Perfluorosulfonic acids

Perfluorosulfonic acids (PFSAs) are chemical compounds of the formula CnF(2n+1)SO3H and thus belong to the family of perfluorinated and polyfluorinated alkyl compounds (PFASs). The simplest example of a perfluorosulfonic acid is the trifluoromethanesulfonic acid. Perfluorosulfonic acids with six or more perfluorinated carbon atoms, i.e. from perfluorohexanesulfonic acid onwards, are referred to as long-chain.[1]

Properties

Perfluorosulfonic acids are organofluoroanalogues of conventional alkanesulfonic acids, but they are several pKA units stronger (and are therefore strong acids). Their perfluoroalkyl chain has a highly hydrophobic character.

Use

Perfluorooctanesulfonic acid, for example, has been used in hard chromium plating. Since the early 2000's 6:2-Fluorotelomersulfonic acid has been used as a replacement for Perfluorooctanesulfonic acid.[2]

Regulation

Perfluorooctanesulfonic acid was included in Annex B of the Stockholm Convention in 2009 and subsequently in the EU POPs Regulation.[3]

Perfluorohexanesulfonic acid including its salts and related compounds was proposed for inclusion in the Stockholm Convention.[4]

Examples

Name Abbreviation Structural formula Molecular weight (g/mol) CAS No.
Perfluoropropanesulfonic acid PFPrS C3F7SO3H 250.09 423-41-6
Perfluorobutanesulfonic acid PFBS C4F9SO3H 300.10 375-73-5
Perfluoropentanesulfonic acid PFPS C5F11SO3H 350.11 2706-91-4
Perfluorohexanesulfonic acid PFHxS C6F13SO3H 400.12 355-46-4
Perfluoroheptanesulfonic acid PFHpS C7F15SO3H 450.12 375-92-8
Perfluorooctanesulfonic acid PFOS C8F17SO3H 500.13 1763-23-1
Perfluorononanesulfonic acid PFNS C9F19SO3H 550.14 68259-12-1
Perfluorodecanesulfonic acid PFDS C10F21SO3H 600.15 335-77-3

Literature

  • OECD, ed. (2022), "3. Perfluoroalkane sulfonic (a) and sulfinic (b) acids", Fact Cards of Major Groups of Per- and Polyfluoroalkyl Substances (PFASs), OECD Environment, Health and Safety Publications 68 Series on Risk Management, pp. 31–41

References

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