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Polychlorinated Diphenyl Ethers
Polychlorinated diphenyl ethers (PCDEs) are structurally similar to polychlorinated biphenyls (PCBs), both which may be toxic polyhalogenated compounds and some PCDE congeners have been reported to cause toxic responses similar to those caused by some of the non- ortho-substituted PCBs, which are mediated by the aryl hydrocarbon receptor ( AhR). Congeners The family of PCDEs consists of 209 possible substances, which are called congeners. See also * Polybrominated diphenyl ethers References {{reflist Chloroarenes Immunotoxins ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polychlorinated Biphenyls
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 1979 and internationally by the Stockholm Convention on Persistent Organic Pollutants in 2001. They are organic chlorine compounds with the formula C12 H10−''x'' Cl''x''; they were once widely used in the manufacture of carbonless copy paper, as heat transfer fluids, and as dielectric and coolant fluids for electrical equipment. Because of their longevity, PCBs are still widely in use, even though their manufacture has declined drastically since the 1960s, when a host of problems were identified. With the discovery of PCBs' environmental toxicity, and classification as persistent organic pollutants, their production was banned by United States federal law in 1978, and by the Stockholm Convention on Persistent Organic Pollutants in 2001. The International Agency f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyhalogenated Compound
Polyhalogenated compounds (PHCs) are any compounds with multiple substitutions of halogens. They are of particular interest and importance because they bioaccumulate in humans, and comprise a superset of which has many toxic and carcinogenic industrial chemicals as members. PBDEs, PCBs, dioxins (PCDDs) and PFCs are all polyhalogenated compounds. They are generally non-miscible in organic solvents or water, but miscible in some hydrocarbons from which they often derive. Uses PHCs are used in a vast array of manufactured products, from wood treatments to cookware coatings, to non-stick, waterproof, and fire-resistant coatings, cosmetics, medicine, electronic fluids, food containers, and wrappings, in everything from furniture and furnishings, automobiles, airplanes, plastics, clothing and cloth, surgery, insulation, adhesives, paints, sealants, lubricating oils, polyurethane foams, cancer therapy, and medical imaging. They are also heavily used in pest control. Safety PHCs i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congener (chemistry)
In chemistry, congeners are chemical substances "related to each other by origin, structure, or function". Common origin and structure Any significant quantity of a polyhalogenated compound is by default a blend of multiple molecule types because each molecule forms independently, and chlorine and bromine do not strongly select which site(s) they bond to. * Polychlorinated biphenyls (PCBs) are a family of 209 congeners. * Polybrominated biphenyls and polychlorinated diphenyl ethers are also families of 209 congeners. Similarly polychlorinated dibenzodioxins, polychlorinated dibenzofurans, polychlorinated terphenyls, polychlorinated naphthalene, polychloro phenoxy phenol, and polybrominated diphenyl ethers (PBDEs) (pentabromodiphenyl ether, octabromodiphenyl ether, decabromodiphenyl ether), etc. are also groups of congeners. Common origin * Congener (alcohol), substances other than alcohol (desirable or undesirable) also produced during fermentation. *Congeners of oleic a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ortho-substituted
Arene substitution patterns are part of organic chemistry IUPAC nomenclature and pinpoint the position of substituents other than hydrogen in relation to each other on an aromatic hydrocarbon. ''Ortho'', ''meta'', and ''para'' substitution * In ''ortho''-substitution, two substituents occupy positions next to each other, which may be numbered 1 and 2. In the diagram, these positions are marked R and ''ortho''. * In ''meta''-substitution the substituents occupy positions 1 and 3 (corresponding to R and ''meta'' in the diagram). * In ''para''-substitution, the substituents occupy the opposite ends (positions 1 and 4, corresponding to R and ''para'' in the diagram). The toluidines serve as an example for these three types of substitution. Synthesis Electron donating groups, for example amino, hydroxyl, alkyl, and phenyl groups tend to be ''ortho''/''para''-directors, and electron withdrawing groups such as nitro, nitrile, and ketone groups, tend to be ''meta''-directors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polybrominated Diphenyl Ethers
Polybrominated diphenyl ethers or PBDEs, are a class of organobromine compounds that are used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, furnishings, motor vehicles, airplanes, plastics, polyurethane foams, and textiles. They are structurally akin to polychlorinated diphenyl ethers (PCDEs), polychlorinated biphenyls (PCBs) and other polyhalogenated compounds, consisting of two halogenated aromatic rings. PBDEs are classified according to the average number of bromine atoms in the molecule. The health hazards of these chemicals have attracted increasing scrutiny, and they have been shown to reduce fertility in humans at levels found in households. Because of their toxicity and persistence, the industrial production of some PBDEs is restricted under the Stockholm Convention, a treaty to control and phase out major persistent organic pollutants (POPs). Classes of PBDEs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroarenes
In organic chemistry, an aryl halide (also known as haloarene) is an aromatic compound in which one or more hydrogen atoms, directly bonded to an aromatic ring are replaced by a halide. The haloarene are different from haloalkanes because they exhibit many differences in methods of preparation and properties. The most important members are the aryl chlorides, but the class of compounds is so broad that there are many derivatives and applications. Preparation The two main preparatory routes to aryl halides are direct halogenation and via diazonium salts. Direct halogenation In the Friedel-Crafts halogenation, Lewis acids serve as catalysts. Many metal chlorides are used, examples include iron(III) chloride or aluminium chloride. The most important aryl halide, chlorobenzene is produced by this route. Monochlorination of benzene is always accompanied by formation of the dichlorobenzene derivatives. Arenes with electron donating groups react with halogens even in the absence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
