Chemistry: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]
PFSA resins are specialty polymers consisting of a fluoropolymer backbone of polytetrafluoroethylene with a side chain of perfluorinated vinyl ether comonomer bearing sulfonic acid functional groups. The side chain may vary in length, which imparts different properties.[3] These polymers are used as membranes in fuel cells and water electrolyzers for example.[4] Chemical brand names include Nafion, Aquivion, and Fumapen.
Regulation
Perfluorooctanesulfonic acid was included in Annex B of the Stockholm Convention in 2009 and subsequently in the EU POPs Regulation.[5]
Perfluorohexanesulfonic acid was included in Annex A of the Stockholm Convention in 2022.[6]
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 |
See also
- Perfluoro(4-ethylcyclohexane)sulfonic acid, a cyclic analogue
Literature
- "3. Perfluoroalkane sulfonic (a) and sulfinic (b) acids" (in English), Fact Cards of Major Groups of Per- and Polyfluoroalkyl Substances (PFASs), OECD Environment, Health and Safety Publications 68 Series on Risk Management, 2022, pp. 31–41, https://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/cbc/mono(2022)1&doclanguage=en
References
- ↑ "Terminology | FluoroCouncil". https://fluorocouncil.com/fluorotechnology/terminology/.
- ↑ Bohannon, Meredith E; Narizzano, Allison M; Guigni, Blas A; East, Andrew G; Quinn, Michael J (2023). "Next-generation PFAS 6:2 fluorotelomer sulfonate reduces plaque formation in exposed white-footed mice" (in en). Toxicological Sciences 192 (1): 97–105. doi:10.1093/toxsci/kfad006.
- ↑ Zhou, Libo; Hao, Bonan; Zhang, Ming; Zhao, Yanxin; Xu, Shengjie; Zhang, Yongming (September 2025). "The impact of varying side-chain content on the macroscopic properties and microscopic structure of perfluorosulfonic acid ion exchange membranes". Materials Today Communications 48. doi:10.1016/j.mtcomm.2025.113290.
- ↑ Delfino, Samuele; Villa, Davide Carlo; Giannetti, Alice; Tomasino, Daniela Valeria; Oldani, Claudio; Storti, Giuseppe; Sponchioni, Mattia (January 2026). "Short Side‐Chain Perfluorosulfonic Acid Aquivion: From Production to Application". Macromolecular Materials and Engineering 311 (1). doi:10.1002/mame.202500262.
- ↑ Regulation (EU) 2019/1021 of the European Parliament and of the Council of 20 June 2019 on persistent organic pollutants
- ↑ "UN experts recommend elimination of additional hazardous chemicals to protect human health and the environment" (in en-GB). http://chm.pops.int/Implementation/PublicAwareness/PressReleases/POPRC15expertsrecommendeliminationofPFHxS/tabid/8153/Default.aspx.
 |  |
