Organohalogen compounds

Organohalogen Compounds. The compression of tetrafluoromethane has been recently studied by two groups. Kalfoglou and Miller covered the temperature range 300 to 770 K (pressures 3 to 50 bar), whilst Lange and Steincovered 203 to 368 K (pressures 6 to 80 bar) values of B and C were calculated from both sets of results. 

Low-pressure densities of trifluoromethane were measured by Hajjar and MacWood, and values of B for 40, 70,100, and 130 °C were derived. The compressibility of trifluoromethane (243 to 368 K 6 to 45 bar) was measured by Lange and Stein, who derived values of B and C. 

The density of difluoromethane (298 to 473 K 8 to 20 bar) was measured by Mears et al., who gave constants for a Martin-Hou equation of state. 

The densities of five chlorofluoromethanes, viz. CHFaCl, CHFCla, CFCI3, CF3CI, and CFgCla, were studied by Hajjar and MacWood in the temperature range 40 to 130 °C. From the results, values of Bp were calculated. Kunz and Kapner derived values of B for three of these compounds from an analysis of technical data. 

Haworth and Sutton measured Bp (25 to 50 °C) for CHF3, CHFaCl, CFsCl, CFaCla, CFa CHa, CHgBr, and CaHgCl. 

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Metallic Antimonides. Numerous binary compounds of antimony with metallic elements are known. The most important of these are indium antimonide [1312-41 -0] InSb, gallium antimonide [12064-03-8] GaSb, and aluminum antimonide [25152-52-7] AlSb, which find extensive use as semiconductors. The alkali metal antimonides, such as lithium antimonide [12057-30-6] and sodium antimonide [12058-86-5] do not consist of simple ions. Rather, there is appreciable covalent bonding between the alkali metal and the Sb as well as between pairs of Na atoms. These compounds are useful for the preparation of organoantimony compounds, such as trimethylstibine [594-10-5] (CH2)2Sb, by reaction with an organohalogen compound. 

Reactions of carbon nucleophiles with organohalogen compounds have great diversity for the construction of now carbon-carbon bonds. The intriguing synthon, ethoxyethynylsodium, is generated and alkylated in 1-ETHOXY-1-BUTANE. Following an alkylation of propynylsodium, a vinyl halide is generated in a stereoselective manner... 

Organohalogenated compounds and substances which may form such compounds in the aquatic environment Organophosphorus compounds Organotin compounds... 

As recently as 1970, only about 30 naturally occurring organohalogen compounds were known. It was simply assumed that chloroform, halogenated phenols, chlorinated aromatic compounds called PCBs, and other such substances found in the environment were industrial pollutants. Now, only a third of a century later, the situation js quite different. More than 5000 organohalogen compounds have been found to occur naturally, and tens of thousands more surely exist. From a simple compound like chloromethane to an extremely complex one like vancomycin, a remarkably diverse range of organohalogen compounds exists in plants, bacteria, and animals. Many even have valuable physiological activity. Vancomycin, for instance, is a powerful antibiotic produced by the bacterium Amycolatopsis orientalis and used clinically to treat methicillin-resistant Staphylococcus aureus (MRSA). 

Marine corals secrete organohalogen compounds that act as a feeding deterrent to Starfish. 

Some naturally occurring organohalogen compounds are produced in massive quantities. Forest fires, volcanoes, and marine kelp release up to 5 million tons of CH3CI per year, for example, while annual industrial emissions... 

Much remains to be learned—only a few hundred of the more than 500,000 > known species of marine organisms have been examined—but it is clear that organohalogen compounds are an integral part of the world around us. 

Organohalogen compounds are of serious concern also as contaminants. The most feared material in this category is dioxin (2,3,7,8-tetrachlorodibenzo-para-dioxin, TCDD) that has already caused several catastrophes and has even been detected in effluent and sludge from paper mills that use chlorine bleach and also in... 

D. Neubert, Organohalogen Compounds, O. Hutzinger and H. Fiedler, Eds., Ecoinforma Press, p. 317-319, Bayreuth, (1990). 

Hirose A, Takagi A, Nishimura T, Ema M (2004) Review of reproductive and developmentai toxicity induced by organotins in aquatic organisms and experimentai animais. Organohalogen Compounds, 66 3042-3047. 

Legler J, van den Brink C, Brouwer A, et al. 1998. Assessment of (anti-)estrogenic compounds using a stably transfected luciferase reporter gene assay in the human T47-D breast cancer cell line. Organohalogen Compounds 37 265. 

Two important examples of reductive metabolism of xenobiotics are the reductive dehalogenation of organohalogen compounds, and the reduction of nitroaromatic compounds. Examples of each are shown in Figure 2.13. Both types of reaction can take place in hepatic microsomal preparations at low oxygen tensions. Cytochrome P450 can catalyze both types of reduction. If a substrate is bound to P450 in the... 

Klasson-Wehler, E., Kuroki, H., and Athanasiadou, M. et al. (1992). Selective retention of hydroxylated PCBs in blood. In Organohalogen Compounds Vol 10 Toxicology, Epidemiology, Risk Assessment, and Management, Helsinki Finnish Institute of Occupational Health 121-122. 

Marsh, G., Bergman, A., and Bladh, L.G. et al. (1998). Synthesis of p-hydroxybromodiphenyl ethers and binding to the thyroid receptor. Organohalogen Compounds 37, 305-308. 

These are of primary signihcance in the biosynthesis of organohalogen compounds (Neilson 2003), which are distributed among mammals, marine biota, bacteria, and fungi. 

Kurata A, T Kurihara, H Kamachi, N Esaki (2005) 2-haloacrylate reductase a novel enzyme of the medium-chain dehydrogenase/reductase superfamily that catalyzes the reduction of carbon-carbon double bond of unsaturated organohalogen compounds. J Biol Chem 280 20286-20291. 

In the Grignard reaction, which is very important in the manufacture of a variety of fine chemicals, the continuous reactor for production of the reagent consists of a column of magnesium particles through which a solution of the organohalogen compound in an ether-class solvent is passed. The continuous mode of operation reduces side reactions, particularly Wurtz-type coupling, which make many reactions impractical. 

G. Neumann, A. Hiilster, and V. Romheld, PCDD/PCDF-mobilizing compounds in root exudates of zucchini. Organohalogen Compounds 4I 33 (1999). 

Fiirst P (2006) Dioxins, PCB, and other organohalogen compounds in human milk. Mol Nutr Food Res 50 922-933... 

Gomera, B., Gonzalez, M.J. (2003). Enantiomeric separation of chiral PCBs in eggs of predatory birds from Donana National Park (Spain) by using multidimensional gas chromatographic techniques. Organohalogen Compounds 62, 273-276. 

For those organohalogen compounds which can undergo intramolecular dehydrohalogenation, reaction sequence [1] has been proposed as the principal route to the generation of volatile antimony containing species (3, 5, 7, 18, 20). ... 

For those organohalogen compounds which cannot readily undergo intramolecular dehydrohalogenation, two alternative reaction sequences, (2) and [3], for the generation of volatile antimony containing species have been proposed (9, 21, 22). 

Mechanism [4] was based on studies involving the direct reaction of antimony metal with DBDPO in the absence of a hydrogen source. The data from these experiments clearly show that if the oxide is reduced to the metal, direct interaction with DBDPO would occur, and that this is a specific and highly exothermic reaction. However, no direct evidence for the presence of metallic antimony in mixtures containing antimony oxide, a polymer substrate and an organohalogen compound was obtained. 

All of the organohalogen compounds studied were commercial products obtained from various manufacturers and used as received. Only the DBDPO was purified further by recrystallization for some of the chromatography and thermal analysis experiments. Samples of antimony trioxide and antimony pentoxide were also obtained from commercial sources. The ultrapure antimony trioxide, bismuth trioxide, bismuth metal, antimony metal, dibenzofuran and diphenyl ether were all obtained from Aldrich Chemicals. The poly(propylene) (PP) resin was 0.7 mfi, food grade from Novamont and the poly(ethylene) was unstabilized, high molecular weight, HDPE from American Hoechst. 

Odsjo, T., A. Bignert, M. Olsson, L. Asplund, U. Eriksson, L. Haggberg, K. Litzen, C. de Wit, C. Rappe, and K. Aslund. 1997. The Swedish environmental specimen bank — application in trend monitoring of mercury and some organohalogenated compounds. Chemosphere 34 2059-2066. 

Fiedler, H. (1995). EPA DIOXIN-reassessment Implications for Germany. Organohalogen compounds, 22, 209-228. 

Fiedler H, Hoff J, Tolls J, Mertens A, Gruber A, Hutzinger O (1994) Environmental fate of organochlorines in the aquatic environment. In Organohalogen compounds, vol 15. ECO-INFORMA, Bayreuth, p 199... 

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