Chlorine organochlorine compounds

Concern has been expressed over the formation of chlorinated dibenzo[l,4]dioxins and dibenzofurans during the thermal transformation of organic material in the presence of chloride or organochlorine compounds. 

Amaral OC, Otero R, Grimalt JO, Albaiges J (1996) Volatile and semi-volatile organochlorine compounds in tap and riverine waters in the area of influence of a chlorinated organic solvent factory. Water Res 30(8) 1876-1884... 

GC is coupled with many detectors for the analysis of pesticides in wastewater. At the present time the most popular is GC-MS, which will be discussed in more detail later in this section. The flame ionization detector (FID) is another nonselective detector that identifies compounds containing carbon but does not give specific information on chemical structure (but is often used for quantification because of the linear response and sensitivity). Other detectors are specific and only detect certain species or groups of pesticides. They include electron capture,nitrogen-phosphorus, thermionic specific, and flame photometric detectors. The electron capture detector (ECD) is very sensitive to chlorinated organic pesticides, such as the organochlorine compounds (OCs, DDT, dieldrin, etc.). It has a long history of use in many environmental methods,... 

McIntyre et al. [58, 59] described a method for the analysis of polychlorobiphenyls and chlorinated insecticides in sewage sludges in which homogenized samples are extracted with hexane, concentrated and cleaned up on an alumina/alumina plus silver nitrate column and eluted with hexane. After concentration of the eluent, polychlorobiphenyl and organochlorine compounds were determined by a silica gel chromatographic procedure and gas chromatography. 

The use of chlorine for disinfecting wastewaters or drinking water has become widespread in this century. Recently, however, the increasing presence and variety of aquatic contaminants has raised the question of the chemical fate of these contaminants when subjected to aqueous chlorination [36]. In fact, the production of organochlorine compounds in chlorinated water, including mutagenic and carcinogenic substances, is well established [37,38], A number of alternatives to chlorination are used in many parts of the world, but the risks associated with their by-products are even less well established [39],... 

In addition, chlorine derivatives are important as intermediates in the chemical industry, and there are numerous chlorine-containing pharmaceuticals for which no substitutes are presently available. Furthermore, organochlorine compounds, some very toxic, do occur naturally on a large scale. Clearly, however, we must endeavor to avoid adding unnecessarily to the natural load of toxins as the old adage goes, it is the dose that makes the poison.4 Certainly, problems exist that require an intelligent and chemically informed resolution, but the total ban advocated by some on the use of chlorine and chlorinated compounds is neither necessary nor acceptable. 

The highest concentrations of studied chlorophenols (2,4-, 2,4,6- and 2,3,4,6-) have been found in kidney, liver and spleen and the lowest concentrations in muscle and brain, either after parenteral administration of these chlorophenols themselves or as metabolites of other organochlorine compounds. Over 80% of the dose is excreted in urine and 5-20% in faeces. Metabolism varies somewhat depending on chlorine content the low-chlorine substances tend to be excreted as glucuronide and sulfate conjugates with higher chlorine substitution, excretion of the unchanged substance tends to increase. Formation of chlorinated 1,4-quinones is a minor pathway except for 2,3,5,6-tetrachlorophenol (WHO, 1989). 

X-ray absorption spectroscopy has revealed the formation of organochlorine compounds from chloride and chloroperoxidase in weathering plant material (172-174). Moreover, this technique has uncovered the bromide-to-organobromine conversion in environmental samples (174). In addition to chloroperoxidase mediated chlorination, the abiotic chlorination in soils and sediments involving the alkylation of halides during Fe(III) oxidation of natural organic phenols in soils and sediments has been discovered (175-177). 

Monde K, Satoh H, Nakamura M, Tamura M, Takasugi M (1998) Organochlorine Compounds from a Terrestrial Higher Plant Structures and Origin of Chlorinated Orcinol Derivatives from Diseased Bulbs of Lilium maximowiczii. J Nat Prod 61 913... 

Much of the effort on environmental chemicals that contaminate food has concentrated on a small range of chlorinated chemicals. In addition to the chlorinated PCDDs, PCDFs and PCBs already mentioned, other chlorinated compounds can be separated into two groups chlorinated aromatic compounds and chlorinated aliphatic compounds. Although there is a number of organochlorine pesticides that are persistent in the environment, these will not be considered here, as they comprise an extensive field of study in their own right. 

The phenomenal success of DDT stimulated further research, and by 1946 the two DDT analogs, DDD and methoxychlor (Table 1,A) had been produced (Tables are at the end of the chapter). The observation of greater insecticidal activity in those organochlorine compounds that lose their HC1 more easily led to yet another group of chlorinated derivatives, the condensed ring chlorocyclodienes (Table 1,B). Thus, nearly all of the chlorinated pesticides currently in use had been... 

In addition to combustion, alkanes undergo substitution reactions in which one or more H atoms on an alkane are replaced by atoms of another element. The most common such reaction is the replacement of H by chlorine, to yield organochlorine compounds. For example, methane reacts with chlorine to give chloromethane. This reaction begins with the dissociation of molecular chlorine, usually initiated by ultraviolet electromagnetic radiation ... 

As seen from the structural formulas in Figure 16.4, the organochlorine insecticides are of intermediate molecular mass and contain at least one aromatic or nonaromatic ring. They can be placed in four major chemical classes. The first of these consists of the chloroethylene derivatives, of which DDT and methoxychlor are the prime examples. The second major class is composed of chlorinated cyclodiene compounds, including aldrin, dieldrin, and heptachlor. The most highly chlorinated members of this class, such as chloredecone, are manufactured from hexachlorocyclo-pentadiene (see Section 16.3). The benzene hexachloride stereoisomers make up a third class of organochlorine insecticides, and the third group, known collectively as toxaphene, constitutes a fourth. 

The use of chlorinated hydrocarbons has declined worldwide and is banned in many countries for three main reasons (1) concern over the buildup of residues, (2) the increasing tendency of some insects to develop resistance to the materials, and (3) the advent of insecticides that can replace the organochlorine compounds. 

Many undesirable organochlorine compounds are produced by the chlorination of drinking water. Among these are chloroacetic acids and trihalo-methanes. Studies have reported the radiolytic decomposition of CHC13 and related compounds [11-14], An example is shown in Fig. 1, where the concentration decrease for various bromochloromethanes is plotted vs. absorbed dose. A proposed mechanism for the decomposition of CHC13 and formation of by-products, involving the three important radical products of water radiolysis is shown ... 

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