Xn:Harmful;
127-18-4Relevant articles and documents
A novel method of CCl4 disposal by disproportionation with CH4 over Pt on various supports
Bae, Jong Wook,Lee, Jae Sung,Lee, Kyung Hee,Lee, Byeongno,Yang, Duck Joo
, p. 264 - 265 (2001)
In disproportionation of CCl4 with CH4 into CH3Cl and CHCl3, platinum supported on SrCO3, SiO2, MgO and MgAl2O4 showed stable activity and high selectivities around 700 K, providing a novel disposal method of ozone-depleting CCl4.
Influence of amine buffers on carbon tetrachloride reductive dechlorination by the iron oxide magnetite
Danielsen, Karlin M.,Gland, John L.,Hayes, Kim F.
, p. 756 - 763 (2005)
The influence of amine buffers on carbon tetrachloride (CCI4) reductive dechlorination by the iron oxide magnetite (FeIIFe II2O4) was examined in batch reactors. A baseline was provided by monitoring the reaction in a magnetite suspension containing NaCl as a background electrolyte at pH 8.9. The baseline reaction rate constant was measured at 7.1 × 10-5 ± 6.3 × 10-6 L m-2 h-1. Carbon monoxide (CO) was the dominant reaction product at 82% followed by chloroform (CHCI3) at 5.2%. In the presence of 0.01 M tris-(deuteroxymethyl) aminomethane (TRIS d), the reaction rate constant nearly tripled to 2.1 × 10 -4 ± 6.5 × 10-6 L m-2 h -1 but only increased the CHCI3 yield to 11% and did not cause any statistically significant changes to the CO yield. Reactions in the presence of triethylammonium (TEAd) (0.01 M) increased the rate constant by 17% to 8.6 × 10-5 ± 8.1 × 10 -6 L m-2 h-1 but only increased the CHCI 3 yield to 8.8% while leaving the CO yield unchanged. The same concentration of N,N,N′,N′-tetraethylethylenediamine (TEEN) increased the reaction rate constant by 18% to 8.7 × 10-5 ± 4.8 × 10-6 L m-2 h-1 but enhanced the CHCI3 yield to 34% at the expense of the CO yield that dropped to 35%. Previous work has shown that CHCI3 can be generated either through hydrogen abstraction by a trichloromethyl radical ( .CCI3), or through proton abstraction by the trichlorocarbanion (-:CCI3). These two possible hydrogenolysis pathways were examined in the presence of deuterated buffers. Deuterium tracking experiments revealed that proton abstraction by the trichlorocarbanion was the dominant hydrogenolysis mechanism in the magnetite-buffered TRISd and TEAd systems. The only buffer that had minimal influence on both the reaction rate and product distribution was TEAd. These results indicate that buffers should be prescreened and demonstrated to have minimal impact on reaction rates and product distributions prior to use. Alternatively, it may be preferable, to utilize the buffer capacity of the solids to avoid organic buffer interactions entirely.
Dynamic behaviour of chlorofluoroethanes at fluorinated chromia aerogels and fluorinated zinc(II) or magnesium(II) doped chromia aerogels
Bozorgzadeh, Hamid,Kemnitz, Erhard,Nickkho-Amiry, Mahmood,Skapin, Toma?,Winfield, John M.
, p. 83 - 92 (2003)
The preparation and characterisation of two series of fluorinated chromia aerogel materials, lightly doped with zinc(II) or magnesium(II), are described. They behave as heterogeneous catalysts for transformations of 1,1,2-trichlorotrifluoroethane under HF
Chlorination and dehydrochlorination reactions relevant to the manufacture of trichloroethene and tetrachloroethene: Part 1. Reaction pathways
Sutherland, Iain W.,Hamilton, Neil G.,Dudman, Christopher C.,Jones, Peter,Lennon, David,Winfield, John M.
, p. 1 - 11 (2011)
Factors which affect the selectivity of the chlorination of 1,2-dichloroethane and the associated dehydrochlorination reactions have been examined using approximate thermodynamic calculations, equilibrium measurements, and a continuous flow micro-reactor. There is a balance between surface and gas-phase chemistry within the system. Heterogeneous catalysis is not necessary to effect dehydrochlorination of 1,1,2,2-tetrachloroethane to trichloroethene but an attapulgite-supported copper(II) chloride catalyst favours formation of pentachloroethane and its dehydrochlorination product, tetrachloroethene. The latter is the thermodynamic minimum of the system. Below 473 K and with long reaction times (2 h, batch reactor), radical chlorination to form pentachloroethane is dominant. Above 573 K and under flow conditions, free radical dehydrochlorination to form trichloroethene becomes dominant. Heterogeneous chlorination under flow conditions provides a route to pentachloroethane and thence tetrachloroethene. High conversions favour the formation of oligomeric products.
Bidinosti, D. R.,Porter, R. F.
, p. 3737 - 3743 (1961)
A homoleptic tetravalent cerium silylamide
Crozier, Alan R.,Bienfait, Andre M.,Maichle-Moessmer, Caecilia,Toernroos, Karl W.,Anwander, Reiner
, p. 87 - 89 (2013)
Treatment of Ce[N(SiHMe2)2]3(thf) 2 with the chlorinating agents PhICl2, Ph3CCl or C2Cl6 gave the homoleptic Ce(iv) silylamide Ce[N(SiHMe2)2]4. When performed in the absence of donating (solvent) molecules, the trivalent cluster Ce 5[N(SiHMe2)2]8Cl7 was isolated.
Sidebottom, H. W.,Tedder, J. M.,Walton, J. C.
, p. 755 - 762 (1969)
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Boeeseken,Schimmel
, p. 112,125 (1913)
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Effects of AgI, AuIII, and CuII on the reductive dechlorination of carbon tetrachloride by green rust
O'Loughlin, Edward J.,Kemner, Kenneth M.,Burris, David R.
, p. 2905 - 2912 (2003)
Green rusts (GRs), mixed iron(II)/iron(III) hydroxide minerals found in many suboxic environments, have been shown to reduce a range of organic and inorganic contaminants, including several chlorinated hydrocarbons. Many studies have demonstrated the catalytic activity of transition metal species in the reduction of chlorinated hydrocarbons, suggesting the potential for enhanced reduction by GR in the presence of an appropriate transition metal catalyst. Reductive dechlorination of carbon tetrachloride (CT) was examined in aqueous suspensions of GR amended with AgI, AuIII, or CuII. The CT reduction rates were greatly increased for systems amended with CuII, AuIII, and AgI (listed in order of increasing rates) relative to GR alone. Observed intermediates and products included chloroform, dichloromethane, chloromethane, methane, acetylene, ethene, ethane, carbon monoxide, tetrachloroethene, and various nonchlorinated C3 and C4 compounds. Product distributions for the reductive dechlorination of CT were highly dependent on the transition metal used. A reaction pathway scheme is proposed in which CT is reduced primarily to methane and other nonchlorinated end products, largely through a series of one-electron reductions forming radicals and carbenes/carbenoids. Recently, X-ray absorption fine structure analysis of aqueous GR suspensions amended with AgI, AuIII, or CuII showed that the metals were reduced to their zerovalent forms. A possible mechanism for CT reduction is the formation of a galvanic couple involving the zerovalent metal and GR, with reduction of CT occurring on the surface of the metal and GR serving as the bulk electron source. The enhanced reduction of CT by GR suspensions amended with AgI, AuIII, or CuII may prove useful in the development of improved materials for remediation of chlorinated organic contaminants.
MULTIPHOTON IONIZATION OF CHLOROMETHANES WITH 193-NM EXCIMER LASER RADIATION IN ARGON MATRICES
Machara, Nicholas P.,Ault, Bruce S.
, p. 1908 - 1913 (1989)
The 193-nm output of an excimer laser has been coupled with the matrix isolation technique to demonstrate the feasibility of multiphoton ionization of matrix-isolated species.CCl4, CHCl3, and CH2Cl2 were, in turn, deposited in argon and (in some cases) nitrogen matrices and irradiated for between 5 min and 3 h.For CCl4 and CH2Cl2, the major product was the parent cation or species derived directly thereform, while more varied species, including the CHCL3(-) anion, were observed in the CHCl3 studies.In addition, neutral fragments were observed in a manner similar to previous resonance radiation and proton-beam radiolysis studies.Irradiation of the sample mixture during the deposition process led to increased product yield, as well as additional products for some of the systems.The laser irradiation time, power, and repetition rate were varied over a wide range, and a relative insensitivity to these parameters was noted.
Maynard
, p. 112 (1963)
Experimental study on the thermal oxidation of 1,3-hexachlorobutadiene at 500-1100°C
Baillet,Fadli,Sawerysyn
, p. 1261 - 1273 (1996)
Thermal degradation processes of 1,3-hexachlorobutadiene (C4Cl6) have been studied using a tubular flow reactor at 1 atm over the temperature range 500-1100°C for residence times of 2 seconds. Kinetic studies were performed with mixtures of 1000 ppmV of C4Cl6 in air. Overall Arrhenius parameters for the destruction of C4Cl6 were determined between 700 and 850°C. About 30 molecular halogenated products from C1 to C8 formed by pyrolysis or oxidation of 1,3-hexachlorobutadiene over the investigated temperature range were identified. Concentration profiles of major products (CO2, Cl2, CO, COCl2, C2Cl4, CCl4) and some minor products (C3Cl4O, C4Cl4O, C6Cl6, C3Cl4 and C3Cl6) have been measured as a function of temperature. Phosgene is the major chlorinated intermediate product. Detection of some aromatics such as hexachlorobenzene and octachlorostyrene show the importance of the molecular growth pathways in the chemical mechanism. Reaction pathways of main products are proposed and corresponding reaction enthalpies are estimated.
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West,Schmerling
, p. 3525 (1950)
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Transformation of chlorinated aliphatic compounds by ferruginous smectite
Cervini-Silva,Larson,Wu,Stucki
, p. 805 - 809 (2001)
A series of chlorinated aliphatic compounds (RCI, including carbon tetrachloride (PCM), 1,1,1-trichloroethane (TCA), 1,1,2,2-tetrachloroethane (TeCA), pentachloroethane (PCA), hexachloroethane (HCA), trichloroethene (TCE), tetrachloroethene (PCE), trichloronitromethane (chloropicrin, CP), and trichloroacetonitrile (TCAN)) was reacted with ferruginuous smectite (sample SWa-1 from The Source Clays Repository), SWa, in aqueous suspension under anoxic conditions. Compounds highly polarizable or sharing substituents that facilitate charge delocalization adsorbed faster by reduced (SWa-R) than by unaltered (SWa-U) clay, indicating stronger dipole-dipole interactions between the substituents and the clay surface and/or hydrating water molecules. The reduction of the clay accelerated RCI adsorption up to 100-fold. Incubations with SWa-R promoted RCI reduction (CP, TCAN) or dehydrochlorination (TeCA and PCA). The reduction of structural Fe catalyzes the transformation of RCI via Bronsted and Lewis-basic promoted pathways. This study indicates that oxidation state of the structural Fe in SWa greatly alters surface chemistry and has a large impact on clay-organic interactions.
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Weiser,Wightman
, p. 415 (1919)
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Kinetics and mechanism of the sonolytic degradation of CCL4: Intermediates and byproducts
Hua, Inez,Hoffmann, Michael R.
, p. 864 - 871 (1996)
The sonolytic degradation of aqueous carbon tetrachloride is investigated at a sound frequency of 20 kHz and 135 W (112.5 W cm-2) of power. The observed first-order degradation rate constant in an Ar-saturated solution is 3.3 x 10-3 s-1 when the initial CCh concentration, [CCl4](i), is 1.95 x 10-4 mol L-1 and increases slightly to 3.9 x 10-3 s-1 when [CCl4](i) = 1.95 x 10-5 mol L-1. Low concentrations (10-8-10-7 mol L-1) of the organic byproducts, hexachloroethane and tetrachloroethylene, are detected, as well as the inorganic products chloride ion and hypochlorous acid. The chlorine mass balance after sonolysis is determined to be >70%. The reactive intermediate, dichlorocarbene, is identified and quantified by means of trapping with 2,3-dimethyl-2-butene. The presence of ozone in the sonicated solution does not significantly effect the rate of degradation of carbon tetrachloride; however, O3 inhibits the accumulation of hexachloroethane and tetrachloroethylene. Ultrasonic irradiation of an aqueous mixture of p-nitrophenol (p-NP) and carbon tetrachloride results in the acceleration of the sonochemical degradation of p-NP. The sonolytic rate of degradation of p-NP appears to be enhanced by the presence of hypochlorous acid, which results from the sonolysis of CCl4.
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Carpenter,W.
, p. 3082 - 3084 (1965)
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McBee,Hass,Pierson
, p. 181,185 (1941)
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Skell, P. S.,Harris, R. F.
, p. 5807 - 5808 (1965)
Kinetics and Thermochemistry of the Cl(2PJ) + C2Cl4 Association Reaction
Nicovich, J. M.,Wang, S.,McKee, M. L.,Wine, P. H.
, p. 680 - 688 (1996)
A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of the Cl(2PJ) + C2Cl4 association reaction as a function of temperature (231-390 K) and pressure (3-700 Torr) in nitrogen buffer gas.The reaction is found to be in the falloff regime between third and second order over the range of conditions investigated, although the second-order limit is approached at the highest pressures and lowest temperatures.At temperatures below 300 K, the association reaction is found to be irreversible on the experimental time scale of ca. 20 ms.The kinetic data at T 0298 = -18.1 +/- 1.3 kcal mol-1, ΔH00 = -17.6 +/- 1.3 kcal mol-1, and ΔS0298 = -27.7 +/- 3.0 cal mol-1 K-1.In conjunction with the well-known heats of formation of Cl(2PJ) and C2Cl4, the above ΔH values lead to the following heats of formation for C2Cl5 at 298 and 0 K: ΔH0f,298 = 8.0 +/- 1.3 kcal mol-1 and ΔH0f,0 = 8.1 +/- 1.5 kcal mol-1.The kinetic and thermochemical parameters reported above are compared with other reported values, and the significance of reported association rate coefficients for understanding tropospheric chlorine chemistry is discussed.
Natural organic matter as reductant for chlorinated aliphatic pollutants
Kappler, Andreas,Haderlein, Stefan B.
, p. 2714 - 2719 (2003)
Humic acids (HA) are ubiquitous redox-active compounds of natural aquatic and soil systems. Here we studied the potential of HA as reductants for chlorinated aliphatic pollutants. To avoid artifacts potentially involved when studying chemically reduced HA, we prepared electrochemically reduced soil, aquatic and synthetic HA, and anthrahydroquinone-2,6-disulfonic acid (AHQDS), a model compound for hydroquinone moieties in HA. Both reduced HA and AHQDS reduced hexachloroethane (HCE) at appreciable rates. Some reduction of HCE by HA, however, occurred even before electrochemical reduction of the humic acids. This indicates that a small fraction of reduced moieties in HA persists at oxic conditions for some time. The initial reaction followed pseudo-first-order reaction kinetics, and tetrachloroethylene was the only halogenated product. The relatively small variations in carbonnormalized rate constants, kDOC, found indicate that despite inherent variations in concentration, accessibility, and reactivity of redox-active groups in HA of various origins their overall dechlorination activity is fairly constant. However, HCE transformation rate constants and reducing capacities of different HA did not correlate. Rate constants normalized to both carbon content and reducing capacity of HA clearly indicate that reduced functional groups in different HA exhibit different reactivities. Our results together with the factthat reduced HA can be formed by a variety of microbiological and chemical processes suggest that HA could play a significant role as reductants in the reductive transformation of subsurface contaminants and that such a process could potentially be enhanced at contaminated sites by addition of reducible natural organic matter.
Role of copper species in chlorination and condensation reactions of acetylene
Wehrmeier, Andreas,Lenoir, Dieter,Sidhu, Sukh S.,Taylor, Philip H.,Rubey, Wayne A.,Kettrup, Antonious,Dellinger, Barry
, p. 2741 - 2748 (1998)
We examined the thermally induced acetylene chlorination and condensation reactions on different types of copper salt impregnated surfaces. The System for Thermal Diagnostic Studies provided a powerful tool to study these reactions under defined reaction conditions, which were related to typical conditions in postcombustion incineration processes. Experiments were conducted with acetylene or acetylene/HCl mixtures in a quarts reactor filled with a borosilicate foam of known pore size at temperatures between 150 and 500 °C. Borosilicate was also used as the catalytic support for gas-solid reactions of acetylene and acetylene/HCl mixtures with CuCl2 and CuO. Reaction products were trapped in-line and analyzed by GC/MS. It was shown that borosilicate is not able to catalyze acetylene condensation reactions. CuCl2-impregnated borosilicate was a highly effective catalyst for acetylene chlorination/condensation reactions at temperatures above 150 °C. The same behavior was found for CuO- impregnated borosilicate in the presence of HCl. However, temperatures above 300 °C were required for this catalytic system. Mainly perchlorinated C-2 to C-8 hydrocarbons were trapped as reaction products in the gas phase. Maximum yields for acetylene chlorination/condensation reactions in each related catalytic system were found at temperatures between 300 and 400 °C. Results of the surface-catalyzed acetylene chlorination and condensation reactions were summarized in a global mechanism. A ligand transfer oxidative chlorination of acetylene with CuCl2 was proposed to be the initiation of acetylene with CuCl2 was proposed to be the initiating step. Chlorinated acetylene then condenses to higher molecular weight compounds, catalyzed by CuCl in metallacyclization reactions. We examined the thermally induced acetylene chlorination and condensation reactions on different types of copper salt impregnated surfaces. The System for Thermal Diagnostic Studies provided a powerful tool to study these reactions under defined reaction conditions, which were related to typical conditions in postcombustion incineration processes. Experiments were conducted with acetylene or acetylene/HCl mixtures in a quartz reactor filled with a borosilicate foam of known pore size at temperatures between 150 and 500 °C. Borosilicate was also used as the catalytic support for gas-solid reactions of acetylene and acetylene/HCl mixtures with CuCl2 and CuO. Reaction products were trapped in-line and analyzed by GC/MS. It was shown that borosilicate is not able to catalyze acetylene condensation reactions. CuCl2-impregnated borosilicate was a highly effective catalyst for acetylene chlorination/condensation reactions at temperatures above 150 °C. The same behavior was found for CuO-impregnated borosilicate in the presence of HCl. However, temperatures above 300 °C were required for this catalytic system. Mainly perchlorinated C-2 to C-8 hydrocarbons were trapped as reaction products in the gas phase. Maximum yields for acetylene chlorination/condensation reactions in each related catalytic system were found at temperatures between 300 and 400 °C. Results of the surface-catalyzed acetylene chlorination and condensation reactions were summarized in a global mechanism. A ligand transfer oxidative chlorination of acetylene with CuCl2 was proposed to be the initiating step. Chlorinated acetylene then condenses to higher molecular weight compounds, catalyzed by CuCl in metallacyclization reactions.
Kinetics of the transformation of halogenated aliphatic compounds by iron sulfide
Hayes,Butler
, p. 422 - 429 (2000)
The transformation of nine halogenated aliphatic compounds, i.e., pentachloroethane (PCA), 1,1,2,2- and 1,1,1,2-tetrachloroethanes (1122-TeCA and 1112-TeCA), 1,1,1- and 1,1,2-trichloroethanes (111-TCA and 112-TCA), 1,1- and 1,2-dichloroethanes (11-DCA and 12-DCA), carbon tetrachloride (CT), and tribromomethane (TBM), by 10 g/L FeS at pH 8.3 was investigated in batch experiments. 11-DCA, 12-DCA, and 112-TCA showed no significant transformation by FeS over ~ 120 days, but the other compounds were transformed with half-lives of hours to days. PCA and 1122-TeCA underwent dehydrohalogenation faster than FeS-mediated reductive dehalogenation reactions. The remaining compounds for which considerable transformation was observed underwent FeS-mediated reactions more rapidly than hydrolysis or dehydrohalogenation. For 1112-TeCA, the dihaloelimination product, i.e., 1,1-dichlroethylene, was the only reaction product observed. For 111-TCA, CT, and TBM, hydrogenolysis products were the only products detected, even though their mass recoveries were significantly 100%. Two simple log-linear correlations between rate constants and either one-electron reduction potentials or homolytic bond dissociation enthalpies were developed, with determination coefficients of 0.48 and 0.82, respectively. These results were consistent with a rate-limiting step involving homolytic bond dissociation. However, neither correlation precisely characterized the reactivity of all the compounds, indicating distinctions among the mechanisms for reductive dehalogenation of the compounds by FeS or the influence of additional molecular or thermodynamic parameters on rate constants.
Pyrolysis of hexachloroethane in the gas phase: computer aided kinetic study
Huybrechts,Theys,Van Mele
, p. 755 - 761 (1996)
The pyrolysis of C2Cl6 has been studied between 652 and 735 K at pressures ranging from 19 to 50 torr. The observed total pressure- and Cl2 pressure-time curves show S-shapes with an induction period depending on temperature and pressure. Further, the total pressure goes through a maximum to finally reach a lower constant value. These curves are explained in terms of a recently proposed reaction model using a parameter optimization computer program.
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Benkeser,R.A.,Smith,W.E.
, p. 5307 - 5309 (1968)
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Three-dimensionally ordered macroporous Cr2O3?CeO2: High-performance catalysts for the oxidative removal of trichloroethylene
Zhang, Xing,Liu, Yuxi,Deng, Jiguang,Zhao, Xingtian,Zhang, Kunfeng,Yang, Jun,Han, Zhuo,Jiang, Xiyun,Dai, Hongxing
, p. 200 - 209 (2019/02/14)
Three-dimensionally ordered macroporous (3DOM) CeO2, 3DOM Cr2O3, 3DOM xCr2O3?CeO2 (x (the weight percentage of Cr2O3) = 3.5, 5.5, and 8.0 wt%), and 5.5 wt% Cr2O3/3DOM CeO2 samples were prepared using the polymethyl methacrylate (PMMA)-templating and incipient wetness impregnation methods, respectively. A number of techniques were used to characterize physicochemical properties of the materials, and their catalytic activities were evaluated for the oxidation of trichloroethylene (TCE). These samples possessed a good-quality 3DOM structure and a surface area of 35?47 m2/g. The 3DOM 5.5Cr2O3?CeO2 sample performed the best (the temperature at TCE conversion = 90% = 255 °C at a space velocity of 20,000 mL/(g h)). Effects of water vapor and carbon dioxide on activity of the 5.5Cr2O3?CeO2 sample were also examined. It is observed that partial deactivation induced by H2O introduction of the 5.5Cr2O3?CeO2 sample was reversible, while that induced by CO2 addition was irreversible. Based on the activity data and characterization results, it is concluded that the good catalytic activity and thermal stability of 3DOM 5.5Cr2O3?CeO2 was associated with its high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Cr2O3 and CeO2. We believe that the 3DOM 5.5Cr2O3?CeO2 catalyst is promising in the application for oxidative removal of chlorinated volatile organic compounds.
METHOD OF PRODUCING VINYL CHLORIDE
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Paragraph 0031; 0038; 0039, (2020/01/27)
A method of producing vinyl chloride is provided in the present invention. The method includes the following steps. First, 1,2-dichloroethane (EDC) is introduced into a reactor, and a residence time of the EDC in an ionic liquid catalyst is 5 seconds to 100 seconds, so as to perform a catalytic cleavage reaction. The ionic liquid catalyst is in a liquid phase. The ionic liquid catalyst includes tributylalkyl phosphonium halide, and the alkyl includes an alkyl group having 3 to 16 carbon atoms.
