- Catalytic Dehydrochlorination of 1,1,2-Trichloroethane (TCE) into 1,1-Dichloroethene (DCE) over Cesium Nitrate Supported on Silica Gel
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Catalytic activity of silica gel-supported cesium salts was examined for the dehydrochlorination of TCE into DCE by recovering hydrogen chloride.Among the salts, CsNO3 showed the best activity, although it was converted into CsCl during the reaction.High dispersion of CsNO3 on silica gel may be a major reason of the high activity.
- Mochida, Isao,Yasumoto, Yoshinori,Fujitsu, Hiroshi,Kojima, Yasuhiro
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Read Online
- HIGH CATALYTIC ACTIVITY OF CsCl SUPPORTED ON SILICA GEL FOR THE SELECTIVE DEHYDROCHLORINATION OF 1,1,2-TRICHLOROETHANE
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CsCl supported on a particular silica gel dryed at 120 deg C, exhibited a remarkable activity fot selective dehydrochlorination of TCE into 1,1-DCE after the calcination around 500 deg C.The proper heat-treatment before and after impregnation of CsCl on the silica gel strongly influenced the activity of the catalyst.
- Mochida, Isao,Miyazaki, Tatsuro,Takagi, Takeshi,Fujitsu, Hiroshi
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Read Online
- Interaction and Catalytic Decomposition of 1,1,1-Trichloroethane on High Surface Area Alumina. An Infrared Spectroscopic Study
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Transmission infrared spectroscopy has been used to study the catalytic decomposition of 1,1,1-trichloroethane, CH3CCl3, on high surface area alumina, Al2O3, in the temperature range 300 - 600 K.At 300K CH3CCl3 is reversibly adsorbed on the isolated surface hydroxyl groups of Al2O3 via hydrogen bonding.At T >/= 400 K an α,β-HCl elimination occurs, forming CH2=CCl2(g).A small amount of surface carboxylate was also formed by means of a minor reaction pathway.It was found that Lewis acid (Al3+) surface sites were involved in causing the primary reaction.This was shown by the observation that irreversible adsorption of pyridine on the Al3+ sites efficiently quenched the surface reaction.Conversely, surface Al-OH groups are not involved in the CH3CCl3 decomposition.
- Ballinger, Todd H.,Yates, John T.
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Read Online
- Mesoporous carbon nitride as a basic catalyst in dehydrochlorination of 1,1,2-trichloroethane into 1,1-dichloroethene
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1,1-Dichloroethene has many applications in industrial production and it holds great promise in developing a vapor phase catalytic dehydrochlorination process. We synthesized a carbon nitride material by dissolving dicyandiamide in N,N-dimethylformamide (DMF) as a precursor and using SBA-15 as a template. A carbon nitride material with a mesoporous structure and textured pores has been obtained and then characterized by N2-adsorption measurements, XRD, HRTEM, EDS and FT-IR. A mesoporous carbon nitride material with a surface area of 350 m2 g-1 and pore volume of 0.72 cm3 g-1 was fabricated, which also possessed triazine N heterocycles with extra amino groups. It is an outstanding heterogeneous base catalyst in the selective catalytic dehydrochlorination of 1,1,2-trichloroethane into 1,1-dichloroethene reaction with a maximum 1,1,2-trichloroethane conversion of 23.96% and maximum 1,1-dichloroethene selectivity of 100%. A total of 110 h stability experiment of the catalyst was provided and the selectivity stayed above 99% all through the experiment and the conversion remained no less than 15% for 35 h.
- Tian, Cong,Lu, Chunshan,Wang, Bolin,Xie, Xiangzhou,Miao, Yangsen,Li, Xiaonian
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p. 103829 - 103833
(2015)
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Read Online
- 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 0095-0100
(2020/08/06)
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- Nitrogen-Doped Carbon-Assisted One-pot Tandem Reaction for Vinyl Chloride Production via Ethylene Oxychlorination
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A bifunctional catalyst comprising CuCl2/Al2O3 and nitrogen-doped carbon was developed for an efficient one-pot ethylene oxychlorination process to produce vinyl chloride monomer (VCM) up to 76 % yield at 250 °C and under ambient pressure, which is higher than the conventional industrial two-step process (≈50 %) in a single pass. In the second bed, active sites containing N-functional groups on the metal-free N-doped carbon catalyzed both ethylene oxychlorination and ethylene dichloride (EDC) dehydrochlorination under the mild conditions. Benefitting from the bifunctionality of the N-doped carbon, VCM formation was intensified by the surface Cl*-looping of EDC dehydrochlorination and ethylene oxychlorination. Both reactions were enhanced by in situ consumption of surface Cl* by oxychlorination, in which Cl* was generated by EDC dehydrochlorination. This work offers a promising alternative pathway to VCM production via ethylene oxychlorination at mild conditions through a single pass reactor.
- Chen, De,Chen, Qingjun,Fuglerud, Terje,Ma, Guoyan,Ma, Hongfei,Qi, Yanying,Rout, Kumar R.,Wang, Yalan
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supporting information
p. 22080 - 22085
(2020/10/02)
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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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- Efficient Electrocatalysis for the Preparation of (Hetero)aryl Chlorides and Vinyl Chloride with 1,2-Dichloroethane
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Although the application of 1,2-dichloroethane (DCE) as a chlorinating reagent in organic synthesis with the concomitant release of vinyl chloride as a useful byproduct is a fantastic idea, it still presents a tremendous challenge and has not yet been achieved because of the harsh dehydrochlorination conditions and the sluggish C?H chlorination process. Here we report a bifunctional electrocatalysis strategy for the catalytic dehydrochlorination of DCE at the cathode simultaneously with anodic oxidative aromatic chlorination using the released HCl as the chloride source for the efficient synthesis of value-added (hetero)aryl chlorides. The mildness and practicality of the protocol was further demonstrated by the efficient late-stage chlorination of bioactive molecules.
- Liang, Yujie,Lin, Fengguirong,Adeli, Yeerlan,Jin, Rui,Jiao, Ning
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supporting information
p. 4566 - 4570
(2019/02/14)
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- New method for synthesizing ranitidine
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The invention discloses a new method for synthesizing ranitidine. The method comprises the steps of synthesizing vinylidene chloride, synthesizing 1, 1-dichloro-2-nitroethylene, carrying out a ring-closing reaction, carrying out a ring-opening reaction in presence of a desiccant, and synthesizing the ranitidine. The method adopts an anhydrous environment in the preparation process of a ring-opening product, thus avoiding the interference with the reaction and the generation of impurities due to the presence of water, reducing the post-treatment work and increasing the utilization rate of the raw materials. The preparation method provided by the invention effectively increases the reaction yield of the ring-opening product, improves the purity of the ring-opening reaction, and reduces the reaction time; therefore, the yield and purity of the product ranitidine are improved, the production cost is lowered, and the method is more beneficial to industrial production.
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Paragraph 0034-0036; 0047-049; 0059-0061
(2018/12/14)
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- Method for synthesizing ranitidine
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A method for synthesizing ranitidine includes following steps: 1), dropwise adding sodium hydroxide water solution into 1, 1, 2-trichloroethane at 30-35 DEG C for reaction to obtain vinylidene chloride, wherein a mass ratio of 1, 1, 2-trichloroethan to sodium hydroxide is 1:0.3-0.33; 2), dropwise adding vinylidene chloride into mixed acid of concentrated hydrochloric acid and concentrated nitric acid at 20-25 DEG C for reaction for 2-4h, wherein a consumption ratio of vinylidene chloride to the mixed acid is 1:2-3; 3), adding cysteamine hydrochloride into sodium hydroxide and potassium hydroxide solution, and dropwise adding a product of the step 2) at 50-55 DEG C to obtain a closed-loop product; 4), enabling the closed-loop product to react with alcohol or methanol solution at room temperature for 14-18h to obtain an open-loop product; 5), adding the open-loop product and 2-[(dimethylamino)methyl]-5 chloromethyl-furan into potassium hydroxide or sodium hydroxide water solution for reaction at 40-50 DEG C for 2-4h to obtain ranitidine. The method lowers potential safety hazards and is simple and easy for industrial production.
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Paragraph 0034; 0035; 0045; 0046; 0056; 0057; 0067; 0068
(2017/10/09)
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- POLYVINYL ALCOHOL PARTICLES, PHARMACEUTICAL BINDER USING SAME, PHARMACEUTICAL TABLET, SUSTAINED-RELEASE PHARMACEUTICAL TABLET, AND METHOD FOR PRODUCING POLYVINYL ALCOHOL PARTICLES
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Provided herein is a polyvinyl alcohol fine particle suitable for a pharmaceutical binder for obtaining a pharmaceutical tablet of properties including good sustained release, high hardness, and excellent friability. The polyvinyl alcohol tine particle of the present invention contains 25 mol % or more of a gauche structure in polyvinyl alcohol molecules within a 0.8-nm region inside the particle from the particle surface.
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- LJ reaction in the preparation wittich reagent and application of glufosinate in
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The present invention relates to an application of a new LJ intramolecular isomerization reaction in preparation of a wittig reagent and a herbicide of glufosinate-ammonium. With the application, a new approach of a synthesis route for preparing the wittig reagent and the glufosinate-ammonium is developed, the disadvantages of the existing wittig reaction are improved, and the industrial design of the glufosinate-ammonium production is improved.
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Paragraph 0047; 0110; 0111
(2017/12/04)
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- PROCESS FOR THE PRODUCTION OF ETHYLENE, VINYLIDENE, AND HYDROGEN CHLORIDE FROM ETHANE
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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.
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Page/Page column 5-8
(2016/06/13)
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- PROCESS FOR THE PRODUCTION OF ETHYLENE, VINYLIDENE, AND HYDROGEN CHLORIDE FROM ETHANE
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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.
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Page/Page column 5-8
(2016/06/13)
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- PROCESS FOR THE DEHYDROCHLORINATION OF CHLORINATED HYDROCARBONS
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A process for the dehydrochlorination of a chlorinated hydrocarbon comprising at least one chlorine atom and at least one hydrogen atom on vicinal carbon atoms to yield the corresponding unsaturated hydrocarbon, said process comprising contacting the chlorinated hydrocarbon with a guanidinium salt or its guanidine precursor.
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Paragraph 0057-0066; 0073
(2015/02/25)
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- Active carbon-supported nickel-palladium catalysts for hydrodechlorination of 1,2-dichloroethane and 1,1,2-trichloroethene
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Norit active carbon-supported Ni-Pd catalysts were prepared, by incipient wetness impregnation, from the metal chlorides NiCl2.6H2O and PdCl2. The catalysts were characterized by temperature-programmed reduction, X-ray diffraction, and scanning electron microscopy, and by temperature-programmed hydrogenation (TPH) of the catalysts after use. When the catalysts were used for gasphase hydrodechlorination (HDC) of 1,2-dichloroethane (1,2-DCA) and 1,1,2-trichloroethene (TCE), very high activity and stability at a relatively low reaction temperature (503 K) were observed. Hydrodechlorination of TCE led to formation of hydrocarbons as the main products. Use of Ni and Ni-Pd catalysts for hydrodechlorination of 1,2-DCA resulted in very high (~100 %) selectivity for ethene. TPH of the catalysts after use for HDC of 1,2-DCA and TCE revealed the presence of carbon and chlorine-containing deposits on the surfaces of the catalysts. Formation of the NiCx fcc phase and the Ni3C hcp carbide phase were detected for the monometallic nickel and Ni95Pd05 catalysts.
- Kamińska,?r?bowata
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p. 9267 - 9280
(2015/03/14)
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- Catalytic conversion of trichloroethylene on nickel containing beta zeolites into value added products
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Nickel containing BEA zeolites, NiSiBEA and NiHAlBEA, with 2 wt% of Ni were prepared by a two-step postsynthesis method and conventional wet impregnation. The calcination of NiSiBEA and NiHAlBEA at 773 K for 3 h in air led to the formation of C-NiSiBEA and C-NiHAlBEA. After reduction at 873 K for 3 h in flowing 10% H2/Ar, red-C-NiSiBEA and red-C-NiHAlBEA were obtained and investigated as the catalysts in hydrodechlorination of trichloroethylene at 503 K. Comparative study performed on red-C-NiSiBEA and red-C-NiHAlBEA showed very high stability of the catalyst prepared by a two-step postsynthesis method and strong deactivation of the catalyst prepared by conventional wet impregnation during ~ 17 h of reaction. Application of both catalysts resulted in high selectivity to unsaturated hydrocarbons that are the most desired products in HDC processes. TPH of the catalysts after kinetic run have shown that the main cause of deactivation of NiHAlBEA is the formation of carbonaceous species during hydrodechlorination of trichloroethylene.
- ?r?bowata,Baran,Lisovytskiy,Kamińska,Dzwigaj
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p. 107 - 110
(2014/12/09)
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- A contribution to the direct observation of transient phosphanylidene complexes [RP=W(CO)5] (R: Me, Ph): A revisited approach to their electronic structure by UV-photoelectron spectroscopy
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An original approach involving a coupling in the gas phase between flash vacuum thermolysis (FVT) and UV-photoelectron spectroscopy (UV-PES) allowed the transient terminal electrophilic phosphanylidene complex [MeP=W(CO)5] to be characterized; this is the first direct observation of this P-Me derivative. This approach also permitted the electronic structure of [PhP=W(CO)5] to be revisited and confirmed the results obtained with the methylated analogues. In contrast, [p-NC-C6H4P=W(CO) 5] proved to be too reactive to be detected under our experimental conditions. These [RP=W(CO)5] phosphanylidene complexes (R: Me, Ph) were identified by their ionization potentials, which are real fingerprints . These experimental data, supported by density functional calculations, give an overall electronic cartography of these transient species. For generation in the gas phase of these phosphanylidene complexes, the thermal degradation of two kinds of precursors were investigated. The joint experimental/theoretical approach allowed us to conclude that phosphanorbornadiene complexes are more suitable precursors than phosphirane complexes. Copyright
- Labat, Stéphane,Miqueu, Karinne,Sotiropoulos, Jean-Marc,Baylère, Patrick,Pfister-Guillouzo, Geneviève,Huy, Ngoc Hoa Tran,Mathey, Fran?ois
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p. 1694 - 1705
(2014/04/17)
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- A contribution to the direct observation of transient phosphanylidene complexes [RP=W(CO)5] (R: Me, Ph): A revisited approach to their electronic structure by UV-photoelectron spectroscopy
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An original approach involving a coupling in the gas phase between flash vacuum thermolysis (FVT) and UV-photoelectron spectroscopy (UV-PES) allowed the transient terminal electrophilic phosphanylidene complex [MeP=W(CO)5] to be characterized; this is the first direct observation of this P-Me derivative. This approach also permitted the electronic structure of [PhP=W(CO)5] to be revisited and confirmed the results obtained with the methylated analogues. In contrast, [p-NC-C6H4P=W(CO)5] proved to be too reactive to be detected under our experimental conditions. These [RP=W(CO)5] phosphanylidene complexes (R: Me, Ph) were identified by their ionization potentials, which are real fingerprints . These experimental data, supported by density functional calculations, give an overall electronic cartography of these transient species. For generation in the gas phase of these phosphanylidene complexes, the thermal degradation of two kinds of precursors were investigated. The joint experimental/theoretical approach allowed us to conclude that phosphanorbornadiene complexes are more suitable precursors than phosphirane complexes. By using an original coupling involving FVT and UV-photoelectron spectroscopy, the electronic structure of the transient electrophilic phosphanylidene complex [MeP=W(CO)5] has been described for the first time and that of [PhP=W(CO)5] has been revisited. These intermediates were generated in the gas phase and unambiguously characterized by their ionization potentials, real fingerprints .
- Labat, Stéphane,Miqueu, Karinne,Sotiropoulos, Jean-Marc,Baylère, Patrick,Pfister-Guillouzo, Geneviève,Huy, Ngoc Hoa Tran,Mathey, Fran?ois
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p. 1694 - 1705
(2015/04/27)
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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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- Composition For the Vapor Phase Dehydrohalogenation of 1,1,2-Trihaloethane To 1,1-Dihaloethylene and Methods For Preparing and Using Such Composition
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Described are compositions adapted to catalyze the vapor phase dehydrohalogenation of 1,1,2-trihaloethane to 1,1-dihaloethylene, e.g., 1,1,2-trichloroethane to vinylidene chloride. These materials include activated carbon and at least one benzimidazole-containing material defined herein as including benzimidazole, a derivative thereof, a salt thereof or mixtures thereof. Also described are methods for producing and using these catalytic compositions.
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Page/Page column 7
(2008/12/07)
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- γ-Alumina-supported boron trifluoride: Catalysis, radiotracer studies and computations
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The irreversible adsorption of boron trifluoride on calcined γ-alumina and amorphous chromia, in both cases at room temperature, has been studied using [18F]-labelled BF3. Although the resulting γ-alumina surface has some catalytic activity for the room temperature fluorination by anhydrous HF of CH3CCl3 under static conditions, its activity is far lower than that of γ-alumina, which has been fluorinated with SF4, nominally at room temperature. A possible explanation for the observed behaviour is given.
- Klap?tke, Thomas M.,McMonagle, Fiona,Spence, Ronald R.,Winfield, John M.
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p. 1446 - 1453
(2008/09/19)
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- COMPOSITION FOR THE VAPOR PHASE DEHYDROHALOGENATION OF 1,1,2-TRIHALOETHANE TO 1,1-DIHALOETHYLENE AND METHODS FOR PREPARING AND USING SUCH COMPOSITIONS
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Described are compositions adapted to catalyze the vapor phase dehydrohalogenation of 1,1,2-trihaloethane to 1,1-dihaloethylene, e.g., 1,1,2-trichloroethane to vinylidene chloride. These materials include activated carbon and at least one benzimidazole-containing material defined herein as including benzimidazole, a derivative thereof, a salt thereof or mixtures thereof. Also described are methods for producing and using these catalytic compositions.
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Page/Page column 16-27; 31-32
(2010/11/25)
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- PURIFICATION METHOD, PRODUCTION PROCESS, AND USE OF, 1, 1-DIFLUOROETHANE
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Crude 1,1-difluoroethane containing at least one compound selected from the group consisting of unsaturated compounds each having two carbon atoms within the molecule and saturated chlorine-containing compounds each having two carbon atoms within the molecule is brought into contact with a zeolite and/or a carbonaceous adsorbent, or crude 1,1-difluoroethane containing hydrogen fluoride and, as impurities, at least one compound selected from the group consisting of unsaturated compounds each having two carbon atoms within the molecule is brought into contact with a fluorination catalyst in a gas phase state. High-purity 1,1-difluoroethane usable as a cryogenic refrigerant, or as an etching gas, can be produced in an industrially advantageous manner.
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Page/Page column 16-17
(2008/06/13)
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- Method of stabilizing trichloroethane during production
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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.
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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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- Pd-catalyzed TCE dechlorination in water: Effect of [H2](aq) and H2-utilizing competitive solutes on the TCE dechlorination rate and product distribution
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The aqueous-phase H2 concentration ([H2](aq)) and the presence of H2-utilizing competitive solutes affect trichloroethylene (TCE) dechlorination efficiency in Pd-based in-well treatment reactors. Batch kinetic studies in m
- Reinhard,Lowry
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p. 696 - 702
(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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- 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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- 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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- 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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- Reductive Dechlorination of Tetrachloroethylene and Trichlproethylene Catalyzed by Vitamin B12 in Homogeneous and Heterogeneous Systems
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The reduction of tetrachloroethylene (PCE) and trichloroethylene (TCE) catalyzed by vitamin B12 was examined in homogeneous and heterogeneous (B12 bound to agarose) batch systems using titanium(III) citrate as the bulk reductant. The solution and surface-mediated reaction rates at similar B12 loadings were comparable, indicating that binding vitamin B12 to a surface did not lower catalytic activity. No loss in PCE reducing activity was observed with repeated usage of surface-bound vitamin B12. Carbon mass recoveries were 81-84% for PCE reduction and 89% for TCE reduction, relative to controls. In addition to sequential hydrogenolysis, a second competing reaction mechanism for the reduction of PCE and TCE by B12, reductive β-elimination, is proposed to account for the observation of acetylene as a significant reaction intermediate. Reductive β-elimination should be considered as a potential pathway in other reactive systems involving the reduction of vicinal polyhaloethenes. Surface-bound catalysts such as vitamin B12 may have utility in the engineered degradation of aqueous phase chlorinated ethenes.
- Burris, David R.,Delcomyn, Carrie A.,Smith, Mark H.,Lynn Roberts
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p. 3047 - 3052
(2007/10/03)
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- Substituent effects and threshold energies for the unimolecular elimination of HCl (DCl) and HF (DF) from chemically activated CFCl2CH3 and CFCl2CD3
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Combination of CFCl2 and methyl-d0 and -d3 radicals form CFCl2CH3-d0 and -d3 with 100 and 101 kcal/mol of internal energy, respectively. An upper limit for the rate constant ratio of disproportionation to combination, kd/kc, for Cl transfer is 0.07 ± 0.03 for collision of two CFCl2 radicals and 0.015 ± 0.005 for CH3 and CFCl2 radicals. The chemically activated CFCl2CH3 undergoes 1,2-dehydrochlorination and 1,2-dehydrofluorination with rate constants of 3.9 × 109 and 4.9 × 107 s-1, respectively. For CFCl2CD3 the rate constants are 8.7 × 108 s-1 for loss of DCl and 1.1 × 107 s-1 for DF. The kinetic isotope effect is 4.4 ± 0.9 for HCl/DCl and appears to be identical for HF/DF. Threshold energies are 54 kcal/mol for loss of HCl and 68 kcal/mol for HF; the E0's for the deuterated channels are 1.4 kcal/mol higher. Comparison of these threshold energies with other haloethanes suggests that for HF and HCl elimination the transition states are developing charges of different signs on the carbon containing the departing halogen and that chlorine and fluorine substituents exert similar inductive effects.
- McDoniel, J. Bridget,Holmes, Bert E.
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p. 3044 - 3050
(2007/10/03)
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- A Method for the Rapid Dechlorination of Low Molecular Weight Chlorinated Hydrocarbons in Water
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1,1,2-Trichloroethylene (TCE), 1,1-dichloroethylene, cis and trans-1,2-dichloroethylene and tetrachloroethylene (PCE), at concentrations of 20 ppm in aqueous solutions were rapidly hydrodechlorinated to ethane (in a few minutes), on the surface of palladized iron in batch experiments that were performed in closed vials. No intermediate reaction products such as 1,1-dichloroethylene, 1,2-dichloroethylenes and vinyl chloride were detected at concentrations > 1 ppm either in the headspace or in solution. The chloromethanes, CCl4, CHCl3 and CH2Cl2 were also dechlorinated to methane on palladized iron; the CCl4 was dechlorinated in a few minutes, the CHCl3, in less than an hour and the CH2Cl2, in 4-5 h. These results indicate that an above-ground treatment method can be designed for the treatment of groundwater contaminated with low molecular weight chlorinated hydrocarbons.
- Muftikian, Rosy,Fernando, Quintus,Korte, Nic
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p. 2434 - 2439
(2007/10/03)
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- Hydrogen-Atom-Induced Decomposition of Trichloroethylene at High Temperatures
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Mechanisms and rate constants for hydrogen atom attack on trichloroethylene have been determined in single-pulse shock tube experiments near 1050 K.Products from all the decomposition channels have been observed.The predominant process is the displacement of the chlorine at the least substituted site.The following rate expressions have been determined: k(H* + HClC=CCl2 -> H2C=CCl2 + Cl*) = 6 x 1E13 exp(-2439/T) cm3 mol-1 s-1; k(H* + HClC=CCl2 -> HClC=CClH (cis + trans) + Cl*) = 3.7 x 1E13 exp(-3946/T) cm3 mol-1 s-1; k(H* + HClC=CCl2 -> *HC=CCl2 or HClC=CCl* + HCl) = 3.8 x 1E14 exp(-6686/T) cm3 mol-1 s-1.An upper limit for the rate constant of the abstraction process H* + HClC=CCl2 -> *ClC=CCl2 + H2 is 6.5 x 1E10 cm3 mol-1 s-1 at 1050 K.Rate constants for chlorine attack on H2 at these temperatures are a factor of 13 smaller than those on mesitylene.The results are compared with those for hydrogen atom reactions with other unsaturated compounds.Some implications regarding the incineration of chlorinated organics will be discussed.
- Tsang, Wing,Walker, James A.
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p. 3156 - 3161
(2007/10/02)
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- CH3CF3-nCln haloalkanes and CH2=CF2-nCln halo-olefins on γ-alumina catalysts: reactions, kinetics and adsorption
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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
- Hess, A.,Kemnitz, E.
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- Liquid-phase fluorination and dehydrochlorination of 1,1,1-trichloroethane
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During the liquid-phase fluorination of 1,1,1-trichloroethane with SbCl5*HF, 1,1-dichloroethene is formed.This reacts to give linear and branched oligomers.The hydrolysis of these by-products affords 3,5-dichlorophenol, 6-methyl-4-chloro-2-pyran-2-one and 2-methyl-5,7-dichlorochromone whose source is the acid-catalyzed reaction of water with the trimer and pentamer of 1,1-dichloroethene.
- Brunet, Sylvette,Batiot, Catherine,Barrault, Joeel,Blanchard, Michel,Coustard, Jean-Marie
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p. 227 - 232
(2007/10/02)
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- Dehydrohalogenation of 1,1,2-trichloroethane using cyclic amines
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In a process for production of vinylidene chloride by dehydrohalogenation of 1,1,2-trichloroethane using a base, improved selectively for formation of vinylidene chloride is obtained by using as the base a cyclic amine having a pKa greater than about 11 as dehydrohalogenating agent.
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- Laser Photolysis/Laser-Induced Fluorescence Studies of the Reaction of OH with 1,1,1-Trichloroethane over an Extended Temperature Range
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Absolute rate coefficients are determined for the gas-phase reaction of OH radicals with 1,1,1-trichloroethane over an extended temperature range.Employing a laser photolysis/laser-induced fluorescence technique, experiments were conducted with a flow system at a total pressure of 740 +/- 10 Torr using He as diluent and carrier gas.The rate coefficients, obtained over the temperature range 298-761 K, exhibited pronounced non-Arrhenius behavior and were best described by the modified Arrhenius equation k(T)=(3.95 +/- 0.78) x 10-13(T/300)2.08exp cm3 molecule-1 s-1.Comparison of the data with numerous lower temperature measurements is presented.The temperature dependence of the data is compared with empirical and transition-state model calculations.The reactivity of this compound with OH compared to other chlorinated ethanes at both lower and higher reaction temperatures is presented and discussed.
- Jiang, Zhen,Taylor, Philip H.,Dellinger, Barry
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p. 8961 - 8964
(2007/10/02)
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- Laser Photolysis/Laser-Induced Fluorescence Studies of the Reaction of OH with 1,1-Dichloroethane over an Extended Temperature Range
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Absolute rate coefficients are determined for the gas-phase reaction of OH radicals with 1,1-dichloroethane over an extended temperature range using a laser photolysis/laser-induced fluorescence technique.Experiments were performed in a flow system at a total pressure of 740 +/- 10 Torr using He as diluent and carrier gas.The rate coefficients, obtained over the temperature range 294-800 K, exhibited pronounced non-Arrhenius behavior and were best described by the modified Arrhenius equation k(T)=(8.29 +/- 0.36) x 10-14(T/300)2.67exp cm3 molecule-1 s-1.Comparison of the data with one previous room-temperature measurement is presented.The temperature dependence of the data is compared with empirical and transition-state model calculations.The influence of C-H bond energy and Cl substitution is discussed.
- Jiang, Zhen,Taylor, Philip H.,Dellinger, Barry
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p. 8964 - 8966
(2007/10/02)
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- Liquid-phase fluorination of 1,1,1-trichloroethane
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The reaction of HF with SbCl5 at 60 deg C and 1 MPa provides antimony mixed halides whose empirical formulae have been determined.The product is a mixture of SbClF4 and SbClF2 solvated by HF and its activity has been measured for the conversion of 1,1,1-trichloroethane (F140a) into mono- and difluorochloroethane (F141b and F142b).
- Brunet, S.,Batiot, C.,Barrault, J.,Blanchard, M.
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- Dehydrohalogenation using magnesium hydroxide
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A process comprising contacting a solvent, magnesium hydroxide, and a halogenated hydrocarbon at a pressure sufficient to keep the solvent and the halogenated hydrocarbon under liquid conditions, and a temperature greater than 150° C. under conditions suitable to dehydrohalogenate the halogenated hydrocarbon, and recovering the dehydrohalogenated product.
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- A Novel Laser-induced Synthesis of 1,1-Dichloroethylene from 1,1-Dichloroethane
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The laser-induced photochlorination of 1,1-dichloroethane followed by its dehydrochlorination has been examined in a flow reactor under normal pressure at 25 - 200 deg C, which has been proved to be a novel direct synthesis of vinylidene chloride.
- Oshima, Yoshito,Iguchi, Kayoko,Tominaga, Hiro-o,Koda, Seiichiro
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p. 2101 - 2104
(2007/10/02)
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- Fluorinated γ-Alumina. Catalytic Fluorination of 1,1,1-Trichloroethane at Ambient Temperature
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γ-Alumina, fluorinated with sulphur tetrafluoride followed by treatment with 1,1,1-trichloroethane, behaves as a catalyst for the room temperature fluorination of CH3CCl3 with anhydrous HF, giving a mixture of chlorofluorohydrocarbons.
- Thomson, James,Webb, Geoffrey,Winfield, John M.
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p. 323 - 324
(2007/10/02)
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- Aluminium(III) Chloride-Chlorohydrocarbon Chemistry. Fourier Transform Infra-red Spectroscopic Studies of the Reactions between Solid Aluminium(III) Chloride and 1,1,1-Trichloroethane or 1,1-Dichloroethene Vapours
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The reactions of 1,1,1-trichloroethane and 1,1-dichloroethene vapours with solid aluminium(III) chloride have been studied using Fourier-transform i.r. spectroscopy to determine stoicheiometries as a function of time.Dehydrochlorination of 1,1,1-trichloroethane to give 1,1-dichloroethene and hydrogen chloride appears to be the only important process in the initial stage of the reaction, but the 1,1-dichloroethene formed reacts with the solid phase and the main product is a mixture of involatile chlorohydrocarbon species.The quantity of hydrogen chloride evolved indicates that the involatile material is highly unsaturated and in both reactions AlCl3 becomes progressively coated with a strongly purple-coloured tar.Small quantities of carbon tetrachloride are also produced in both reactions.
- McBeth, David G.,Winfield, John M.,Cook, Bernard W.,Winterton, Neil
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p. 671 - 676
(2007/10/02)
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- CATALYSIS OF LIQUID-PHASE DEHYDROCHLORINATION OF 1,1,2-TRICHLOROETHANE.
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Experiments show that vinylidene chloride can be obtained in virtually quantitative yield by the use of triethylbenzylammonium alkoxides as catalysts of 1,1,2-trichloroethane dehydrochlorination. Catalyst anions containing an unsaturated carbon bond in the position relative to oxygen increase catalyst activity. The catalyst is present in the organic phase and is not transferred from one phase into the other.
- Shavanov,Tolstikov,Viktorov,Shutenkova
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p. 139 - 141
(2007/10/02)
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- CO2 Laser-induced Decomposition of 1,1,2-Trichloroethane
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CH2ClCHCl2 was photolyzed with a focusing geometry using the P(24) line of the 10.6 μm CO2 band (940.6 cm-1).The final products of neat photolysis were cis- and trans-CHCl=CHCl, CH2=CCl2, CH2=CHCl, CHCCl, CHCH, and C4H2.The relative yield of CH2=CCl2 in particular was strongly dependent on CH2ClCHCl2 pressure and sensitive to the addition of H atom containing molecules.A series of diagnostic experiments shows that the dichloroethene isomers are formed by three different processes, i.e., infrared multiphoton decomposition, collision-induced decomposition, and radical chain reaction.Infrared multiphoton decomposition and collision-induced decomposition give rise to cis- and trans-CHCl=CHCl predominantly, while the radical chain reaction generates the dichloroethane isomers in comparable amounts at high reactant pressures, the most probable initiation step being the C-Cl bond-scission reaction of the parent molecule.Formation mechanisms for other minor products are also discussed.
- Ogura, Hiroo
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p. 3528 - 3534
(2007/10/02)
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