Pyrosulfate

Chemical structure of the disulfate anion

In chemistry, disulfate or pyrosulfate is the anion with the molecular formula S2O72−. Disulfate is the IUPAC name. It has a dichromate-like structure and can be visualised as two corner-sharing SO4− tetrahedra, with a bridging oxygen atom. 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 SO3 + ROH → ROSO2−O−SO3H
ROSO2−O−SO3H → ROSO3H + SO3

Several million tons are produced annually.

See also

References

  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. 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. Bibcode:2005JSSCh.178.1697S. doi:10.1016/j.jssc.2005.03.022.
  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.