Xn:Harmful;
71-55-6Relevant articles and documents
Natural formation of vinyl chloride in the terrestrial environment
Keppler, Frank,Borchers, Reinhard,Pracht, Jens,Rheinberger, Stefan,Scholer, Heinz F.
, p. 2479 - 2483 (2002)
Vinyl chloride is a highly reactive and toxic substance which is widely used in industry. It is the parent compound of poly(vinyl chloride) (PVC), one of the most important industrial polymers. Until now, it was thought that vinyl chloride found in the environment is exclusively man-made or results from the degradation of other anthropogenic substances, such as trichloroethylene and tetrachloroethylene. Here, we demonstrate that vinyl chloride also has natural sources. Soil air and ambient air from a rural area in Northern Germany were investigated for volatile chlorinated halocarbons. The concentrations of vinyl chloride in the soil air were significantly enhanced as compared to ambient air, indicating a natural formation of this compound in the soil. A series of laboratory experiments using different soils and model compounds was conducted, which clearly proved that vinyl chloride could be produced during soil processes. We propose that this highly reactive compound can be formed during the oxidative degradation of organic matter in soil, for example, in a reaction between humic substances, chloride ions and an oxidant (ferric ions or hydroxyl radicals). The redox-sensitive aromatic compounds in soil such as catechols and o-quinones can be degraded to CO2, accompanied by the release of vinyl chloride and other volatile chlorinated compounds. This process could have started in the Late Silurian to Early Devonian, 400 million years ago, when the first soils on earth evolved.
Effect of preparation method on the performance of porous RuOx/Co3O4 catalysts for 1, 2-dichloroethane oxidation
Deng, Wei,Gao, Biao,Guo, Limin,Jia, Ziye,Liu, Dongqi,Zhu, Simin
, (2021/08/20)
Porous Co3O4 with high yield was synthesized through calcination from plate-like Co(OH)(OCH3). Then, a series of Co3O4 supported RuOx catalysts were prepared using three different loading methods, including homogeneous precipitation (HP), precipitation-deposition (DP), and wet impregnation (IM). Their physicochemical properties were investigated by various characterization techniques, and their performance for catalytic oxidation of 1, 2-dichloroethane (1, 2-DCE) was also evaluated. RuOx/Co3O4-HP possessed the most outstanding low-temperature reducibility, more oxygen vacancies, and surface active oxygen, correspondingly exhibited a better catalytic activity and lower selectivity of polychlorinated by-products. Moreover, RuOx/Co3O4-HP also presented an excellent performance for other types of hydrocarbons abatement. The stability test showed that the RuOx/Co3O4-HP showed highly stable activity for 1, 2-DCE oxidation, and the beneficial effect of water was further confirmed.
PROCESS FOR THE PRODUCTION OF ETHYLENE, VINYLIDENE, AND HYDROGEN CHLORIDE FROM ETHANE
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Page/Page column 5-8, (2016/06/13)
A process is provided for the chlorination of ethane using chlorine as the chlorinating agent to produce vinylidene (1,1-dichloroethylene), hydrogen chloride and ethylene.
On the mechanism of action of gated molecular baskets: The synchronicity of the revolving motion of gates and in/out trafficking of guests
Hermann, Keith,Rieth, Stephen,Taha, Hashem A.,Wang, Bao-Yu,Hadad, Christopher M.,Badjic, Jovica D.
body text, p. 90 - 99 (2012/03/09)
We used dynamic 1H NMR spectroscopic methods to examine the kinetics and thermodynamics of CH3CCl3 (2) entering and leaving the gated molecular basket 1. We found that the encapsulation is first-order in basket 1 and guest 2, while the decomplexation is zeroth-order in the guest. Importantly, the interchange mechanism in which a molecule of CH3CCl3 directly displaces the entrapped CH 3CCl3 was not observed. Furthermore, the examination of the additivity of free energies characterizing the encapsulation process led to us to deduce that the revolving motion of the gates and in/out trafficking of guests is synchronized, yet still a function of the affinity of the guest for occupying the basket: Specifically, the greater the affinity of the guest for occupying the basket, the less effective the gates are in "sweeping" the guest as the gates undergo their revolving motion.
Method of stabilizing trichloroethane during production
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Page 4, (2008/06/13)
Trichloroethane, e.g., 1,1,1-trichloroethane, is stabilized during processing at temperatures at which it is susceptible to thermal decomposition by conducting such processing in the presence of a stabilizing amount of a stable free radical stabilizer, e.g., a material having a 2,2,6,6-tetra(lower alkyl)-1-piperidinyloxy-yl free radical group such as 2,2,6,6-tetramethyl-4-hydroxy-1-piperidinyloxy.
Transient puffs of trace organic emissions from a batch-fed waste propellant incinerator
Hart, John R.
, p. 559 - 569 (2007/10/03)
Emissions data have been obtained from a waste propellant incinerator. The incinerator is a dual fixed hearth, controlled air incinerator equipped with acid gas and particulate scrubbing. Puffing has been evident in this waste propellant incinerator by spikes in the CO concentration. Transient puffs of organics may travel down the combustion chambers and lead to stack emissions. The major conclusions from this study are that (1) transient puffs are formed due to the semi-batch feed nature of the combustion process (causing a local oxygen deficiency) and high water content of the desensitized propellant; (2) in batch-fed combustors, puffs can contribute to most of the organic emissions (which are relatively low) measured with US EPA sampling and analytical methods; (3) it is estimated that batch-fed combustion contributes up to 7-18 times more emissions than steady-state combustion will generate; (4) by applying dispersion analyses to determine the amount of oxygen deficiency in the flame zone, the combustion zone concentration of CO during batch-fed operation could be as high as 160,000 ppm, compared to a measured peak stack concentration of 1200 ppm CO; and (5) an organic sample is collected and averaged over at least a 2-h period that smooths out the transient peaks of organics emissions during batch-fed operation. For emissions that are associated with long-term potential health impacts, this is an appropriate sampling method. However, if a compound has a short-term potential health impact, it may be important to measure the time-resolved emissions of the compound.
Reactions of chlorinated vinylsilanes with hydrogen chloride
Lakhtin, V. G.,Ryabkov, V. L.,Kisin, A. V.,Nosova, V. M.,Chernyshev, E. A.
, p. 375 - 378 (2007/10/03)
Catalytic hydrochlorination of a series of chloro(chlorovinyl)methylsilanes was studied. The course of the reaction depends on the number and position of the chlorine atoms in the initial monomers.
Kinetics of the R + Cl2 (R = CH2Cl, CHBrCl, CCl3 and CH3CCl2) reactions. An ab initio study of the transition states
Seetula, Jorma A.
, p. 3561 - 3567 (2007/10/03)
The kinetics of the reactions of CH2Cl, CHBrCl, CCl3 and CH3CCl2 radicals with molecular chlorine were investigated in a heatable tubular reactor coupled to a photoionization mass spectrometer. The reactions were studied under pseudo-first-order conditions. The radicals were photogenerated at 248 nm. The pressure-independent rate constants determined were fitted to the following Kooij and Arrhenius expressions (units in cm3 molecule-1 s-1): k-(CH2Cl) = 7.56 × 10-17(T)1.45 exp(-350 J mol-1/RT), k(CHBrCl) = 5.83 × 10-20(T)2.3 exp(-300 J mol-1/RT), k(CCl3) = (8.4 ± 2.9) × 10-13 exp[-(25 ± 9) kJ mol-1/RT] and k(CH3CCl2) = 1.10 × 10-26(T)4.3 exp(+15000 J mol-1/RT). The Arrhenius rate expression for the Cl + CCl4 reaction was determined to be k(Cl + CCl4) = (3.9 ± 3.2) × 10-13 exp[-(71 ± 9) kJ mol-1/RT] using the kinetics measured and the thermochemistry of the CCl3 radical. Errors for the Kooij expressions were estimated to be 25% overall, and for the Arrhenius expressions they were calculated to be 1σ + Student's t values. The transition states of the measured R + Cl2 and four other similar reactions were localized and fully optimized at the MP2/6-31G(d,p) level of theory by ab initio methods. The energetics of the reactions were considered by determining thermochemical and activation parameters of the reactions. The reactivity differences of the radicals studied were explained by a free-energy correlation using an electronegativity difference scale.
CH3CF3-nCln haloalkanes and CH2=CF2-nCln halo-olefins on γ-alumina catalysts: reactions, kinetics and adsorption
Hess, A.,Kemnitz, E.
, p. 27 - 36 (2007/10/03)
The heterogeneously catalyzed reactions of the haloalkane, CH3CF(3-n)Cln, and halo-olefin, CH2=CF(2-n)Cl(n), series have been studied on a γ-alumina catalyst and the experimental results compared with calculated thermodynamic data.The main reactions occurring in this system can be explained by the following reaction paths: dehydrohalogenation, hydrohalogenation, F/Cl and Cl/F exchange with hydrogen halides.Dismutation reactions which are observed in other halocarbon series are unimportant in this system.A survey of the dominant reactions is given.In addition, the kinetic behaviour of CH3CF2Cl on the γ-alumina catalyst and the adsorption of various halocarbons have been investigated.The isosteric enthalpies of adsorption demonstrate that the interaction between the haloalkanes and the solid surface is more dominant than simple condensation. - Keywords: Chlorofluorocarbons; γ-Alumina catalysts; Heterogeneous catalysis; Kinetics; Adsorption; Enthalpy of adsorption
MECHANISMS OF FREE-RADICAL REACTIONS XXX. MECHANISM OF FREE-RADICAL CHLORINATION OF ORGANIC COMPOUNDS BY SODIUM HYPOCHLORITE IN THE PRESENCE OF PHASE-TRANSFER CATALYSTS
Dneprovskii, A. S.,Eliseenkov, E. V.
, p. 235 - 240 (2007/10/02)
The reaction of hydrocarbons and their derivatives with sodium hypochlorite in the presence of phase-transfer catalysts and also with dichlorine monoxide takes place by a common free-radical mechanism, and the hydrogen atom is abstracted both by the chloroxy radical and by the chlorine radical.In the range of pH 7-9 it is possible to conduct the free-radical chlorination process with a minimal contribution from the site processes involving oxidation and ionic chlorination of the alkyl aromatic substrates.The relative rate constants for a series of organic substrates was measured by the method of competing reactions.The observed selectivity of the process is a quantity that depends on the relative contribution from the two competing mechanisms.
