Halogenations dibenzofuran

Watanabe I, Kawano M, Tatsukawa R (1994), Organohalogen Compounds 19 235-238. The photolysis of halogenated dibenzofurans in hexane solution and on airborne dust by sunlight", Eds. University of Kyoto, Japan... 

J. A. Moore, et al., "Comparative Toxicity of Three Halogenated Dibenzofurans in Guinea Pigs, Mice, and Rhesus Monkeys," Ann. N.Y. Acad. Sci., 320 151-163, 1979. 

Naturally occurring oxaarenes based on polycyclic pyrans encompass a plethora of structures including the plant polyphenols such as anthocyanins and a-tocopherol (vitamin E). Halogenated dibenzo-p-dioxins and dibenzofurans are formed both as by-products during the manufacture of chlorophenols, and from the incineration of organic matter in the presence of inorganic halides. 

Rordorf, B.F. Prediction of vapor pressures, boiling points and enthalpies of fusion for twenty-nine halogenated dibenzo-p-dioxins and fifty-five dibenzofurans by a vapor pressure correlation method. Chemosphere, 18(l-6) 783-788,1989. Rosen, J.D. and Carey, W.F. Preparation of the photoisomers of aldrin and dieldrin. 7 Agric. Food Chem., 16(3) 536-537,1968. Rosen, J.D. and Strusz, R.F. Photolysis of 3-(p-bromophenyl)-l-methoxy-l-methylurea, 7 Agric. Food Chem., 16(4) 568-573, 1968. 

For halogenated aromatic hydrocarbons like polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and polychlorinated dibenzo-p-dioxins (PCDDs) the binding to the aryl hydrocarbon (Ah) receptor regulates their toxicity [89]. The Ah receptor controls the induction of one of the cytochrome P450 enzymes in the liver. Toxic responses such as thymic atrophy, iveight loss, immu-notoxicity and acute lethality are associated ivith the relative affinity of PCBs, PCDFs and PCDDs for the Ah receptor [89]. The quantitative structure-activity relationship (QSAR) models predicting the affinity of the halogenated aromatic hydrocarbons ivith the Ah receptor describe the electron acceptor capability as well as the hydrophobicity and polarizability of the chemicals [89[. 

Halogenation of dibenzofuran produces the 2-halo compounds. Bromina-tion can be achieved in good yield with bromine in acetic acid " or with N-bromosuccinimide in boiling carbon tetrachloride. The 2,8-dibromo compound has been made, using dioxane dibromide. Chlorination of dibenzofuran in acetic acid in the presence of iron powder can be controlled to yield the 2-chloro or the 2,8-dichloro compounds. 2-Chlorodi-benzofuran is best prepared by reaction of dibenzofuran with phosphorus pentachloride. 2-Iododibenzofuran (45%) results from treatment of dibenzofuran with iodine in boiling chloroform in the presence of nitric acid. 2,8-Diododibenzofuran is best prepared by reaction of dibenzofuran with iodine and iodic acid in aqueous acetic acid. ... 

Loganathan BG, Kannn K, Watanabe, et al. 1995. Isomer-specific determination and toxic evaluation of polychlrinated biphenyls, polychlorinated/brominated dibenzo-p-dioxins and dibenzofurans, polybrominated biphenyl ethers, and extractable organic halogen in carp from the Buffalo River, New York. Environ Sci Technol 29(7) 1832-1838. 

Weber LW, Greim H. 1997. The toxicity of brominated and mixed-halogenated dipenzo-p-dioxins and dibenzofurans an overview. J Toxicol Environ Health 50(3) 195-215. 

For biphenyls, dibenzofurans, dibenzo-p-dioxins, and their halogenated derivatives, Doucette and Andren [55] fitted solubility data with the following equation ... 

Nonhalogenated SVOCs do not contain halogens. The degree of volatilization from nonhalogenated SVOCs is much less than for nonhalogenated VOCs. The most common types of nonhalogenated SVOCs include pyrene, fluorene, and dibenzofuran. 

Rordorf, B.F. 1989. Prediction of vapor pressures, boiling points and enthalpies of fusion for twenty-nine halogenated dibenzo-p-dioxins and fifty-five dibenzofurans by a vapor pressure correlation method. Chemosphere 18 783-88. 

A comprehensive review of the metabolism of PCBs was published in 1976 by Sundstrom et al. (ref. 139a) confirming the importance of degree of substitution and location of halogens on toxicity. The lesser chlorinated biphenyls are more readily metabolized. The presence of at least two adjacent hydrogens—preferably in positions 3. 4, 5 or 3, 4, 5 —is required for the rapid metabolism of PCBs. This requirement is satisfied by all mono-, di- and trichlorobiphenyls, and by the tetrachlorobiphenyls with the exception of the 3. 3. 5. 5 -chlorinated PCB. This compound was reported particularly toxic to monkeys, and the intermediate formation of chlorinated dibenzofuran was postulated to account for this toxicity (ref. 139c). 

Akimoto, Y. and Y. Inouye. 1999. Behaviour of extractable organic halogens in a municipal solid waste incinerator and the relationship with that of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. J. Health Sci. 45 256-261. 

Kawano, M., M. Ueda, M. Matsui, Y. Kashima, M. Matsuda, and T. Wakimoto. 1998. Extractable organic halogens (EOX Cl, Br, and I), polychlorinated naphthalenes and polychlorinated dibenzo-p-dioxins and dibenzofurans in ashes from incinerators located in Japan. Organohalogen Compd. 36 221-224. 

Fiedler, H., Schramm, K.-W. (1990) QSAR generated octanol-water partition coefficients of selected mixed halogenated dibenzo-dioxins and dibenzofurans. Chemosphere 20, 1597-1602. 

Rordorf, B.F. (1990) Thermodynamic properties of halogenated dibenzo-p-dioxins, dibenzofurans and pesticides. In Proceedings of The International Conference on Organohalogen Compounds (Dioxin 1990) Belgium. 

Rordorf, B.F., Sama, L.P, Webster, G.R.B., Safe, S.H., Safe, L.M., Lenoir, D., Schwind, K.H., Hutzinger, O. (1990) Vapor pressure measurements on halogenated dibenzo-p-dioxins and dibenzofurans. An extended data set for a correlation method. Chemosphere 20, 1603-1609. 

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