![]() | This article has multiple issues. Please help improve it or discuss these issues on the talk page . (Learn how and when to remove these template messages)
|
![]() | |
Names | |
---|---|
IUPAC name IUPAC 4,5,11,12-tetrachloro-8-oxatricyclo[7.4.0.02,7]trideca-1(13),2,4,6,9,11-hexaene | |
Other names
| |
Identifiers | |
3D model (JSmol) | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.223.045 |
KEGG | |
PubChem CID | |
CompTox Dashboard (EPA) | |
| |
| |
Properties | |
C12H4Cl4O | |
Molar mass | 305.96 g·mol−1 |
Appearance | Colorless Crystals |
Melting point | 227 °C (441 °F; 500 K) |
6.92e-07 mg/mL at 26 °C [1] [ full citation needed ] | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
2,3,7,8-Tetrachlorodibenzofuran (TCDF) is a polychlorinated dibenzofuran with a chemical formula of C12H4Cl4O. TCDF is part of the chlorinated benzofuran (CDF) family that contain between 1 and 8 chlorine atoms attached to the parent dibenzofuran ring system. The CDF family includes 135 compounds, of which only a few have been studied.
TCDF was discovered in the mid-20th century along with other CDFs. It was found to be an unwanted by-product in the manufacturing of chlorinated compounds; it is not commercially used or produced itself. TDCF is directly released into the environment via emissions of waste incineration, fires with PCB transformers, vehicle exhausts using leaded fuel, and bleaching of industrial products.
TCDF and other CDFs are known to have a lasting impact on the environment. TDCF can exist as both a gas and particles in the atmosphere, which result in deposition in the soil. It has an estimated half-life of around 60 days in the soil and atmosphere. This molecule can easily accumulate in the food chain, leading to potential human exposure. TDCF is listed as a hazardous air pollutant in the Clean Air Act of the 1990s. Monitoring programmes are established to keep track of the levels on TDCF in various environmental compartments to avoid damaging ecosystems.
TCDF is not purposefully manufactured. [2] It is formed as a by-product of industrial manufacturing processes which place chlorine atoms in favorable reaction conditions, which include alkaline mediums, temperatures over 150°C, and exposure to UV light, or radical forming substances. [2] In the production of chlorinated pesticides CDFs are formed as byproducts by intermolecular condensation of ortho-chlorophenols. [2] Intramolecular cyclization reactions of predibenzofurans also result in CDFs. [2] In thermal waste treatment processes CDFs are produced by combustion and pyrolysis of organochlorine or non-chlorinated organic compounds in the presence of chlorides. [2] The recycling of metal cables also leads to the formation of CDFs as chlorine is formed by burning the insulator polyvinylchloride which causes new CDFs. [2] From PCBs, the production of CDFs can happen by the loss of two ortho clorines, loss of ortho as well as chlorine, loss of an ortho hydrogen and chlorine with an additional shift of chlorine from the 2 to 3 position, or loss of two ortho hydrogens. [2]
TCDF is not made industrially and there are no commercial uses for it. [2] TCDF is released into the air as vapour after burning of hazardous waste, fires involving PCB mixtures and a byproduct of bleaching pulp.[ citation needed ] Some of this vapour remains in the air as particles but some of it gets deposited into the soil as well as water.[ citation needed ] Most of the exposure and available forms is through the air and the consumption of high fat meats that were exposed to the 2,3,7,8-Tetrachloro-dibenzofuran. [2]
TCDF is one of the most toxic congeners of the polychlorinated dibenzofurans. [3] Its toxicity is associated with fatty liver disease. [4] Mainly the toxicity of TCDF has been recorded through testing of breast milk, adipose tissue and blood serum. It is at this moment not yet classifiable as to its carcinogenicity to humans, classified therefore as type 3 of the IARC (International Agency for Research on Cancer). Toxicity levels and baselines are not yet known in humans but are being tested on animals. [5]
The recorded effects on animals are most commonly investigated in the house mouse as well as male guinea pigs. Exposure to TCDF has led to problems in multiple organs within mice such as its liver, jejunum, cecum, small intestine, large intestine. In general, the liver is the main target of TCDF, which leads to induced hepatic lipogenesis. [4] When testing on female mice, the effects on embryos were recorded, showing that TCDF has the strongest effect on fetal kidneys and leads to 100% of fetuses to be teratogenic at toxicity levels which are not fatal for the mother. [3] The exposure to TCDF leads to a decrease in glucose homeostasis leading to an abundance of glucose in the mouse body. It also promotes the increment in bile acid metabolic processes which leads to an increase in multiple acids such as deoxycholic acid, glycocholic acid, taurochenodeoxycholic acid, tauromuricholic acid, lithocholic acid, chenodeoxycholic acid, taurolithocholic acid, and an abundance of bile acids and salts.[ citation needed ] As mentioned previously, it affects the liver as it results in a positive regulation of lipid biosynthetic processes leading to an abundance of unsaturated fatty acids.[ citation needed ] The baseline toxicity levels for TCDF are known for the mouse, the guinea pig and monkey, being at LD50 Guinea pig (Hartley, male, 3-4 wk old) oral 5-10 ug/kg, LD50 Mouse (C57B1/6, male, 6 wk old) oral >6,000 ug/kg, and LD50 monkey (Macaca mulatta, female, 2.0-3.7 kg) oral 1,000 ug/k. [6]
Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1976 and internationally by the Stockholm Convention on Persistent Organic Pollutants in 2001.
Polychlorinated dibenzodioxins (PCDDs), or simply dioxins, are a group of long-lived polyhalogenated organic compounds that are primarily anthropogenic, and contribute toxic, persistent organic pollution in the environment.
Chloracne is an acneiform eruption of blackheads, cysts, and pustules associated with exposure to certain halogenated aromatic compounds, such as chlorinated dioxins and dibenzofurans. The lesions are most frequently found on the cheeks, behind the ears, in the armpits and groin region.
Ethion (C9H22O4P2S4) is an organophosphate insecticide. Ethion is known to affect a neural enzyme called acetylcholinesterase and prevent it from working.
Hexachlorobenzene, or perchlorobenzene, is an aryl chloride and a six-substituted chlorobenzene with the molecular formula C6Cl6. It is a fungicide formerly used as a seed treatment, especially on wheat to control the fungal disease bunt. It has been banned globally under the Stockholm Convention on Persistent Organic Pollutants.
This is a complete list of polychlorinated biphenyl (PCB) congeners.
Benzotrichloride (BTC), also known as α,α,α-trichlorotoluene, phenyl chloroform or (trichloromethyl)benzene, is an organic compound with the formula C6H5CCl3. Benzotrichloride is an unstable, colorless or somewhat yellowish, viscous, chlorinated hydrocarbon with a penetrating odor. Benzotrichloride is used extensively as a chemical intermediate for products of various classes, i.e. dyes and antimicrobial agents.
1,1,2,2-tetrachloroethane (TeCA), also known by the brand names Bonoform, Cellon and Westron, is an organic compound. It is colorless liquid and has a sweet odor. It is used as an industrial solvent and as a separation agent. TeCA is toxic and it can be inhaled, consumed or absorbed through the skin. After exposure, nausea, dizziness or even liver damage may occur.
1,4-Dioxin (also referred as dioxin or p-dioxin) is a heterocyclic, organic, non-aromatic compound with the chemical formula C4H4O2. There is an isomeric form of 1,4-dioxin, 1,2-dioxin (or o-dioxin). 1,2-Dioxin is very unstable due to its peroxide-like characteristics.
Polychlorinated dibenzofurans (PCDFs) are a family of organic compounds with one or several of the hydrogens in the dibenzofuran structure replaced by chlorines. For example, 2,3,7,8-tetrachlorodibenzofuran (TCDF) has chlorine atoms substituted for each of the hydrogens on the number 2, 3, 7, and 8 carbons. Polychlorinated dibenzofurans with chlorines at least in positions 2,3,7 and 8 are much more toxic than the parent compound dibenzofurane, with properties and chemical structures similar to polychlorinated dibenzodioxins. These groups together are often inaccurately called dioxins. They are known developmental toxicants, and suspected human carcinogens. PCDFs tend to co-occur with polychlorinated dibenzodioxins (PCDDs). PCDFs can be formed by pyrolysis or incineration at temperatures below 1200 °C of chlorine containing products, such as PVC, PCBs, and other organochlorides, or of non-chlorine containing products in the presence of chlorine donors. Dibenzofurans are known persistent organic pollutants (POP), classified among the dirty dozen in the Stockholm Convention on Persistent Organic Pollutants.
Dinoseb is a common industry name for 6-sec-butyl-2,4-dinitrophenol, a herbicide in the dinitrophenol family. It is a crystalline orange solid which does not readily dissolve in water. Dinoseb is banned as an herbicide in the European Union (EU) and the United States because of its toxicity.
Dioxins and dioxin-like compounds (DLCs) are a group of chemical compounds that are persistent organic pollutants (POPs) in the environment. They are mostly by-products of burning or various industrial processes or, in the case of dioxin-like PCBs and PBBs, unwanted minor components of intentionally produced mixtures.
Norbormide is a toxic compound used as a rodenticide. It has several mechanisms of action, acting as a vasoconstrictor and calcium channel blocker, but is selectively toxic to rats and has relatively low toxicity to other species, due to a species specific action of opening the permeability transition pores in rat mitochondria.
Chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) are a group of compounds comprising polycyclic aromatic hydrocarbons with two or more aromatic rings and one or more chlorine atoms attached to the ring system. Cl-PAHs can be divided into two groups: chloro-substituted PAHs, which have one or more hydrogen atoms substituted by a chlorine atom, and chloro-added Cl-PAHs, which have two or more chlorine atoms added to the molecule. They are products of incomplete combustion of organic materials. They have many congeners, and the occurrences and toxicities of the congeners differ. Cl-PAHs are hydrophobic compounds and their persistence within ecosystems is due to their low water solubility. They are structurally similar to other halogenated hydrocarbons such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). Cl-PAHs in the environment are strongly susceptible to the effects of gas/particle partitioning, seasonal sources, and climatic conditions.
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a polychlorinated dibenzo-p-dioxin (sometimes shortened, though inaccurately, to simply 'dioxin') with the chemical formula C12H4Cl4O2. Pure TCDD is a colorless solid with no distinguishable odor at room temperature. It is usually formed as an unwanted product in burning processes of organic materials or as a side product in organic synthesis.
Toxic equivalency factor (TEF) expresses the toxicity of dioxins, furans and PCBs in terms of the most toxic form of dioxin, 2,3,7,8-TCDD. The toxicity of the individual congeners may vary by orders of magnitude.
Methacrylonitrile, MeAN in short, is a chemical compound that is an unsaturated aliphatic nitrile, widely used in the preparation of homopolymers, copolymers, elastomers, and plastics and as a chemical intermediate in the preparation of acids, amides, amines, esters, and other nitriles. MeAN is also used as a replacement for acrylonitrile in the manufacture of an acrylonitrile/butadiene/styrene-like polymer. It is a clear and colorless liquid, that has a bitter almond smell.
Persistent, bioaccumulative and toxic substances (PBTs) are a class of compounds that have high resistance to degradation from abiotic and biotic factors, high mobility in the environment and high toxicity. Because of these factors PBTs have been observed to have a high order of bioaccumulation and biomagnification, very long retention times in various media, and widespread distribution across the globe. Most PBTs in the environment are either created through industry or are unintentional byproducts.
1,2,3,4,6,7,8-Heptachlorodibenzo-para-dioxin (often referred to as 1,2,3,4,6,7,8-HpCDD) is a polychlorinated derivative of dibenzo-p-dioxin and can therefore be categorized as polychlorinated dibenzo-p-dioxin (PCDD), a subclass of dioxins which includes 75 congeners. HpCDD is the dibenzo-p-dioxin which is chlorinated at positions 1, 2, 3, 4, 6, 7, and 8. It is a polycyclic heterocyclic organic compound, since HpCDD contains multiple cyclic structures (two benzene rings connected by a 1,4-dioxin ring) in which two different elements (carbon and oxygen) are members of its rings. HpCDD has molecular formula C12HCl7O2 and is an off-white powder, which is insoluble in water.
2,2',3,3',4,4'-Hexachlorobiphenyl is an organic chemical and belongs to a group of compounds called polychlorinated biphenyls. This group of organic compounds was used in transformers as dielectric fluids, until production was banned in 1979. While only being a part of this mixture, it is sometimes referred to as Aroclor 1260.