythionates, O3S(Sx-2)SO32. Example trithionate, tetrathionate, pentathionate, hexathionate, heptathionate, octathionate, nonathionate, decathionate, undecathionate, dodecathionate, tridecathionate and tetradecathionate. Examples known with x= 3, 4, 5, 6, 7, 8, 10, 12, 14.
Thiosulfurous acid H2S2O2 I Thiosulfites Not known

References

  1. Raman spectroscopic discovery of the hydrogenthiosulphate anion, HSSO3, in solid NH4HS2O3 Steudel Rr.; Prenzel A Zeitschrift für Naturforschung 1989,44, 12, 1499-1502

See also

External links

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