Perfluorinated compound

From Wikipedia, the free encyclopedia
  (Redirected from Perfluorinated compounds)
Jump to: navigation, search

A perfluorinated compound (PFC) per- or polyfluoroalkyl chemical is an organofluorine compound containing only carbon-fluorine bonds (no C-H bonds) and C-C bonds but also other heteroatoms. PFCs have properties that represent a blend of fluorocarbons (containing only C-F and C-C bonds) and the parent functionalized organic species. For example, perfluorooctanoic acid functions as a carboxylic acid but with strongly altered surfactant and hydrophobic characteristics.[1] Fluorosurfactants are ubiquitously used in teflon, water resistant textiles and fire-fighting foam.

Properties[edit]

A perfluorinated compound (PFC) is an organofluorine compound containing only carbon-fluorine bonds, C-C bonds and other heteroatoms (no C-H bonds). PFCs have properties that represent a blend of fluorocarbons (containing only C-F and C-C bonds) and the parent functionalized organic species.Fluorosurfactants powerfully reduce surface tension by concentrating at the liquid-air interface due to the lipophobicity of fluorocarbons. This is due to the polar functional group added to the fluorocarbon chain. Elements commonly incorporated into fluorocarbon based compounds include oxygen, such as in the carboxyl group present in some flourosurfactants, and chlorine, in chlorofluorocarbons, which were formerly used as refrigerants and are implicated in ozone degradation.

Applications[edit]

Perfluorinated compounds are used ubiquitously: For example, fluorosurfactants are widely used in the production of teflon and related fluorinated polymers. They have been used to confer hydrophobicity, stain-resistance to fabrics and as fire-fighting foam.[2]

Classes of PFCs by functional group[edit]

Representative members of this large family of compounds are listed below. Also numerous are compounds that contain many fluoride centers but also some hydrogen, e.g., trifluoroethanol.

Perfluorinated alkyl and aryl halides[edit]

Fluorochloroalkenes[edit]

Perfluoroethers and epoxides[edit]

Perfluoroalcohols[edit]

  • Pentafluorophenol, a moderately strong acid

Perfluorinated alcohols are unstable with respect to dehydrofluorination.

Perfluoroamines[edit]

Perfluoroketones[edit]

Perfluorocarboxylic acids[edit]

Perfluoronitriles and isonitriles[edit]

  • Trifluoromethylisocyanide, the simplest perfluorinated isonitrile.
  • Trifluoromethylacetonitrile, the simplest perfluorinated nitrile

Perfluorosulfonic acids and related derivatives[edit]

Perfluorinated aryl borates[edit]


Environmental and health concerns[edit]

While there are some natural fluorocarbons such as tetrafluoromethane, which has been reported in rocks,[3] the vast majority are man-made.

Low-boiling perfluoroalkanes are potent greenhouse gases, in part due to their very long atmospheric lifetime. Their use is covered by the Kyoto Protocol.

Fluorosurfactants[edit]

The fluorocarbons PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate) have both been investigated by the EU and the United States Environmental Protection Agency (EPA) which regards them being harmful to the environment.[4]

Fluorosurfactants tend to bioaccumulate, since they are extremely stable and can be stored in the bodies of humans and animals. Examples include PFOA and PFOS, frequently present in water resistant textiles and sprays conferring water resistant properties to textiles and fire-fighting foam.[4] Data from animal studies of PFOA indicate that it can cause several types of tumors and neonatal death and may have toxic effects on the immune, liver, and endocrine systems. As of 2010 data on the human health effects of PFOA were sparse.[5]

As of 2015, the U.S. Air Force had been testing 82 former and active US military installations for fluorosurfactants contained in fire fighting foam.[6] In 2015, PFCs were found in groundwater at Naval Air Station Brunswick, Maine and Grissom Air Reserve Base, Indiana, and in well water at Pease Air Force Base, New Hampshire, where 500 people including children had blood tests as part of a bio-monitoring plan through the state Department of Health and Human Services. The U.S. Department of Defense´s research programs have been trying to define nature and extent of PFAS contamination at U.S. military sites, especially in groundwater.[7]

A 2016 study covering 2/3 of drinking water supplies in the United States found unsafe levels of fluorosurfactants at the minimum reporting levels required by the EPA, the safety limit of 70 parts per trillion (ng/L) for PFOS and PFOA. In 194 out of 4,864 water supplies in 33 U.S. states. Thirteen states accounted for 75% of the detections, including, in order of frequency: California, New Jersey, North Carolina, Alabama, Florida, Pennsylvania, Ohio, New York, Georgia, Minnesota, Arizona, Massachusetts, and Illinois. Firefighting foam was singled out as a major contributor.[8]

See also[edit]

References[edit]

  1. ^ Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick "Fluorine Compounds, Organic" Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a11_349
  2. ^ Sedlak, Meg (October 2016). "Profile - Perfluorooctane Sulfonate (PFOS)" (PDF). sfei.org. San Francisco Estuary Institute. Retrieved 2 November 2016. 
  3. ^ Murphy CD, Schaffrath C, O'Hagan D.: "Fluorinated natural products: the biosynthesis of fluoroacetate and 4-fluorothreonine in Streptomyces cattleya" Chemosphere. 2003 Jul;52(2):455-61.
  4. ^ a b US Environmental Protection Agency. "FAQ". Perfluorooctanoic Acid (PFOA) and Fluorinated Telomers. Retrieved 11 May 2011. 
  5. ^ Steenland, Kyle; Fletcher, Tony; Savitz, David A. (2010). "Epidemiologic Evidence on the Health Effects of Perfluorooctanoic Acid (PFOA)". Environmental Health Perspectives. 118 (8): 1100–8. PMC 2920088Freely accessible. PMID 20423814. doi:10.1289/ehp.0901827. Retrieved 2011-05-11. 
  6. ^ Associated Press (19 September 2015). "Grissom officials: Well tests show no chemical pollution". LIN Television Corporation. Retrieved 19 September 2015. 
  7. ^ Strategic Environmental Research and Development Program (SERDP), Environmental Security Technology Certification Program (ESTCP) Per- and Polyfluoroalkyl Substances (PFASs): Analytical and Characterization Frontiers webinarslides, January 28, 2016
  8. ^ Unsafe levels of toxic chemicals found in drinking water for 6 million Americans Science X network, phys.org, August 9, 2016