Hydrocarbon chlorinated

The accumulation of chlorinated hydrocarbons in organisms depends on the dose, type of organism and its detoxication capacity, age, sex, way of penetration into the organism, interactions with the other substances, etc. A greater accumulation of pesticides occurs when administering smaller doses over short-time intervals as compared to one total dose. 

In the initial period after the penetration into the organism, pesticides are distributed by the blood circulation so that their concentration in particular tissues depends on the level of the blood supply. For example, in the liver or in the brain, their concentration is higher than that in the fat tissue. The final distribution of chlorinated hydrocarbons is, however, governed by their solubility in fats which is much higher than that in water, so that concentrations in the lipid tissue may be higher by a factor of 100 to 300 as compared to those in the blood. 

A portion of pesticides administered is accumulated in an unaltered form, and a further fraction may undergo different biotransformations. For example, DDT can be partially metabolized to DDA, DDD or DDE depending on the organism. HCH is accumulated in the form of alpha, beta, gamma and delta isomers. The accumulation of compounds in the organism is also altered on changing their chemical structure. 

The most common chlorinated hydrocarbons used as insecticides may be listed in order of their decreasing rate of accumulation as follows hep-tachloroepoxide dieldrin endrin DDT lindane [25]. 

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 approved uses for chlorinated chemicals have now become so restricted that for some of them at least they are now more likely to contaminate food as a result of their persistence in the environment rather than from their direct use on the food chain. A former pesticide in this category is hexachlorobenzene. There 

There are 12 chlorobenzene compounds monochlorobenzene (MCB), three dichlorobenzenes (1,2-, 1,3,- and 1,4-DCB), three trichlorobenzenes (1,2,3-, 

4- and 1,3,5-TCB), three tetrachlorobenzenes (1,2,3,4-, 1,2,3,5- and 1,2,4,5-TeCB), pentachlorobenzene (PeCB) and hexachlorobenzene (HCB). HCB has been used in the UK as a pesticide, while the other chlorobenzenes all have industrial uses, mostly as intermediates in the production of pesticides and dyes, with 1,4-DCB used as a disinfectant. In addition, MCB is used as a solvent and the higher chlorobenzenes are used in dielectric fluids.54 

Chlorobenzenes are widely dispersed in the environment as a result of their industrial usages and emissions from incinerators. Chlorobenzenes have an increasing tendency to bioaccumulate and to become more persistent as the number of chlorine atoms increases. They are also present in sewage sludge and have been shown to be taken up by carrots via this route.55 There have been reports of some chlorobenzenes being found in foodstuffs in meat, fish, vegetables and crude seed oils in the UK,54 56 in cod from the North Sea,57 in fish and shellfish in Canada,58 in fish from contaminated waters in Europe59-61 and in human milk in Canada.62 

Chlorinated derivatives of methane include methyl chloride, methylene chloride, chloroform, carbon tetrachloride, and several chlorofluorohydrocarbons (CFCs). We discuss carbon tetrachloride (CT) as a representative example of this group. CT was originally prepared in 1839 and was one of the first organic chemicals to be produced on a large scale by the end of the nineteenth century and beginning of the twentieth century. CT is the most toxic of the chloromethanes and the most unstable on thermal oxidation (Holbrook 2000). 

Chlorinated ethanes and ethylenes comprise ethyl chloride, ethylene dichloride (1,2 dichloroethane), vinyl chloride, trichloroethylene (TCE), perchloroethylene (RCE), and several CFCs. Some of the major uses of these compounds are as degreasing agents, dry-cleaning solvents, building blocks for manufacturing of polymers (e.g., RVC, ethyl cellulose), and raw material for the production of tetraethyl lead and CECs. We discuss ethylene dichloride, trichloroethylene, and perchloroethylene as examples of this group. 

Overexposure to tetrachloroethylene by inhalation affects the central nervous system and the liver. Dizziness, headache, confusion, nausea, and eye and mucous tissue irritation occur during prolonged exposure to vapor concentrations of 200ppm (Rowe et al. 1952). These effects are intensified and include lack of coordination and drunkenness at concentrations in excess of 600 ppm. At concentrations in excess of 1,000 ppm, anesthetic and respiratory depression effects can cause unconsciousness and death (Hickman 2000). 

Chlorinated aromatics, including monochlorobenzene (MCB), o-dichloroben-zene (o-DCB), and p-dichlorobenzene (p-DCB), are the major chlorinated aromatic species produced on an industrial scale. MCB is used as both a chemical intermediate and a solvent. As an intermediate, it is used to produce chloroni-trobenzene, pesticides, and pharmaceutical products. In solvent applications, MCB is used in the manufacture of isocyanates. Its high solvency allows it to be used with many types of resins, adhesives, and coatings. The o-dichlorobenzene is used primarily for organic synthesis, especially in the production of 3,4-dichlo-roaniline herbicides. Like MCB, it can be used as a solvent, especially in the production of isocyanates. It is also used in motor oil and paint formulations. The p-dichlorobenzene is used as a moth repellent and for the control of mildew and fungi. It also is used for odor control. It is a chemical intermediate for the manufacture of pharmaceuticals and other organic chemicals. 

Hollies et ah [18] foimd that choro-n-paraffins could be chromatographed on a silica gel plate from which an image of the chromatogram could be printed on an aluminium oxide plate by heating the two face to face so at the high sensitivity of detection on aluminium oxide could be utilised. 

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In early designs, the reaction heat typically was removed by cooling water. Crude dichloroethane was withdrawn from the reactor as a liquid, acid-washed to remove ferric chloride, then neutralized with dilute caustic, and purified by distillation. The material used for separation of the ferric chloride can be recycled up to a point, but a purge must be done. This creates waste streams contaminated with chlorinated hydrocarbons which must be treated prior to disposal. 

The substance is examined in a dilute solution in a solvent. A wide choice of solvents, transparent to ultraviolet radiation, is available. The paraffin hydrocarbons are all suitable, as are the ahphatic alcohols and the chlorinated hydrocarbons, such as chloroform and carbon tetrachloride. The most useful solvents are re-hexane, cycZohexane, chloro-... 

The most abundant natural steroid is cholesterol. It can be obtained in large quantides from wool fat (15%) or from brain or spinal chord tissues of fat stock (2-4%) by extraction with chlorinated hydrocarbons. Its saturated side-chain can be removed by chromium trioxide oxidation, but the yield of such reactions could never be raised above 8% (see page 118f.). 

Alkali metals Moisture, acetylene, metal halides, ammonium salts, oxygen and oxidizing agents, halogens, carbon tetrachloride, carbon, carbon dioxide, carbon disul-flde, chloroform, chlorinated hydrocarbons, ethylene oxide, boric acid, sulfur, tellurium... 

Nitric oxide Aluminum, BaO, boron, carbon disulflde, chromium, many chlorinated hydrocarbons, fluorine, hydrocarbons, ozone, phosphine, phosphorus, hydrazine, acetic anhydride, ammonia, chloroform, Fe, K, Mg, Mn, Na, sulfur... 

Chloroacetic acid forms a2eotropes with a number of organic compounds. It can be recrystaUized from chlorinated hydrocarbons such as trichloroethylene, perchloroethylene, and carbon tetrachloride. The freezing poiat of aqueous chloroacetic acid is shown ia Figure 1. 

Chlorine reacts with saturated hydrocarbons either by substitution or by addition to form chlorinated hydrocarbons and HCl. Thus methanol or methane is chlorinated to produce CH Cl, which can be further chlorinated to form methylene chloride, chloroform, and carbon tetrachloride. Reaction of CI2 with unsaturated hydrocarbons results in the destmction of the double or triple bond. This is a very important reaction during the production of ethylene dichloride, which is an intermediate in the manufacture of vinyl chloride ... 

CeUulose triacetate is insoluble in acetone, and other solvent systems are used for dry extmsion, such as chlorinated hydrocarbons (eg, methylene chloride), methyl acetate, acetic acid, dimethylformamide, and dimethyl sulfoxide. Methylene chloride containing 5—15% methanol or ethanol is most often employed. Concerns with the oral toxicity of methylene chloride have led to the recent termination of the only triacetate fiber preparation faciHty in the United States, although manufacture stiH exists elsewhere in the world (49). 

The FDA has pubhshed methods for the deterrnination of residual solvents in spice extracts such as oleoresins and has limited the concentrations of those specific solvents that are permitted. Chlorinated hydrocarbons and benzene have been almost completely removed from use as extracting solvents in the United States their use continues overseas where toxicity regulations are less stringent. The presence of pesticides or herbicides in spices is rigidly controHed by the FDA. 

Hydrogen chloride is produced by the direct reaction of hydrogen and chlorine, by reaction of metal chlorides and acids, and as a by-product from many chemical manufacturing processes such as chlorinated hydrocarbons. 

Chlorinated C2> Perchloroethylene (PCE) and trichloroethylene (TCE) can be produced either separately or as a mixture in varying proportions by reaction of C2-chlorinated hydrocarbons, eg, C2-chlorinated waste streams or ethylene dichloride, with a mixture of oxygen and chlorine or HCl. 

The performance of SCWO for waste treatment has been demonstrated (15,16). In these studies, a broad number of refractory materials such as chlorinated solvents, polychlorinated biphenyls (PCBs), and pesticides were studied as a function of process parameters (17). The success of these early studies led to pilot studies which showed that chlorinated hydrocarbons, including 1,1,1-trichloroethane /7/-T5-6y,(9-chlorotoluene [95-49-8] and hexachlorocyclohexane, could be destroyed to greater than 99.99997, 99.998, and 99.9993%, respectively. In addition, no traces of organic material could be detected in the gaseous phase, which consisted of carbon dioxide and unreacted oxygen. The pilot unit had a capacity of 3 L/min of Hquid effluent and was operated for a maximum of 24 h. 

Both CI2 and HCl have been shown to chlorinate hydrocarbons on fly ash particles. Pilot-scale data involving the injection of fly ash from municipal waste combustion (33) show that intermediate oxygen concentrations (4—7%) produce the highest levels of PCDD and PCDF. These data also show significant reductions in PCDD and PCDF emissions with the upstream injection of Ca(OH)2 at about 800°C. 

Pesticides. Chlorinated hydrocarbon pesticides (qv) are often found in feed or water consumed by cows (19,20) subsequently, they may appear in the milk, where they are not permitted. Tests for pesticides are seldom carried out in the dairy plant, but are most often done in regulatory or private specialized laboratories. Examining milk for insecticide residues involves extraction of fat, because the insecticide is contained in the fat, partitioning with acetonitrile, cleanup (FlorisH [26686-77-1] column) and concentration, saponification if necessary, and determination by means of paper, thin-layer, microcoulometric gas, or electron capture gas chromatography (see Trace and residue analysis). 

Solubility. Poly(ethylene oxide) is completely soluble in water at room temperature. However, at elevated temperatures (>98° C) the solubiUty decreases. It is also soluble in several organic solvents, particularly chlorinated hydrocarbons (see Water-SOLUBLE polymers). Aromatic hydrocarbons are better solvents for poly(ethylene oxide) at elevated temperatures. SolubiUty characteristics are Hsted in Table 1. 

Solubility. Cross-linking eliminates polymer solubiUty. Crystallinity sometimes acts like cross-linking because it ties individual chains together, at least well below T. Thus, there are no solvents for linear polyethylene at room temperature, but as it is heated toward its (135°C), it dissolves in a variety of aUphatic, aromatic, and chlorinated hydrocarbons. A rough guide to solubiUty is that like dissolves like, ie, polar solvents tend to dissolve polar polymers and nonpolar solvent dissolve nonpolar polymers. 

Aluminum alkoxides are easily soluble in hydrocarbons and in chlorinated hydrocarbons, but sparingly soluble in alcohols. They are sensitive to moisture and dry storage is essential. Aluminum alkoxides are used extensively as intermediates, for example, in the Meerwein-Poimdorf reaction (94). 

Rosin is compatible with many materials because of its polar functionaUty, cycloaUphatic stmcture, and its low molecular weight. It has an acid number of ca 165 and a saponification number of ca 170. It is soluble in aUphatic, aromatic, and chlorinated hydrocarbons, as well as esters and ethers. Because of its solubiUty and compatibiUty characteristics, it is useful for modifying the properties of many polymers. 

Process Raw Material. Industrial solvents are raw materials in some production processes. Eor example, only a small proportion of acetone is used as a solvent, most is used in producing methyl methacrylate and bisphenol A. Alcohols are used in the manufacture of esters and glycol ethers. Diethylenetriamine is also used in the manufacture of curing agents for epoxy resins. Traditionally, chlorinated hydrocarbon solvents have been the starting materials for duorinated hydrocarbon production. 

Physical Properties. Thionyl chloride [7719-09-7], SOCI2, is a colorless fuming Hquid with a choking odor. Selected physical and thermodynamic properties are Hsted in Table 6. Thionyl chloride is miscible with many organic solvents including chlorinated hydrocarbons and aromatic hydrocarbons. It reacts quickly with water to form HCl and SO2. Thionyl chloride is stable at room temperature however, slight decomposition occurs just... 

In the chemical industry, titanium is used in heat-exchanger tubing for salt production, in the production of ethylene glycol, ethylene oxide, propylene oxide, and terephthaHc acid, and in industrial wastewater treatment. Titanium is used in environments of aqueous chloride salts, eg, ZnCl2, NH4CI, CaCl2, and MgCl2 chlorine gas chlorinated hydrocarbons and nitric acid. 

Uranium hexafluoride [7783-81-5], UF, is an extremely corrosive, colorless, crystalline soHd, which sublimes with ease at room temperature and atmospheric pressure. The complex can be obtained by multiple routes, ie, fluorination of UF [10049-14-6] with F2, oxidation of UF with O2, or fluorination of UO [1344-58-7] by F2. The hexafluoride is monomeric in nature having an octahedral geometry. UF is soluble in H2O, CCl and other chlorinated hydrocarbons, is insoluble in CS2, and decomposes in alcohols and ethers. The importance of UF in isotopic enrichment and the subsequent apphcations of uranium metal cannot be overstated. The U.S. government has approximately 500,000 t of UF stockpiled for enrichment or quick conversion into nuclear weapons had the need arisen (57). With the change in pohtical tides and the downsizing of the nation s nuclear arsenal, debates over releasing the stockpiles for use in the production of fuel for civiUan nuclear reactors continue. 

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