Perfluorocarbons

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Perfluorohexane , a perfluorocarbon
Different representations of perfluorodecalin

Perfluorocarbons ( PFC ), also known as perfluorinated hydrocarbons or fluorocarbons , are carbon compounds that are completely substituted by fluorine (i.e. they no longer contain hydrogen atoms). They belong to the fluorocarbons (PFCs; English hydrofluorocarbons , HFC ), fluorinated derivatives of hydrocarbons .

Simple carbon chains such as the perfluorinated octane derivative perfluorooctane (C 8 F 18 ) are just as common as complex, cyclic fluorocarbon compounds. The formally simplest representative is tetrafluoromethane .

Perfluorocarbons are to be distinguished from the perfluorinated and polyfluorinated chemicals , which are also abbreviated to PFC.

use

Perfluorocarbons are used as refrigerants and as insulation e.g. B. in transformers .

One of the most prominent representatives is polytetrafluoroethylene (PTFE), known worldwide under the trade name Teflon ® , a thermoplastic with a high melting point of over 300 ° C. It can hardly be attacked chemically and has many uses in household and technology.

PFCs are used for medical purposes in ophthalmology . Perfluorocarbons can also be used for liquid ventilation. Many perfluorocarbons have a low surface tension and, due to their high expansion coefficient, spread very easily on surfaces. Perfluorocarbons owe their use in ventilation to these properties and the great potential for transporting gases such as oxygen , carbon dioxide or nitrogen monoxide .

PFCs are sometimes used as doping agents because they carry oxygen in a similar way to red blood cells . They can be detected in doping tests, for example by gas chromatography .

Analytics

PFC, such as perfluorooctane , can be detected using mass spectrometry . For ionisation in this connection are plasma -based methods, such as the atmospheric-pressure chemical ionization (APCI) or the silent electric discharge (DBDI).

criticism

Due to their very long mean residence time in the atmosphere , all perfluorocarbons, similar to chlorofluorocarbons (CFCs), have very high global warming potentials . They can also be detected in human blood. In addition, they have now been measured in remote areas such as the Arctic and Antarctic and are considered to be climate-relevant.

Biologically, perfluorocarbons are inert, apart from important exceptions : an essential characteristic for biological harmlessness is the lack of property of perfluorocarbons to form radicals , but it is precisely this property that is characteristic of persistent substances and perfluorocarbons could sooner or later become the focus of the EU Chemicals regulation REACH fall. There is currently disagreement about whether and in what form incorporated perfluorocarbons are able to directly influence intra- and intercellular signaling pathways .

See also

Individual evidence

  1. ↑ A.D. McNaught, A. Wilkinson: fluorocarbons . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . 2nd Edition. Blackwell Scientific Publications, Oxford 1997, ISBN 0-9678550-9-8 , doi : 10.1351 / goldbook.F02459 (English, corrected version (XML; 2006–) by M. Nic, J. Jirat, B. Kosata; with updates by A. Jenkins - Version: 2.3.3).
  2. ↑ Günter K. Kriegelstein (Ed.): Glaukom 2005. A discussion forum. Springer, Berlin a. a. 2005, ISBN 3-540-29677-8 , p. 81.
  3. ↑ Sigrid Schäfer, Frank Kirsch, Gottfried Scheuermann, Rainer Wagner: Specialist care ventilation. 5th edition. Elsevier, Urban & Fischer, Munich a. a. 2009, ISBN 978-3-437-25183-2 , p. 238.
  4. ↑ Neal E. Flomenbaum, Lewis R. Goldfrank, Robert S. Hoffman, Mary Ann Howland, Neal A. Lewin (eds.): Goldfrank's Toxicologic Emergencies. 8th edition, McGraw-Hill, New York et al. a. 2006, ISBN 0-07-147914-7 , p. 691.
  5. ↑ Schütz et al .: Dielectric Barrier Discharge Ionization of Perfluorinated Compounds . In: Anal. Chem. Band 87 , no. 22 , 2015, p. 11415-11419 , doi : 10.1021 / acs.analchem.5b03538 .
  6. ↑ Gyr et al .: Mechanistic Understanding Leads to Increased Ionization Efficiency and Selectivity in Dielectric Barrier Discharge Ionization Mass Spectrometry: A Case Study with Perfluorinated Compounds . In: Anal. Chem. Band 87 , no. 22 , 2018, p. 11415-11419 , doi : 10.1021 / acs.analchem.7b04711 .
  7. ↑ Piers Forster, Venkatachalam Ramaswamy et al .: Changes in Atmospheric Constituents and in Radiative Forcing. In: Susan Solomon et al. (Ed.): Climate Change 2007. The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge u. a. 2007, ISBN 978-0-521-88009-1 , pp. 212-213, ( PDF; 7.67 MB) .
  8. ↑ Persistent pulmonary hypertension in the newborn. The “PFC Syndrome” at thieme-connect.com, accessed on November 23, 2018.
  9. ↑ The forgotten greenhouse gas. In: Bild der Wissenschaft , July 3, 2008. Retrieved June 2, 2012.

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