Perfluorosulfonic acids (PFSAs) are chemical compounds of the formula CnF(2n+1)SO3H and thus belong to the family of perfluorinated and polyfluorinated alkyl compounds (PFASs). The simplest example of a perfluorosulfonic acid is the trifluoromethanesulfonic acid. Perfluorosulfonic acids with six or more perfluorinated carbon atoms, i.e. from perfluorohexanesulfonic acid onwards, are referred to as long-chain. [1]
Perfluorosulfonic acids are organofluoroanalogues of conventional alkanesulfonic acids, but they are several pKA units stronger (and are therefore strong acids). Their perfluoroalkyl chain has a highly hydrophobic character.
Perfluorooctanesulfonic acid, for example, has been used in hard chromium plating. Since the early 2000's 6:2 fluorotelomersulfonic acid has been used as a replacement for perfluorooctanesulfonic acid. [2]
Perfluorooctanesulfonic acid was included in Annex B of the Stockholm Convention in 2009 and subsequently in the EU POPs Regulation. [3]
Perfluorohexanesulfonic acid was included in Annex B of the Stockholm Convention in 2022. [4]
| Name | Abbreviation | Structural formula | Molecular weight (g/mol) | CAS No. |
|---|---|---|---|---|
| Perfluoropropanesulfonic acid | PFPrS | C3F7SO3H | 250.09 | 423-41-6 |
| Perfluorobutanesulfonic acid | PFBS | C4F9SO3H | 300.10 | 375-73-5 |
| Perfluoropentanesulfonic acid | PFPS | C5F11SO3H | 350.11 | 2706-91-4 |
| Perfluorohexanesulfonic acid | PFHxS | C6F13SO3H | 400.12 | 355-46-4 |
| Perfluoroheptanesulfonic acid | PFHpS | C7F15SO3H | 450.12 | 375-92-8 |
| Perfluorooctanesulfonic acid | PFOS | C8F17SO3H | 500.13 | 1763-23-1 |
| Perfluorononanesulfonic acid | PFNS | C9F19SO3H | 550.14 | 68259-12-1 |
| Perfluorodecanesulfonic acid | PFDS | C10F21SO3H | 600.15 | 335-77-3 |
A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism. The US Environmental Protection Agency (EPA) uses a slightly different definition for biocides as "a diverse group of poisonous substances including preservatives, insecticides, disinfectants, and pesticides used for the control of organisms that are harmful to human or animal health or that cause damage to natural or manufactured products". When compared, the two definitions roughly imply the same, although the US EPA definition includes plant protection products and some veterinary medicines.
Perfluorooctanoic acid is a perfluorinated carboxylic acid produced and used worldwide as an industrial surfactant in chemical processes and as a material feedstock. PFOA is considered a surfactant, or fluorosurfactant, due to its chemical structure, which consists of a perfluorinated, n-heptyl "tail group" and a carboxylic acid "head group". The head group can be described as hydrophilic while the fluorocarbon tail is both hydrophobic and lipophobic.
Perfluorooctanesulfonic acid (PFOS) 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-made) fluorosurfactant, now regarded as a global pollutant. PFOS was the key ingredient in Scotchgard, a fabric protector made by 3M, and related stain repellents. The acronym "PFOS" refers to the parent sulfonic acid and to various salts of perfluorooctanesulfonate. These are all colorless or white, water-soluble solids. Although of low acute toxicity, PFOS has attracted much attention for its pervasiveness and environmental impact. It was added to Annex B of the Stockholm Convention on Persistent Organic Pollutants in May 2009.
Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty, signed on 22 May 2001 in Stockholm and effective from 17 May 2004, that aims to eliminate or restrict the production and use of persistent organic pollutants (POPs).
Nafion is a brand name for a sulfonated tetrafluoroethylene based fluoropolymer-copolymer discovered in the late 1960s by Dr. Walther Grot of DuPont. Nafion is a brand of the Chemours company. It is the first of a class of synthetic polymers with ionic properties that are called ionomers. Nafion's unique ionic properties are a result of incorporating perfluorovinyl ether groups terminated with sulfonate groups onto a tetrafluoroethylene (PTFE) backbone. Nafion has received a considerable amount of attention as a proton conductor for proton exchange membrane (PEM) fuel cells because of its excellent chemical and mechanical stability in the harsh conditions of this application.
Persistent organic pollutants (POPs) are organic compounds that are resistant to degradation through chemical, biological, and photolytic processes. They are toxic and adversely affect human health and the environment around the world. Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released.
In organic chemistry, sulfonic acid refers to a member of the class of organosulfur compounds with the general formula R−S(=O)2−OH, where R is an organic alkyl or aryl group and the S(=O)2(OH) group a sulfonyl hydroxide. As a substituent, it is known as a sulfo group. A sulfonic acid can be thought of as sulfuric acid with one hydroxyl group replaced by an organic substituent. The parent compound is the parent sulfonic acid, HS(=O)2(OH), a tautomer of sulfurous acid, S(=O)(OH)2. Salts or esters of sulfonic acids are called sulfonates.
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.
Per- and polyfluoroalkyl substances are a group of synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain. The PubChem database lists more than 6 million unique compounds in this group. PFASs started being used in the mid-20th century to make fluoropolymer coatings and products that resist heat, oil, stains, grease, and water. They are used in a variety of products including waterproof clothing, furniture, adhesives, food packaging, heat-resistant non-stick cooking surfaces, and the insulation of electrical wire. They have played a key economic role for companies such as DuPont, 3M, and W. L. Gore & Associates that use them to produce widely known materials such as Teflon or Gore-Tex.
Perfluorobutanesulfonic acid (PFBS) is a PFAS 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 a colorless liquid or a corrosive solid. Its conjugate base is perfluorobutanesulfonate which functions as the hydrophobe in fluorosurfactants.
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, CO2H, chlorine, O, and SO3H. Electrofluorination is the predominant method for PFC production. Due to their chemical stability, some of these perfluorinated compounds bioaccumulate.
Perfluoroalkyl carboxylic acids (PFCAs), or perfluorocarboxylic acids are compounds of the formula CnF(2n+1)CO2H that belong to the class of per- and polyfluoroalkyl substances. The simplest example is trifluoroacetic acid. These compounds are organofluorine analogues of ordinary carboxylic acids, but they are stronger by several pKa units and they exhibit great hydrophobic character. Perfluoroalkyl dicarboxylic acids (PFdiCAs) are also known, e.g. C2F4(CO2H)2.
Hazard statements form part of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). They are intended to form a set of standardized phrases about the hazards of chemical substances and mixtures that can be translated into different languages. As such, they serve the same purpose as the well-known R-phrases, which they are intended to replace.
A substance of very high concern (SVHC) is a chemical substance which has been proposed as a candidate for inclusion on the Authorization or Restriction list of REACH. The addition of a substance to the SVHC Candidate List by the European Chemicals Agency (ECHA) is the first step in the procedure for the authorisation or restriction of a chemical. It is expected that industries operating in EU member states abide by the regulations of REACH and submit chemicals for consideration when appropriate.
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.
GenX is a Chemours trademark name for a synthetic, short-chain organofluorine chemical compound, the ammonium salt of hexafluoropropylene oxide dimer acid (HFPO-DA). It can also be used more informally to refer to the group of related fluorochemicals that are used to produce GenX. DuPont began the commercial development of GenX in 2009 as a replacement for perfluorooctanoic acid.
Perfluorodecanoic acid (PFDA) is a fluorosurfactant and has been used in industry, with applications as wetting agent and flame retardant.
Perfluorohexanesulfonic acid (PFHxS) is a synthetic chemical compound. It is one of many compounds collectively known as per- and polyfluoroalkyl substances (PFASs). It is an anionic fluorosurfactant and a persistent organic pollutant with bioaccumulative properties. Although the use of products containing PFHxS and other PFASs have been banned or are being phased out in many jurisdictions, it remains ubiquitous in many environments and within the general population, and is one of the most commonly detected PFASs.
Sulfluramid (N-EtFOSA) is a chemical compound from the group of sulfonic acid amides and per- and polyfluoroalkyl substances (PFASs) that is effective as an insecticide.
Perfluoropropanesulfonic acid (PFPrS) is a PFAS chemical compound having a three-carbon fluorocarbon chain and a sulfonic acid functional group. It has been used within the manufacturing process of Aqueous Fire Fighting Foam (AFFF).