Aromatics chlorinated

The reductive dechlorination of chlorinated aromatics is more compHcated in that the initial dechlorination of more highly chlorinated compounds may be either chemical or enzymatic, eg, PGP, whereas the dechlorination of less chlorinated compounds or dechlorinated products is typically enzymatic. For example, the first dechlorination of 2,4-dichlorophenol (ortho position) can occur either chemically or enzymatically the second dechlorination (para position) is enzymatic (eq. 10). 

G. S. Sayler, Microbial Decomposition of Chlorinated Aromatic Compounds, USEPA 600/2-86/090, Washington, D.C., 1986. 

The cleavage products of several sulfonates are utilized on an industrial scale (Fig. 3). The fusion of aromatic sulfonates with sodium hydroxide [1310-73-2J and other caustic alkalies produces phenohc salts (see Alkylphenols Phenol). Chlorinated aromatics are produced by treatment of an aromatic sulfonate with hydrochloric acid and sodium chlorate [7775-09-9J. Nitriles (qv) (see Supplement) can be produced by reaction of a sulfonate with a cyanide salt. Arenesulfonates can be converted to amines with the use of ammonia. This transformation is also rather facile using mono- and dialkylamines. 

Ref. 14 contains a more general and simplistic order of decreasing biodegradabihty straight-chain compounds, aromatic compounds, chlorinated straight-chain compounds, and chlorinated aromatic compounds. 

In order to assure control of the reaction, the vapor-phase inhibitor concentration must be closely controlled in the ppm range. Although several compounds have been claimed to be useful, it is likely that commercial processes use only ethylene dichloride or some of the simpler chlorinated aromatics (102). In general, the choice between inhibitors is not based on their differences in performance, but rather on the designers preference for dealing with the type of control problems each inhibitor system imposes (102). 

Many reagents are able to chlorinate aromatic pyrazole derivatives chlorine-water, chlorine in carbon tetrachloride, hypochlorous acid, chlorine in acetic acid (one of the best experimental procedures), hydrochloric acid and hydrogen peroxide in acetic acid, sulfuryl chloride (another useful procedure), etc. iV-Unsubstituted pyrazoles are often used as silver salts. When methyl groups are present they are sometimes chlorinated yielding CCI3 groups. Formation of dimers and trimers (308 R = C1) has also been observed. 

Your facility uses 20,000 pounds of a solvent that your supplier has told you contains 80 percent "chlorinated aromatic," their generic name for a chemical subject to reporting under section 313. You therefore know that you have used 16,000 pounds of some listed toxic chemical which exceeds the "othenwise use threshold. You would file a Form R and enter the name chlorinated aromatic in the space provided in Part III, Section 2. 

Oxidation of phenols with chlorine dioxide or chlorine produces chlorinated aromatic intermediates before ring rupture. Oxidation of phenols with either chlorine dioxide or ozone produces oxidized aromatic compounds as intermediates which undergo ring rupture upon treatment with more oxidant and/or longer reaction times. In many cases, the same nonchlorinated, ringruptured aliphatic products are produced using ozone or chlorine dioxide. 

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). 

De Voogt, R (1996). Ecotoxicology of chlorinated aromatic hydrocarbons. In Chlorinated Organic Micropollutants, No 6 in series Issues in Environmental Science and Technology. R.E. Hester and R.M. Harrison (Eds.) Royal Society of Chemistry 89-112. 

The photolysis of chlorinated aromatic compounds occurs by several processes which follow predictable routes 13). They frequently undergo photochemical loss of chlorine by dissociation of the excited molecule to free radicals or, alternatively, through a nucleophilic displacement reaction with a solvent or substrate molecule. Either mechanism is plausible, and the operation of one or the other may be influenced by the reaction medium and the presence of other reagents. 

Industrial workers involved in chlorinated aromatic production including chlorophenol suffered dioxin-induced chloracne 2,3). Chloracne and other serious health disturbances have been attributed to polychloro-dibenzo-p-dioxins in workers involved in manufacturing 2,4,5-T 4, 5). Dioxins are toxic to chick embryos, guinea pigs, rabbits, and monkeys 6, 7, 8, 9, 10). 

Chlorinated aromatic hydrocarbons Volatile methyl-silicon compounds Methylcyclopentadienyl manganese (CO)3... 

The pyrolysis of vinylidene chloride produced a range of chlorinated aromatic compounds including polychlorinated benzenes, styrenes, and naphthalenes (Yasahura and Morita 1988), and a series of chlorinated acids including chlorobenzoic acids has been identified in emissions from a municipal incinerator (Mowrer and Nordin 1987). 

Yasahura A, M Morita (1988). Eormation of chlorinated aromatic hydrocarbons by thermal decomposition of vinylidene chloride polymer. Environ Sci Technol 22 646-650. 

The signiflcance of toxic metabolites is important in diverse metabolic situations (a) when a pathway results in the synthesis of a toxic or inhibitory metabolite, and (b) when pathways for the metabolism of two (or more) analogous substrates supplied simultaneously are incompatible due to the production of a toxic metabolite by one of the substrates. A number of examples are provided to illustrate these possibilities that have achieved considerable attention in the context of the biodegradation of chlorinated aromatic compounds (further discussion is given in Chapter 9, Part 1) ... 

Klecka GM, WJ Maier (1988) Kinetics of microbial growth on mixtures of pentachlorophenol and chlorinated aromatic compounds. Biotechnol Bioeng 31 328-335. 

Application of NMR has been made to a restricted range of chlorinated aromatic compounds (Kolehmainen et al. 1992), and has been used to establish the source of oxygen in the metabolites produced from acetate and 02 by Aspergillus melleus (Staunton and Sutkowski 1991). 

There is an additional problem that has important implications for the bioremediation of contaminated sites when two substrates such as a chlorinated and an alkylated aromatic compound are present. The extradiol fission pathway is generally preferred for the degradation of alkylbenzenes (Figure 9.17), although this may be incompatible with the degradation of chlorinated aromatic compounds since the 3-chlorocatechol produced inhibits the activity of the catechol-2,3-oxygenase (Klecka and Gibson 1981 Bartels et al. 1984). 

Fennell DE, I Nijenhuis, SF Wilson, SH Zinder, MM Haggblom (2004) Dehalococcoides ethenogenes strain 195 reductively dechlorinates diverse chlorinated aromatic pollutants. Environ Sci Technol 38 2075-2081. 

Shimizu et al. 2002). It was therefore shown that it is possible to produce transgenic plants with the capability of degrading chlorinated aromatic compounds, which are degraded with the formation of 3-chlorocatechol. 

Feidieker D, P Kampfer, W Dott (1994) Microbiological and chemical evaluation of a site contaminated with chlorinated aromatic compounds and hexachlorocyclohexanes. EEMS Microbiol Ecol 15 265-278. 

Lang E, H Viedt, J Egestorff, HH Hanert (1992) Reaction of the soil microflora after contamination with chlorinated aromatic compounds and HCH. EEMS Microbiol Ecol 86 275-282. 

Before the 1960s, products were introduced based on alkyl aryl phosphates that could contain chlorinated aromatic hydrocarbons. Such products have now entirely disappeared from commercial use, and the vast majority of the industrial organophosphate esters are based on triaryl phosphates with no halogenated components (Marino 1992). However, at older waste disposal sites, hydraulic fluid site contaminants could contain chlorinated hydrocarbons. As with the PCBs formerly included as additives in other forms... 

Liang J, Komarov S, Hayashi N, Kasai E (2007) Recent trends in the decomposition of chlorinated aromatic hydrocarbons by ultrasound irradiation and Fenton s reagent. J Mat Cycles Waste Manage 9(1) 47—55... 

These QSPR (quantitative structure-property relationship) plots display the usual approximately linear relationships similar to those of the alkyl and chlorinated aromatic hydrocarbons. 

Shiu, W.-Y., Gobas, F. A. P. C., Mackay, D. (1987) Physical-chemical properties of three congeneric series of chlorinated aromatic hydrocarbons. In QSAR in Environmental Toxicology II. Kaiser, K. L. E., Ed., pp. 347-362, D. Reidel Publishing, Dordrecht, The Netherlands. 

Bioconcentration factors of dioxins in fishes are relatively low compared to other chlorinated aromatic compounds because of the low metabolic conversion of dioxins, their low available concentrations in test systems, and their highly variable uptake rates (de Voogt et al. 1990). In general, bioconcentration factors for persistent superlipophilic chemicals, such as OCDD, derived for freshwater fishes from supersaturated solutions may seriously underestimate the true BCF (Geyer... 

Safe, S., D. Jones, J. Kohli, and L.O. Ruzo. 1976. The metabolism of chlorinated aromatic pollutants by the frog. Canad. Jour. Zool. 54 1818-1823. 

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