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Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene [4] or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one hydrogen (the site at which it is attached) may use the prefixes xenyl or diphenylyl .
Biphenylene was first synthesized by Lothrop in 1941. [12] The biphenylene structure can also be understood as a dimer of the reactive intermediate benzyne, which in fact serves as a major synthetic route, by heating the benzenediazonium-2-carboxylate zwitterion prepared from 2-aminobenzoic acid. [13]
Polychlorinated biphenyls (PCBs) are organochlorine compounds with the formula C 12 H 10−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. [2]
The aromatic hydrocarbon structure gives PCBs relatively high molecular stability. The chlorine substitution further reinforces its insolubility and chemical stability. Hence, the degradation of PCBs in the natural environment is very slow, which can range from 3 to 37 years depending on the number of chloride substitutions and their positions.
If deinking is not performed then the BPA remains in the fibers, paper recycled this way is usually made into corrugated fiberboard. [9] Ethoxylated BPA finds minor use as a 'levelling agent' in tin electroplating. Several drug candidates have also been developed from bisphenol A, including ralaniten, ralaniten acetate, and EPI-001.
The USEPA Reference dose (RfD) for BPA is 50 μg/kg/day which is not enforceable but is the recommended safe level of exposure. The most sensitive animal studies show effects at much lower doses, [ 92 ] [ 173 ] and several studies of children, who tend to have the highest levels, have found levels over the EPA's suggested safe limit figure.
A polyhalogenated compound (PHC) is any compound 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.
In general, the term polycyclic includes polycyclic aromatic compounds, including polycyclic aromatic hydrocarbons, as well as heterocyclic aromatic compounds with multiple rings (where heteroaromatic compounds are aromatic compounds that contain sulfur, nitrogen, oxygen, or another non-carbon atoms in their rings in addition to carbon).