Chemistry:Pyrosulfate

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In chemistry, disulfate or pyrosulfate is the anion with the molecular formula S2O2−7. Disulfate is the IUPAC name. [1] It has a dichromate-like structure and can be visualised as two corner-sharing SO4 tetrahedra, with a bridging oxygen atom.[2] In this anion, sulfur has an oxidation state of +6. Disulfate is the conjugate base of the hydrogen disulfate (hydrogen pyrosulfate) ion HS2O7, which in turn is the conjugate base of disulfuric acid (pyrosulfuric acid).

Role in sulfation

Industrial production of sulfate ester-based surfactants involves the reaction (sulfation) of fatty alcohols with sulfur trioxide. For example, dodecyl alcohol is sulfated using sulfur trioxide. The reaction proceeds by initial formation of the pyrosulfate:

2 SO
3
+ ROH → ROSO
2
–O–SO
3
H
ROSO
2
–O–SO
3
H → ROSO
3
H + SO
3

Several million tons are produced annually.[3]

See also

References

  1. International Union of Pure and Applied Chemistry (2005). Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSCIUPAC. ISBN 0-85404-438-8. p. 130. Electronic version.
  2. Ståhl, K.; Balic-Zunic, T.; da Silva, F.; Eriksen, K.M.; Berg, R.W.; Fehrmann, R. (October 2005). "The crystal structure determinations and refinements of K2S2O7, KNaS2O7 and Na2S2O7 from X-ray powder and single crystal diffraction data". Journal of Solid State Chemistry 178 (10): 1697–1704. doi:10.1016/j.jssc.2005.03.022. Bibcode2005JSSCh.178.1697S. 
  3. Holmberg, Krister (2019). "Surfactants". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–56. doi:10.1002/14356007.a25_747.pub2. ISBN 978-3-527-30673-2.