- Cloning of a novel dehalogenase from environmental DNA
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Cloning of pce A, the gene of tetrachloroethene (PCE)- reductive dehalogenase, was undertaken from environmental DNA. Two genes were amplified using PCR primer deduced from pee A. Functional expression of these genes was unsuccessful in Escherichia coli, but PceA1 synthesized in vitro was enzymatically active. In recombinant E. coli, PceA1 formed a complex with host DnaK and caused filamentous growth.
- Kimoto, Hisashi,Suye, Shin-Ichiro,Makishima, Hirokazu,Arai, Jun-Ichirou,Yamaguchi, Sachiko,Fujii, Yutaka,Yoshioka, Toshihito,Taketo, Akira
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Read Online
- Ionic strength and buffer effects in the elimination reaction of 1,1,2,2-tetrachloroethane
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The rate constant for the abiotic reaction of 1,1,2,2-tetrachloroethane in aqueous solution has been studied as a function of ionic strength, buffer composition, temperature, and pH. The rate of reaction is found to be independent of ionic strength and buffer composition, with the parent compound quantitatively converted into trichloroethene by a base mediated elimination reaction for values of pH > 3.5. The Arrhenius parameters for the elimination reaction are log10 A = 16.32 ± 0.40; E(a) = 95.0 ± 2.5 kJ/mol. No evidence for a neutral hydrolysis reaction was found, indicating that the rate constant for such a reaction is -7 s-1 at 90°C.
- Joens,Slifker,Cadavid,Martinez,Nickelsen,Cooper
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Read Online
- Reductive dechlorination of tetrachloroethylene in soils by Fe(II)-based degradative solidification/stabilization
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Fe(II)-based degradative solidification/stabilization (DS/S) is a modification of conventional solidification/stabilization (S/S) that uses Fe(II) as a reducing agent for chlorinated organics while immobilizing inorganic contaminants. Feasibility of the Fe(II)-based DS/S technology in treating soils contaminated with tetrachloroethylene (PCE) was tested in this study. The results of the PCE degradation experiments conducted in the presence of a humic acid suggest that natural organic matter would not significantly interfere with the degradative reaction by the Fe(II)-containing reactive species in DS/S systems. Solid-phase degradation experiments showed that the DS/S technology could effectively treat PCE in soils without substantial production of chlorinated intermediates. A pseudo-first-order rate law reasonably described degradation kinetics. The half-lives of PCE ranged from 13 to 335 days, which are within time spans allowable for typical in-situ DS/S application. Trichloroethylene (TCE) was the only chlorinated product observed in the solid-phase experiments, and its presence was generally transitory with the amount being less than 7% of the initial amount of PCE on a molar basis. A surface reaction appears to control observed PCE degradation kinetics rather than mass transfer to the reactive surface.
- Hwang,Batchelor
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Read Online
- IR spectroscopic study of the dichloromethyl peroxyl radical and its deuterated analogs in the argon matrix
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The dichloromethyl peroxyl radical (CHCl2OO?) and its deuterated analog formed in the reaction of the corresponding dichloromethyl radicals with O2 were studied by matrix IR spectroscopy. Dichloromethyl radicals are genera
- Baskir, E. G.,Nefedov, O. M.
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p. 2236 - 2240
(2022/01/22)
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- Method for eliminating hydrogen chloride by catalytic cracking of chloralkane
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The invention discloses a method for eliminating hydrogen chloride by catalytic cracking of chloralkane, comprising the following steps of: carrying out a cracking reaction on chloralkane under the action of a biomass-based nitrogen-doped carbon catalyst to eliminate hydrogen chloride so as to prepare corresponding olefin, wherein the biomass-based nitrogen-doped carbon catalyst is prepared by carbonizing biomass or a mixture of biomass and a nitrogen source at 400-1000 DEG C, and the biomass is selected from at least one of bamboo processing leftovers, wood processing leftovers, plant straws,plant leaves, cereals, beans, cereal processing leftovers, bean processing leftovers and livestock manure. The method disclosed by the invention has the advantages of simple preparation process, easily available raw materials, low cost, strong process controllability, easiness in large-scale production, high catalytic cracking conversion rate of the chloralkane, high product selectivity, low energy consumption and the like.
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Paragraph 0101-0105
(2020/08/06)
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- METHOD OF PRODUCING VINYL CHLORIDE
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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.
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Paragraph 0031; 0038; 0039
(2020/01/27)
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- Rational design of CrOx/LaSrMnCoO6 composite catalysts with superior chlorine tolerance and stability for 1,2-dichloroethane deep destruction
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1,2-dichloroethane (1,2-DCE) is a representative industrial chlorinated volatile organic compound (CVOC) making great hazardous to the environment and human health. In this work, LaSrMnCoO6 (LSMC) double perovskite-type materials with high thermal stability and coke resistance in 1,2-DCE oxidation were prepared by a facile sol-gel method. Based on this, a series of CrOx/LaSrMnCoO6 catalysts (Cr/LSMC, CrOx loading = 5 to 20 wt.%) which combine the merits of CrOx (high activity and chlorine tolerance) and LaSrMnCoO6 were synthesized and adopted in deep oxidation of 1,2-DCE for the first time. As expected, obvious synergistic effects between CrOx and LSMC on 1,2-DCE destruction were observed. Amongst, 10 wt.% CrOx/LaSrMnCoO6 (10Cr/LSMC) shows the best catalytic activity with 90% of 1,2-DCE destructed at 400 °C. Furthermore, the outstanding catalytic durability and water resistance of 10Cr/LSMC in 1,2-DCE oxidation were also demonstrated. In addition to this, the reaction pathway of 1,2-DCE decomposition over Cr/LSMC materials was discussed based on the results of online product analysis. We found that the enhanced catalytic performance of Cr/LSMC materials can be reasonably attributed to their high reducibility, excellent 1,2-DCE adsorption capability, and large amounts of surface active lattice oxygen species. It can be anticipated that the Cr/LSMC catalysts are promising materials for CVOC elimination and the results from this work could also provide some new insights into the design of catalysts for CVOC efficient destruction.
- Tian, Mingjiao,Jian, Yanfei,Ma, Mudi,He, Chi,Chen, Changwei,Liu, Chao,Shi, Jian-Wen
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- Chlorination reactions relevant to the manufacture of trichloroethene and tetrachloroethene; Part 2: Effects of chlorine supply
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The behaviour of 1,1,2,2-tetrachloroethane and trichloroethene in chlorination reactions where the supply of chlorine is varied, either by change in chlorocarbon: Cl2 feed ratio or the quantity of supported copper(II) chloride catalyst or by the use of an anhydrous hydrogen chloride/dioxygen feed as the source of chlorine, i.e. oxychlorination conditions, is described. Depending on the exact conditions used, the products are trichloroethene, pentachloroethane or tetrachloroethene. The products and the conditions under which they are observed are both in harmony with a previously proposed reaction scheme in which there is interplay between heterogeneous and homogeneous reactions. It is possible to define sets of reaction conditions which lead to improvements in selectivity towards the formation of either CHCl=CCl2 or CCl2=CCl2 without significant formation of oligomeric species.
- Sutherland, Iain W.,Hamilton, Neil G.,Dudman, Christopher C.,Jones, Peter,Lennon, David,Winfield, John M.
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p. 149 - 156
(2014/04/03)
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- Chlorination and dehydrochlorination reactions relevant to the manufacture of trichloroethene and tetrachloroethene: Part 1. Reaction pathways
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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.
- Sutherland, Iain W.,Hamilton, Neil G.,Dudman, Christopher C.,Jones, Peter,Lennon, David,Winfield, John M.
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experimental part
p. 1 - 11
(2012/02/01)
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- Catalytic fluorination of 1,1,1-trifluoro-2-chloro-ethane in the presence of oxygen over chromium based catalyst doped or not by zinc supported over partially fluorinated alumina
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The addition of zinc in low amount to chromium based catalyst supported over partially fluorinated alumina has a positive effect for the fluorination reaction of CF3CH2Cl in the presence of dioxygen in order to prevent the catalyst deactivation. However, under these operating conditions, the Deacon reaction by reaction with HCl produced by Cl/F exchanges could be involved. The formation of various by-products was observed corresponding to the addition of HCl or Cl2 into halogenated double bonds.
- Loustaunau,Fayolle-Romelaer,Celerier,Brunet
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experimental part
p. 1262 - 1265
(2011/12/21)
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- ArF laser photolytic deposition and thermal modification of an ultrafine chlorohydrocarbon
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MW ArF laser irradiation of gaseous cis-dichloroethene results in fast decomposition of this compound and in deposition of solid ultrafine Cl- and H-containing carbonaceous powder which is of interest due to its sub-microscopic structure and possible reactive modification of the C-Cl bonds. The product was characterized by electron microscopy, and FTIR and Raman spectra and it was revealed that HCl, H2, and C/H fragments are lost and graphitic features are adopted upon heating to 700°C.
- Pola, Josef,Galikova, Anna,Subrt, Jan,Ouchi, Akihiko
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experimental part
p. 625 - 629
(2011/10/19)
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- Preparation and reactivity of vitaminB12-TiO2 hybrid catalyst immobilized on a glass plate
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The vitaminB12-TiO2 hybrid catalyst was effectively immobilized on a glass plate, and the immobilized catalyst shows an efficient reactivity for various molecular transformations, such as the 1,2-migration of a phenyl group and dechlorination of perchloroethylene during irradiation by UV light.
- Shimakoshi, Hisashi,Abiru, Makoto,Kuroiwa, Keita,Kimizuka, Nobuo,Watanabe, Midori,Hisaeda, Yoshio
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experimental part
p. 170 - 172
(2010/05/15)
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- Influence of sorption to dissolved humic substances on transformation reactions of hydrophobic organic compounds in water. Part II: Hydrolysis reactions
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The effect of dissolved humic acid (HA) on two types of hydrolysis reactions was investigated: (I) dehydrochlorination of γ-hexachlorocyclohexane (HCH) and 1,1,2,2-tetrachloroethane (TeCA) as a reaction involving hydroxide ions (OH-) and (II) hydrolysis of 1-octyl acetate (OA) which is catalyzed by H+ at the applied pH value (pH 4.5). The rate of TeCA hydrolysis was not affected by addition of 2 g l-1 of HA at pH 10 (k′ = 0.33 h-1) but HCH hydrolysis was significantly inhibited (k′ = 4.6 × 10-3 h-1 without HA and 2.8 × 10-3 h-1 at 2 g l-1 HA). HCH is sorbed by 51% whereas TeCA sorption is insignificant at this HA concentration. Sorbed HCH molecules are effectively protected due to electrostatic repulsion of OH- by the net negative charge of the HA molecules. In contrast, OA hydrolysis at pH 4.5 (k′ = 1.6 × 10-5 h-1) was drastically accelerated after addition of 2 g l-1 HA (k′ = 1.1 × 10-3 h-1). The ratio of the pseudo-first-order rate constants of the sorbed and the freely dissolved ester fraction is about 70. H+ accumulation in the microenvironment of the negatively charged HA molecules was suggested to contribute to the higher reaction rate for the sorbed fraction in case of this H+-catalyzed reaction. Analogous effects from anionic surfactants are known as micellar catalysis.
- Georgi, Anett,Trommler, Ulf,Reichl, Annett,Kopinke, Frank-Dieter
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p. 1452 - 1460
(2008/09/17)
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- INTEGRATED PROCESS FOR PRODUCING 1,2-DICHLOROETHYLENE
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Describes an integrated process for preparing 1,2-dichloroethylenes. In the described process organic feed material, e.g., C2-C4 aliphatic hydrocarbons and/or chlorinated derivatives of such aliphatic hydrocarbons, is introduced into a first reaction zone 10, e.g., a chlorination zone such as an oxychlorination zone, or a thermal cracking zone; first product effluent from the first reaction zone is forwarded to a second reaction zone 9; trichloroethane is introduced into the second reaction zone and into heat exchange contact with the first product effluent from the first reaction zone, which has a heat content sufficient to cause thermal dehydrochlorination of trichloroethane in the second reaction zone; and second product effluent is removed from the second reaction zone. 1,2-dichloroethylene is recovered by conventional distillation recovery methods from the second product effluent.
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Page/Page column 6-7
(2008/06/13)
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- Addition of tetrachloromethane to oct-1-ene initiated by amino alcohols
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The kinetics and mechanism of an addition of CCl4 to oct-1-ene initiated by amines, aromatic alcohols, and amino alcohols (structural analogs of ephedrin) were studied. The radical mechanism of the reaction was established by ESR using the technique of spin traps. Aromatic amino alcohols as initiators are more active than amines and aromatic alcohols of similar structure. They are more selective compared to the amines and aromatic alcohols and react with CCl4 already at room temperature to form predominantly benzaldehyde. The scheme of initiation by aromatic amino alcohols of the addition of CCl 4 to olefins was proposed on the basis of the experimental data.
- Tarkhanova,Gantman,Chizhov,Smirnov
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p. 1624 - 1630
(2007/10/03)
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- Kinetics and inhibition of reductive dechlorination of chlorinated ethylenes by two different mixed cultures
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Kinetic studies with two different anaerobic mixed cultures (the PM and the EV cultures) were conducted to evaluate inhibition between chlorinated ethylenes. The more chlorinated ethylenes inhibited the reductive dechlorination of the less chlorinated ethylenes, while the less chlorinated ethylenes weakly inhibited the dechlorination of the more chlorinated ethylenes. Tetrachloroethylene (PCE) inhibited reductive trichloroethylene (TCE) dechlorination but not cis-dichloroethylene (c-DCE) dechlorination, while TCE strongly inhibited c-DCE and VC dechlorination. c-DCE also inhibited vinyl chloride (VC) transformation to ethylene (ETH). When a competitive inhibition model was applied, the inhibition constant (KI) for the more chlorinated ethylene was comparable to its respective Michaelis-Menten half-velocity coefficient, KS. Model simulations using independently derived kinetic parameters matched the experimental results well. k max and KS values required for model simulations of anaerobic dechlorination reactions were obtained using a multiple equilibration method conducted in a single reactor. The method provided precise kinetic values for each step of the dechlorination process. The greatest difference in kinetic parameters was for the VC transformation step. VC was transformed more slowly by the PM culture (kmax and KS values of 2.4 ± 0.4 μmol/mg of protein/day and 602 ± 7 μM, respectively) compared to the EV culture (8.1 ± 0.9 μmol/mg of protein/day and 62.6 ± 2.4 μM). Experimental results and model simulations both illustrate how low KS values corresponded to efficient reductive dechlorination for the more highly chlorinated ethylenes but caused strong inhibition of the transformation of the less chlorinated products. Thus, obtaining accurate K S values is important for modeling both transformation rates of parent compounds and their inhibition on daughter product transformation.
- Yu, Seungho,Dolan, Mark E.,Semprini, Lewis
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p. 195 - 205
(2007/10/03)
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- Reactivity of Fe(II)-Bearing Minerals toward Reductive Transformation of Organic Contaminants
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Fe(II) present at surfaces of iron-containing minerals can play a significant role in the overall attenuation of reducible contaminants in the subsurface. As the chemical environment, i.e., the type and arrangement of ligands, strongly affects the redox potential of Fe(II), the presence of various mineral sorbents is expected to modulate the reactivity of surficial Fe(II)-species in aqueous systems. In a comparative study we evaluated the reactivity of ferrous iron in aqueous suspensions of siderite (FeCO 3), nontronite (ferruginous smectite SWa-1), hematite (α-Fe2O3), lepidocrocite (γ-FeOOH), goethite (α-FeOOH), magnetite (Fe3O4), sulfate green rust (FeII4FeIII2(OH)12SO 4·4H2O), pyrite (FeS2), and mackinawite (FeS) under similar conditions (pH 7.2, 25 m2 mineral/L, 1 mM Fe(II)aq, O2 (aq) 0.1 g/L). Surface-area-normalized pseudo first-order rate constants are reported for the reduction of hexachloroethane and 4-chloronitrobenzene representing two classes of environmentally relevant transformation reactions of pollutants, i.e., dehalogenation and nitroaryl reduction. The reactivities of the different Fe(II) mineral systems varied greatly and systematically both within and between the two data sets obtained with the two probe compounds. As a general trend, surface-area-normalized reaction rates increased in the order Fe(II) + siderite Fe(II) + iron oxides Fe(II) + iron sulfides. 4-Chloronitrobenzene was transformed by mineral-bound Fe(II) much more rapidly than hexachloroethane, except for suspensions of hematite, pyrite, and nontronite. The results demonstrate that abiotic reactions with surface-bound Fe(II) may affect or even dominate the long-term behavior of reducible pollutants in the subsurface, particularly in the presence of Fe(III) bearing minerals. As such reactions can be dominated by specific interactions of the oxidant with the surface, care must be taken in extrapolating reactivity data of surface-bound Fe(II) between different compound classes.
- Elsner, Martin,Schwarzenbach, Rene P.,Haderlein, Stefan B.
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p. 799 - 807
(2007/10/03)
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- Reductive capacity of natural reductants
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The reductive capacities of soil minerals and Silawa soil for Cr(VI) and chlorinated ethylenes were determined and characterized to understand in situ treatment using these natural reductions. The reductive capacity of soil minerals for Cr(VI) was 3-16 times greater than that for tetrachloroethylene (PCE), indicating that Cr(VI) is more susceptible to the reduction by soil minerals than PCE. Green rust (GRSO4) showed the greatest reductive capacity for Cr(VI) and PCE followed by magnetite, pyrite, biotite, montmorillonite, and vermiculite. The major transformation product in pyrite and GRSO4 suspensions was acetylene rather than dichloroethylene (DCE) and vinyl chloride (VC). For VC degradation, ethylene was the main transformation product with a low concentration of ethane observed. Fe(II) content in soil minerals was directly proportional to the reductive capacity of soil minerals for Cr(VI) and PCE, suggesting that Fe(II) content is an important factor that significantly affects reductive transformations of target contaminants in natural systems.
- Lee, Woojin,Batchelor, Bill
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p. 535 - 541
(2007/10/03)
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- Synthesis of 1,1,1-trifluoroethane by fluorination of 1-chloro-1, 1-difluoroethane
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The subject of the invention is the manufacture of 1,1,1-trifluoroethane by fluorination or 1-chloro-1,1-difluoroethane with anhydrous hydrofluoric acid. The reaction is carried out in the liquid phase and in the presence of a fluorination catalyst.
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- Abiotic reductive dechlorination of chlorinated ethylenes by iron-bearing soil minerals. 1. Pyrite and magnetite
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Abiotic reductive dechlorination of chlorinated ethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), cis- dichloroethylene (cis-DCE), and vinyl chloride (VC)) by pyrite and magnetite was characterized in a batch reactor system. Dechlorination kinetics was adequately described by a modified Langmuir-Hinshelwood model that includes the effect of a decreasing reductive capacity of soil mineral. The kinetic rate constant for the reductive dechlorination of target organics at reactive sites of soil minerals was in the range of 0.185 (±0.023) to 1.71 (±0.06) day-1. The calculated specific reductive capacity of soil minerals for target organics was in the range of 0.33 (±0.02) to 2.26 (±0.06) μM/g and sorption coefficient was in the range of 0.187 (±0.006) to 0.7 (±0.022) mM-1. Surface area-normalized pseudo-first-order initial rate constants for target organics by pyrite were found to be 23.5 to 40.3 times greater than those by magnetite. Target organics were mainly transformed to acetylene and small amount of chlorinated intermediates, which suggests that β-elimination was the main dechlorination pathway. The dechlorination of VC followed a hydrogenolysis pathway to produce ethylene and ethane. The addition of Fe(II) increased the dechlorination rate of cis-DCE and VC in magnetite suspension by nearly a factor of 10. The results obtained in this research provide basic knowledge to better predict the fate of chlorinated ethylenes and to understand the potential of abiotic processes in natural attenuation.
- Lee, Woojin,Batchelor, Bill
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p. 5147 - 5154
(2007/10/03)
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- Transient puffs of trace organic emissions from a batch-fed waste propellant incinerator
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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.
- Hart, John R.
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p. 559 - 569
(2007/10/03)
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- Effects of alcohols, anionic and nonionic surfactants on the reduction of PCE and TCE by zero-valent iron
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The effects of surfactants, sodium dodecyl sulfate (SDS) and Triton X-a00 (TX), and alcohols (methanol, ethanol, and propanol) on the dehalogenation of TCE and PCE by zero-valent iron were examined. Surface concentrations of PCE and TCE on the iron were dependent on aqueous surfactant concentrations. At concentrations above the CMC, sorbed halocarbon concentrations declined and concentrations associated with solution phase micelles increased. The anionic surfactant SDS ([SDS]a mixed effect on reactivity, increasing the PCE reduction rate, but not affecting TCE removal. Production of TCE from PCE increased in the presence of TX. Similar experiments showed that methanol, ethanol, and propanol inhibited reduction of TCE and PCE by metallic iron. Zero-valent iron may be useful in recycling soil washing effluents contaminated with TCE and PCE. Copyright
- Loraine, Gregory A
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p. 1453 - 1460
(2007/10/03)
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- Transformation of chlorinated aliphatic compounds by ferruginous smectite
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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.
- Cervini-Silva,Larson,Wu,Stucki
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p. 805 - 809
(2007/10/03)
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- Hazardous air pollutants formation from reactions of raw meal organics in cement kilns
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Thermally induced chlorination, condensation, and formation reactions of raw meal organic surrogates were investigated on different types of 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 the preheater zone of cement kiln. Experiments were conducted with benzene and benzene/myristic acid (C6H6/C13H27COOH) mixtures in a quartz reactor containing different chlorinating catalysts/reagents over a temperature range of 300-500°C. Reaction products were trapped in-line and analyzed by GC-MS. A mixture of chlorides of calcium, potassium, aluminium and iron was highly effective for chlorination/condensation reactions of benzene and benzene/myristic acid mix at temperatures above 300°C. The same behavior was observed only when calcium chloride and potassium chloride were used as chlorinating catalyst/reagent. This result showed that transition metal chlorides like FeCl3 are not necessary for chlorination/condensation of organics under post-combustion conditions. Methylene chloride was the major chlorinated product followed by chloroform and various other C1, C2 and C6 chlorinated products. Yields of chlorinated aliphatics were highest at 400°C for both benzene and benzene/myristic acid mix. C6 products were mainly mono- to hexa-chlorinated benzenes with trace amounts of chlorinated phenols. The major chlorinated products observed in this study (i.e., methylene chloride, chloroform, chloroethanes and monochlorobenzene) were also present as major chlorinated hydrocarbons in the cement kiln field emission data.
- Sidhu, Sukh,Kasti, Nabil,Edwards, Phil,Dellinger, Barry
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p. 499 - 506
(2007/10/03)
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- Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene
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The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C2 through C8 organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene. (C) 2000 Elsevier Science Ltd.
- Taylor, Philip H.,Wehrmeier, Andreas,Sidhu, Sukh S.,Lenoir, Dieter,Schramm,Kettrup
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p. 1297 - 1303
(2007/10/03)
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- Kinetics of the transformation of halogenated aliphatic compounds by iron sulfide
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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.
- Hayes,Butler
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p. 422 - 429
(2007/10/03)
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- Copyrolysis of polychloroethanes
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Pyrolysis of tetrachloroethanes at 713-773 K for a time shorter than 7 s was studied. The rate constants of pyrolysis of pure tetrachloroethanes and their mixtures with penta- and hexachloroethane were compared.
- Bykov,Solyannikov,Berlin
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p. 1595 - 1599
(2007/10/03)
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- Kinetics of the Tansformation of Trichloroethylene and Tetrachloroethylene by Iron Sulfide
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The transformation of trichloroethylene (TCE), tetrachloroethylene (PCE), and 1,1-dichloroethylene (1,1-DCE) by 10 g/L (0.5 m2/L) FeS in aqueous solution at pH 8.3 was studied in batch experiments. TCE and PCE were transformed by FeS with pseudo-first-order rate constants, corrected for partitioning to the sample headspace, of (1.49 +/- 0.14) E-3 h-1 (TCE) and (5.7 +/- 1.0) E-4 h-1 (PGE). A 17 percent decrease in the concentration of 1,1-DCE was observed over 120 days; however, no reaction products were detected. TCE and PCE transformation data were fit to a rate law assuming transformation of TCE via parallel reaction pathways to acetylene and cis-1,2-dichloroethylene (cis-DCE) and transformation of PCE via parallel reaction pathways to acetylene and TCE. Acetylene was the major reaction product for both TCE and PCE. Determination of rate constants for each reaction pathway indicated that TGE was transformed to acetylene 11.8 +/- 1.1 times faster than to cis-DCE and that PCE was transformed to acetylene 8.2 +/-1.8 times faster than to TCE. Additional minor reaction products were vinyl chloride (VC) for TCE and cis-DCE for PCE. Detection of acetylene as the major product of both TCE and PCE transformation by FeS contrasts with the sequential hydrogenolysis products typically observed in the microbial transformation of these compounds, making acetylene a potential indicator of abiotic transformation of TCE and PCE by FeS in natural systems.
- Bulter, Elizabeth C.,Hayes, Kim F.
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p. 2021 - 2027
(2007/10/03)
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- Reactions of chlorinated vinylsilanes with hydrogen chloride
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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.
- Lakhtin, V. G.,Ryabkov, V. L.,Kisin, A. V.,Nosova, V. M.,Chernyshev, E. A.
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p. 375 - 378
(2007/10/03)
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- Generation of radical species in surface reactions of chlorohydrocarbons and chlorocarbons with fluorinated gallium(III) oxide or indium(III) oxide
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The reactions of C1 and C2 chlorohydrocarbons and chlorocarbons have been studied with the Lewis acid catalysts fluorinated gallium(III) oxide and fluorinated indium(III) oxide, respectively. Product analysis shows chlorine-for-fluorine exchange reactions together with the formation of 2-methylpropane and its chlorinated analogues 2-chloromethyl-1,3-dichloropropane and 2-chloromethyl-1,2,3-trichloropropane. Reactivities of the chlorohydrocarbon probe molecules show fluorinated gallium(III) oxide to be a stronger Lewis acid than fluorinated indium(III) oxide. The formation of the symmetrical butyl compounds is consistent with the generation of surface radical species and is also consistent with a 1,2-migration mechanism operating within radical moieties at the Lewis acid surface.
- Thomson
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p. 1881 - 1885
(2007/10/03)
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- Role of copper species in chlorination and condensation reactions of acetylene
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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.
- Wehrmeier, Andreas,Lenoir, Dieter,Sidhu, Sukh S.,Taylor, Philip H.,Rubey, Wayne A.,Kettrup, Antonious,Dellinger, Barry
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p. 2741 - 2748
(2007/10/03)
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- Pathways of chlorinated ethylene and chlorinated acetylene reaction with Zn(O)
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To successfully design treatment systems relying on reactions of chlorocarbons with zero-valent metals, information is needed concerning the kinetics and pathways through which transformations occur. In this study, pathways of chlorinated ethylene reaction with Zn(O) have been elucidated through batch experiments. Data for parent compound disappearance and product appearance were fit to pseudo-first-order rate expressions in order to develop a complete kinetic model. Results indicate that reductive β- elimination plays an important role, accounting for 15% of tetrachloroethylene (PCE), 30% of trichloroethylene (TCE), 85% of cis- dichloroethylene (cis-DCE), and 95% of trans-dichloroethylene (trans-DCE) reaction. The fraction of PCE, TCE, trans-DCE, and cis-DCE transformation that occurs via reductive elimination increases as the two-electron reduction potential (E2) for this reaction becomes more favorable relative to hydrogenolysis. In the case of PCE and TCE, reductive elimination gives rise to chlorinated acetylenes. Chloroacetylene and dichloroacetylene were synthesized and found to react rapidly with zinc, displaying products consistent' with both hydrogenolysis and reduction of the triple bond. Surface area-normalized rate constants (k(SA))for chlorinated ethylene disappearance correlate well with both one-electron (E1) and two-electron (E2) reduction potentials for the appropriate reactions. Correlation with E2 allows prediction of the distribution of reaction products as well as the rate of disappearance of the parent compound. To successfully design treatment systems relying on reactions of chlorocarbons with zero-valent metals, information is needed concerning the kinetics and pathways through which transformations occur. In this study, pathways of chlorinated ethylene reaction with Zn(0) have been elucidated through batch experiments. Data for parent compound disappearance and product appearance were fit to pseudo-first-order rate expressions in order to develop a complete kinetic model. Results indicate that reductive β-elimination plays an important role, accounting for 15% of tetrachloroethylene (PCE), 30% of trichloroethylene (TCE), 85% of cis-dichloroethylene (cis-DCE), and 95% of trans-dichloroethylene (trans-DCE) reaction. The fraction of PCE, TCE, trans-DCE, and cis-DCE transformation that occurs via reductive elimination increases as the two-electron reduction potential (E2) for this reaction becomes more favorable relative to hydrogenolysis. In the case of PCE and TCE, reductive elimination gives rise to chlorinated acetylenes. Chloroacetylene and dichloroacetylene were synthesized and found to react rapidly with zinc, displaying products consistent with both hydrogenolysis and reduction of the triple bond. Surface area-normalized rate constants (kSA) for chlorinated ethylene disappearance correlate well with both one-electron (E1) and two-electron (E2) reduction potentials for the appropriate reactions. Correlation with E2 allows prediction of the distribution of reaction products as well as the rate of disappearance of the parent compound.
- Arnold, William A.,Lynn Roberts
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p. 3017 - 3025
(2007/10/03)
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- Decomposition of acenaphthylene by ultrasonic irradiation
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Polycyclic aromatic hydrocarbons were extracted from a soil sample using ultrasound and dichloromethane-, cyclohexane-, and toluene-water mixtures. It was found that when dichloromethane is used as an extractant, acenaphthylene reacts with the solvent Several chlorinated and oxygenated derivatives were identified. The results show that chlorinated solvents should be avoided because of their sonolytic decomposition. Particularly unsaturated nonaromatic compounds might react with intermediate decomposition radicals of the solvent
- Leonhardt,Stahl
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p. 1228 - 1230
(2007/10/03)
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- Catalytic synthesis of 1,1,1,2-tetrafluoroethane from 1,1,1,2-tetrachloroethane - A mechanistic consideration
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1,1,1,2-Tetrachloroethane and its fluorinated derivatives as well as trichloroethene are fluorinated by hydrogen fluoride in the presence of a pre-conditioned chromia catalyst. The reaction pathways are derived under different conditions. Fluorinated haloalkanes are formed both by dehydrochlorination/hydrofruorination mechanism as well as chlorine/ fluorine exchange mechanism. Thus, beside fluorinated alkanes considerable amounts of haloolefins occur in the product mixture. A survey is given on the reaction pathway showing dependence on the reaction conditions. It is discussed with respect to calculated thermodynamic data. Kinetic and mechanistic investigations of the isomerisation reactions of 1.1.2.2-tetrafluoroethane on a CFC-conditioned chromia catalyst are also presented. The desired 1.1.1.2- tetrafluoroethane can be obtained from its symmetric isomer in the presence of a chromia catalyst conditioned exclusively with chlorine-free fluorocarbons. Mechanistic information is obtained by employing DCl which behaves similar to HF during the consecutive isomerisation reaction of 1.1.2.2- tetrafluoroethane. Thus, it is most probable that dehydrohalogenation/hydrohalogenation processes (elimination/addition mechanism) are mainly responsible for the formation of the haloolefins and halocarbons observed on chromia.
- Kemnitz,Niedersen,Kohne
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p. 485 - 493
(2007/10/03)
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- Corrinoid-mediated reduction of tetrachloroethene, trichloroethene, and trichlorofluoroethene in homogeneous aqueous solution: Reaction kinetics and reaction mechanisms
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It is shown that in homogeneous aqueous solution containing titanium(III) citrate or titanium(III)-NTA as bulk electron donor, cobalamin, cobinamide, and cobamide are effective electron transfer mediators for the reduction of tetrachloroethene (PCE), trichloroethene (TCE), and trichlorofluoroethene (TCFE). For a given chlorinated ethene, the reaction rate varied only slightly with pH and type of corrinoid present and was about 5 and 50 times faster for PCE as compared to TCFE and TCE, respectively. Evidence is presented that the first and rate-limiting step of the reduction of PCE, TCE, and TCFE by super-reduced corrinoids is a dissociative one- electron transfer yielding the corresponding vinyl radicals. Furthermore, the elimination of a chloride radical from the 1,1-dichlorovinyl radical yielding chloroacetylene and subsequently acetylene is proposed to account for the direct formation of acetylene out of TCE. Finally, it is demonstrated that at higher reduction potentials the corrinoid mediators may be blocked by the formation of addition products.
- Glod, Guy,Angst, Werner,Holliger, Christof,Schwarzenbach, Rene P.
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p. 253 - 260
(2007/10/03)
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- Intramolecular Geminal and Vicinal Element Effects in Substitution of Simple Bromo(chloro)alkenes by Methoxide and Thiolate Ions. An Example of a Single Step Substitution?
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Intramolecular element effects kBr/kCl for substitution of geminal bromochloroalkenes BrC(Cl)=C-(Br)Cl (1), BrC(Cl)=CCl2 (2), Me2C=C(Br)Cl (3), and XCH=C(Br)Cl (X = Cl, 4; X = Br, 5), with MeO- and RS- nucleophiles were investigated. 3 did not give substitution, and 4 and 5 gave substitution with MeO- via an initial elimination (to acetylene)-addition route, followed by further reactions. In reactions of 4 with thiolates, geminal element effects of 2-10 were obtained. Formation of RSC(Cl)=C(Cl)Y, Y = SR, Br, is ascribed to an initial halophilic reaction, followed by addition of RSCl to the formed acetylene. Reaction of 2 with MeO- gave a high vicinal element effect, and RS- gave a high geminal element effect. Reaction of 1 with both MeO- and RS- ions gave high (2 orders of magnitude) geminal element effects, which were interpreted as indicating a rate-determining C-X bond cleavage. This is supported by the high kBr/kCl intermolecular element effects (k(1)/k(Cl2C=CCl2) with MeO- and PhCH2S- ions. Mechanistic alternatives based on these observations are discussed.
- Beit-Yannai, Michal,Rappoport, Zvi,Shainyan, Bagrat A.,Danilevich, Yuri S.
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p. 8049 - 8057
(2007/10/03)
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- High utility of Saccharomyces cerevisiae harboring rat liver cytochrome P450 1A2 cDNA in haloethanes dehalogenations
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Yeast harboring rat liver P450 1A2 efficiently degraded trichloroethylene, pentachloroethane and hexachloroethane. Since liver P450s catalyze degradation of thousands of chemicals, this method is promising for chemical-directed degradation of environmental pollutants.
- Yanagita, Kazutaka,Sagami, Ikuko,Shimizu, Toru
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p. 561 - 562
(2007/10/03)
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- Mechanistic aspects of the isomerization reactions of 1,1,2,2-tetrafluoroethane on a CFC-conditioned chromia catalyst
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The mechanism of the isomerization reactions of 1,1,2,2-tetrafluoroethane on a CFC-conditioned chromia catalyst was investigated. The desired 1,1,1,2-tetrafluoroethane can be obtained from its symmetric isomer in the presence of a chromia catalyst conditioned exclusively with chlorine-free fluorocarbons. In the presence of chlorofluorocarbons, hydrogen chloride is formed as a result of the decomposition reactions of the haloalkane used and is strongly adsorbed on to the surface. This HCl causes a very complex system of side-reactions. In addition, a second kind of chlorine, inactive chloride bonded to chromium, is formed which can only be removed as the result of a very slow solid-gas reaction. Mechanistic information was obtained by examining the effects of substituting DCl for HCl as the chlorine source for the reaction with consecutive isomerization products of 1,1,2,2-tetrafluoroethane. Thus, it is most probable that dehydrohalogenation/hydrohalogenation processes (elimination/addition mechanism) are mainly responsible for the formation of the halo-olefins and halocarbons observed on chromia. As the HCl/DCl adsorbed on the surface is very quickly removed by the reactions with the halocarbons and halo-olefins, it is advantageous to employ pulse techniques to evaluate this reaction system.
- Kemnitz,Niedersen
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p. 111 - 119
(2007/10/03)
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- Effect of temperature, pH and electron donor on the microbial reductive dechlorination of chloroalkenes
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In order to elucidate the effect of environmental conditions such as pH, temperature, and electron donor on the microbial reductive dechlorination of tetrachloroethylene and its transformation products, batch, acetate-fed methanogenic cultures were developed from a field contaminated soil and incubated within a pH range of 4 to 9.5 and a temperature range of 5 to 45°C. Optimum conditions for reductive dechlorination were achieved at pH and temperature values of around 7 and 35°C, respectively. Methane production was more affected by pH and temperature than was the rate of dechlorination. Increased levels of electron donor (acetate) resulted in faster rates of both methanogenesis and reductive dechlorination. The effect of pH and temperature on the dechlorination rate and methane production were simulated by using previously established relationships pertaining to the activation and deactivation of enzymatic processes.
- Zhuang,Pavlostathis
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p. 3537 - 3548
(2007/10/03)
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- Liquid-phase chlorination of C-chlorovinylsilanes
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Liquid-phase chlorination of a number of chloro(chlorovinyl)methylsilanes was investigated.A number of novel C-chlorosilanes were characterized by IR and 1H NMR spectra.Some regularities of these reactions were determined: correlations between the structure of chloro(chlorovinyl)methylsilanes and their reactivities were identified. - Key words: chloro(chlorovinyl)methylsilanes; chlorine; chlorination; chloroethylsilanes; C-chlorosilanes; IR spectra; 1H NMR spectra.
- Lakhtin, V. G.,Ryabkov, V. L.,Kisin, A. V.,Nosova, V. M.,Polyakova, M. V.,Chernyshev, E. A.
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p. 2163 - 2167
(2007/10/03)
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- Heterogeneous catalyzed synthesis of 1,1,1,2-tetrafluoroethane from 1,1,1,2-tetrachloroethane - thermodynamics and reaction pathways
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1,1,1,2-Tetrachloroethane and its fluorinated derivatives, as well as trichloroethene, were fluorinated by hydrogen fluoride in the presence of a preconditioned chromia catalyst.The reaction pathways were derived under different conditions.Fluorinated haloalkanes are formed both by dehydrochlorination/hydrofluorination mechanisms as well as a chlorine/fluorine exchange mechanism.Thus, beside fluorinated alkanes considerable amounts of halo-olefins occur in the product mixture.A survey is given of the reaction pathways showing their dependence on the reaction conditions.These are discussed with respect to the calculated thermodynamic data. - Keywords: Heterogenous catalysis; Chlorofluorocarbon; Hydrofluorocarbon; Halocarbon; Fluorination; HFC-134a formation
- Kohne, A.,Kemnitz, E.
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p. 103 - 110
(2007/10/03)
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- Reductive Dechlorination of Tetrachloroethylene by a Chlorobenzoate-Enriched Biofilm Reactor
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This study evaluates the potential and technical feasibility of treating chloroaliphatics, common groundwater contaminants, using a specialized microbial consortium under fixed-film conditions. The reactor was developed using 3-chlorobenzoate (3-CB) as a substrate under anaerobic conditions and the enrichment that harbored an unusual dechlorinator, Desulfomonile tiedjei DCB-1. The dechlorination rate of both PCE and 3-CB increased with increasing flow rates up to 50 mL/h. The maximum observed dechlorination rates of PCE and 3-CB fed at 6.0 and 1000 μM were 2.0 and 414 μmol L h-1, respectively. This corresponds to a PCE consumption rate of 3.7 nmol h-1 (mg of protein)-1 -1 day-1>. The rate of PCE dechlorination increased from 2.0 to 10.3 μmol L-1 h-1 when the influent PCE was increased from 6.0 to 120 μM, respectively; however, concentrations of 60 μM and above damaged reactor performance. PCE was mainly converted to TCE and cis- and trans-DCE at all the tested flow rates. Vinyl chloride (VC) was never detected, thus suggesting dechlorination of PCE to non-chlorinated products. Although the PCE dechlorination activity of the biofilm was dependent on 3-CB, the activity could be sustained for 4-5 days on cheaper substrates such as acetate or benzoate after a 1-day pulse feeding of 3-CB. In addition to PCE dechlorination, the biofilm also dechlorinated other compounds such as chloroform (CF) and 1,1,2-trichloroethane (1,1,2-TCA). The present study is important, since D. tiedjei was previousely shown to dechlorinate many other chloroaromatic and aliphatic compounds.
- Fathepure, Babu Z.,Tiedje, James M.
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p. 746 - 752
(2007/10/03)
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- Transformation of chlorinated organic compounds by iron and manganese powders in buffered water and in landfill leachate
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Tetrachloroethylene was transformed by iron powder (4.1 g/L) in oxygen-free, HEPES-buffered (pH 7) water at 50°C with a half-life of 20 days. The only products observed were the reactive intermediate, trichloroethylene, and ethene and ethane. 1,1,1-Trichloroethane, 1,1-dichloroethylene, and tetrachloroethylene were transformed by iron at room temperature in both autoclaved buffered water and in two non-autoclaved landfill leachates. The pattern and degree of removal were similar in all cases. Dichloromethane, 1,1-dichloroethane, and 1,4-dichlorobenzene were also tested, but were not removed from any of the systems. If manganese rather than iron was used, the substrates transformed depended upon the aqueous phase. Some biological transformations were seen in Leachate 2, but the activity was reduced by manganese and completely suppressed by iron.
- Schreier, Cindy G.,Reinhard, Martin
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p. 1743 - 1753
(2007/10/03)
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- Anhydrous, stable, crystalline δ-form of prazosin hydrochloride
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Anhydrous, stable, crystalline δ-form of prazosin hydrochloride, having an infrared spectrum in potassium bromide of FIG. 1 having the following sharp absorption bands at 7.95μ, 13.3μ and a triplet at 9.95μ and the x-ray diffractogram of FIG. 2 having sharp bands in 10.5°, 12.0°, 16.9° and doublets in 24.5° and 26.5°. The δ-form of prazosin hydrochloride is prepared by removing the water of crystallization of prazosin hydrochloride hydrate by azeotropic distillation with selected organic solvents having a boiling point in the range of 55°-160° C. The δ-form of prazosin hydrochloride is useful as a hypotensive agent.
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- N,N-DICHLOROARENESULFONAMIDES IN REACTION WITH 1,2-DICHLOROETHYLENE
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The reaction of N,N-dichloroarenesulfonamides with cis- and trans-1,2-dichloroethylene under the conditions of free-radical initiation lead to the formation of the N-arylsulfonylimines of dichloroacetaldehyde and the products from their further transformation, i.e., 2,2-dichloro-1,1-di(arylsulfonylamino)ethanes.The arylsulfonylimines of chloral, arenesulfonamides, trichloroethylene, and the products from chlorination of 1,2-dichloroethylene are formed as side products.
- Mirskova, A. N.,Drozdova, T. I.,Levkovskaya, G. G.,Kalikhman, I. D.,Voronkov, M. G.
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p. 1129 - 1135
(2007/10/02)
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- THE SYNTHETIC UTILITY OF DIOXYPHOSPHORANES IN ORGANIC SYNTHESIS
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Diethoxytriphenylphosphorane, DTPP, prepared by reaction of triphenylphosphine and diethyl peroxide, is a "hydrolytically active" dioxyphosphorane which promotes mild and efficient cyclodehydration of diols to cyclic ethers in neutral media.Simple 1,2-, 1,4-, and 1,5-diols afford good yields of the cyclic ethers but 1,3-propanediol and 1,6-hexanediol give mainly 3-ethoxy-1-propanol and 6-ethoxy-1-hexanol, respectively, with DTPP.Tri- and tetra-substituted 1,2-diols afford the relatively stable 1,3,2-dioxaphospholanes in the presence of DTPP and the reaction conditions dictate whether epoxides, ketones, or allylic alcohols are obtained.
- Robinson, Philip L.,Kelly, Jeffery W.,Evans, Slayton A.
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- Methyl-halogenated Allyl Methyl Sulfoxides and Sulfones and the Synthesis of Halogenated Sulfines
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Allyl methyl sulfoxides R1R2R3C-S(O)-CH2CH=CH2 1a-7a (R1, R2, R3 = H, F, Cl, CF3) as well as the corresponding sulfones 1b-7b were synthesized.The sulfoxides substituted at the methyl group are in equilibrium with the allyl sulfenates R1R2R3-S-OCH2CH=CH2 depending on temperature and kind of substitution.By pyrolysis of the sulfoxides 2a, 3a, 4a, and 7a the sulfines Cl2C=SO and (CF3)2C=SO could be prepared, and evidence for the existence of the sulfines ClFC=SO and F2C=SO could be obtained.The new pentenes 12 and 14 are described.
- Holoch, Jan,Sundermeyer, Wolfgang
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p. 269 - 278
(2007/10/02)
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