Type of organic chemical
Pentafluorophenol
, a perfluorinated compound.
A
perfluorinated compound
(
PFC
) or
perfluoro compound
is an
organofluorine compound
that lacks C-H bonds. Many perfluorinated compounds have properties that are quite different from their C-H containing analogues. Common functional groups in PFCs are
OH
,
CO
2
H
,
chlorine
,
O
, and
SO
3
H
.
Electrofluorination
is the predominant method for PFC production. Due to their chemical stability, some of these perfluorinated compounds
bioaccumulate
.
Applications
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]
One class of perfluorinated compounds, the fluorosurfactants, are widely used in the production of
teflon
(PTFE) and related fluorinated polymers. They also have been used to confer
hydrophobicity
and stain-resistance to fabrics. They are components of
fire-fighting foam
.
[1]
Fluorosurfactants
(PFAS) reduce
surface tension
by concentrating at the liquid-air interface due to the
lipo
phobicity of polyfluorocarbons.
Chlorofluorocarbons
are perfluorinated compounds that were formerly used as refrigerants (
Freon
) until they were implicated in
ozone degradation
.
Production
[
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]
A common industrial method for synthesizing perflurocompounds is
electrofluorination
.
Examples by functional group
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]
Perfluorinated alkyl halides
[
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]
Perfluoroalkenes
[
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]
Perfluoroethers and epoxides
[
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]
- Hexafluoropropylene oxide
, precursor to perfluoromethyl vinyl ether (CF
2
=CFOCF
3
), the monomer precursor to
Krytox
, perfluorinated polyether used in special oils and greases.
Perfluoroalcohols
[
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]
Primary and secondary perfluorinated alcohols are unstable with respect to
dehydrofluorination
.
Perfluoroamines
[
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]
Perfluoroketones
[
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]
Perfluorocarboxylic acids
[
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]
Perfluoronitriles and isonitriles
[
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]
- Trifluoromethylisocyanide
, the simplest perfluorinated isonitrile.
- Trifluoromethylacetonitrile, the simplest perfluorinated nitrile.
Perfluorosulfonic acids and related derivatives
[
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]
Perfluorinated aryl borates
[
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]
Environmental and health concerns
[
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]
Several environmental and health concerns surround the industrial production and use of perfluoroalkane compounds. The exceptional stability of perfluorinated compounds is desirable from the applications perspective is also a cause for environmental and health concerns.
Perfluoroalkanes
[
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]
Low-boiling perfluoroalkanes are potent
greenhouse gases
, in part due to their very long atmospheric lifetime. The environmental concerns for perflurocompounds are similar to
chlorofluorocarbons
and other
halogenated compounds
used as refrigerants and fire suppression materials. The history of use, environmental impact, and recommendations for use are included in the
Kyoto Protocol
.
Fluorosurfactants
[
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]
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.
[2]
Specifically, studies found that PFOS caused "unusual and serious effects in animal toxicity tests, that it was present around the world in humans and wildlife, and that it was highly persistent in the environment."
[3]
(Similar concerns followed for PFOA.)
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
.
[2]
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
[update]
data on the human health effects of PFOA were sparse.
[4]
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.
[5]
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.
[6]
A 2018 report to Congress indicated that "at least 126 drinking water systems on or near military bases" were contaminated with PFAS compounds.
[7]
[8]
A 2016 study found unsafe
[9]
levels of fluorosurfactants in 194 out of 4,864 water supplies in 33 U.S. states. Covering two-thirds of drinking water supplies in the United States, the study found thirteen states accounted for 75% of the detections. In order of frequency, these were: 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.
[10]
See also
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]
References
[
edit
]
- ^
Sedlak, Meg (October 2016).
"Profile - Perfluorooctane Sulfonate (PFOS)"
(PDF)
.
sfei.org
. San Francisco Estuary Institute
. Retrieved
2 November
2016
.
- ^
a
b
US Environmental Protection Agency.
"FAQ"
.
Perfluorooctanoic Acid (PFOA) and Fluorinated Telomers
. Retrieved
11 May
2011
.
- ^
Auer, Charles, Frank Kover, James Aidala, Marks Greenwood.
“Toxic Substances: A Half Century of Progress.”
EPA Alumni Association. March 2016.
- ^
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.
doi
:
10.1289/ehp.0901827
.
PMC
2920088
.
PMID
20423814
.
- ^
"Grissom officials: Well tests show no chemical pollution"
.
LIN Television Corporation
. Associated Press. 19 September 2015
. Retrieved
19 September
2015
.
- ^
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
- ^
Lustgarten, Abrahm (2018-06-20).
"Suppressed Study: The EPA Underestimated Dangers of Widespread Chemicals"
.
ProPublica
. Lisa Song, Talia Buford
. Retrieved
2018-06-23
.
- ^
Associated Press (2017-07-31).
"Air Force won't pay for towns' water contamination costs"
.
Air Force Times
. Retrieved
2018-06-23
.
- ^
Above the minimum reporting levels required by the EPA ? 70 parts per trillion (ng/L) for PFOS and PFOA
- ^
Unsafe levels of toxic chemicals found in drinking water for 6 million Americans
Science X network, phys.org, August 9, 2016
External links
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]