Perfluoroalkyl carboxylic acids

Trifluoroacetic acid is a widely employed acid, used for example in the synthesis of peptides. Its esters are useful in analytical chemistry.

Longer-chain perfluoroalkyl carboxylic acids, e.g. with five to nine carbons, are useful fluorosurfactants and emulsifiers used in the production of polytetrafluoroethylene (Teflon) and related fluoropolymers.

These compounds are typically prepared by electrochemical fluorination of the carboxylic acid fluorides followed by hydrolysis:

:C_nH_(2n+1)COF + (2n+1) HF → C_nF_(2n+1)COF + (2n+1) H₂

:C_nF_(2n+1)COF + H₂O → C_nF_(2n+1)CO₂H + HF

Long-chain PFCAs such as perfluorooctanoic acid (PFOA) are either banned or being under scrutiny because they are extremely persistent and bioaccumulative. Short-chain PFCAs (scPFCAs) are formed from atmospheric oxidation of fluorotelomer compounds and chlorofluorocarbon (CFC) replacements introduced as a result of the Montreal Protocol.{{cite web | vauthors = McGrath M | url = https://www.bbc.co.uk/news/science-environment-52663694 | title = Ozone layer: Concern grows over threat from replacement chemicals | work = BBC News | date = 14 May 2020|access-date=23 May 2024}}{{cite journal | vauthors = Pickard HM, Criscitiello AS, Persaud D, Spencer C, Muir DC, Lehnherr I, Sharp MJ, De Silva AO, Young CJ | display-authors = 6 | date = 28 May 2020| title = Ice Core Record of Persistent Short‐Chain Fluorinated Alkyl Acids: Evidence of the Impact From Global Environmental Regulations| journal = Geophysical Research Letters| volume = 47| issue = 10| doi = 10.1029/2020GL087535| doi-access = free }}

Side-chain fluorinated polymers (SCFPs), in which fluorotelomers are attached to a polymer backbone, may release fluorotelomer alcohols through hydrolysis. The latter are then degraded to PFCAs.{{Cite book |url=https://www.oecd.org/chemicalsafety/portal-perfluorinated-chemicals/synthesis-report-on-understanding-side-chain-fluorinated-polymers-and-their-life-cycle.pdf |title=Synthesis Report on Understanding Side-Chain Fluorinated Polymers and Their Life Cycle | series = OECD Series on Risk Management | volume = 73 |publisher=Environment, Health and Safety, Environment Directorate, OECD |year=2022}}{{cite journal | vauthors = Letcher RJ, Chu S, Smyth SA | title = Side-chain fluorinated polymer surfactants in biosolids from wastewater treatment plants | journal = Journal of Hazardous Materials | volume = 388 | pages = 122044 | date = April 2020 | pmid = 31955025 | doi = 10.1016/j.jhazmat.2020.122044 | s2cid = 210830499 }}{{cite journal | vauthors = Brendel S, Fetter É, Staude C, Vierke L, Biegel-Engler A | title = Short-chain perfluoroalkyl acids: environmental concerns and a regulatory strategy under REACH | journal = Environmental Sciences Europe | volume = 30 | issue = 1 | pages = 9 | date = 2018-02-27 | pmid = 29527446 | pmc = 5834591 | doi = 10.1186/s12302-018-0134-4 | doi-access = free }}

File:Urethane SCFP hydrolysis simplified.svg, PFHpA and PFBA).]]

• Per- and polyfluoroalkyl substances
• Surflon S-111

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• {{cite book |title=Fact Cards of Major Groups of Per- and Polyfluoroalkyl Substances (PFASs)|series=OECD Environment, Health and Safety Publications Series on Risk Management | volume = 68 |issue=ENV/CBC/MONO(2022)1 | pages = 16–32 | chapter = Chapter 2: Perfluoroalkyl carboxylic (a) and dicarboxylic (b) acids |date= January 2022 |language=English |url=https://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/cbc/mono(2022)1&doclanguage=en

| publisher = The Organisation for Economic Co-operation and Development (OECD) }}

• {{cite web | vauthors = Guo Z, Liu X, Krebs KA, Roache NF | title = Perfluorocarboxylic acid content in 116 articles of commerce. | location = Research Triangle Park, NC | publisher = US Environmental Protection Agency | date = March 2009 | url = http://chm.pops.int/Portals/0/download.aspx?d=UNEP-POPS-NIP-GUID-ArticlePaperPFOSInv-3.En.Pdf }}

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