Names | |
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Preferred IUPAC name 4,4′-(Propane-2,2-diyl)diphenol | |
Other names
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Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard | 100.001.133 |
EC Number |
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KEGG | |
PubChem CID | |
RTECS number |
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UNII | |
UN number | 2430 |
CompTox Dashboard (EPA) | |
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Properties | |
C15H16O2 | |
Molar mass | 228.291 g·mol−1 |
Appearance | White solid |
Odor | Phenolic, medical |
Density | 1.217 g/cm3 [1] |
Melting point | 155 °C (311 °F; 428 K) [2] |
Boiling point | 250–252 °C (482–486 °F; 523–525 K) [2] at 13 torrs (0.017 atm) |
0.3 g/L (25 °C) [3] | |
log P | 3.41 [4] |
Vapor pressure | 5×10−6 Pa (25 °C) [5] |
Hazards [6] | |
GHS labelling: | |
Danger | |
H317, H318, H335, H360, H411 [6] | |
P201, P202, P261, P273, P302+P352, P304+P340, P305+P351+P338, P308+P313, P333+P313, P363, P403+P233 [6] | |
NFPA 704 (fire diamond) | |
Flash point | 227 °C (441 °F; 500 K) [6] |
510 °C (950 °F; 783 K) [6] | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is soluble in most common organic solvents, but has very poor solubility in water. [3] [7] BPA is produced on an industrial scale by the condensation reaction of phenol and acetone. Global production in 2022 was estimated to be in the region of 10 million tonnes. [8]
BPA's largest single application is as a co-monomer in the production of polycarbonates, which accounts for 65–70% of all BPA production. [9] [10] The manufacturing of epoxy resins and vinyl ester resins account for 25–30% of BPA use. [9] [10] The remaining 5% is used as a major component of several high-performance plastics, and as a minor additive in PVC, polyurethane, thermal paper, and several other materials. It is not a plasticizer, [11] although it is often wrongly labelled as such.
The health effects of BPA have been the subject of prolonged public and scientific debate. [12] [13] [14] BPA is a xenoestrogen, exhibiting hormone-like properties that mimic the effects of estrogen in the body. [15] Although the effect is very weak, [16] the pervasiveness of BPA-containing materials raises concerns, as exposure is effectively lifelong. Many BPA-containing materials are non-obvious but commonly encountered, [17] and include coatings for the inside of food cans, [18] clothing designs, [19] shop receipts, [20] and dental fillings. [21] BPA has been investigated by public health agencies in many countries, as well as by the World Health Organization. [12] While normal exposure is below the level currently associated with risk, several jurisdictions have taken steps to reduce exposure on a precautionary basis, in particular by banning BPA from baby bottles. There is some evidence that BPA exposure in infants has decreased as a result of this. [22] BPA-free plastics have also been introduced, which are manufactured using alternative bisphenols such as bisphenol S and bisphenol F, but there is also controversy around whether these are actually safer. [23] [24] [25]
Bisphenol A was first reported in 1891 by the Russian chemist Aleksandr Dianin. [26]
In 1934, workers at I.G. Farbenindustrie reported the coupling of BPA and epichlorohydrin. Over the following decade, coatings and resins derived from similar materials were described by workers at the companies of DeTrey Freres in Switzerland and DeVoe and Raynolds in the US. This early work underpinned the development of epoxy resins, which in turn motivated production of BPA. [27] The utilization of BPA further expanded with discoveries at Bayer and General Electric on polycarbonate plastics. These plastics first appeared in 1958, being produced by Mobay, General Electric, and Bayer. [28]
The British biochemist Edward Charles Dodds tested BPA as an artificial estrogen in the early 1930s. [29] [30] [31] Subsequent work found that it bound to estrogen receptors tens of thousands of times more weakly than estradiol, the major natural female sex hormone. [32] [16] Dodds eventually developed a structurally similar compound, diethylstilbestrol (DES), which was used as a synthetic estrogen drug in women and animals until it was banned due to its risk of causing cancer; the ban on use of DES in humans came in 1971 and in animals, in 1979. [29] BPA was never used as a drug. [29]
The synthesis of BPA still follows Dianin's general method, with the fundamentals changing little in 130 years. The condensation of acetone (hence the suffix 'A' in the name) [33] with two equivalents of phenol is catalyzed by a strong acid, such as concentrated hydrochloric acid, sulfuric acid, or a solid acid resin such as the sulfonic acid form of polystyrene sulfonate. [34] An excess of phenol is used to ensure full condensation and to limit the formation of byproducts, such as Dianin's compound. BPA is fairly cheap to produce, as the synthesis benefits from a high atom economy and large amounts of both starting materials are available from the cumene process. [7] As the only by-product is water, it may be considered an industrial example of green chemistry. Global production in 2022 was estimated to be in the region of 10 million tonnes. [8]
Usually, the addition of acetone takes place at the para position on both phenols, however minor amounts of the ortho-para (up to 3%) and ortho-ortho isomers are also produced, along with several other minor by‑products. [35] These are not always removed and are known impurities in commercial samples of BPA. [36] [35]
BPA has a fairly high melting point but can be easily dissolved in a broad range of organic solvents including toluene, ethanol and ethyl acetate. [37] It may be purified by recrystallisation from acetic acid with water. [38] Crystals form in the monoclinic space group P 21/n (where n indicates the glide plane); within this individual molecules of BPA are arraigned with a 91.5° torsion angle between the phenol rings. [39] [40] [41] Spectroscopic data is available from AIST. [42]
About 65–70% of all bisphenol A is used to make polycarbonate plastics, [9] [10] which can consist of nearly 90% BPA by mass. Polymerisation is achieved by a reaction with phosgene, conducted under biphasic conditions; the hydrochloric acid is scavenged with aqueous base. [43] This process converts the individual molecules of BPA into large polymer chains, effectively trapping them.
About 25–30% of all BPA is used in the manufacture of epoxy resins and vinyl ester resins. [9] [10] For epoxy resin, it is first converted to its diglycidyl ether (usually abbreviated BADGE or DGEBA). [44] [45] This is achieved by a reaction with epichlorohydrin under basic conditions.
Some of this is further reacted with methacrylic acid to form bis-GMA, which is used to make vinyl ester resins. Alternatively, and to a much lesser extent, BPA may be ethoxylated and then converted to its diacrylate and dimethacrylate derivatives (bis-EMA, or EBPADMA). These may be incorporated at low levels in vinyl ester resins to change their physical properties [46] and see common use in dental composites and sealants. [47] [48]
The remaining 5% of BPA is used in a wide range of applications, many of which involve plastic. [49] BPA is a main component of several high-performance plastics, the production of these is low compared to other plastics but still equals several thousand tons a year. Comparatively minor amounts of BPA are also used as additives or modifiers in some commodity plastics. These materials are much more common but their BPA content will be low.
Concerns about the health effects of BPA have led some manufacturers replacing it with other bisphenols, such as bisphenol S and bisphenol F. These are produced in a similar manner to BPA, by replacing acetone with other ketones, which undergo analogous condensation reactions. [7] Thus, in bisphenol F, the F signifies formaldehyde. Health concerns have also been raised about these substitutes. [66] [24] Alternative polymers, such as tritan copolyester have been developed to give the same properties as polycarbonate (durable, clear) without using BPA or its analogues.
Structural formula | Name | CAS | Reactants | |
---|---|---|---|---|
Bisphenol AF | 1478-61-1 | Phenol | Hexafluoroacetone | |
Bisphenol F | 620-92-8 | Phenol | Formaldehyde | |
Bisphenol S | 80-09-1 | Phenol | Sulfur trioxide | |
Bisphenol Z | 843-55-0 | Phenol | Cyclohexanone | |
Tetramethyl bisphenol F | 5384-21-4 | 2,6-xylenol | Formaldehyde |
As a result of the presence of BPA in plastics and other commonplace materials, most people are frequently exposed to trace levels of BPA. [67] [68] [69] The primary source of human exposure is via food, as epoxy and PVC are used to line the inside of food cans to prevent corrosion of the metal by acidic foodstuffs. Polycarbonate drink containers are also a source of exposure, although most disposable drinks bottles are actually made of PET, which contains no BPA. Among the non-food sources, exposure routes include through dust, [10] thermal paper, [20] clothing, [19] dental materials, [70] and medical devices. [17] Although BPA exposure is common it does not accumulate within the body, with toxicokinetic studies showing the biological half-life of BPA in adult humans to be around two hours. [71] [72] The body first converts it into more water-soluble compounds via glucuronidation or sulfation, which are then removed from the body through the urine. This allows exposure to be easily determined by urine testing, facilitating convenient biomonitoring of populations. [22] [17] [73] Food and drink containers made from Bisphenol A-containing plastics do not contaminate the content to cause any increased cancer risk. [74]
The health effects of BPA have been the subject of prolonged public and scientific debate, [12] [13] [14] with PubMed listing more than 18,000 scientific papers as of 2024. [75] Concern is mostly related to its estrogen-like activity, although it can interact with other receptor systems as an endocrine-disrupting chemical. [76] These interactions are all very weak, but exposure to BPA is effectively lifelong, leading to concern over possible cumulative effects. Studying this sort of long‑term, low‑dose interaction is difficult, and although there have been numerous studies, there are considerable discrepancies in their conclusions regarding the nature of the effects observed as well as the levels at which they occur. [12] A common criticism is that industry-sponsored trials tend to show BPA as being safer than studies performed by academic or government laboratories, [14] [77] although this has also been explained in terms of industry studies being better designed. [13] [78]
In the 2010s public health agencies in the EU, [79] [80] [81] US, [82] [83] Canada, [84] Australia [85] and Japan as well as the WHO [12] all reviewed the health risks of BPA, and found normal exposure to be below the level currently associated with risk. Regardless, due to the scientific uncertainty, many jurisdictions continued to take steps to reduce exposure on a precautionary basis. In particular, infants were considered to be at greater risk, [86] leading to bans on the use of BPA in baby bottles and related products by the US, [87] Canada, [88] and EU [89] amongst others. Bottle producers largely switched from polycarbonate to polypropylene and there is some evidence that BPA exposure in infants has decreased as a result of this. [22] The European Food Safety Authority completed a re-evaluation into the risks of BPA in 2023, concluding that its tolerable daily intake should be greatly reduced. [90] This lead to a European Union resolution passed in early 2024 to ban BPA in all the food contact materials, including plastic and coated packaging. If adopted the ban would come into force after an implementation period of up to three years.
BPA exhibits very low acute toxicity (i.e. from a single large dose) as indicated by its LD50 of 4 g/kg (mouse). Reports indicate that it is a minor skin irritant as well, although less so than phenol. [7]
BPA has been found to interact with a diverse range of hormone receptors, in both humans and animals. [76] It binds to both of the nuclear estrogen receptors (ERs), ERα and ERβ. BPA is a selective estrogen receptor modulator (SERM), or partial agonist of the ER, so it can serve as both an estrogen agonist and antagonist. However, it is 1000- to 2000-fold less potent than estradiol, the major female sex hormone in humans. At high concentrations, BPA also binds to and acts as an antagonist of the androgen receptor (AR). In addition to receptor binding, the compound has been found to affect Leydig cell steroidogenesis, including affecting 17α-hydroxylase/17,20 lyase and aromatase expression and interfering with LH receptor-ligand binding. [91]
Bisphenol A's interacts with the estrogen-related receptor γ (ERR-γ). This orphan receptor (endogenous ligand unknown) behaves as a constitutive activator of transcription. BPA seems to bind strongly to ERR-γ (dissociation constant = 5.5 nM), but only weakly to the ER. [92] BPA binding to ERR-γ preserves its basal constitutive activity. [92] It can also protect it from deactivation from the SERM 4-hydroxytamoxifen (afimoxifene). [92] This may be the mechanism by which BPA acts as a xenoestrogen. [92] Different expression of ERR-γ in different parts of the body may account for variations in bisphenol A effects. BPA has also been found to act as an agonist of the GPER (GPR30). [93]
BPA has been detectable in the natural environment since the 1990s and is now widely distributed. [94] It is primarily a river pollutant, [95] but has also been observed in the marine environment, [96] in soils, [97] and lower levels can also be detected in air. [98] The solubility of BPA in water is low (~300 g per ton of water) [3] but this is still sufficient to make it a significant means of distribution into the environment. [97] Many of the largest sources of BPA pollution are water-based, particularly wastewater from industrial facilities using BPA. Paper recycling can be a major source of release when this includes thermal paper, [9] [99] leaching from PVC items may also be a significant source, [95] as can landfill leachate. [100]
In all cases, wastewater treatment can be highly effective at removing BPA, giving reductions of 91–98%. [101] Regardless, the remaining 2–9% of BPA will continue through to the environment, with low levels of BPA commonly observed in surface water and sediment in the U.S. and Europe. [102]
Once in the environment BPA is aerobically biodegraded by a wide a variety of organisms. [94] [103] [104] Its half life in water has been estimated at between 4.5 and 15 days, degradation in the air is faster than this, while soil samples degrade more slowly. [97] BPA in sediment degrades most slowly of all, particularly where this is anaerobic. Abiotic degradation has been reported, but is generally slower than biodegradation. Pathways include photo-oxidation, or reactions with minerals such as goethite which may be present in soils and sediments. [105]
BPA is an environmental contaminant of emerging concern. [100] Despite its short half-life and non-bioaccumulating character, the continuous release of BPA into the environment causes continuous exposure to both plant [106] and animal life. Although many studies have been performed, these often focus on a limited range of model organisms and can use BPA concentrations well beyond environmental levels. [107] As such, the precise effects of BPA on the growth, reproduction, and development of aquatic organism are not fully understood. [107] Regardless, the existing data shows the effects of BPA on wildlife to be generally negative. [108] [109] BPA appears able to affect development and reproduction in a wide range of wildlife, [109] [110] with certain species being particularly sensitive, such as invertebrates and amphibians. [108]
Polycarbonates (PC) are a group of thermoplastic polymers containing carbonate groups in their chemical structures. Polycarbonates used in engineering are strong, tough materials, and some grades are optically transparent. They are easily worked, molded, and thermoformed. Because of these properties, polycarbonates find many applications. Polycarbonates do not have a unique resin identification code (RIC) and are identified as "Other", 7 on the RIC list. Products made from polycarbonate can contain the precursor monomer bisphenol A (BPA).
Nalgene is a brand of plastic products developed originally for laboratory use, including items such as jars, bottles, test tubes, and Petri dishes, that were shatterproof and lighter than glass. The properties of plastic products make them suitable for work with many substances in various temperature ranges.
Endocrine disruptors, sometimes also referred to as hormonally active agents, endocrine disrupting chemicals, or endocrine disrupting compounds are chemicals that can interfere with endocrine systems. These disruptions can cause numerous adverse human health outcomes, including alterations in sperm quality and fertility; abnormalities in sex organs‚ endometriosis‚ early puberty‚ altered nervous system or immune function; certain cancers; respiratory problems; metabolic issues; diabetes, obesity, or cardiovascular problems; growth, neurological and learning disabilities, and more. Found in many household and industrial products, endocrine disruptors "interfere with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body that are responsible for development, behavior, fertility, and maintenance of homeostasis ."
Carbonless copy paper (CCP), non-carbon copy paper, or NCR paper is a type of coated paper designed to transfer information written on the front onto sheets beneath. It was developed by chemists Lowell Schleicher and Barry Green, as an alternative to carbon paper and is sometimes misidentified as such.
Nonylphenols are a family of closely related organic compounds composed of phenol bearing a 9 carbon-tail. Nonylphenols can come in numerous structures, all of which may be considered alkylphenols. They are used in manufacturing antioxidants, lubricating oil additives, laundry and dish detergents, emulsifiers, and solubilizers. They are used extensively in epoxy formulation in North America but its use has been phased out in Europe. These compounds are also precursors to the commercially important non-ionic surfactants alkylphenol ethoxylates and nonylphenol ethoxylates, which are used in detergents, paints, pesticides, personal care products, and plastics. Nonylphenol has attracted attention due to its prevalence in the environment and its potential role as an endocrine disruptor and xenoestrogen, due to its ability to act with estrogen-like activity. The estrogenicity and biodegradation heavily depends on the branching of the nonyl sidechain. Nonylphenol has been found to act as an agonist of the GPER (GPR30).
Xenoestrogens are a type of xenohormone that imitates estrogen. They can be either synthetic or natural chemical compounds. Synthetic xenoestrogens include some widely used industrial compounds, such as PCBs, BPA, and phthalates, which have estrogenic effects on a living organism even though they differ chemically from the estrogenic substances produced internally by the endocrine system of any organism. Natural xenoestrogens include phytoestrogens which are plant-derived xenoestrogens. Because the primary route of exposure to these compounds is by consumption of phytoestrogenic plants, they are sometimes called "dietary estrogens". Mycoestrogens, estrogenic substances from fungi, are another type of xenoestrogen that are also considered mycotoxins.
Thermal paper is a special fine paper that is coated with a material formulated to change color locally when exposed to heat. It is used in thermal printers, particularly in inexpensive devices such as adding machines, cash registers, and credit card terminals and small, lightweight portable printers.
Tetrabromobisphenol A (TBBPA) is a brominated flame retardant. The compound is a white solid, although commercial samples appear yellow. It is one of the most common flame retardants.
Triphenyl phosphate (TPhP) is the chemical compound with the formula OP(OC6H5)3. It is the simplest aromatic organophosphate. This colourless solid is the ester (triester) of phosphoric acid and phenol. It is used as a plasticizer and a fire retardant in a wide variety of settings and products.
The bisphenols are a group of industrial chemical compounds related to diphenylmethane; commonly used in the creation of plastics and epoxy resins. Most are based on two hydroxyphenyl functional groups linked by a methylene bridge. Exceptions include bisphenol S, P, and M. "Bisphenol" is a common name; the letter following denotes the variant, which depends on the additional substituents. Bisphenol A is the most popular representative of the group, with millions of metric tons produced globally in the past decade, often simply called "bisphenol".
Obesogens are certain chemical compounds that are hypothesised to disrupt normal development and balance of lipid metabolism, which in some cases, can lead to obesity. Obesogens may be functionally defined as chemicals that inappropriately alter lipid homeostasis and fat storage, change metabolic setpoints, disrupt energy balance or modify the regulation of appetite and satiety to promote fat accumulation and obesity.
Bisphenol S (BPS) is an organic compound with the formula (HOC6H4)2SO2. It has two phenol functional groups on either side of a sulfonyl group. It is commonly used in curing fast-drying epoxy resin adhesives. It is classified as a bisphenol, and a close molecular analog of bisphenol A (BPA). BPS differentiates from BPA by possessing a sulfone group (SO2) as the central linker of the molecule instead of a dimethylmethylene group (C 2), which is the case of bisphenol A.
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be molded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to their widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives.
Bisphenol AF (BPAF) is a fluorinated organic compound that is an analogue of bisphenol A in which the two methyl groups are replaced with trifluoromethyl groups. It exists as a white to light-gray powder.
4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP) is a metabolite of bisphenol A (BPA). MBP has potent estrogenic activity in vitro and in vivo, up to thousandfold stronger than BPA. It may also play a role in neuronal cell apoptosis and may increase risk for several forms of cancer.
Tritan, a copolymer offered by the Eastman Chemical Company since 2007, is a transparent plastic intended to replace polycarbonate, because of health concerns about Bisphenol A (BPA). Tritan is a copolymer made from three monomers: dimethyl terephthalate (DMT), cyclohexanedimethanol (CHDM), and 2,2,4,4-Tetramethyl-1,3-cyclobutanediol (CBDO). Tritan (PCTG) is made without using any bisphenols or phthalates.
3,3'-Dinitrobisphenol A is an organic compound with the formula (HO(O2N)C6H3)2C(CH3)2. It is a yellow-orange solid prepared by nitration of bisphenol A
Bisphenol F is an organic compound with the chemical formula (HOC
6H
4)
2CH
2. It is structurally related to bisphenol A (BPA), a popular precursor for forming plastics, as both belong to the category of molecules known as bisphenols, which feature two phenol groups connected via a linking group. In BPF, the two aromatic rings are linked by a methylene connecting group. In response to concern about the health effects of BPA, BPF is increasingly used as a substitute for BPA.
Bisphenol A controversy centers on concerns and debates about the biomedical significance of bisphenol A (BPA), which is a precursor to polymers that are used in some consumer products, including some food containers. The concerns began with the hypothesis that BPA is an endocrine disruptor, i.e. it mimics endocrine hormones and thus has the unintended and possibly far-reaching effects on people in physical contact with the chemical.
Tetramethyl bisphenol F (TMBPF) is a new coating intended as a safer replacement for bisphenol A and bisphenol F to use in epoxy linings of aluminium cans and steel cans. It was previously suggested as an insulator in electronic circuit boards.
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: CS1 maint: overridden setting (link)COMMISSION DIRECTIVE 2011/8/EU of 28 January 2011 amending Directive 2002/72/EC as regards the restriction of use of Bisphenol A in plastic infant feeding bottles