Polyhalogenated hydrocarbons

Skalsky HL, Farris MW, Blanke RV, et al. 1979. The role of plasma proteins in the transport and distribution of chlordecone (Kepone ) and other polyhalogenated hydrocarbons. In Nicholson WJ, Moore JA, eds. Annals of the New York Academy of Sciences, Health Effects of Halogenated Aromatic Hydrocarbons International Symposium, New York, NY, USA, June 24-27, 1978. New York, NY New York Academy of Sciences, 320 231-237. 

From phosphorus trichloride, benzyl alcohol and 2 mol. of a tertiary base, dibenzyl hydrogen phosphite (XIV), is obtained which on treatment with chlorine or a chlorinating agent (e.g. sulphuryl chloride)4 gives the phosphorochloridate (XV). Although not isolated, (XV) is almost certainly obtained by treatment of (XIV) with a polyhalogen hydrocarbon because reaction in the presence of an alcohol or of a primary or secondary amine gives a triester (XVI) or a phosphoramidate. 

Fiorucci L, Monti A, Testai E, et al. 1988. In vitro effects of polyhalogenated hydrocarbons on liver mitochondria respiration and microsomal cytochrome p-450. Drug Chem Toxicol 11 387-403. 

Yamada M, Ishiwada A, Hobo T, et al. 1982. Novel chemiluminescence detector for determination of volatile polyhalogenated hydrocarbons by gas chromatography. J Chromatogr 238 347. 

Polyhalogenated hydrocarbons such as PCBs and PBBs cat such extensive induction in theliver and kidneys that the liver will dramatically increase in size and weight. TCDD, a dioxin, also alter some drug biotransformations as does DDT. 

Why do so many high-volume production chemicals contain several halogen atoms Why are polyhalogenated hydrocarbons rather persistent in the environment ... 

Give at least five examples of polyhalogenated hydrocarbons and explain what kind of environmental problems they cause. 

Table 13.7 Kinetic Data on Nucleophilic Substitution and Nonreductive Elimination (Dehydrohalogenation) Reactions of Some Polyhalogenated Hydrocarbons in Aqueous Solution at 25 °C ... 

Although dehydrohalogenation of polyhalogenated hydrocarbons is not hydrolysis by the strictest definition, it is an environmentally important reaction in water because many haloge-nated compounds are environmentally important. Equation (25) shows dehydrohalogenation ... 

Bis[dihydrobis(l-pyrazolyl)borato]nickel(II), m.p. 181-182°C., forms well-shaped orange crystals, readily soluble in methylene chloride, chloroform, and aromatic hydrocarbons. The latter are preferred since polyhalogenated hydrocarbons react slowly with this compound at room temperature and rapidly in hot solutions. Its infrared spectrum exhibits a complex BH2 multiplet in the 2200-2500-cm.-1 region. 

Polyhalogenated Hydrocarbons Used as Anesthetics Halogenation A Medical Perspective ... 

Admittedly haloolefins in which the halogen is attached to doubly bonded carbon are prepared both in the laboratory and industrially by removing halogen (X2) or hydrogen halide (HX) from polyhalogenated hydrocarbons. 

Fig. 15.4 Multi-sampler for collection of polyhalogenated hydrocarbons in diesel exhaust, (a) Side view, (b) Top view. (Reproduced from [30] with permission of Marcel Dekker, Inc.).

Although valence-band electron holes on most semiconductors are strong oxidants, their conduction-band electrons are not very powerful. In spite of persistant efforts, success in some reductive semiconductor-mediated photo-catalytic processes, such as fixation of carbon dioxide and nitrogen, has been limited. However, reductive degradation of some electron-deficient compounds such as polyhalogenated hydrocarbons and metal recovery have shown promising results [84]. In addition, a reductive process is easier to control and thus more suitable for organic synthesis. 

Such carbene complexes may also be formed reductively by cytochrome P450 of liver microsomes from geminal polyhalogenated hydrocarbons. In the case of halothane a complex with a Soret absorption band at 470 nm is formed which was explained by a carbene formation according to the equations given in Fig. 

Figure 5.18 Relation between the excretion rate constant ( 2) and octanol-water partition coefficient (ATd,oct) for polyhalogenated hydrocarbons chlorinated dibenzofurans O, chlorinated dibenzodioxins O, brominated biphenyls T, chlorinated naphthalenes , brominated benzenes , chlorinated biphenyls , chlorinated benzenes. [Reproduced with permission from A. Opperhuizen and D. T. H. M. Sijm, Environ. Toxicol. Chem. 9, 175 (1990). Copyright SETAC, Pensacola, FL, USA.]...

Numerous studies have demonstrated that the facile reduction of organic pollutants such as nitroaromatics, azo compounds, and polyhalogenated hydrocarbons can occur in anaerobic environments with exceedingly fast reaction rates. The most abundant electron donors in these systems include reduced iron and sulfur species. Laboratory studies, however, indicate that the rates of reduction by these bulk reductants are much slower than those observed in natural reducing systems. The addition of electron carriers or mediators to the laboratory systems is found to greatly accelerate the measured reduction rates. An electron shuttle system has been postulated to account for the enhanced reactivity observed in these laboratory studies and presumably in reducing natural systems (Dunnivant et al., 1992). 

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