![Pentafluorophenol](https://upload.wikimedia.org/wikipedia/commons/5/52/Pentafluorophenol.svg)
A perfluorinated compound (PFC) or perfluoro compound is an
organofluorine compound containing only
carbon-fluorines and C−C bonds, as well as potentially
heteroatom
In chemistry, a heteroatom () is, strictly, any atom that is not carbon or hydrogen.
Organic chemistry
In practice, the term is usually used more specifically to indicate that non-carbon atoms have replaced carbon in the backbone of the molecula ...
s. Perfluorinated compounds have properties that result from the presence of
fluorocarbon
Fluorocarbons are chemical compounds with carbon-fluorine bonds. Compounds that contain many C-F bonds often has distinctive properties, e.g., enhanced stability, volatility, and hydrophobicity. Fluorocarbons and their derivatives are commerci ...
s (containing only C−F and C−C bonds) and any
functional group
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...
. Common functional groups in PFCs are
OH,
CO2H,
chlorine
Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
,
O, and
SO3H.
Electrofluorination is the predominant method of production.
Some of these compounds known as
perfluoroalkanes can remain in our atmosphere for a long time. They
bioaccumulate
Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
due to their chemical stability. Because of their potential contribution to
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, they were regulated under the Kyoto Protocol. Some fluorosurfactants have proven toxic in animal testing while widespread industrial applications continue.
Applications
Perfluorinated compounds are used ubiquitously: For example, fluorosurfactants are widely used in the production of
teflon
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemou ...
(PTFE) and related fluorinated polymers. They confer
hydrophobicity
In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water.
Hydrophobic molecules tend to be nonpolar and, th ...
and stain-resistance to fabrics. They are components of
fire-fighting foam
Firefighting foam is a foam used for fire suppression. Its role is to cool the fire and to coat the fuel, preventing its contact with oxygen, thus achieving suppression of the combustion. Firefighting foam was invented by the Russian engineer and ...
.
Fluorosurfactant
Per- and polyfluoroalkyl substances (PFASs) are synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain. An early definition, from 2011, required that they contain at least one perfluoroalkyl mo ...
s (PFAS) reduce
surface tension
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to f ...
by concentrating at the liquid-air interface due to the ''lipo''phobicity of polyfluorocarbons.
Chlorofluorocarbons
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propan ...
are perfluorinated compounds that were formerly used as refrigerants (
Freon
Freon ( ) is a registered trademark of the Chemours Company and generic descriptor for a number of halocarbon products. They are stable, nonflammable, low toxicity gases or liquids which have generally been used as refrigerants and as aerosol prop ...
) until they were implicated in
ozone degradation.
Production
A common industrial method for synthesizing perflurocompounds is
electrofluorination.
Examples by functional group
Perfluorinated alkyl halides
*
Trifluoroiodomethane
Trifluoroiodomethane, also referred to as trifluoromethyl iodide is a halomethane with the formula CF3I. It is an experimental alternative to Halon 1301 (CBrF3) in unoccupied areas. It would be used as a gaseous fire suppression flooding agent ...
, an
alkylating
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting ...
agent.
*
Pentafluoroethyl iodide
Pentafluoroethyl iodide is a suggested component of a fire-extinguishing composition.US patent application 20010048094
Production
Pentafluoroethyl iodide can be produced by electrochemical fluorination of 1,1,2,2-tetrafluoro-1,2-diiodoethane.
: ...
, an alkylating agent.
*
Perfluorooctyl bromide
Perflubron ( INN/USAN, or perfluorooctyl bromide; brand name Imagent) is a contrast medium for magnetic resonance imaging, computer tomography and sonography. It was approved for this use in the United States by the Food and Drug Administration i ...
, or ''perflubron'', a
contrast medium
A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radio ...
for
magnetic resonance imaging
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio wave ...
(MRI),
computed tomography (CT) and
sonography
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, musc ...
; fluid used in
liquid breathing
Liquid breathing is a form of respiration in which a normally air-breathing organism breathes an oxygen-rich liquid (such as a perfluorocarbon), rather than breathing air.
By selecting a liquid that is capable of holding large amounts of oxy ...
.
*
Dichlorodifluoromethane, a refrigerant.
Perfluoroalkenes
*
Tetrafluoroethylene
Tetrafluoroethylene (TFE) is a fluorocarbon with the chemical formula C2 F4. It is the simplest perfluorinated alkene. This gaseous species is used primarily in the industrial preparation of fluoropolymers.
Properties
Tetrafluoroethylene is a ...
, precursor to
polytetrafluoroethylene
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemour ...
(PTFE).
*
Chlorotrifluoroethylene
Chlorotrifluoroethylene (CTFE) is a chlorofluorocarbon with chemical formula CFCl=CF2. It is commonly used as a refrigerant in cryogenic applications. CTFE has a carbon-carbon double bond and so can be polymerized to form polychlorotrifluoroethy ...
,
refrigerant
A refrigerant is a working fluid used in the heat pump and refrigeration cycle, refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Ref ...
and precursor to
polychlorotrifluoroethylene
Polychlorotrifluoroethylene (PCTFE or PTFCE) is a thermoplastic chlorofluoropolymer with the molecular formula , where ''n'' is the number of monomer units in the polymer molecule. It is similar to polytetrafluoroethene (PTFE), except that it is a ...
(PCTFE).
*
Dichlorodifluoroethylene
A dichlorodifluoroethylene (systematically named dichlorodifluoroethene) is one of three compounds with the chemical formula . Dichlorodifluoroethylenes are colourless gases, and are some of the simplest chlorodifluoroalkenes.
The structural iso ...
(three isomers).
Perfluoroethers and epoxides
*
Hexafluoropropylene oxide
Hexafluoropropylene oxide (HFPO) is an intermediate used in industrial organofluorine chemistry; specifically it is a monomer for fluoropolymers. This colourless gas is the epoxide of hexafluoropropylene, that is fluorinated analog of propylene ...
, precursor to perfluoromethyl vinyl ether (CF
2=CFOCF
3), the monomer precursor to
Krytox
Krytox is a registered trademark of The Chemours Company. It refers to a group of colourless synthetic lubricants (oils and greases) with a variety of applications. Invented by researchers at DuPont, Krytox oils are fluorocarbon ether polyme ...
, perfluorinated polyether used in special oils and greases.
Perfluoroalcohols
*
Pentafluorophenol
Pentafluorophenol is the organofluorine compound (specifically a fluoroalcohol) with the formula C6F5OH. This is the perfluorinated analogue of phenol. It is a white odorless solid that melts just above room temperature. With a pKa of 5.5, it is o ...
, a moderately strong acid.
Primary and secondary perfluorinated alcohols are unstable with respect to
dehydrofluorination
In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications.
Dehydrohalogenation from alkyl halid ...
.
Perfluoroamines
*
Perfluorotripentylamine
Perfluorotripentylamine is a perfluorocarbon. It is used as an electronics coolant, and has a high boiling point. It is colorless, odorless, and insoluble in water. Unlike ordinary amines, perfluoroamines are of low basicity. Perfluorinated ami ...
(and related derivatives) are found in
Fluorinert
Fluorinert is the trademarked brand name for the line of electronics coolant liquids sold commercially by 3M. As perfluorinated compounds (PFCs), all Fluorinert variants have an extremely high Global Warming Potential (GWP), so should be used wit ...
, electronic coolants.
Perfluoroketones
*
Hexafluoroacetone
Hexafluoroacetone (HFA) is a chemical compound with the formula (CF3)2CO. It is structurally similar to acetone; however, its reactivity is markedly different. It a colourless, hygroscopic, nonflammable, highly reactive gas characterized by a mus ...
, a building block in
organofluorine chemistry
Organofluorine chemistry describes the chemistry of the organofluorines, organic compounds that contain the carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from Lipophobicity, oil and hydrophobe, water repellents ...
.
Perfluorocarboxylic acids
*
Trifluoroacetic acid
Trifluoroacetic acid (TFA) is an organofluorine compound with the chemical formula CF3CO2H. It is a structural analogue of acetic acid with all three of the acetyl group's hydrogen atoms replaced by fluorine atoms and is a colorless liquid with ...
, a moderately strong acid useful in organic chemistry.
*
Heptafluorobutyric acid
Perfluorobutanoic acid (PFBA) is a perfluoroalkyl carboxylic acid with the formula C3F7CO2H. As the perfluorinated derivative of butyric acid, this colourless liquid is prepared by electrofluorination of the corresponding butyryl fluoride.{{ ...
, a moderately strong acid that is useful in organic and analytical chemistry.
*
Pentafluorobenzoic acid, a moderately strong acid of interest in research community.
*
Perfluorooctanoic acid
Perfluorooctanoic acid (PFOA; conjugate base perfluorooctanoate; also known colloquially as C8, for its 8 carbon chain structure) is a perfluorinated carboxylic acid produced and used worldwide as an industrial surfactant in chemical processes an ...
(PFOA),a
surfactant
Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming ...
used to make
fluoropolymer
A fluoropolymer is a fluorocarbon-based polymer with multiple carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases. The best known fluoropolymer is polytetrafluoroethylene under the brand name "Teflon ...
s such as
Teflon
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemou ...
.
*
Perfluorononanoic acid
Perfluorononanoic acid, or PFNA, is a synthetic perfluorinated carboxylic acid and fluorosurfactant that is also an environmental contaminant found in people and wildlife along with PFOS and PFOA.
Chemistry and properties
In acidic form it is a h ...
(PFNA), a surfactant in the
emulsion polymerization Emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomer, and surfactant. The most common type of emulsion polymerization is an oil-in-water emulsion, in which droplets of monomer ...
of fluoropolymers, like PFOA.
Perfluoronitriles and isonitriles
*
Trifluoromethylisocyanide
Trifluoromethylisocyanide is the chemical compound with the formula CF3NC. It is an isocyanide and a fluorocarbon. Polymerisation occurs even at temperatures below its boiling point of −80 °C. As a ligand in coordination chemistry, this ...
, the simplest perfluorinated isonitrile.
*Trifluoromethylacetonitrile, the simplest perfluorinated nitrile.
Perfluorosulfonic acids and related derivatives
*
Triflic acid
Triflic acid, the short name for trifluoromethanesulfonic acid, TFMS, TFSA, HOTf or TfOH, is a sulfonic acid with the chemical formula CF3SO3H. It is one of the strongest known acids. Triflic acid is mainly used in research as a catalyst for este ...
, a useful strong acid
*
perfluorobutanesulfonic acid
Perfluorobutanesulfonic acid (PFBS) is a chemical compound having a four-carbon fluorocarbon chain and a sulfonic acid functional group. It is stable and unreactive because of the strength of carbon–fluorine bonds. It can occur in the form of ...
(PFBS) used as a replacement for PFOS in
3M's reformulated
Scotchgard
Scotchgard is a 3M brand of products, a stain and durable water repellent applied to fabric, furniture, and carpets to protect them from stains. Scotchgard products typically rely on organofluorine chemicals as the main active ingredient along ...
.
*
perfluorobutane sulfonamide (FBSA), sulfonamide derivative of PFBS.
*
perfluorooctanesulfonyl fluoride
Perfluorooctanesulfonyl fluoride (POSF) is a synthetic perfluorinated compound with a sulfonyl fluoride functional group. It is used to make perfluorooctanesulfonic acid (PFOS) and PFOS-based compounds. These compounds have a variety of industria ...
(POSF), precursor to PFOS-based compounds.
*
perfluorooctanesulfonamide
Perfluorooctanesulfonamide (PFOSA) is a synthetic organofluorine compound. It is a fluorocarbon derivative and a perfluorinated compound, having an eight-carbon chain and a terminal sulfonamide functional group. PFOSA, a persistent organic pollut ...
(PFOSA), used in 3M's Scotchgard formulation.
*
perfluorooctanesulfonic acid
Perfluorooctanesulfonic acid (PFOS) (conjugate base perfluorooctanesulfonate) is a chemical compound having an eight-carbon fluorocarbon chain and a sulfonic acid functional group and thus a perfluorosulfonic acid. It is an anthropogenic (man-ma ...
(PFOS), used in the semiconductor industry, 3M's former Scotchgard formulation, and 3M's former fire-fighting foam mixture.
Perfluorinated aryl borates
*Na
6F5)4">(C6F5)4 salt of a
weakly coordinating anion
Anions that interact weakly with cations are termed non-coordinating anions, although a more accurate term is weakly coordinating anion. Non-coordinating anions are useful in studying the reactivity of electrophilic cations. They are commonly found ...
.
Environmental and health concerns
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
Low-boiling perfluoroalkanes are potent
greenhouse gases
A greenhouse gas (GHG or GhG) is a gas that absorbs and emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor (), carbon dioxide (), methane ...
, in part due to their very long atmospheric lifetime. The environmental concerns for perflurocompounds are similar to
chlorofluorocarbon
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and prop ...
s 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
The Kyoto Protocol was an international treaty which extended the 1992 United Nations Framework Convention on Climate Change (UNFCCC) that commits state parties to reduce greenhouse gas emissions, based on the scientific consensus that (part ...
.
Fluorosurfactants
The fluorocarbons
PFOA
Perfluorooctanoic acid (PFOA; conjugate base perfluorooctanoate; also known colloquially as C8, for its 8 carbon chain structure) is a perfluorinated carboxylic acid produced and used worldwide as an industrial surfactant in chemical processes a ...
(perfluorooctanoic acid) and
PFOS
Perfluorooctanesulfonic acid (PFOS) (conjugate base perfluorooctanesulfonate) is a chemical compound having an eight-carbon fluorocarbon chain and a sulfonic acid functional group and thus a perfluorosulfonic acid. It is an anthropogenic (man ...
(perfluorooctane sulfonate) have both been investigated by the EU and the
United States Environmental Protection Agency
The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...
(EPA) which regards them being harmful to the environment.
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. (Similar concerns followed for PFOA.)
Fluorosurfactants tend to
bioaccumulate
Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
, 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
Firefighting foam is a foam used for fire suppression. Its role is to cool the fire and to coat the fuel, preventing its contact with oxygen, thus achieving suppression of the combustion. Firefighting foam was invented by the Russian engineer and ...
.
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. data on the human health effects of PFOA were sparse.
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.
In 2015, PFCs were found in groundwater at
Naval Air Station Brunswick
Naval Air Station Brunswick , also known as NAS Brunswick, was a military airport located southeast of Brunswick, Maine, with a number of Navy-operated maritime patrol aircraft. As of November 28, 2009, the last aircraft ( P-3 Orions) left. The ...
, Maine and
Grissom Air Reserve Base
Grissom Air Reserve Base is a United States Air Force base, located about north of Kokomo in Cass and Miami counties in Indiana. The facility was established as a U.S. Navy installation, Naval Air Station Bunker Hill, in 1942 and was an active ...
, Indiana, and in well water at
Pease Air Force Base
Pease, in Middle English, was a noun referring to the vegetable pea; see that article for its etymology. The word survives into modern English in pease pudding.
Pease may also refer to:
People
* Pease family (Darlington), a prominent family in D ...
, 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.
A 2018 report to Congress indicated that "at least 126 drinking water systems on or near military bases" were contaminated with PFAS compounds.
A 2016 study found unsafe 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
Firefighting foam is a foam used for fire suppression. Its role is to cool the fire and to coat the fuel, preventing its contact with oxygen, thus achieving suppression of the combustion. Firefighting foam was invented by the Russian engineer and ...
was singled out as a major contributor.
Unsafe levels of toxic chemicals found in drinking water for 6 million Americans
Science X network, phys.org, August 9, 2016
See also
*Per- and polyfluoroalkyl substances
Per- and polyfluoroalkyl substances (PFASs) are synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain. An early definition, from 2011, required that they contain at least one perfluoroalkyl mo ...
*Fluorocarbons
Fluorocarbons are chemical compounds with carbon-fluorine bonds. Compounds that contain many C-F bonds often has distinctive properties, e.g., enhanced stability, volatility, and hydrophobicity. Fluorocarbons and their derivatives are commerci ...
References
External links
*
{{DEFAULTSORT:Perfluorinated Compounds