Perfluorooctanesulfonyl fluoride
Encyclopedia
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 industrial and consumer uses, but POSF-derived substances ultimately degrade to form PFOS.
Because of environmental concerns over PFOS, 3M
ceased POSF use in 2002 and global production plummeted. However, Chinese production grew after 3M's phaseout. As of May 2009, POSF and PFOS are listed as persistent organic pollutant
s (POPs) included in Annex B of the Stockholm Convention
.
(ECF). From 1966 to the 1990s, 3M production increased to meet demand for POSF-based compounds. In 1999, 3M reported POSF was its most highly produced fluorochemical. Before 2000, 3M was the largest global producer of POSF (mainly at their Decatur, AL
and Antwerp facilities) and global production peaked at ~4500 tonnes per year.
In 1999, the U.S. Environmental Protection Agency
began investigating perfluorinated compounds
after receiving data on the global distribution and toxicity of PFOS, the key ingredient in Scotchgard
. For these reasons, and USEPA pressure, the primary American producer of PFOS, 3M, announced, in May 2000, the phaseout of the production of PFOS, PFOA
, and PFOS-related products. 3M stated that they would have made the same decision regardless of USEPA pressure.
Immediately after the 2000–2002 3M phaseout, production plummeted, but dominant and growing production shifted to China. In 2004 Chinese production of PFOS-based compounds was estimated to be <50 tonne
s. In 2005 global production was estimated to be between 73–162 tonnes, and by 2006 Chinese production was estimated at >200 tonnes. Total historical global production was estimated at ~120,000 tonnes in 2009.
"[M]ost, if not all" industrially synthesized perfluorooctanesulfonyl derivatives, such as PFOS, have POSF as their precursor.
by (ECF) of octanesulfonyl fluoride in anhydrous
hydrogen fluoride
by the equation
:
This reaction
results in a 25% yield for POSF, less than that for shorter perfluorosulfonyl fluorides. The POSF obtained is impure as it is a mixture of linear and branched isomers, with ∼70% linear. POSF can also be obtained by ECF of the sulfonyl halide
octanesulfonyl chloride.
in water
, however, occurs slowly.
POSF reacts with base
s such as potassium hydroxide
to form PFOS salts:
Upon treatment with sulfuric acid
the sulfonic acid
PFOS tetrahydrate
is obtained.
POSF also reacts with ammonia
to form perfluorooctanesulfonamide
:
Sulfonamides and sulfonamidoethanols synthesized from POSF can in turn react to form a variety of different functional group
s for different applications and products.
s, POSF-derivatives have chemical properties that are hydrophobic ("water-afraid"), lipophobic ("fat-afraid"), and surface tension
lowering (as fluorosurfactants). The main uses of chemical substance
s derived from POSF have been:
The Stockholm Convention lists a variety of acceptable purposes and specific exemptions for POSF and PFOS (and it salts) including
(Annex B) in May 2009. As such, POSF is not "banned" but has approved uses and exemptions—along with a program (SC-4/19) in Annex B that encourages reduced production.
Perfluorinated compounds
A perfluorinated compound is an organofluorine compound with all hydrogens replaced by fluorine on a carbon chain—but the molecule also contains at least one different atom or functional group. Thus, PFCs have properties similar to fluorocarbons as they are fluorocarbon derivatives...
with a sulfonyl fluoride
Sulfonyl halide
Sulfonyl halide groups occur when a sulfonyl functional group is singly bonded to a halogen atom. They have the general formula R-SO2-X where X is a halogen.-Sulfonyl fluorides:...
functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
. It is used to make perfluorooctanesulfonic acid (PFOS) and PFOS-based compounds. These compounds have a variety of industrial and consumer uses, but POSF-derived substances ultimately degrade to form PFOS.
Because of environmental concerns over PFOS, 3M
3M
3M Company , formerly known as the Minnesota Mining and Manufacturing Company, is an American multinational conglomerate corporation based in Maplewood, Minnesota, United States....
ceased POSF use in 2002 and global production plummeted. However, Chinese production grew after 3M's phaseout. As of May 2009, POSF and PFOS are listed as persistent organic pollutant
Persistent organic pollutant
thumb|right|275px|State parties to the Stockholm Convention on Persistent Organic PollutantsPersistent organic pollutants are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes...
s (POPs) included in Annex B of the Stockholm Convention
Stockholm Convention on Persistent Organic Pollutants
Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty, signed in 2001 and effective from May 2004, that aims to eliminate or restrict the production and use of persistent organic pollutants .- History :...
.
Production
In 1949, 3M began producing POSF by electrochemical fluorinationElectrochemical fluorination
Electrochemical fluorination , or electrofluorination, is a foundational organofluorine chemistry method for the preparation of fluorocarbon-based organofluorine compounds. The general approach represents an application of electrosynthesis...
(ECF). From 1966 to the 1990s, 3M production increased to meet demand for POSF-based compounds. In 1999, 3M reported POSF was its most highly produced fluorochemical. Before 2000, 3M was the largest global producer of POSF (mainly at their Decatur, AL
Decatur, Alabama
Decatur is a city in Limestone and Morgan Counties in the U.S. state of Alabama. The city, affectionately known as "The River City", is located in Northern Alabama on the banks of Wheeler Lake, along the Tennessee River. It is the largest city and county seat of Morgan County...
and Antwerp facilities) and global production peaked at ~4500 tonnes per year.
In 1999, the U.S. Environmental Protection Agency
United States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
began investigating perfluorinated compounds
Perfluorinated compounds
A perfluorinated compound is an organofluorine compound with all hydrogens replaced by fluorine on a carbon chain—but the molecule also contains at least one different atom or functional group. Thus, PFCs have properties similar to fluorocarbons as they are fluorocarbon derivatives...
after receiving data on the global distribution and toxicity of PFOS, the key ingredient in Scotchgard
Scotchgard
Scotchgard is a 3M brand of products used to protect fabric, furniture, and carpets from stains.The original formula for Scotchgard was discovered accidentally in 1952 by 3M chemists Patsy Sherman and Samuel Smith...
. For these reasons, and USEPA pressure, the primary American producer of PFOS, 3M, announced, in May 2000, the phaseout of the production of PFOS, PFOA
Perfluorooctanoic acid
Perfluorooctanoic acid , also known as C8 and perfluorooctanoate, is a synthetic, stable perfluorinated carboxylic acid and fluorosurfactant. One industrial application is as a surfactant in the emulsion polymerization of fluoropolymers. It has been used in the manufacture of such prominent...
, and PFOS-related products. 3M stated that they would have made the same decision regardless of USEPA pressure.
Immediately after the 2000–2002 3M phaseout, production plummeted, but dominant and growing production shifted to China. In 2004 Chinese production of PFOS-based compounds was estimated to be <50 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
s. In 2005 global production was estimated to be between 73–162 tonnes, and by 2006 Chinese production was estimated at >200 tonnes. Total historical global production was estimated at ~120,000 tonnes in 2009.
"[M]ost, if not all" industrially synthesized perfluorooctanesulfonyl derivatives, such as PFOS, have POSF as their precursor.
Synthesis
POSF is synthesizedOrganic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
by (ECF) of octanesulfonyl fluoride in anhydrous
Anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...
hydrogen fluoride
Hydrogen fluoride
Hydrogen fluoride is a chemical compound with the formula HF. This colorless gas is the principal industrial source of fluorine, often in the aqueous form as hydrofluoric acid, and thus is the precursor to many important compounds including pharmaceuticals and polymers . HF is widely used in the...
by the equation
Chemical equation
A chemical equation is the symbolic representation of a chemical reaction where the reactant entities are given on the left hand side and the product entities on the right hand side. The coefficients next to the symbols and formulae of entities are the absolute values of the stoichiometric numbers...
:
- C8H17SO2F + 17 F– → C8F17SO2F + 17 H+ + 34 e–.
This reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
results in a 25% yield for POSF, less than that for shorter perfluorosulfonyl fluorides. The POSF obtained is impure as it is a mixture of linear and branched isomers, with ∼70% linear. POSF can also be obtained by ECF of the sulfonyl halide
Sulfonyl halide
Sulfonyl halide groups occur when a sulfonyl functional group is singly bonded to a halogen atom. They have the general formula R-SO2-X where X is a halogen.-Sulfonyl fluorides:...
octanesulfonyl chloride.
Reactivity
POSF and POSF-based polymers degrade to form PFOS which is not known to degrade by any environmental processes. POSF hydrolysisHydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
in water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
, however, occurs slowly.
POSF reacts with base
Base (chemistry)
For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...
s such as potassium hydroxide
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...
to form PFOS salts:
- C8F17SO2F + KOH → C8F17O2SO3–K+.
Upon treatment with sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
the sulfonic acid
Sulfonic acid
Sulfonic acid usually refers to a member of the class of organosulfur compounds with the general formula RS2–OH, where R is an alkyl or aryl. The formal part of acid, HS2–OH, are formally derivatives of the "parent" inorganic compound with the formula HSO2.-Preparation:Sulfonic acid is...
PFOS tetrahydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
is obtained.
POSF also reacts with ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
to form perfluorooctanesulfonamide
Perfluorooctanesulfonamide
Perfluorooctanesulfonamide is a synthetic organofluorine compound. It is a fluorocarbon derivative, or perfluorinated compound, with eight carbons and a terminal sulfonamide functional group. PFOSA was an ingredient in 3M's former Scotchgard formulation and the compound was used to repel grease...
:
- C8F17SO2F + NH3 → C8F17O2SNH2.
Sulfonamides and sulfonamidoethanols synthesized from POSF can in turn react to form a variety of different functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
s for different applications and products.
Uses
Because of multiple carbon–fluorine bondCarbon–fluorine bond
The carbon–fluorine bond is a bond between carbon and fluorine that is a component of all organofluorine compounds. It is the strongest single bond in organic chemistry—and relatively short—due to its partial ionic character. The bond also strengthens and shortens as more fluorines are...
s, POSF-derivatives have chemical properties that are hydrophobic ("water-afraid"), lipophobic ("fat-afraid"), and surface tension
Surface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
lowering (as fluorosurfactants). The main uses of chemical substance
Chemical substance
In chemistry, a chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e. without breaking chemical bonds. They can be solids, liquids or gases.Chemical substances are...
s derived from POSF have been:
- as stain and soil repellents for carpet;
- as water repellents for clothing;
- as fat and oil repellents in food packagingFood packagingFood packaging is packaging for food. It requires protection, tampering resistance, and special physical, chemical, or biological needs. It also shows the product that is labeled to show any nutrition information on the food being consumed....
; - an specialty applications such as semiconductorSemiconductorA semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
manufacturing and hydraulic fluidHydraulic fluidHydraulic fluids, also called hydraulic liquids, are the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water...
s for airplanes; and - in aqueous film forming foam (fire fighting foam) as fluorosurfactants.
The Stockholm Convention lists a variety of acceptable purposes and specific exemptions for POSF and PFOS (and it salts) including
- photo-imaging;
- photo-resist and anti-reflective coatings for semiconductors;
- etching agent for compound semiconductors and ceramicCeramicA ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
filters; - aviation hydraulic fluids;
- metal plating (hard metal plating) only in closed-loop systems;
- certain medical devices (such as ethylene tetrafluoroethylene copolymer (ETFE) layers and radio-opaque ETFE production, in-vitro diagnostic medical devices, and CCD colour filters);
- fire fighting foam;
- insect baits for control of leaf-cutting ants from AttaAttaAtta is a genus of New World ants of the subfamily Myrmicinae. It contains at least 16 known species.Leaf-cutter ants are relatively large, rusty red or brown in colour, and have a spiny body and long legs. There are three main castes within a nest: the queen, worker and soldier. Only the queens...
spp. and AcromyrmexAcromyrmexAcromyrmex is a genus of New World ants of the subfamily Myrmicinae. It contains 31 known species.-Distribution:This genera is found in South America and parts of Central America and the Caribbean islands.-Overview:...
spp.; - photo masks in the semiconductor and liquid crystal displayLiquid crystal displayA liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....
(LCD) industries; - metal plating (hard metal plating);
- metal plating (decorative plating);
- electric and electronic parts for some colour printers and colour copy machines;
- insecticideInsecticideAn insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s for control of red imported fire ants and termites; - chemically driven oil production;
- carpets;
- leather and apparel;
- textiles and upholstery;
- paper and packaging;
- coatings and coating additives; and
- rubber and plastics.
International status
At the Fourth Conference of Parties, decision SC-4/17 put POSF, along with PFOS, in the Stockholm Convention on Persistent Organic PollutantsStockholm Convention on Persistent Organic Pollutants
Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty, signed in 2001 and effective from May 2004, that aims to eliminate or restrict the production and use of persistent organic pollutants .- History :...
(Annex B) in May 2009. As such, POSF is not "banned" but has approved uses and exemptions—along with a program (SC-4/19) in Annex B that encourages reduced production.
Environmental concern
The POSF degradation product, PFOS, is the dominant perfluorinated compound detected in biomonitoring studies, where concentrations that have been detected are considered sufficient to "alter health parameters".External links
- PFOS Information submitted to the Stockholm Convention.
- Perfluorooctane Sulfonyl Fluoride as an Initiator in Hot-Filament Chemical Vapor Deposition of Fluorocarbon Thin Films (PDF).