Chemistry:Fluorotelomer alcohol

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8:2 fluorotelomer alcohol (8:2 FTOH)

Fluorotelomer alcohols, or FTOHs, are fluorotelomers with an alcohol functional group. They are volatile precursors to perfluorinated carboxylic acids, such as PFOA and PFNA, and other compounds.

Naming

Commonly, an individual fluorotelomer alcohol molecule is named by the number of carbons that are fluorinated versus the number that are hydrocarbon-based. For example, 8:2 fluorotelomer alcohol would represent a molecule with 8 fluorinated carbons and a 2 carbon ethyl alcohol group. The structure of a fluorotelomer alcohol is most commonly F(CF2)nCH2CH2OH, where n is an even number.

Chemistry

The synthesis of fluorotelomer alcohols requires a varying number of tetrafluoroethylene monomers that form an oligomer with a pentafluoroethyl iodide telogen. The fluorinated iodide then undergoes an addition with ethylene to form an organoiodine compound with increased synthesis possibilities.[1] The terminal iodine is replaced by a hydroxyl group to yield the fluorotelomer alcohol. The fluorotelomer alcohol can then be used to produce acrylate polymers with the fluorotelomer alcohols attached via ester functional groups.[2]

Environmental and health concerns

Fluorotelomer alcohols are volatile and widely detected in air.[3][4]

Acrylate polymers with fluorotelomer substituents are under investigation for their potential to degrade into environmental contaminants."[2] The USEPA has carried out environmental degradation studies with two DuPont acrylate polymers in four soils and water.[5][6] These studies reported environmental degradation half-life ranges for these commercial fluorotelomer-based polymers of 33 to 112 years.[5][6] FTOHs can also be used as intermediates in the production of surfactants.[7]

Fluorotelomer alcohols can biodegrade to perfluorinated carboxylic acids, which persist in the environment and are found in the blood serum of populations and wildlife, such as the toxic PFOA and PFNA.[8][9]

Aerobic biotransformation pathways of 8:2 FTOH in soil[10]

The fluorotelomer alcohols 6:2 FTOH and 8:2 FTOH have been found to be estrogenic.[11]

10:2 fluorotelomer alcohol (10:2 FTOH)

The atmospheric oxidation of fluorotelomer alcohols can also result in anthropogenic perfluorinated carboxylic acids.[12] In addition to perfluorinated carboxylic acids, fluorotelomer alcohols can degrade to form unsaturated carboxylic acids which have been detected in bottlenose dolphins.[13] Fluorotelomer alcohols such as 4:2 FTOH, 6:2 FTOH, 8:2 FTOH, and 10:2 FTOH, have been identified as residuals in consumer products such as stain repellents, Zonyl FSE, and windshield wash, among others.[14] The United States Environmental Protection Agency has asked eight chemical companies to reduce the amount of residuals, including fluorotelomer alcohols, from products.[14]

References

  1. ↑ Lehmler HJ (March 2005). "Synthesis of environmentally relevant fluorinated surfactants—a review". Chemosphere 58 (11): 1471–96. doi:10.1016/j.chemosphere.2004.11.078. PMID 15694468. Bibcode: 2005Chmsp..58.1471L. 
  2. ↑ 2.0 2.1 Renner, Rebecca (February 2008). "Do perfluoropolymers biodegrade into PFOA?". Environ. Sci. Technol. 42 (3): 648–50. doi:10.1021/es087093l. PMID 18323078. Bibcode: 2008EnST...42..648R. 
  3. ↑ "Current levels of airborne polyfluorinated telomers in Japan". Chemosphere 73 (6): 932–7. October 2008. doi:10.1016/j.chemosphere.2008.06.069. PMID 18701130. Bibcode: 2008Chmsp..73..932O. 
  4. ↑ "Semivolatile fluorinated organic compounds in Asian and western U.S. air masses". Environ. Sci. Technol. 41 (24): 8248–55. December 2007. doi:10.1021/es0713678. PMID 18200847. Bibcode: 2007EnST...41.8248P. 
  5. ↑ 5.0 5.1 Washington, John W.; Jenkins, Thomas M.; Rankin, Keegan; Naile, Jonathan E. (2015-01-20). "Decades-Scale Degradation of Commercial, Side-Chain, Fluorotelomer-Based Polymers in Soils and Water" (in en). Environmental Science & Technology 49 (2): 915–923. doi:10.1021/es504347u. ISSN 0013-936X. https://pubs.acs.org/doi/10.1021/es504347u. 
  6. ↑ 6.0 6.1 Washington, John W.; Jenkins, Thomas M. (2015-12-15). "Abiotic Hydrolysis of Fluorotelomer-Based Polymers as a Source of Perfluorocarboxylates at the Global Scale" (in en). Environmental Science & Technology 49 (24): 14129–14135. doi:10.1021/acs.est.5b03686. ISSN 0013-936X. PMID 26526296. https://pubs.acs.org/doi/10.1021/acs.est.5b03686. 
  7. ↑ "Bioactivation of fluorotelomer alcohols in isolated rat hepatocytes". Chem. Biol. Interact. 177 (3): 196–203. February 2009. doi:10.1016/j.cbi.2008.11.001. PMID 19041856. 
  8. ↑ "Perfluorooctanoic acid and perfluorononanoic acid in fetal and neonatal mice following in utero exposure to 8-2 fluorotelomer alcohol". Toxicol. Sci. 95 (2): 452–61. February 2007. doi:10.1093/toxsci/kfl162. PMID 17093205. 
  9. ↑ "Immunotoxic effects of perfluorononanoic acid on BALB/c mice". Toxicol. Sci. 105 (2): 312–21. October 2008. doi:10.1093/toxsci/kfn127. PMID 18583369. 
  10. ↑ Zhang, Wenping; Pang, Shimei; Lin, Ziqiu; Mishra, Sandhya; Bhatt, Pankaj; Chen, Shaohua (2021). "Biotransformation of perfluoroalkyl acid precursors from various environmental systems: advances and perspectives" (in en). Environmental Pollution 272: 115908. doi:10.1016/j.envpol.2020.115908. https://linkinghub.elsevier.com/retrieve/pii/S0269749120365970. 
  11. ↑ "Estrogen-like properties of fluorotelomer alcohols as revealed by mcf-7 breast cancer cell proliferation". Environ. Health Perspect. 114 (1): 100–5. January 2006. doi:10.1289/ehp.8149. PMID 16393665. PMC 1332663. http://ehpnet1.niehs.nih.gov/members/2005/8149/8149.html. 
  12. ↑ "Atmospheric chemistry of 4:2 fluorotelomer alcohol (n-C4F9CH2CH2OH): products and mechanism of Cl atom initiated oxidation in the presence of NOx". J Phys Chem A 109 (9): 1849–56. March 2005. doi:10.1021/jp045672g. PMID 16833516. Bibcode: 2005JPCA..109.1849S. http://pubs.acs.org/doi/abs/10.1021/jp0493576. 
  13. ↑ "Polyfluoroalkyl compounds in free-ranging bottlenose dolphins (Tursiops truncatus) from the Gulf of Mexico and the Atlantic Ocean". Environ. Sci. Technol. 39 (17): 6591–8. September 2005. doi:10.1021/es0506556. PMID 16190216. Bibcode: 2005EnST...39.6591H. 
  14. ↑ 14.0 14.1 Renner R; Eichenseher, Tasha; Thrall, Lizz (March 2006). "Leftovers may explain perfluorinated compound puzzle". Environ. Sci. Technol. 40 (5): 1376–7. doi:10.1021/es0626436. PMID 16568742. Bibcode: 2006EnST...40.1376R. 



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