Industrial solvents carbon tetrachloride

Alkyl halides are primarily used as industrial solvents. Carbon tetrachloride, CCI4, was once used extensively in the dry-cleaning process, but it has been replaced because of its toxicity and carcinogenic effects. (See the Chemistry in Action on p. 506.)... 

For example, the reactive metabolites of the drug allobarbital (epoxide), the industrial chemical vinyl chloride (epoxide), and the solvent carbon tetrachloride (CC13 radical) all damage cytochrome P-450 by this type of mechanism (see chap. 7). 

Alkyl halides are used primarily as industrial and household solvents. Carbon tetrachloride (CC14) was once used for dry cleaning, spot removing, and other domestic cleaning. Carbon tetrachloride is toxic and carcinogenic (causes cancer), however, so dry cleaners now use 1,1,1-trichloroethane and other solvents instead. 

Chlorination of various hydrocarbon feedstocks produces many usehil chlorinated solvents, intermediates, and chemical products. The chlorinated derivatives provide a primary method of upgrading the value of industrial chlorine. The principal chlorinated hydrocarbons produced industrially include chloromethane (methyl chloride), dichloromethane (methylene chloride), trichloromethane (chloroform), tetrachloromethane (carbon tetrachloride), chloroethene (vinyl chloride monomer, VCM), 1,1-dichloroethene (vinylidene chloride), 1,1,2-trichloroethene (trichloroethylene), 1,1,2,2-tetrachloroethene (perchloroethylene), mono- and dichloroben2enes, 1,1,1-trichloroethane (methyl chloroform), 1,1,2-trichloroethane, and 1,2-dichloroethane (ethylene dichloride [540-59-0], EDC). 

Many very hazardous solvents, such as benzene and carbon tetrachloride, were widely used until the 1970s. The situation was very similar for the use of pesticides. Among the toxic pesticides that were still in wide use 20 years ago were chlorophenols, DDT, lindane, and arsenic salts, all of which are classified as human carcinogens as well as being acutely toxic. Fortunately, use of these kinds of very toxic chemicals is now limited in the industrialized world. However, because the number of chemicals used in various industries continues to increase, the risks of long-term health hazards due to long-term exposure to low concentrations of chemicals continues to be a problem in the workplace. 

The best way to control exposure is to replace dangerous agents with safer ones. Today, highly toxic solvents, such as benzene, bromobenzenc, carbon tetrachloride, and chloroform are no longer extensively used. Benzene remains, however, an important chemical in the petrochemical industry, but the processes where it is used are clc)sed. 

For lab prepns, and occasionally in industrial use, more expensive nitrating agents may be employed, as for example solns of nitric acid in inert organic solvents (chlf, carbon tetrachloride, eth, nitromethane, etc), or a soln of nitric acid in phosphoric or acetic acids or in acetic anhydride, trifluoroacetic anhydride or trifluoro-me thane sulfonic acid (Ref 94)... 

The reaction is best carried out at low temperature, about 30°C, and is nearly complete and rapid. When alcohols are solid at this temperature, sulfation is made at a temperature slightly above the melting point of the alcohol. Inert solvents such as chloroform, carbon tetrachloride, or tetrachloroethylene can also be used, mainly when alcohols are solid, but this was seldom done on an industrial scale. 

All Group 14/IV elements form liquid molecular tetrachlorides. The least stable is PbCl4, which decomposes to solid PbCl2 when it is warmed to about 50°C. Carbon tetrachloride, CC14 (tetrachloromethane), was widely used as an industrial solvent however, now that it is known to be carcinogenic, it is used primarily as the starting point for the manufacture of chlorofluorocarbons. Carbon tetrachloride is formed by the action of chlorine on methane ... 

C14-0119. Both CCI4 (carbon tetrachloride) and CS2 (carbon disulfide) are liquids used as solvents in special industrial applications, (a) Using data Irom Appendix D, calculate A 77 ° and A G ° for combustion... 

Used industrially as a chemical intermediate in the production of rayon, carbon tetrachloride, xanthogenates, flotation agents, and pesticides used in the cold vulcanization of vulcanized rubber, in adhesive compositions for food packaging as a solvent for phosphorus, sulfur, selenium, bromine, iodine, fats, resins, rubbers, waxes, lacquers, camphor, resins and in the production of optical glass, paints, enamels, varnishes, paint removers, tallow, putty preservatives, rubber cement, soil disinfectants, explosives, rocket fuel, and electronic vacuum tubes. 

Topical application of a single 2 mL dose of undiluted -hexane had no effect on survival or body weight in exposed guinea pigs observed for 35 days after exposure (Wahlberg and Boman 1979). Deaths and/or effects on body weight were seen with similar doses of other common industrial solvents tested in this study (carbon tetrachloride, dimethylformamide, ethylene glycol monobutylether, 1,1,1-trichloroethane, and trichlorethylene). 

Carbon tetrachloride was at one time widely used in industry, and still is to a certain extent, although its use as a degreaser or common solvent has been banned in many jurisdictions. Until recently, however, it was commonly used as a degreaser and a solvent for oils, fats, lacquers, varnishes, rubber waxes, and resins. Two of its most common uses were in the dry cleaning industry and in portable fire extinguishers. 

In addition to the use of chlorine as an antiseptic for swimming pools and drinking water, large amounts are used during industrial processes that produce paper, plastics, textiles, dyes, medicines, insecticides, solvents, and some paints. Following are some of the more important compounds of chlorine used in industries hydrochloric acid (HCl + H O), table salt (NaCl), chloroform (CHCL ), carbon tetrachloride (CCy, magnesium chloride (MgCl ), chlorine dioxide (CIO ), potassium chloride (KCl), and lithium chloride (LiCl). 

Carbon disulfide is used in the manufacture of rayon, cellophane, electronic vacuum tubes, and xanthogenates. It is used to make carbon tetrachloride. It also is used as an industrial solvent and as an analytical solvent. Because of its low response to GC-FID, it is used widely in air analysis of organic compounds. 

Carbon tetrachloride is used in refrigerants in fumigants for crops in metal degreasing and in the manufacture of semiconductors. It also is used as a solvent in many industrial processes. It is an excellent solvent for organic compounds that are nonpolar or have low polarity. 

The magnitude of the effect of this scheduled phaseout on total carbon tetrachloride production is uncertain, since the Halogenated Solvents Industry Alliance estimates that only about 3% of the chemical manufactured in the U.S. is used in nonfeedstock applications (EPA 1991). Nevertheless, since the major current use of carbon tetrachloride is in the production of chlorofluorocarbons (see Section 4.3), and production of these chemicals has dropped significantly in recent years (C EN 1993) and is also scheduled for phase-out by 1996, a significant reduction in carbon tetrachloride production is expected during this decade. 

The induction of unconsciousness may be the result of exposure to excessive concentrations of toxic solvents such as carbon tetrachloride or vinyl chloride, as occasionally occurs in industrial situations (solvent narcosis). Also, volatile and nonvolatile anesthetic drugs such as halothane and thiopental, respectively, cause the same physiological effect. The mechanism(s) underlying anesthesia is not fully understood, although various theories have been proposed. Many of these have centered on the correlation between certain physicochemical properties and anesthetic potency. Thus, the oil/water partition coefficient, the ability to reduce surface tension, and the ability to induce the formation of clathrate compounds with water are all correlated with anesthetic potency. It seems that each of these characteristics are all connected to hydrophobicity, and so the site of action may be a hydrophobic region in a membrane or protein. Thus, again, physicochemical properties determine biological activity. 

The SGOT and SGPT tests are also important in occupational medicine, to determine whether people exposed to carbon tetrachloride, chloroform, or other industrial solvents have suffered liver damage. Liver degeneration caused by these solvents is accompanied by leakage of various enzymes from injured hepato-cytes into the blood. Aminotransferases are most useful in the monitoring of people exposed to these chemicals, because these enzyme activities are high in liver and can be detected in very small amounts. 

These agents find wide use as industrial solvents, degreasing agents, and cleaning agents. The substances include carbon tetrachloride, chloroform, trichloroethylene, tetrachloroethylene (perchloroethylene), and 1,1,1-trichloroethane (methyl chloroform). See Table 57-1 for recommended threshold limit values. 

Other than ethanol, the xenobiotic chemical best known to cause steatosis is carbon tetrachloride, CC14. This compound was once widely used in industry as a solvent, and even in consumer items as a stain remover. As discussed in some detail in Chapter 16, it is converted by enzymatic action in the liver to C13C- radical, then by reaction with 02 to Cl3COO- radical, which reacts with unsaturated lipids in the liver to cause fatty liver. 

Many metal salts are well-known primary skin irritants. These substances include antimony trioxide, arsenic trioxide, chromium and alkaline chromates, cobalt sulfate, nickel sulfate, mercury chloride, and zinc chloride. In addition to the above industrial chemicals, several solvents are known to act as primary skin irritants among workers, such as, carbon tetrachloride (CCI4), chloroform, ethylene dichloride, epichlorohydrin, ethylene chlorohydrin, perchloroethylene, and trichloroethylene, in addition to cool tar solvents such as naphtha, toluene, and xylene. 

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