Biphenyls dichlorinated

Starting from different dichlorinated acetylenes 485,494 and 495, and using dichlorodi-methylsilane or dichlorodimethylgermane as electrophiles, the corresponding macrocyclic diynes 496-498 were obtained via a biphenyl-catalyzed (ca 20%) lithiation in THF at -20 °C (Scheme... 

Working with a dichlorinated disilane or dichlorophosphines as electrophiles, 499 and 500 were prepared in low yields from dichlorinated acetylenes 485 and 494 and using a biphenyl-catalyzed (ca 20%) lithiation (Scheme 139) . 

The corresponding catalytic version of this reaction was performed using either naphthalene- or biphenyl-supported polymers 594 or 595, respectively, which were prepared by cross-coupling copolymerization of 2-vinylnaphthalene or 4-vinylbiphenyl with vinyl-benzene and divinylbenzene promoted by AIBN in THF and polyvinyl alcohoP . These polymers have been used as catalysts (10%) in lithiation reactions involving either chlorinated functionalized compounds or dichlorinated materials in THF at —78°C and were re-used up to ten times without loss of activity, which is comparable to the use of the corresponding soluble arenes. 

According to the literature survey of Sundstrom and Hutzinger [11], there have been many patents for PCDEs and desired applications have included use as hydraulic fluids, electric insulators, flame retardants, lubricants, and plasticizers. Ethers have had wide use in industry and they appear in heat transfer agents like a mixture of diphenyl ether (73.5%) and biphenyl (26.5%), Dowtherm A [12]. Lower chlorinated PCDEs, mono- and dichlorinated, have... 

CZE 01 Jan 1999 The chemical is severely restricted. Production, import, export and distribution of the preparations containing more than 0.005% by weight of the substance is banned (with exception of mono-and dichlorinated biphenyls). The production and import ofthe substance for research, scientific and analytic purposes in quantity less than 100 g per year from one producer or importer is permitted. 

A second group of specific xenobiotics in Teltow Canal sediments are halogenated aromatics. Several chlorinated and brominated mono- and diaromatic hydrocarbons were detected in high amounts within the extractable organic matter as reported previously (Schwarzbauer et al. 2001). The halogenated arenes identified in the hydrolysis extracts included mono- and dichlorinated naphthalenes 12+13. mono- and dihrominated naphthalenes 14+15. tetra- to hexachlorinated biphenyls (PCB) and 2,4,6-tribomoaniline. The peak pattern of the chlorinated naphthalenes was similar to the congener distribution in technical mixtures e.g. Halowax 1000 (Falandysz 1998). 

A. Botta el al. (28) show that K-zeolite L enables the selective dichlorination of biphenyl 27 to give the 4,4 isomer 28. In addition, Lewis acid catalysed chlorination of biphenyl gives mixtures consisting mainly of 29, 30 - 32. 

Polychlorinated (not mono- and dichlorinated) biphenyls (PCB), biphenyls, polychlorinated terphenyls (PCT), and preparations including waste oils with a PCB or PCT content higher than 0.005 % by weight may not be used. 

Mono- and dichlorinated biphenyls can be metabolised to dihydroxy compounds and further oxidised to reactive metabolites which form adducts with nitrogen and sulphur nucleophiles including DNA (Amaro et al. 1996, Oakley et al. 1996). The former studies also demonstrated that during the metabolism of polychlorinated biphenyls superoxide... 

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