Aromatic organohalogenated

Aromatic organohalogens such as chlorobenzene are synthesized by treatment of benzene with halogen and a Lewis acid catalyst such as alu- catalyst substance that aids in a reaction minum chloride. retaining its own chemical identity... 

Next to PCBs and PCDD/Fs, other families of environmentally relevant aromatic organohalogenated pollutants rapidly attracted the attention of researchers working with GCxGC. Because of their widespread use and rapid increase of their environmental levels during the last decades, most attention was directed to flame retardants and, in particular, to PBDEs [23,27]. 

A large amount of fuel and environmentally based analysis is focused on the determination of aliphatic and aromatic content. These types of species are often notoriously difficult to deconvolute by mass spectrometric means, and resolution at the isomeric level is almost only possible by using chromatographic methods. Similarly, the areas of organohalogen and flavours/fragrance analysis are dominated by a need to often quantify chiral compounds, which in the same way as aliphatic... 

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). 

Brouwer A. 1998. Structure-dependent multiple interactions of polyhalogenated aromatic hydrocarbons with the thyroid hormone system. Organohalogen Compounds 37 225-232. 

Other important parameters in providing successful GC are the column packing, temperature conditions, and selection of a detector as specific to the analyte as possible. Maximum resolution of the halocar-bons is achieved with an 8-ft X 0.1-in. i.d. column of Carbopack-B coated with 1% SP-1000. The initial temperature of 45 °C is held for 3 min and then programmed at 8 °C/min to 220 °C. An organohalogen detector (OHD) is used. The aromatics are best resolved with a 6-ft X 0.085-in. i.d. column of Supelcoport coated with 5% SP-1200 plus 1.75 Bentone-34. They are measured with a photoionization detector. The temperature conditions are as follows 50 °C for 2 min then programmed at 6 °C/min to 90 °C. A 10-ft X 2-mm i.d. Porapak-QS (80-100 mesh) column at a temperature of 110 °C for 1.5 min and rapidly heated to 150 °C is now used for acrolein and acrylonitrile. This method employs a flame ionization detector (FID). 

THE ORGANOHALOGEN AROMATIC AND CYCLIC PESTICIDES AND RELATED COMPOUNDS... 

Blumenstock, M. Zimmermann, R. Schraumm, L. W. Kaune, A. Henkelmann, B. Kettrup. A. Presence of polychlorinated dibenzo-p-dioxins (PCCD), dibenzofurans (PCDFs), biphenyls (PCB), chlorinated benzenes (PCBz) and polycyclic aromatic hydrocarbons (PAH) under various combustion conditions in a post combustion chamber, Organohalogen Compounds, 1998, 36, 59-63. 

Luijk R, Dorland K, Smit P, Govers HAJ (1993), in Polycyclic aromatic compounds", prediction of the gas chromatographic retention behaviour of polybrominated dibenzo-p-dioxins , p. 565-572, Garrigues Ph, Lamotte M (Eds.), Gordon and Breach, Yverdon Weber R, Hagenmaier H (1994), Organohalogen Compounds 19 7-11. Polyfluorinated diben-zodioxins/furans - Synthesis, analysis and formation", Eds. University of Kyoto, Japan... 

Even a cursory examination of the literature shows that analysis of virtually every environmental sample reveals contamination from polycyclic aromatic hydrocarbons — resulting from incomplete combustion processes — and a range of the more recalcitrant organohalogen compounds such as DDT (together with its degradation product DDE), PCBs, hexachlorocyclohexanes, compounds related to aldrin, and mixtures present in commercial toxaphene preparations. Possibly the most disturbing fact, which has already been noted, is the occurrence of these compounds in samples from remote and largely isolated locations in the Arctic and Antarctic. 

Most organohalogens produced by fungi have an aromatic structure important groups include the chlorinated anisyl metabolites, drosophilins, and other chlorinated hydroquinone methyl ethers, chlorinated sesquiterpenens, chlorinated anthraquinones and strobulirins [72]. 

The organohalogen FRs can be classified into three groups aromatic, aliphatic, and cycloaliphatic compounds. The halogen is either chlorine or bromine. Fluorinated compounds are expensive and generally not effective iodinated compounds are effective but unstable and are therefore not used. 

Another important group of industrial chemicals are phthalates. These are used mainly as additives to plastics, but may also have other uses such as solvents for pesticides. They are much less toxic and persistent than many of the organohalogen compounds, but are used in larger quantities. Somewhat related to phthalates are other esters such as adipates and citrates, but they are biodegraded more rapidly because of the absence of the aromatic ring of phthalates. 

Ogura I, Masunaga S, Nakanishi J (2001) Parameters characterizing atmospheric behavior of PCDDs/PCDFs. Organohalogen Compd 52 483-486 Pandit GG, Sahu SK, Puranik VD, Venkat Raj V (2006) Exchange of polycyclic aromatic hydrocarbons across the air-water interface at the creek adjoining Mumbai harbour. India Environ Int 32 259-264... 

US Department of Health and Human Services, Washington Naumova YY, Eisenreich SJ, Turpin BJ et al (2002) Polycyclic aromatic hydrocarbons in the indoor and outdoor air of three cities in the US. Environ Sci Technol 36 2552-2559 Naumova YY, Offenberg JH, Eisenreich SJ et al (2003) Gas/particle distribution of polycyclic aromatic hydrocarbons in coupled outdoor/indoor atmospheres. Atmos Environ 37 703-719 Offenberg JH, Baker JE (1999) Aerosol size distributions of polycyclic aromatic hydrocarbons in urban and over-water atmospheres. Environ Sci Technol 33 3324-3331 Ohta S, Nakao T, Nishimura H et al (2002) Contamination levels of PBDEs, TBBPA, PCDDs/ DFs, PBDDs/DFs and PXDDs/DFs in the environment of Japan. Organohalogen Compd 57 57-60... 

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