Halogenated hydrocarbons 1.1.1- trichloroethane

Several lower partially halogenated hydrocarbons (dichloromethane, bromo-methane, trichloroethylene, 1,1,1-trichloroethane) have no measurable flash point, but are nonetheless capable of forming flammable and explosive mixtures with air, and several such accidents are recorded. 

Halogenated Hydrocarbons. A few halogenated hydrocarbons were studied by the usual procedure, using mixtures in air over the platinum filament. Neither dichlorodifluoromethane (CC12F2) nor 1,1-dichloro-ethene yielded a measurable ion current at temperatures up to 900°C. 1,1,1-Trichloroethane yielded a modest ion current, but the results were erratic and not reproducible. There was some indication that the halogen compounds changed the behavior of the filament. Consequently, no further experiments with halogenated compounds were conducted. This erratic behavior was in contrast with the very reproducible results with hydrocarbons. 

Porphyrinatoiron(IV) carbenes, including that resulting from the reaction of l,l-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), are produced by reaction of poly-halogenated hydrocarbons with PFe (equation 57) i588,i589... 

Aliphatic and aromatic halogenated hydrocarbons are widely used as industrial reagents, cleaning agents and solvents. The toxicity of the individual substances is very varied, e.g. relative to trichloroethane (nominal toxicity = 1), trichloroethylene, chloroform and carbon tetrachloride have a toxicity of 8, 60 and 190, respectively. (s. tab. 30.3)... 

For the synthesis of 6,12-dihydro-6-hydroxy-cannabidiol as the intermediate in accordance with the invention the starting materials are the readily available olivetol (formula II) and cis-p-menth-2-ene-l,8-diol (formula III). The reaction is performed in a suitable solvent, aromatic hydrocarbons such as benzene and toluene, halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane and trichloroethane, ethers such as diethylether, diisopropylether and tetrahydrofuran having proved to be suitable. Furthermore it is possible to use mixtures of the said solvents. Toluene, benzene, methylene chloride and chloroform are the preferred solvents for use in the method of the invention. 

I, 1,1 -trichloroethane and other halogenated hydrocarbons are generally supportive and rely on the body s ability to eliminate rapidly 1,1,1-trichloroethane and its metabolites. Animal studies indicate that intravenous injection or infusion of calcium gluconate or phenylephrine are protective against acute blood pressure reduction caused by exposure to 1,1,1-trichloroethane (Herd et al. 1974). Further animal testing is needed to assess whether these compounds might be used to resuscitate individuals exposed to high concentrations of 1,1,1-trichloroethane. 

G. R. Umbreit (24) has used the gas-equilibration technique to measure several halogenated hydrocarbons, employing both flame ionization detection (FID) and electron capture (EC). Halogenated hydrocarbons included dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, 1,2,2-trichlo-... 

Another type of selectivity effect that can become important during the deactivation of oxidation catalysts for halogenated hydrocarbons arises from the inherent selectivity of the catalyst. Ramanathan and Spivey 0 studied the catalytic oxidation of dichloroethane and of trichloroethane over chromia on alumina catalyst. The selectivity observed is summarized in Figure 9, below ... 

Products of incomplete combustion have been shown to increase as the catalyst deactivates. Agarwal et al. report that the oxidation of a mixed stream of trichloroethylene and C5-C9 hydrocarbons over a chromia alumina catalyst produced CO equal to 32% of the total CO + CO2 with fresh catalyst. With a deactivated catalyst, CO had risen to 54% of the total carbon oxides produced. Pope et al. report products of incomplete combustion for the oxidation of 1,1,1-trichloroethane over a cobalt oxide catalyst. The cause of the catalyst deactivation has not been established, but both Agarwal et al. and Michalowiczl reference evidence of carbonaceous deposits on the catalyst after oxidation of halogenated hydrocarbons. ESCA studies by Hucknall et al. O have always shown a carbon residue on palladium alumina catalysts in addition to adsorbed halogen. 

Effects Solvents are potent CNS depressants. The acute effects of excessive exposure are nausea, vertigo, locomotor disturbances, headache, and coma. Chronic exposure to halogenated hydrocarbons leads to both hepatic dysfunction and nephrotoxicity. Long-term exposure to tetrachloroethylene—or to trichloroethane—has caused peripheral neuropathy. 

Causes of acute chemical hepatitis include exposure to industrial solvents such as halogenated hydrocarbons (methylene chloride, trichloroethylene, and trichloroethane) carbon tetrachloride (only rarely encountered in modem industry) and dimethylformamide, dinitropropane, and di-methylacetamide. The jet and rocket fuel components hydrazine and monomethylhydrazine are also potent hepatotoxins. 

Generally speaking, the halogenated hydrocarbons do not present a significant fire hazard (Table 10). Halogenated solvents commonly used in vapor degreasing, including trichloroethylene, perchloroeth-ylene, 1,1,1-trichloroethane, trichlorotri-fluoroethane, and methylene chloride, do not have a flash point by ASTM flashpoint test methods. They have been shown to be essentially nonflammable under prescribed use conditions. 

Liver halogenated hydrocarbons (e.g., caib[Pg.1319]

Fig. 134. Chromatograms of highly volatile halogenated hydrocarbons on two columns with different polarity 1) = Dichloromethane 2) = Chloroform 3) = Carbon tetrachloride 4) = 1,1,1-trichloroethane 5) = Trichloroethene ...

M,l—TRICHLOROETHANE. CCl CHv In limited laboratory tests. 3003 alloy was resistant to tri-chloroethane at ambient temperature and under refluxing conditions. CAUTION See "Halogenated Hydrocarbons. See also Ref (3) p. 109. (7) p. 185. 

Cooper. W.J., Mehran, M., l nsech, D.J., and Joens, J.A. Abiotic transformations of halogenated organics. 1. Elimination reactionof 1,1,2,2-tetrachloroethaneand formation of 1.1.2-trichloroethane. / v7ro/ .5c7 Technol, 21 (11) 1112-1114,1987. Coover, M.P. and Sims, R.C.C. The effects of temperature on polycyclic aromatic hydrocarbon persistence in an unacclimated agricultural soil, Haz. WasteHaz. Mater., 4 69-82, 1987. 

Researchers believe that the PSVE technology can be used to remove volatile organic compounds (VOCs), halogenated volatile organic compounds (HVOCs), and total petroleum hydrocarbons (TPH). Some chemicals treated with PSVE include carbon tetrachloride, vinyl chloride (VC), chlorobenzene, 1,1-dichloroethane, dichloroethene (DCE), trichloroethane (TCA), and benzene, toluene, ethylbenzene, and xylene (BTEX). 

One of the most important direct uses for nitromethane is in the stabilization of halo-genated hydrocarbons. For example, small amounts of nitromethane are widely used in industry to form stable non-corrosive mixtures with 1,1,1-trichloroethane for vapour degreasing, dry cleaning and for cleaning semiconductors and lenses. It is also used to stabilize the halogenated propellants for aerosols and to inhibit corrosion on the interiors of tin-plated steel cans containing water-based aerosol formulations (Markofsky, 1991 Angus Chemical Co., 1998). 

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