Chlorofluorocarbons are halogenated paraffin hydrocarbons that contain only carbon and fluorine, produced as volatile derivative of methane and propane. They are commonly known by the DuPont brand name Freon; the most common representative is dichlorodifluoromethane. Many CFCs have been used as refrigerants and solvents; because CFCs contribute to ozone depletion in the upper atmosphere, the manufacture of such compounds has been phased out under the Montreal Protocol, they are being replaced with other products such as hydrofluorocarbons and R-134a. As in simpler alkanes, carbon in the CFCs bonds with tetrahedral symmetry; because the fluorine and chlorine atoms differ in size and effective charge from hydrogen and from each other, the methane-derived CFCs deviate from perfect tetrahedral symmetry. The physical properties of CFCs and HCFCs are tunable by changes in the number and identity of the halogen atoms. In general, they are volatile but less so than their parent alkanes; the decreased volatility is attributed to the molecular polarity induced by the halides, which induces intermolecular interactions.
Thus, methane boils at −161 °C whereas the fluoromethanes boil between −51.7 and −128 °C. The CFCs have still higher boiling points because the chloride is more polarizable than fluoride; because of their polarity, the CFCs are useful solvents, their boiling points make them suitable as refrigerants. The CFCs are far less flammable than methane, in part because they contain fewer C-H bonds and in part because, in the case of the chlorides and bromides, the released halides quench the free radicals that sustain flames; the densities of CFCs are higher than their corresponding alkanes. In general, the density of these compounds correlates with the number of chlorides. CFCs and HCFCs are produced by halogen exchange starting from chlorinated methanes and ethanes. Illustrative is the synthesis of chlorodifluoromethane from chloroform: HCCl3 + 2 HF → HCF2Cl + 2 HClThe brominated derivatives are generated by free-radical reactions of the chlorofluorocarbons, replacing C-H bonds with C-Br bonds; the production of the anesthetic 2-bromo-2-chloro-1,1,1-trifluoroethane is illustrative: CF3CH2Cl + Br2 → CF3CHBrCl + HBr The most important reaction of the CFCs is the photo-induced scission of a C-Cl bond: CCl3F → CCl2F.
+ Cl. The chlorine atom, written as Cl. behaves differently from the chlorine molecule. The radical Cl. is long-lived in the upper atmosphere, where it catalyzes the conversion of ozone into O2. Ozone absorbs UV-B radiation, so its depletion allows more of this high energy radiation to reach the Earth's surface. Bromine atoms are more efficient catalysts. CFCs and HCFCs are used in a variety of applications because of their low toxicity and flammability; every permutation of fluorine and hydrogen based on methane and ethane has been examined and most have been commercialized. Furthermore, many examples are known for higher numbers of carbon as well as related compounds containing bromine. Uses include refrigerants, blowing agents, propellants in medicinal applications and degreasing solvents. Billions of kilograms of chlorodifluoromethane are produced annually as precursor to tetrafluoroethylene, the monomer, converted into Teflon. Chlorofluorocarbons: when derived from methane and ethane these compounds have the formulae CClmF4−m and C2ClmF6−m, where m is nonzero.
Hydro-chlorofluorocarbons: when derived from methane and ethane these compounds have the formula CClmFnH4−m−n and C2ClxFyH6−x−y, where m, n, x, y are nonzero. and bromofluorocarbons have formulae similar to the CFCs and HCFCs but include bromine. Hydrofluorocarbons: when derived from methane, ethane and butane, these compounds have the respective formulae CFmH4−m, C2FmH6−m, C3FmH8−m, C4FmH10−m, where m is nonzero. A special numbering system is to be used for fluorinated alkanes, prefixed with Freon-, R-, CFC- and HCFC-, where the rightmost value indicates the number of fluorine atoms, the next value to the left is the number of hydrogen atoms plus 1, the next value to the left is the number of carbon atoms less one, the remaining atoms are chlorine. Freon-12, for example, indicates a methane derivative containing no hydrogen, it is therefore CCl2F2. Another equation that can be applied to get the correct molecular formula of the CFC/R/Freon class compounds is this to take the numbering and add 90 to it.
The resulting value will give the number of carbons as the first numeral, the second numeral gives the number of hydrogen atoms, the third numeral gives the number of fluorine atoms. The rest of the unaccounted carbon bonds are occupied by chlorine atoms; the value of this equation is always a three figure number. An easy example is that of CFC-12, which gives: 90+12=102 -> 1 carbon, 0 hydrogens, 2 fluorine atoms, hence 2 chlorine atoms resulting in CCl2F2. The main advantage of this method of deducing the molecular composition in comparison with the method described in the paragraph above is that it gives the number of carbon atoms of the molecule. Freons containing bromine are signified by four numbers. Isomers, which are common for ethane and propane derivatives, are indicated by letters following the numbers: Carbon tetrachloride was used in fire extinguishers and glass "anti-fire grenades" from the late nineteenth century until around the end of World War II. Experimentation with chloroalkanes for fire suppression on military aircraft began at least as early as the 1920s.
Chloroprene is the common name for 2-chlorobuta-1,3-diene with the chemical formula CH2=CCl−CH=CH2. Chloroprene is a colorless volatile liquid exclusively used as a monomer for the production of the polymer polychloroprene, a type of synthetic rubber. Polychloroprene is better known as the trade name given by DuPont. Chloroprene is produced in three steps from 1,3-butadiene: chlorination, isomerization of part of the product stream, dehydrochlorination of 3,4-dichlorobut-1-ene. Chlorine adds to 1,3-butadiene to afford a mixture of 3,4-dichlorobut-1-ene and 1,4-dichlorobut-2-ene; the 1,4-dichloro isomer is subsequently isomerized to 3,4 isomer, which in turn is treated with base to induce dehydrochlorination to 2-chlorobuta-1,3-diene. This dehydrohalogenation entails loss of a hydrogen atom in the 3 position and the chlorine atom in the 4 position thereby forming a double bond between carbons 3 and 4. In 1983 2,000,000 kg was produced in this manner; the chief impurity in chloroprene prepared in this way is 1-chlorobuta-1,3-diene, separated by distillation.
Until the 1960s, chloroprene production was dominated by the "acetylene process,", modeled after the original synthesis of vinylacetylene. In this process, acetylene is dimerized to give vinyl acetylene, combined with hydrogen chloride to afford 4-chloro-1,2-butadiene, which in the presence of copper chloride, rearranges to the targeted 2-chlorobuta-1,3-diene:This process is energy-intensive and has high investment costs. Furthermore, the intermediate vinyl acetylene is unstable; this "acetylene process" has been replaced by a process, which adds Cl2 to one of the double bonds in 1,3-butadiene, subsequent elimination produces HCl instead, as well as chloroprene. Transportation of uninhibited chloroprene has been banned in the United States by the US Department of Transportation. Stabilized chloroprene is in hazard class 3, its UN number is 1991 and is in packing group 1. As a way to visually communicate hazards associated with chloroprene exposure, the United Nations Globally Harmonized System of Classification and Labeling of Chemicals has designated the following hazards for exposure to chloroprene: flammable, dangerous to the environment, health hazard and irritant.
Chloroprene poses fire hazard. OSHA identifies chloroprene as a category 2 flammable liquid and emphasizes that at least one portable fire extinguisher should be within 10 and no more than 25 feet away from the flammable liquid storage area. OSHA provides resources on addressing flammable liquids at industrial plants, where the exposure to chloroprene exists; as a vapor, chloroprene is heavier than air. According to the National Fire Protection Association's rating system, chloroprene is designated with a category 2 health hazard, a category 3 fire hazard, a category 1 reactivity. Chronic exposure to chloroprene may have the following symptoms: liver function abnormalities, disorders of the cardiovascular system, depression of the immune system; the Environmental Protection Agency designated chloroprene as to be carcinogenic to humans based on evidence from studies that showed a statistically significant association between occupational chloroprene exposure and the risk of lung cancer. As early as 1975, NIOSH had identified the potential health hazards of chloroprene in their bulletin citing two Russian cohort studies from those working with chloroprene in an occupational setting.
OSHA defines hazard determination as "the process of evaluating available scientific evidence in order to determine if a chemical is hazardous pursuant to the HCS." While chemical manufacturers and importers are required to conduct a hazard determination, other companies may voluntarily conduct a hazard determination to ensure worker health and safety. Under the hazard determination framework, any chemical that has a physical or health hazard is considered a hazardous chemical. Physical hazards include fire hazards, reactive hazards, explosion hazards. Heath hazards include target organ effects. Chloroprene is on OSHA's list for substances that are regulated as hazardous. In the European Union, the hazard-determination-equivalent is the Registration, Evaluation and Restriction of Chemicals regulation enacted on June 1, 2007 by the European Chemicals Agency; the goal of REACH is to "improve the protection of human health and the environment from the risks that can be posed by chemicals, while enhancing the competitiveness of the EU chemicals industry."
If risks of chemicals are unmanageable, ECHA may ban its use. Several epidemiological studies and toxicological reports provide evidence of chloroprene's capability to inflict occupational health and safety concerns. However, varying reviews of the degree to which chloroprene should be held responsible for health concerns highlight the criticality of sound scientific research. Nonetheless and safety practices should always be implemented in the workplace; some of these occupational concerns include: cleaning equipment or unclogging pipes coated with chloroprene, inhaling chloroprene off-gas, chloroprene spontaneously reacting with other chemicals and chloroprene inducing a workplace fire. Upon the clogging of equipment associated with occupational chloroprene use, employers should ensure that their employees are wearing the proper PPE and set up administrative controls so that skin exposure to and inhalation of chloroprene is avoided. Only one fatality as a result of chloroprene intoxica
Phthalates, or phthalate esters, are esters of phthalic acid. They are used as plasticizers, i.e. substances added to plastics to increase their flexibility, transparency and longevity. They are used to soften polyvinyl chloride. Lower-molecular-weight phthalates, those derived from C3-C6 alcohols, are being replaced in many products in the United States and European Union over health concerns, they are replaced by high-molecular-weight phthalates. In 2010, the market was still dominated by high-phthalate plasticizers. Due to the ubiquity of plasticized plastics, the majority of people are exposed to some level of phthalates. For example, most Americans tested by the Centers for Disease Control and Prevention have metabolites of multiple phthalates in their urine. In studies of rodents exposed to certain phthalates, high doses have been shown to change hormone levels and cause birth defects. Phthalates are used in a large variety of products, from enteric coatings of pharmaceutical pills and nutritional supplements to viscosity control agents, gelling agents, film formers, dispersants, binders, emulsifying agents, suspending agents.
End-applications include adhesives and glues, agricultural adjuvants, building materials, personal-care products, medical devices and surfactants, children's toys, modelling clay, paints, printing inks and coatings, food products, textiles. Phthalates are frequently used in soft plastic fishing lures, paint pigments, sex toys made of so-called "jelly rubber". Phthalates are used in a variety of household applications such as shower curtains, vinyl upholstery, floor tiles, food containers and wrappers, cleaning materials. Personal-care items containing phthalates include perfume, eye shadow, nail polish, liquid soap, hair spray. Phthalates are found in modern electronics and medical applications such as catheters and blood transfusion devices; the most used phthalates are di phthalate, diisodecyl phthalate, diisononyl phthalate. DEHP was the dominant plasticizer used globally in PVC due to its low cost. Benzylbutylphthalate is used in the manufacture of foamed PVC, used as a flooring material, although its use is decreasing in the Western countries.
Phthalates with small R and R' groups are used as solvents in pesticides. 8.4 million tonnes of plasticizers are produced globally every year, of which European produced accounts for 1.5 million metric tonnes. 70% of those totals are phthalates, down from about 88% in 2005. The remaining 30% are alternative chemistries. Plasticizers contribute 10-60% of total weight of plasticized products. More in Europe and the US, regulatory developments have resulted in a change in phthalate consumption, with the higher phthalates replacing DEHP as the general purpose plasticizer of choice because DIDP and DINP were not classified as hazardous. All of these mentioned phthalates are now restricted in many products. DEHP, although most applications are shown to pose no risk when studied using recognized methods of risk assessment, has been classified as a Category 1B reprotoxin, is now on the Annex XIV of the European Union's REACH legislation. DEHP has been phased out in Europe under REACH and can only be used in specific cases if an authorisation has been granted.
Authorisations are granted by the European Commission, after obtaining the opinion of the Committee for Risk Assessment and the Committee for Socio-economic Analysis of the European Chemicals Agency. The development of cellulose nitrate plastic in 1846 led to the patent of castor oil in 1856 for use as the first plasticizer. In 1870, camphor became the more favored plasticizer for cellulose nitrate. Phthalates were first introduced in the 1920s and replaced the volatile and odorous camphor. In 1931, the commercial availability of polyvinyl chloride and the development of di phthalate began the boom of the plasticizer PVC industry. Phthalate esters are the alkyl aryl esters of phthalic acid; when added to plastics, phthalates allow the long polyvinyl molecules to slide against one another. The phthalates have a clear syrupy liquid consistency and show low water solubility, high oil solubility, low volatility; the polar carboxyl group contributes little to the physical properties of the phthalates, except when R and R' are small.
Phthalates are colorless, odorless liquids produced by reacting phthalic anhydride with an appropriate alcohol. The mechanism by which phthalates and related compounds effect plasticization to polar polymers has been a subject of intense study since the 1960s; the mechanism is one of polar interactions between the polar centres of the phthalate molecule and the positively charged areas of the vinyl chain residing on the carbon atom of the carbon-chlorine bond. For this to be established, the polymer must be heated in the presence of the plasticizer, first above the Tg of the polymer and into a melt state; this enables an i
Alkylphenols are a family of organic compounds obtained by the alkylation of phenols. The term is reserved for commercially important propylphenol, amylphenol, octylphenol, nonylphenol and related "long chain alkylphenols". Methylphenols and ethylphenols are alkylphenols, but they are more referred to by their specific names and xylenols; the long-chain alkylphenols are prepared by alkylation of phenol with alkenes: C6H5OH + RR'C=CHR" → RR'CH−CHR"−C6H4OHIn this way, about 500M kg/y are produced. Alkylphenols are xenoestrogens; the European Union has implemented sales and use restrictions on certain applications in which nonylphenols are used because of their alleged "toxicity and the liability to bioaccumulate" but the United States EPA has taken a slower approach to make sure that action is based on "sound science". The long-chain alkylphenols are used extensively as precursors to the detergents, as additives for fuels and lubricants, as components in phenolic resins; these compounds are used as building block chemicals that are used in making fragrances, thermoplastic elastomers, oil field chemicals and fire retardant materials.
Through the downstream use in making alkylphenolic resins, alkylphenols are found in tires, coatings, carbonless copy paper and high performance rubber products. They have been used in industry for over 40 years
Chlorinated paraffins are complex mixtures of polychlorinated n-alkanes. The chlorination degree of CPs can vary between 30 and 70 wt%. CPs are subdivided according to their carbon chain length into short chain CPs, medium chain CPs and long chain CPs. Depending on chain length and chlorine content, CPs are yellowish liquids or solids. Chlorinated paraffins are synthesized by reaction of chlorine gas with unbranched paraffin fractions at a temperature of 80–100 °C; the radical substitution may be promoted by UV-light. CxH + y Cl2 → CxHCly + y HClWhen the desired degree of chlorination is achieved, residues of hydrochloric acid and chlorine are blown off with nitrogen. Epoxidized vegetable oil, glycidyl ether or organophosphorous compounds may be added to the final product for improved stability at high temperatures. Commercial products have been classified as substances of variable composition. CPs are complex mixtures of chlorinated n-alkanes containing thousands of homologues and isomers which are not separated by standard analytical methods.
CPs are produced in Europe, North America, Brazil, South Africa and Asia. In China, where most of the world production capacity is located, 600,000 tons of chlorinated paraffins were produced in 2007. Production and use volumes of CPs exceeded 1,000,000 tons in 2013. Production of CPs for industrial use started in the 1930s. Over 200 CP formulations are in use for a wide range of industrial applications, such as flame retardants and plasticisers, as additives in metal working fluids, in sealants, adhesives, leather fat and coatings. Short chain CPs are classified as persistent and their physical properties imply a high potential for bioaccumulation. Furthermore, SCCPs are classified as toxic to aquatic organisms, carcinogenic to rats and mice. SCCPs were categorised in group 2B as carcinogenic to humans from the International Agency for Research on Cancer. In 2017, it was agreed to globally ban SCCPs under the Stockholm Convention on Persistent Organic Pollutants; however MCCPs are toxic to the aquatic environment and persistent.
De Boer J. El-Sayed Ali T. Fiedler H. Legler J. Muir D. C. Nikiforov V. A. Tomy G. T. Tsunemi, K.. The handbook of environmental chemistry 10: Chlorinated paraffins. Berlin: Springer-Verlag. ISBN 978-3-642-10760-3 Brooke, DM. Environmental risk assessment: long-chain chlorinated paraffins, Bristol, UK: Environment Agency "Chlorinated paraffins". IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. 48: 55–72. 1990. ISBN 978-92-832-1248-5. PMID 2197463. Kellersohn, Thomas. Chlorinated paraffins, in Ullmann’s encyclopedia of industrial chemistry, electronic release, 6th ed. Weinheim: Wiley-VCH Kenne, Kerstin. ISBN 9241571810 Lassen, Carsten et al.. Survey of short-chain and medium-chain paraffins, Copenhagen: Danish Ministry of Environment, Environmental Protection Agency Tomy, Gregg T. et al.. Quantifying C10-C13 polychloroalkanes in environmental samples by high-resolution gas chromatography/electron capture negative ion high-resolution mass spectrometry, Analytical Chemistry 69, 2764-2765 Bayen, Stéphane.
"Chlorinated paraffins: A review of analysis and environmental occurrence". Environment International. 32: 915–29. Doi:10.1016/j.envint.2006.05.009. PMID 16814386. Cherrie, J. W.. "Dermal Exposure to Metalworking Fluids and Medium-Chain Chlorinated Paraffin". Annals of Occupational Hygiene. 54: 228–35. Doi:10.1093/annhyg/mep081. PMID 19959560. European Chemicals Bureau. European Union Risk assessment report Vol. 4: Alkanes, C10-13, Luxembourg: Office for Official Publications of the European Community European Chemicals Bureau. European Union Risk assessment report Vol. 81: Alkanes, C10-13, Luxembourg: Office for Official Publications of the European Community European Chemicals Bureau. European Union Risk assessment report Vol. 58: Alkanes, C14-17, Part I-Environment, Luxembourg: Office for Official Publications of the European Community European Commission. European Union Risk assessment report: Alkanes, C14-17, chloro. Luxembourg: Office for Official Publications of the European Community European Commission.
European Union Risk assessment report: Alkanes, C14-17, Part II-Human Health, Luxembourg: Office for Official Publications of the European Community Pellizzato, Francesca. "Analysis of short-chain chlorinated paraffins: A discussion paper". Journal of Environmental Monitoring. 9: 924–30. Doi:10.1039/b710053a. PMID 17726552. Tolbert, Paige E.. "Oils and Cancer". Cancer Causes & Control. 8: 386–405. Doi:10.1023/A:1018409422050. JSTOR 3552699. PMID 9498901. Short Chain Chlorinated Paraffins - Proposal for identification of a substance as a CMR, PBT, vPvB or a substance of an equivalent level of concern
Lead is a chemical element with symbol Pb and atomic number 82. It is a heavy metal, denser than most common materials. Lead is soft and malleable, has a low melting point; when freshly cut, lead is silvery with a hint of blue. Lead has the highest atomic number of any stable element and three of its isotopes each include a major decay chain of heavier elements. Lead is a unreactive post-transition metal, its weak metallic character is illustrated by its amphoteric nature. Compounds of lead are found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are limited to organolead compounds. Like the lighter members of the group, lead tends to bond with itself. Lead is extracted from its ores. Galena, a principal ore of lead bears silver, interest in which helped initiate widespread extraction and use of lead in ancient Rome. Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. In 2014, the annual global production of lead was about ten million tonnes, over half of, from recycling.
Lead's high density, low melting point and relative inertness to oxidation make it useful. These properties, combined with its relative abundance and low cost, resulted in its extensive use in construction, batteries and shot, solders, fusible alloys, white paints, leaded gasoline, radiation shielding. In the late 19th century, lead's toxicity was recognized, its use has since been phased out of many applications. However, many countries still allow the sale of products that expose humans to lead, including some types of paints and bullets. Lead is a toxin that accumulates in soft tissues and bones, it acts as a neurotoxin damaging the nervous system and interfering with the function of biological enzymes, causing neurological disorders, such as brain damage and behavioral problems. A lead atom has 82 electrons, arranged in an electron configuration of 4f145d106s26p2; the sum of lead's first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, lead's upper neighbor in the carbon group.
This is unusual. The similarity of ionization energies is caused by the lanthanide contraction—the decrease in element radii from lanthanum to lutetium, the small radii of the elements from hafnium onwards; this is due to poor shielding of the nucleus by the lanthanide 4f electrons. The sum of the first four ionization energies of lead exceeds that of tin, contrary to what periodic trends would predict. Relativistic effects, which become significant in heavier atoms, contribute to this behavior. One such effect is the inert pair effect: the 6s electrons of lead become reluctant to participate in bonding, making the distance between nearest atoms in crystalline lead unusually long. Lead's lighter carbon group congeners form stable or metastable allotropes with the tetrahedrally coordinated and covalently bonded diamond cubic structure; the energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals. In lead, the inert pair effect increases the separation between its s- and p-orbitals, the gap cannot be overcome by the energy that would be released by extra bonds following hybridization.
Rather than having a diamond cubic structure, lead forms metallic bonds in which only the p-electrons are delocalized and shared between the Pb2+ ions. Lead has a face-centered cubic structure like the sized divalent metals calcium and strontium. Pure lead has a silvery appearance with a hint of blue, it tarnishes on contact with moist air and takes on a dull appearance, the hue of which depends on the prevailing conditions. Characteristic properties of lead include high density, malleability and high resistance to corrosion due to passivation. Lead's close-packed face-centered cubic structure and high atomic weight result in a density of 11.34 g/cm3, greater than that of common metals such as iron and zinc. This density is the origin of the idiom to go over like a lead balloon; some rarer metals are denser: tungsten and gold are both at 19.3 g/cm3, osmium—the densest metal known—has a density of 22.59 g/cm3 twice that of lead. Lead is a soft metal with a Mohs hardness of 1.5. It is somewhat ductile.
The bulk modulus of lead—a measure of its ease of compressibility—is 45.8 GPa. In comparison, that of aluminium is 75.2 GPa. Lead's tensile strength, at 12–17 MPa, is low; the melting point of lead—at 327.5 °C —is low compared to most metals. Its boiling point of 1749 °C is the lowest among the carbon group elements; the electrical resistivity of lead at 20 °C is 192 nanoohm-meters an order of magnitude higher than those of other industrial metals. Lead is a superconductor at temperatures lower than 7.19 K.
Bisphenol A is an organic synthetic compound with the chemical formula 2C2 belonging to the group of diphenylmethane derivatives and bisphenols, with two hydroxyphenyl groups. It is a colorless solid, soluble in organic solvents, but poorly soluble in water. BPA is a starting material for the synthesis of plastics certain polycarbonates and epoxy resins, as well as some polysulfones and certain niche materials. BPA-based plastic is clear and tough, is made into a variety of common consumer goods, such as plastic bottles including water bottles, sports equipment, CDs, DVDs. Epoxy resins containing BPA are used to line water pipes, as coatings on the inside of many food and beverage cans and in making thermal paper such as that used in sales receipts. In 2015, an estimated 4 million tonnes of BPA chemical were produced for manufacturing polycarbonate plastic, making it one of the highest volume of chemicals produced worldwide. BPA is a xenoestrogen, exhibiting estrogen-mimicking, hormone-like properties that raise concern about its suitability in some consumer products and food containers.
Since 2008, several governments have investigated its safety, which prompted some retailers to withdraw polycarbonate products. The U. S. Food and Drug Administration has ended its authorization of the use of BPA in baby bottles and infant formula packaging, based on market abandonment, not safety; the European Union and Canada have banned BPA use in baby bottles. World production capacity of BPA was 1 million tons in the 1980s, more than 2.2 million tons in 2009. It is a high production volume chemical; this compound is synthesized by the condensation of acetone with two equivalents of phenol. The reaction is catalyzed by a strong acid, such as hydrochloric acid or a sulfonated polystyrene resin. Industrially, a large excess of phenol is used to ensure full condensation. In 2003, U. S. consumption was 856,000 tons, 72% of which used to make polycarbonate plastic and 21% going into epoxy resins. In the U. S. less than 5% of the BPA produced is used in food contact applications, but remains in the canned food industry and printing applications such as sales receipts.
Bisphenol A and phosgene react to give polycarbonate. The reaction is conducted under biphasic conditions, it is a precursor in production of major classes of resins the vinyl ester resins. This application begins with alkylation of BPA with epichlorohydrin. BPA is a versatile building block. Nitration give dinitrobisphenol A. Bromination gives tetrabromobisphenol A, which exhibits fire retardant properties. BPA is used in the synthesis of polysulfones and some Polyether ether ketones, it is an antioxidant in some plasticizers, as a polymerization inhibitor in PVC. Several drug candidates have been developed from bisphenol A, including Ralaniten, #Ralaniten acetate, EPI-001. In the U. S. plastic packaging is split into seven broad classes for recycling purposes by a Plastic identification code. As of 2014 there are no BPA labeling requirements for plastics in the U. S. "In general, plastics that are marked with Resin Identification Codes 1, 2, 4, 5, 6 are unlikely to contain BPA. Some, but not all, plastics that are marked with the Resin Identification Code 7 may be made with BPA."
Type 7 is the catch-all "other" class, some type 7 plastics, such as polycarbonate and epoxy resins, are made from bisphenol A monomer. Type 3 may contain bisphenol A as an antioxidant in "flexible PVC" softened by plasticizers, but not rigid PVC such as pipe and siding. Bisphenol A was discovered in 1891 by Russian chemist Aleksandr Dianin. In 1934 workers at I. G. Farbenindustrie reported the coupling of epichlorohydrin. Over the following decade 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. 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 and General Electric, Bayer. In terms of the endocrine disruption controversy, the British biochemist Edward Charles Dodds tested BPA as an artificial estrogen in the early 1930s.
He found BPA to be 1 / 37,000 as effective as estradiol. Dodds developed a structurally similar compound, diethylstilbestrol, used as a synthetic estrogen drug in women and animals until it was banned due to its risk of causing cancer. BPA was never used as a drug. BPA's ability to mimic the effects of natural estrogen derive from the similarity of phenol groups on both BPA and estradiol, which enable this synthetic molecule to trigger estrogenic pathways in the body. Phenol-containing molecules similar to BPA are known to exert weak estrogenic activities, thus it is considered an endocrine disrupter and estrogenic chemical. Xenoestrogens is another category the chemical BPA fits under because of its capability to interrupt the network that regulates the signals which control the reproductive development in humans and animals. BPA has been found to bind to both of the nuclear estrogen receptors