Trichloroethylene dechlorination

Dekant W, Metzler M, Henschler D. 1984. Novel metabolites of trichloroethylene through dechlorination reactions in rats, mice and humans. Biochem Pharmacol 33 2021-2027. 

Freedman DL, Gossett JM. 1989. Biological reductive dechlorination of tetrachloroethylene and trichloroethylene to ethylene under methanogenic conditions. Appl Environ Microbiol 55 2144-2151. 

Always based on the use of IR spectrophotometry, a novel attenuated total reflection-Fourier-transform infrared (ATR-FTIR) sensor [42] was proposed for the on-line monitoring of a dechlorination process. Organohalogenated compounds such as trichloroethylene (TCE), tetrachloroethylene (PCE) and carbon tetrachloride (CT) were detected with a limit of a few milligrams per litre, after extraction on the ATR internal-reflection element coated with a hydro-phobic polymer. As for all IR techniques, partial least squares (PLS) calibration models are needed. As previously, this system is promising for bioprocess control and optimization. 

Isotope fractionation between the vapor phase and the dissolved aqueous phase has been studied only for toluene and trichloroethylene (carbon only [545, 690]). Fractionation associated with adsorption has been quantified only for toluene in regard to sample extraction using a poly(dimethylsilo-xane)-coated solid-phase microextraction fiber [373] and qualified for benzene, toluene, and ethylbenzene based on high-pressure liquid chromatography analyses of isotopically labeled and unlabeled compounds (carbon and hydrogen [692]). Isotope fractionation associated with the reductive dechlorination of chlorinated ethylenes by zero-valent iron and zinc has been... 

The measurement technique was the crux of a paper by Acha et al.27 discussing the process of the dechlorination of aliphatic hydrocarbons. An ATR-FTIR sensor was developed to monitor parts per million (ppm) of trichloroethylene (TCE), tetrachloroethylene (PCE), and carbon tetrachloride (CT) in the aqueous effluent of a fixed-bed dechlorinating bioreactor. It was found that the best extracting polymer was polyisobutylene (PIB) as a 5.8 pm film. This afforded detection limits of 2, 3, and 2.5 mg/1 for TCE, PCE, and CT, respectively. The construction and operation of the measurement system are detailed in the paper. 

Butler and Heyes (1998) investigated the reductive dechlorination of hexachloroethane in water by iron sulfide. Tetrachloroethylene was the major product with pentachloroethane as a minor intermediate. Final reaction products were trichloroethylene, c/s-1,2-dichloroethylene, and acetylene. The rate of reaction increased with increasing iron sulfide concentrations and pH. At pH 7.8, first-order rate constants were 0.0726, 0.086, and 0.533/h at iron sulfide concentrations of 10, 25, and 100 g/L, respectively. At an iron sulfide concentration of 100 g/L, first-order rate... 

Zhang and Wang (1997) studied the reaction of zero-valent iron powder and palladium-coated iron particles with trichloroethylene and PCBs. In the batch scale experiments, 50 pL of 200 pg/mL PCB-1254 in methanol was mixed with 1 ml ethanol/water solution (volume ratio = 1/9) and 0.1 g of wet iron or palladium/iron powder in a 2-mL vial. The vial was placed on a rotary shaker (30 rpm) at room temperature for 17 h. Trichloroethylene was completely dechlorinated by the nanoscale palladium/iron powders within the 17-h time period. Only partial dechlorination of PCB-1254 was observed when wet iron powder was used. 

Pentachloroethane is dechlorinated in the presence of a rabbit liver reconstituted cytochrome P450 system or by rat liver microsomes, NADPH and oxygen (without oxygen, it is metabolized to 96% trichloroethylene and 4% 1,1,2,2-tetrachloroethane) (lARC, 1986). 

Burris, D.R., C.A. Delcomyn, M.H. Smith, and A.L. Roberts. 1996. Reductive dechlorination of tetrachloroethylene and trichloroethylene catalyzed by vitamin B12 in homogeneous and heterogeneous systems. Environ. Sci. Technol. 30, 3047-3052. 

Hu S. (1999) Reductive Dechlorination of Trichloroethylene by Metallic Iron Effects oflron Corrosion and Corrosion Inhibition. Master Thesis, New Mexico Institute of Mining and Technology. 

Orth W. S. and Gillham R. W. (1996) Dechlorination of trichloroethylene in aqueous solution using Fe°. Environmental Science Technology 30(1), 66-71. 

The electroreduction of trichloroethylene (0.4 g L 1) on Cu in 0.05 M NaOH was found to be more efficient than on Ag or Cd cathodes [4], with the current efficiency increasing when the applied current density decreased. At a current density of 4 mA cm-2, the current efficiencies for the dehalogenation of monochloroacetic acid, dichloroacetic acid, chloroform, and trichloroethylene were 2%, 10%, 87%, and 29%, respectively. 5-Chlorosalicylic acid could not be dechlorinated on Cu. Nagaoka et al. [17]... 

Many groundwaters are contaminated with the cleaning solvents trichloroethylene (TCE) and perchloroethylene (PCE). They are two of the most common organochlorine compounds found in Superfund sites. Radiation-induced decomposition of TCE in aqueous solutions has been the subject of several recent studies [15-20]. In most of the referenced studies, the complete destruction of TCE was observed. Dechlorination by a combination of oxidative and reductive radiolysis was stoichiometric. Gehringer et al. [15] and Proksch et al. [18] have characterized the kinetics and mechanism of OH radical attack on TCE and PCE in y-ray-irradiated aqueous solution. Trichloroethylene was readily decomposed in exponential fashion, with a reported G value of 0.54 pmol J-1. A 10 ppm (76 pM) solution was decontaminated with an absorbed dose of less than 600 Gy. For each OH captured, one C02 molecule, one formic acid molecule and three Cl- ions were generated. These products were created by a series of reactions initiated by OH addition to the unsaturated TCE carbon, which is shown in Eq. (45) ... 

Chen J-L, Al-Abed SR, Ryan JA, Li Z. Effects of pH on dechlorination of trichloroethylene by zero-valent iron. J Hazard Mater 2001 83 243-254. 

Direct electrolytic dechlorination of 9-chloroanthracene at a mercury electrode occurs at about -1.65 V (see) in a layer of adsorbed cetyltrimethylammonium bromide on the electrode surface233. Similarly, electrochemical degradation of trichloroethylene in acetonitrile resulted in quantitative conversion to chloroacetylene, which was reduced further to acetylene at a more negative reduction potential (-2.8 V) in 96% yield234. Reductive destruction of 1,3,5-trichlorobenzene in the cathode compartment could be observed235. Electrochemical methods presumably can be used for decontamination of chemical warfare agents such as mustard derivatives as an alternative to the chemical methods such as base-catalyzed dehydrohalogenation236. 

Farrell, J., Kason, M., Melitas, N. and Li, T. (2000) Investigation of the long-term performance of zerovalent iron for reductive dechlorination of trichloroethylene. Environ. Sci. Technol. 34, 514-521. 

Preparation of Derivatives. Enoate derivatives are prepared from the corresponding chiral alcohol by treatment with acry-loyl chloride in the presence of Triethylamine and catalytic 4-Dimethylaminopyridine or the appropriate carboxylic acid chloride and Silveril) Cyanide. Alkynyl ethers are readily available from the potassium alkoxide by treating with Trichloroethylene, in situ dechlorination with n-Butyllithium, and electrophilic trapping. Trapping the intermediate anion with a proton source or lodomethane followed by Lindlar reduction of the alkynyl ether affords the corresponding vinyl and l-(Z)-propenyl ether, respectively, while reduction of the alkynyl ether with Lithium Aluminum Hydride affords the l-( )-propenyl ether. 

Alkynylsulfides. A synthesis from alkyl- or arylthiols is accomplished through 5-alkylation with trichloroethylene, complete dechlorination to generate the thioethynyllithium species, and C-alkylation. 

Trichloroethylene is mixed with an excess of combustible solvent and burned in a chemical incinerator equipped with an afterburner and scrubber. It may be destroyed in aqueous waste streams or groundwater by UV peroxidation, involving treatment with hydrogen peroxide in the presence of UV light (Yost 1989 Sundstrom et al. 1990). Oku and Kimura (1990) have reported reductive dechlorination using sodium naphthalenide in tetrahydrofuran at 0°C for 10 minutes. Chlorine is removed as sodium chloride to the extent of 97-100%. 

Oku, A., and K. Kimura. 1990. Complete destruction of tetra- and trichloroethylene by reductive dechlorination using sodium naphthalenide. Chem. Express. 5(3) 181-84 cited in Chem. Abstr. CA 772(20) 185220u. 

Li T, Farrell J. (2000). Reductive dechlorination of trichloroethylene and carbon tetrachloride using iron and palladized iron cathodes. Environmental Science and Technology 34 173-179. 

Kang WH, Hwang I, Park JY (2006) Dechlorination of trichloroethylene by a steel converter slag amended with Fe (II). Chemosphere 62 285-293... 

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