Tetrachloroethylene and trichloroethylene

The flame of the former compound may be stabilized, and exhibits two zones, the first of which is orange-brown and the second, pale blue-green. The temperature in the first region is around 1100—1300 °C and in the second about 200 °C higher. The flame colours suggest Clj O is involved in the flame reaction [154,155]. 

The chlorine photosensitized oxidation of trichloroethylene has been thoroughly investigated [156], the main reaction being 

Minor products include trichloroethylene epoxide, phosgene, chloroform and carbon tetrachloride. 

Tetrachloroethylene burns feebly with a very slow flame in pure oxygen, but not at all in air. 

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Ninety-six percent of the EDC produced in the United States is converted to vinyl chloride for the production of poly(vinyl chloride) (PVC) (1) (see Vinyl polymers). Chloroform and carbon tetrachloride are used as chemical intermediates in the manufacture of chlorofluorocarbons (CECs). Methjiene chloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene have wide and varied use as solvents. Methyl chloride is used almost exclusively for the manufacture of silicone. Vinylidene chloride is chiefly used to produce poly (vinylidene chloride) copolymers used in household food wraps (see Vinylidene chloride and poly(vinylidene chloride). Chloroben2enes are important chemical intermediates with end use appHcations including disinfectants, thermoplastics, and room deodorants. 

Dehydrochlorination of 1,1,2-trichloroethane [25323-89-1] produces vinyHdene chloride (1,1-dichloroethylene). Addition of hydrogen chloride to vinyHdene chloride in the presence of a Lewis acid, such as ferric chloride, generates 1,1,1-trichloroethane. Thermal chlorination of 1,2-dichloroethane is one route to commercial production of trichloroethylene and tetrachloroethylene. 

AH volatile organic solvents are toxic to some degree. Excessive vapor inhalation of the volatile chloriaated solveats, and the central nervous system depression that results, is the greatest hazard for iadustrial use of these solvents. Proper protective equipment and operating procedures permit safe use of solvents such as methylene chloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene ia both cold and hot metal-cleaning operations. The toxicity of a solvent cannot be predicted from its chlorine content or chemical stmcture. For example, 1,1,1-trichloroethane is one of the least toxic metal-cleaning solvents and has a recommended threshold limit value (TLV) of 350 ppm. However, the 1,1,2-trichloroethane isomer is one of the more toxic chloriaated hydrocarboas, with a TLV of only 10 ppm. 

Feeding 1,2-dichloroethane, hydrogen chloride, and oxygen onto a fluidized bed at 400°C produces trichloroethylene and tetrachloroethylene. The catalyst bed consists of cupric chloride and potassium chloride on graphite. A modified oxychlorination technique known as the Transcat process has been developed by the Lummus Co. (32). The feedstock can be a saturated hydrocarbon or chlorohydrocarbon and the process is suited to the production of and chlorohydrocarbons. 

Oxidation. 1,1,1-Trichloroethane is stable to oxidation when compared to olefinic chlorinated solvents like trichloroethylene and tetrachloroethylene. Use of a 48-h accelerated oxidation test gave no hydrogen chloride, whereas trichloroethylene gave 0.4 wt % HCl and tetrachloroethylene gave 0.6 wt % HCl (22). 

Tetrachloroethane [630-20-6] CCI2CH2CI, is used primarily as a feedstock for the production of solvents such as trichloroethylene and tetrachloroethylene. 

Tetrachloroethane is produced by direct chlorination or oxychlorination utilizing ethylene as a feedstock. In most cases, 1,1,2,2-tetrachloroethane is not isolated, but immediately thermally cracked at 454°C to give the desired trichloroethylene and tetrachloroethylene products (122). A two-stage chlorination of 1,2-dichloroethane to give 1,1,2,2-tetrachloroethane has been patented (126). High purity 1,1,2,2-tetrachloroethane is made by chlorinating acetylene. 

In Japan, Toagosei is reported to produce trichloroethylene and tetrachloroethylene by chlorination of ethylene followed by dehydrochlorination. In this process the intermediate tetrachloroethane is either dehydrochlorinated to trichloroethylene or further chlorinated to pentachloroethane [76-01-7] followed by dehydrochlorination to tetrachloroethylene. Partially chlorinated by-products are recycled and by-product HCl is available for other processes. 

Table 5.52 General safety precautions with trichloroethylene and tetrachloroethylene Do not...

Anna CH, Maronpot RR, Pereira MA, et al. 1994. Ras proto-oncogene activation in dichloroacetic acid-, trichloroethylene-and tetrachloroethylene-induced liver tumors in B6C3F, mice. Carcinogenesis 15 2255-2261. 

Bogen KT, Colston BW Jr, Machicao LK. 1992. Dermal absorption of dilute aqueous chloroform, trichloroethylene, and tetrachloroethylene in hairless guinea pigs. Fundam Appl Toxicol 18 30-39. 

Koizumi A. 1989. Potential of physiologically based pharmacokinetics to amalgamate kinetic data of trichloroethylene and tetrachloroethylene obtained in rats and man. Br J Ind Med 46 239-249. 

Ogata M, Takatsuka Y, Tomokuni K. 1971. Excretion of organic chlorine compounds in the urine of persons exposed to vapours of trichloroethylene and tetrachloroethylene. Br J Ind Med 28 386. 

Peers AM. 1985. Method 5 The determination of trichloroethylene and tetrachloroethylene in air. lARC SciPubl 68 205-211. 

Skender LJ, Karacic V, Prpic-Majic D. 1991. A comparative study of human levels of trichloroethylene and tetrachloroethylene after occupational exposure. Arch Environ Health 46 174-178. 

Skender L, Karacic V, Bosner B, et al. 1993. Assessment of exposure to trichloroethylene and tetrachloroethylene in the population of Zagreb, Croatia. Int Arch Occup Environ Health 65 S163-S165. 

Walles SAS. 1986. Induction of single-strand breaks in DNA of mice by trichloroethylene and tetrachloroethylene. Toxicol Lett 31 31-35. 

Mixtures of the tetraoxide with dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, trichloroethylene and tetrachloroethylene are explosive when subjected to shock of 25 g TNT equivalent or less [1], Mixtures with trichloroethylene react violently on heating to 150°C [2], Partially fluorinated chloroalkanes were more stable to shock. Theoretical aspects are discussed in the later reference [2,3], The effect of pressure on flammability limits has been studied [4],... 

In batch kinetic tests, Yan and Schwartz (1999) investigated the oxidative treatment of chlorinated ethylenes in groundwater using potassium permanganate. 1,1-Dichloroethylene reacted more quickly than cis- and /ra/ 5-l, 2-dichloroethylene, trichloroethylene, and tetrachloroethylene. The reaction rate decreased with an increasing number of chlorine substituents. The pseudo-first-order rate constant and half-life for oxidative degradation (mineralization) of 1,1-dichloroethyene were 2.38 x 10 Vsec and 4.9 min, respectively. 

Friberg, L., Kylin, B., and Nystrom, A. Toxicities of trichloroethylene and tetrachloroethylene and Fujiwara s p3n idine-alkali reaction. Acta Pharmacol. Toxicol, 9 303-312,1953. 

The data on the reactivities of trichloroethylene and tetrachloroethylene further illustrate the competitive effects of substitutions on the 1- and 2-positions of ethylene. Trichloroethylene is more reactive than either of the 1,2-dichloroethylenes but less reactive than vinylidene chloride. Tetrachloroethylene is less reactive than trichloroethylene—analogous to the difference in reactivities between vinyl chloride and 1,2-dichloroethylene. The case of polyfluor-oethylenes is an exception to the generally observed large decrease in reactivity with polysubstitution. Tetrafluoroethylene and chlorotrifluoroethylene show enhanced reactivity due apparently to the small size of the fluorine atoms. 

Tetrachloroethanc is an intermediate in one proeess for the manufacture of trichloroethylene and tetrachloroethylene and has been reported to occur as an impurity in these widely used products. It has been detected at low levels in ambient air and in drinking-water. 

Over a period of years Dainton and his co-workers have studied intensively photochlorination processes. Their work also indicated (31) that at temperatures below 150°C. the kinetics of photochlorination of trichloroethylene and tetrachloroethylene are explainable in terms of reactions (l)-(6). Above a characteristic limiting concentration the observed rates are in agreement with eq. (C). However, in a more recent work Ayscough et al. (6) have compared the rates of geometrical isomerization (Ri) of pure cis- and trans-1,2-dichloroethylene with the rates of the simultaneously occurring photochlorination. This work is of... 

Volatile organic compounds (VOCs), especially trihalomethanes, are frequently found in drinking water due to the chlorination of humic acids. When UV irradiation is applied to the pre-ozonation of humic acids, the decomposition of VOC precursors increases (Hayashi et al., 1993). The ozonation rates of compounds such as trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,2-dichloroethane, and 1,2-dichloropropane were found to be dependent on UV intensity and ozone concentration in the aqueous phase by Kusakabe et al. (1991), who reported a linear relationship between the logarithmic value of [C]/[C0] and [03]f for 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene. The other two organochlorines followed the same first-order kinetics with and without UV irradiation (Kusakabe et al., 1991). Thus, the decomposition rate can be expressed as ... 

Burris, D.R., Campbell, T.J., and Manoranjan, V.S., Sorption of trichloroethylene and tetrachloroethylene in a batch reactive metallic iron-water system, Environ. Sci. Technol, 29, 2850-2855, 1995. 

Campbell, T.J., Burris, D.R., Roberts, A.L., and Wells, J.R., Trichloroethylene and tetrachloroethylene reduction in a metallic iron-water-vapor batch system, Environ. Toxicol. Chem., 16(4), 625-630, 1997. 

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