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Biphenyl is a solid at room temperature, with a melting point of 69.2 °C (156.6 °F). In the gas phase the molecule exists in two enantiomorphic twisted forms with an angle between the planes of the two rings of 44.4(2)°. [6] In the room-temperature solid, biphenyl is crystalline with space group P2 1 /c, which does not allow for chiral ...
PCBs share the basic chemical structure of biphenyl and one or more of the hydrogen atoms on the aromatic rings are replaced by chlorine atoms. [1] PCBs is in viscous liquid form at normal temperature and has a poor solubility in water. The aromatic hydrocarbon structure gives PCBs relatively high molecular stability.
The agency has issued guidance publications for safe removal and disposal of PCBs from existing equipment. [184] EPA defined the "maximum contaminant level goal" for public water systems as zero, but because of the limitations of water treatment technologies, a level of 0.5 parts per billion is the actual regulated level (maximum contaminant ...
The industrial synthesis of 4,4′-biphenol was developed by Allan Hay in the 1960s. [2] [3] As the direct oxidative coupling of phenol gives a mixture of isomers, [4] [5] 4,4′-biphenol is instead prepared from 2,6-di-tert-butylphenol, where para-coupling is the only possibility. [3]
HBCD is toxic to water-living organisms. The UNEP Stockholm Convention has listed HBCD for elimination, but allowing a temporary exemption for the use in polystyrene insulation foams in buildings. [4] Tetrabromobisphenol A (TBBPA or TBBP-A) is mainly used in printed circuit boards, as a reactive flame retardant.
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 ]
Some organochlorine compounds, such as sulfur mustards, nitrogen mustards, and Lewisite, are even used as chemical weapons due to their toxicity. [citation needed] However, the presence of chlorine in an organic compound does not ensure toxicity. Some organochlorides are considered safe enough for consumption in foods and medicines.
Dibenzothiophene is prepared by the reaction of biphenyl with sulfur dichloride in the presence of aluminium chloride. [2] Reduction with lithium results in scission of one C-S bond. With butyllithium, this heterocycle undergoes stepwise lithiation at the 4-position. S-oxidation with peroxides gives the sulfoxide. [3]