- An efficient synthesis of 1-chloro-2,2-difluoroethylene via the reductive dechlorination of 1,2,2-trichloro-1,1-difluoroethane
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1-Chloro-2,2-difluoroethylene was prepared from 1,2,2-trichloro-1,1- difluoroethane by reductive dechlorination in the presence of zero-valent zinc. Eleven different solvents were investigated and the best results were obtained in methanol, dimethyl formamide and ethanol at 80 °C. A large-scale experiment using ethanol as a solvent gave 1-chloro-2,2-difluoroethylene in high yield. These results provide a method for producing 1-chloro-2,2- difluoroethylen e on an industrial scale because 1,2,2-trichloro-1,1- difluoroethane is the waste material arising from 2,2-dichloro-1,1,1- trifluoroethane production. These results can also provide a method for solving the recycling problem of 1,2,2- trichloro-1,1-difluoroethane in 2,2-dichloro-1,1,1-trifluoroethane production.
- Wang, Nong,Yang, Lijuan,Xiang, Shaoji
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- Effects of Addition Gases on the IR Multiphoton Dissociation of Haloethanes
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The effects of addition gases on the rate of the IR multiphoton dissociation (IRMPD) of CClF2CH2Cl have been studied.He, CF4, CF3CDBrCl and CCl2CF2 were employed as the addition gases and IRMPD yield was measured as a function of addition gas mole fraction.The results revealed that molecular collisions play an important role in the excitation process and that the reaction rate is determined by the competition of two collision induced processes, one of which suppresses, and the other enhances, the reaction.In the case of 961.9 cm-1 irradiation, both effects have been clearly observed, whereas in the case of 1023.2 cm-1 irradiation, the latter effect seems weak.The results also show that the addition of CF4 or He always lowers the reaction rate.We conclude that the relaxation of the anharmonicity bottleneck by a resonant vibrational-energy transfer is important for IRMPD of this molecule.
- Sakka, Tetsuo,Furuya, Hiroyuki,Iwasaki, Matae,Ogata, Yukio
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- Infrared Multiphoton Absorption and Reaction of 2-Chloro-1,1,1-trifluoroethane
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The infrared multiphoton absorption and dissociation of CF3CH2Cl has been studied by measuring the dependence of the reaction probability and product distribution on the laser fluence and bath gas pressure.Absorption measurements were performed at two laser frequencies to estabilish the absorbed laser energy: the absorption measurements displayed Beer's law behavior except at very low laser fluence.Sensitized reactions with SiF4 were conducted for comparison to the direct laser-induced process: the effective temperature within the irradiated volume for the SiF4 experiments was determined as a function of incident laser energy.The three main reaction channels are four centered HF elimination, three-centered HCl elimination, and C-Cl homolysis: the product ratios were very dependent on the incident laser fluence.Addition of toluene as a bath gas significantly lowered the reaction probability, especially at lower laser fluence, but had only a minor influence on the product distribution.The infrared laser-induced energy absorption and reaction processes of CF3CH3, CF3CH2Cl, and CF3CH2Br are compared.The data provide evidence for a fluence-dependent fractionation of absorbed laser energy producing a two-component energy distribution for the former two compounds.
- Setser, D.W.,Lee, Tsae-Shyan,Danen, Wayne C.
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- Effect of Megnesium Fluoride in Chromium-Magnesium Catalysts on the Fluorination Reaction of 1,1,1-Trifluoro-2-chloroethane
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Magnesium fluoride, mixed with chromium fluoride, enhances the activity, selectivity and lifetime of the chromium catalyst for the vapour-phase fluorination of CF3CH2Cl with anhydrous HF to give CF3CH2F.
- Kim, Honggon,Kim, Hoon S.,Lee, Byung G.,Lee, Hyunjoo,Kim, Sehoon
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- Characterization by Temperature-Programmed Reduction and by Temperature-Programmed Oxidation (TPR-TPO) of Chromium (III) Oxide-Based Catalysts: Correlation with the Catalytic Activity for Hydrofluoroalkane Synthesis
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The catalytic activity of chromium (III) oxide for the fluorination of CF3CH2Cl (HCFC 133a) is proportional to the number of reversibly oxidized sites.The proportionality coefficient depends on the atmosphere employed during the pretreatment of the catalyst.The temperature-programmed reduction and temperature-programmed oxidation experiments constitute a simple technique that allows the number of reversibly oxidized chromium atoms to be measured.The method of preparation of the chromium hydroxide has little effect on the catalytic properties of chromium (III) oxide.The activation atmosphere and the temperature are essential parameters in the formation of chromium (III) oxide from hydroxide.Indeed, the most active chromium (III) oxide for the fluorination of CF3CH2Cl is obtained by thermal treatment of hydroxide at 380 deg C under nitrogen.
- Brunet, S.,Requieme, B.,Matouba, E.,Barrault, J.,Blanchard, M.
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- Properties of chromium (III) oxides involved in the catalytic gas phase fluorination of CF3CH2Cl
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The fluorination of chromium oxides reduces the chromium species on the surface. A low fluorination by HF does not modify the total amount of reversibly oxidizable chromium sites, but increases the strength of these sites. Mobile dioxygen (measured by isotopic exchange) was required to obtain a good fluorination activity. These dioxygen species would be exchanged by HF which is probably active in the fluorination of CF3CH2Cl and would prevent the irreversibly catalyst fluorination.
- Brunet,Boussand,Martin
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- Vacuum-ultraviolet (147 nm) photodecomposition of 1,1,2-trichloro-2,2-difluoroethane
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The 147 nm photolysis of CF2ClCHCl2 has been investigated at 25 deg C as a function of reactant pressure, conversion, and nitric oxide as additive.In the absence of NO the observed reaction products are CF2CHCl, CF2CCl2, and the diastereomers of (CF2ClCHCl)2.At constant reactanr pressure the quantum yields of the olefin decrease with increasing conversion and there is a corresponding increase in the quantum yield of the C4 product.For fixed values of conversion the olefin quantum yields decrease with increasing reactant pressure and approach limiting values at ca. 100 Torr.The addition of NO completely suppresses the formation of the chlorofluorobutanes, while it enhances the olefin quantum yields at higher conversion.These observations are interpreted in terms of reactions of chlorine atoms which result either directly (by near simultaneous expulsion of two Cl atoms), or via the dissociation of an excited Cl2* molecule produced by molecular elimination in the primary process.Chlorine atoms abstract hydrogen from the parent or add to the product olefins.These processes provide the principal source of halo-ethyl radicals in the system.The addition reaction leads to chemically activated radicals with a mean lifetime of τ ca. 0.8*10-8 sec which is commensurate with RRKM-theory predictions.The addition of nitric oxide provides a competing channel for chlorine atom removal by way of their NO-catalyzed recombination.The functional dependence of the olefin quantum yields with conversion in the absence and presence of NO suggests that the major fraction of the principal product, CF2CHCl, derives directly from a primary process, while CF2CCl2 is formed via both, the molecular elimination of HCl and from radical precursors.The limiting quantum yields of CF2CHCl and CF2CCl2 are found to be φ0 ca. 0.68 and φ0' ca. 0.19, in the absence of NO, respectively, and φ0,NO ca. 0.56 and φ0,NO' ca. 0.087 in the presence of NO.The extinction coefficient for CF2ClCHCl2 at 147 nm and 25 deg C has been determined: ε = (1/PL)ln(I0/It) = 404 +/- 40 atm-1cm-1.
- Yano, T.,Tschuikov-Roux, E.
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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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- Photodissociation of 1,1,1-Trifluorodichloroethane at 147 nm. Evidence for Chlorine Atom Reactions
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The 147-nm photolysis of CF3CHCl2 has been investigated at 23 deg C as a function of reactant pressure and conversion (It/N), with and without nitric oxide as additive.The principal reaction product is CF2CHF, with lesser yields of CF2CFCl, CF2CHCl, and four chlorofluorobutanes.At constant CF3CHCl2 pressure the observed quantum yields of the olefins decrease with increasing It/N and there is a corresponding increase in the yields of the C4 products.The quantum yields of the olefins also decrease with increasing reactant pressure at the same values of It/N.The addition of NO completely suppresses the formation of the chlorofluorobutanes, but there is a marked increase in the olefin quantum yields.These observations are interpreted in terms of reactions of chlorine atoms which derive, primarily, from the α,α elimination of the elements of (Cl)2 in the primary process.Clorine atoms so produced abstract hydrogen from the parent and add to the product olefins, processes which are the source of haloethyl radicals in the system.Nitric oxide provides an additional and dominant channel for chlorine atom removal by way of their NO-catalyzed recombination which proceeds through CINO as an intermediate.A reaction mechanism consistent with the observations is proposed and, from the functional dependence of the olefin quantum yields on It/N, limiting values have been obtained by extrapolation.The rate constant ratio for hydrogen abstraction from CF3CHCl2 by Cl atoms to Cl addition to CF2CHF was found to be k5/k6 = (2.2 +/- 0.5)*E-4.The extinction coefficient for CF3CHCl2 at 147 nm (296 K) has been determined as ε = (1/PL) ln(I0/It) = 590 +/- 60 atm-1Cm-1.
- Yano, T.,Jung, K.-H.,Tschuikow-Roux, E.
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- Preparation of Substitutes for CFCs. Catalytic Properties of Chromia for Halogen Exchange involving Hydrogen Fluoride and Trifluorochloroethane
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The catalytic activity of chromia for F to Cl exchange in trifluorochloroethane is proportional to the number of chromium atoms which are reversibly oxidized.
- Barrault, J.,Brunet, S.,Requieme, B.,Blanchard, M.
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- The room temperature preparation of the 1-chloro-2,2-difluorovinylzinc reagent from HCFC-133a (CF3CH2Cl). The first ambient, high yield, one-flask preparation of α-chloro-β,β-difluorostyrenes
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The reaction of LDA (2.0 equiv.) with a THF solution of ZnCl2 (1.0 equiv.) and HCFC-133a (CF3CH2Cl) (1.0 equiv.) at 15-20°C gives a 91% yield of [F2C=CClZnCl]. Addition of ArI and Pd(PPh3)4 at rt to 65°C gives 65-85% isolated yields of ArCCl=CF2. This one-flask procedure provides the first room temperature generation of the 1-chloro-2,2-difluorovinylzinc reagent and the first high yield preparation of α-chloro-β,β-difluorostyrenes from a cheap, readily available industrial precursor.
- Anilkumar,Burton, Donald J.
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- Room temperature preparation of α-chloro-β,β- difluoroethenylzinc reagent (CF2CClZnCl) by the metallation of HCFC-133a (CF3CH2Cl) and a high yield one-pot synthesis of α-chloro-β,β-difluorostyrenes
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α-Chloro-β,β-difluorovinylzinc reagent [CF 2CClZnCl] was generated in 91% yield by the metallation of a THF solution of commercially available HCFC-133a (CF3CH2Cl) and zinc chloride at 15-20 °C using LDA as base. The corresponding reaction with Halothane (CF3CHClBr) produced a poor yield of CF 2CClZnCl. The palladium catalyzed coupling reaction of the CF 2CClZnCl with aryl iodides under mild reaction conditions produced α-chloro-β,β-difluorostyrenes in 64-90% isolated yields. The stability of the intermediate CF2CClLi and the nature of the zinc reagents are discussed.
- Anilkumar,Burton, Donald J.
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- Isoflurane increases the anaerobic metabolites of halothane
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The effect of isoflurane on the anaerobic metabolism of halothane to chlorodifluoroethene (CDE) and chlorotrifluoroethane (CTE) was studied with microsomes of guinea pig liver by gas chromatography. The reaction mixture used to measure the end products of anaerobic metabolism consisted of a microsomal suspension, 3 mM NADPH, halothane and isoflurane (except in control groups) in 0.1 M potassium phosphate buffer solution (pH 7.4). The K(m) values for CDE formation were 601.61 ± 266.91, 254.22 ± 86.58, 257.92 ± 129.11, 268.55 ± 125.66 and 319.22 ± 86.76 μM (mean ± SD, n = 5) at 0 mM (0%), 0.12 mM (0.26%), 0.29 mM (0.64%), 0.58 mM (1.30%) and 1.16 mM (2.59%) isoflurane, respectively. The K(m) values for CTE formation were 1204.74 ± 551.64, 553.75 ± 177.89, 521.14 ± 249.77, 560.67 ± 229.61 and 711.05 ± 317.13 pM (n = 5) at 0 mM (0%), 0.12 mM (0.26%), 0.29 mM (0.64%), 0.58 mM (1.30%) and 1.16 mM (2.59%) isoflurane, respectively. In contrast, the V(max) values for CDE and CTE formation at these isoflurane concentrations were not significantly different than in the control groups. In this study the production of CDE and CTE was significantly (P 0.05) increased by isoflurane, at concentrations up to 0.58 mM (1.30%).
- Rahman,Fujii,Sato,Yuge
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- An Experimental Estimate of the Threshold Barrier for the 1,2-Fluorine Atom Migration in 1,1,1-Trifluoromethylcarbene
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A treshold energy barrier of 29 +/- 4 kcal/mol was estimated for the 1,2-fluorine migration reaction converting 1,1,1-trifluoromethylcarbene, CF3CH, into CF2=CHF in the gas phase.The CF3CH was formed by the 1,1-elimination of HCl from chemically activated CF3CH2Cl containing 97.5 kcal/mol of internal energy.RRKM theory was used to calculate rate constants for the 1,2-fluorine shift that were fitted to the experimental pressure dependence to determine the threshold barrier.
- Holmes, Bert E.,Rakestraw, David J.
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- Infrared Multiphoton Dissociation of CClF2CH2Cl by Relatively Low-fluence CO2 Laser Irradiation
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Infrared multiphoton absorption (IRMPA) and dissociation (IRMPD) of CClF2CH2Cl have been studied by low-fluence CO2 laser irradiation (-2).Laser beams of spatially uniform intensity, obtained by mild focusing and a short irradiation cell length, were used.The IRMPD yields were measured as a function of reactant pressure, added-gas pressure, laser-energy fluence and laser wavenumber, and the IRMPA was measured as a function of reactant pressure, added-rare-gas pressure, and laser-energy fluence.The results of the IRMPD yields plotted against reactant and added-gas pressure show that molecular collisions play an important role in the excitation process.The effects of the reactant pressure and added-rare-gas concentration upon the product yield can be interpreted by a combination of some positive and negative effects of molecular collisions.On the other hand, the dissociation yields obtained as a function of added CF2CHCl pressure suggest that the relaxation of anharmonicity bottlenecking by resonant vibrational energy transfer is also important for IRMPD of this molecule.It can be seen that the other experimental results, i.e. the results of the IRMPA experiments and the frequency dependence of the IRMPD yield are consistent with the above interpretation.
- Sakka, Tetsuo,Iwasaki, Matae,Ogata, Yukio
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- Method for preparing ethyl difluorobromoacetate
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The invention discloses a method for preparing ethyl difluorobromoacetate, which comprises the following steps: by taking CF2Cl-CH2Cl as a raw material, firstly removing HCl to obtain CF2 = CHCl, then carrying out addition on the CF2 = CHCl and bromine to obtain CF2Br-CHClBr, then reacting the CF2Br-CHClBr with oxygen and a photoinitiator under the photocatalysis to obtain CF2Br-COCl, and finally carrying out esterification reaction on the CF2Br-COCl and ethanol to obtain the ethyl difluorobromoacetate. According to the method, a photooxidation reaction process is adopted in the CF2Br-COCl preparation process, the conversion rate of CF2Br-CHClBr and the selectivity of CF2Br-COCl are very high, meanwhile, the use of strong-corrosivity concentrated sulfuric acid or a sulfur trioxide oxidizing agent or a mercury-containing high-toxicity catalyst is avoided, and the process is green and environmentally friendly.
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Paragraph 0031-0032; 0037-0038; 0041-0042; 0045-0046; 0049
(2021/06/22)
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- A two-fluorine bromine acetate preparation method (by machine translation)
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The invention provides a two-fluorine bromine acetate preparation method, comprises the following steps: (1) in order to CF2 X - CHCl2 As raw materials, through the dehydrochlorination cancels out the reaction, bromine addition reaction CF2 Br - CClXBr, wherein X is H or Cl; (2) step (1) in the CF2 Br - CClXBr optical oxidation or with sulfur trioxide oxidation reaction, reaction to obtain the CF2 Br - COCl; (3) the step (2) in the CF2 Br - COCl alcohol in the esterification reaction, after separation, distillation, thus obtaining the product 2, 2 - difluoro - 2 - [...] ester. The invention two fluorine bromine acetate preparation method, so that the 1, 1 - difluoro - 2, 2 - dichloroethane or 1, 1 - difluoro - 1, 2, 2 - trichloroethane two by-product that is utilized, reduce their pollution of the environment, but also the production two fluorine bromines acetate process is environment-friendly, two fluorine bromines acetate yield and safety are relatively high. (by machine translation)
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Paragraph 0021; 0023
(2019/01/22)
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- METHOD FOR PRODUCING 1-CHLORO-2,2-DIFLUOROETHYLENE
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PROBLEM TO BE SOLVED: To provide a method for producing 1-chloro-2,2-difluoroethylene from 1,2-dichloro-1,1-difluoroethane as raw material. SOLUTION: A method for producing 1-chloro-2,2-difluoroethylene includes the reaction of 1,2-dichloro-1,1-difluoroethane in a gas phase in the presence of a solid catalyst to obtain 1-chloro-2,2-difluoroethylene. SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
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Paragraph 0040-0043
(2018/10/03)
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- Preparation method of 1,1-difluoro-2-chloroethylene
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The invention discloses a method for preparing 1,1-difluoro-2-chloroethylene by carrying out dehydrochlorination on dichlorodifluoroethane in presence of a catalyst; the catalyst is prepared from a main catalyst-inorganic base and a cocatalyst-phase transfer catalyst. The method provided by the invention does not need to use an organic solvent, and has the advantages of being high in reaction yield, mild in technology, simple in operation, less in by-products, small in amount of the three wastes, environmentally-friendly, and the like.
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Paragraph 0034; 0035; 0036; 0037; 0038; 0039; 0040-0045
(2017/07/19)
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- Green synthesis method of ethyl bromodifluoroacetate
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The invention provides a green synthesis method of ethyl bromodifluoroacetate. According to the method, 1,1-difluoro-1,2-dichloroethane is used as a starting material; elimination reaction is performed to obtain 1,1-difluoro-2-chloroethylene; the 1,1-difluoro-2-chloroethylene and bromine are subjected to addition to obtain 1,1-difluoro-1,2-dibromo-2-chloroethane; then, the elimination reaction is performed to obtain a 1,1-difluoro-2-bromine-2-chloroethylene; then, the 1,1-difluoro-2-bromine-2-chloroethylene and the bromine are subjected to addition to obtain 1,1-difluoro-1,2,2-tribromo-2-chloroethane; then, sulfur trioxide is used for oxidizing the 1,1-difluoro-1,2,2-tribromo-2-chloroethane; 1,1-difluoro-1-bromoacetyl chloride is obtained; finally, the 1,1-difluoro-1-bromoacetyl chloride and ethyl alcohol are esterified to obtain 2,2-difluoro-2-ethyl bromoacetate. The synthesis method has the advantages that the problems of recovery and utilization of waste materials of 1,1-difluoro-1,2-dichloroethane (R132b) are solved; no organic solvents are used in the reaction process; the oxidation step uses SO3 for oxidation; high temperature and high pressure or concentrated sulfuric acid is not needed; the safety is enhanced; the discharging of waste acid is reduced; the green production requirement is met; the product yield is relatively high; the green synthesis method is suitable for industrial production.
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Paragraph 0009; 0019; 0021; 0023; 0025
(2018/03/01)
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- PROCESS FOR THE PREPARATION OF 1-CHLORO-2,2-DIFLUOROETHANE
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The present invention provides a process for the preparation of 1-chloro-2,2-difluoroethane comprising the following stages : (i) dehydrofluorinating 1,1,1-trifluoro-2-chloroethane to form a product stream comprising 1-chloro-2,2-difluoroethylene, optionally separation of 1-chloro-2,2-difluoroethylene from the product stream and (ii) hydrogenating 1-chloro-2,2-difluoroethylene obtained in stage (i) to give 1-chloro-2,2-difluoroethane.
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Page/Page column 10
(2016/11/07)
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- METHOD OF PRODUCING TRIFLUOROETHYLENE
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PROBLEM TO BE SOLVED: To provide an economically advantageous method for producing industrially useful trifluoroethylene with high productivity by using easily available HCFC-124 as raw material while not using any catalyst. SOLUTION: A method of producing trifluoroethylene includes the step of bringing a reductive compound and 1,1,1,2-tetrafluoro-2-chloroethane into contact with each other, without using any catalyst, at a temperature of 400-1200°C. COPYRIGHT: (C)2016,JPO&INPIT
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Paragraph 0056-0058; 0065
(2017/01/02)
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- Examples of catalytic and selective routes for fluorinated building blocks
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Examples are presented for the catalytic fluorination of chlorinated starting materials in order to produce building blocks or HFCs. The fluorination of CF3CH2Cl, of CCl2=CCl2, of trichloromethoxylbenzenes and trichloromethoxybenzene involving nucleophilic substitution are reported. In all cases, HF was the fluorinating agent. Depending on the chlorinated substrate and the degree of fluorination required, liquid- or gas-phase processes were involved. Usually, catalysts were SbCl 5 in liquid phase and chromium oxide in gas phase. In the presence of SbCl5, at 90 °C under an initial pressure of 10 bar, the fluorination of CCl2=CCl2 leads mainly to the formation of CClF2CHCl2, and the active catalyst is an antimony mixed halide (SbCl3F2). In the same way, the presence of SbCl5 favored the formation of 1-trifluoromethyl-3- trichloromethylbenzene from bis-1,3-trichloromethylbenzene at low temperature (50 °C) and in the presence of a low amount of HF. Moreover, trichloromethoxybenzene was totally transformed into trifluoromethoxybenzene. At 380 °C and at atmospheric pressure, the transformation of CF 3CH2Cl into CF3CH2F was favored over chromium oxide-based catalyst modified by zinc (corresponding to a (Zn/Zn + Cr) molar ratio of 0.22).
- Brunet, Sylvette
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p. 1067 - 1071
(2014/11/27)
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- Unimolecular reactions in the CF3CH2Cl ? CF 2ClCH2F system: Isomerization by interchange of Cl and F atoms
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The recombination of CF2Cl and CH2F radicals was used to prepare CF2ClCH2F* molecules with 93 ± 2 kcal mol-1 of vibrational energy in a room temperature bath gas. The observed unimolecular reactions in order of relative importance were: (1) 1,2-ClH elimination to give CF2=CHF, (2) isomerization to CF 3CH2Cl by the interchange of F and Cl atoms and (3) 1,2-FH elimination to give E- and Z-CFCl=CHF. Since the isomerization reaction is 12 kcal mol-1 exothermic, the CF3CH2Cl* molecules have 105 kcal mol-1 of internal energy and they can eliminate HF to give CF2=CHCl, decompose by rupture of the C-Cl bond, or isomerize back to CF2ClCH2F. These data, which provide experimental rate constants, are combined with previously published results for chemically activated CF3CH2Cl* formed by the recombination of CF3 and CH2Cl radicals to provide a comprehensive view of the CF3CH2Cl* ? CF 2ClCH2F* unimolecular reaction system. The experimental rate constants are matched to calculated statistical rate constants to assign threshold energies for the observed reactions. The models for the molecules and transition states needed for the rate constant calculations were obtained from electronic structures calculated from density functional theory. The previously proposed explanation for the formation of CF2=CHF in thermal and infrared multiphoton excitation studies of CF3CH 2Cl, which was 2,2-HCl elimination from CF3CH 2Cl followed by migration of the F atom in CF3CH, should be replaced by the Cl/F interchange reaction followed by a conventional 1,2-ClH elimination from CF2ClCH2F. The unimolecular reactions are augmented by free-radical chemistry initiated by reactions of Cl and F atoms in the thermal decomposition of CF3CH2Cl and CF 2ClCH2F.
- Enstice, Erin C.,Duncan, Juliana R.,Setser,Holmes, Bert E.
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experimental part
p. 1054 - 1062
(2011/04/18)
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- Catalytic synthesis of polyfluoroolefins
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A catalytic synthesis of polyfluoroolefins was developed proceeding from polyfluorochlorocarbons with the use of industrially produced nickel-chromium catalyst. Three ways of the catalytic synthesis of fluoroolefins were implemented: the cleavage of vicinal chlorine atoms from polyfluorochlorocarbons, the replacement of vinyl chlorine atoms by hydrogen in fluorochloroolrfins, and the reductive dimerization of polyfluorochlorocarbons containing a trichloromethyl group. The condition of a prolonged operation of the nickel-chromium catalyst was found consisting in the application of quartz for absorption of the hydrogen fluoride formed as a side product.
- Stepanov,Delyagina,Cherstkov
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scheme or table
p. 1290 - 1295
(2011/01/04)
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- PROCESS FOR PRODUCTION OF 1,1,1,2-TETRAFLUOROETHANE AND/OR PENTAFLUOROETHANE AND APPLICATIONS OF THE SAME
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A process for producing high purity 1,1,1,2-tetrafluoroethane and/or pentafluoroethane by the step of purifying a crude product obtained by reacting trichloroethylene and/or tetrachloroethylene with hydrogen fluoride comprised of a main product including 1,1,1,2-tetrafluoroethane and/or pentafluoroethane, hydrogen fluoride as an azeotropic component with the main product, and impurity ingredients including at least an unsaturated compound, wherein said purifying step includes a step of bringing a mixture obtained by newly adding hydrogen fluoride into said crude product into contact with a fluorination catalyst in the vapor phase to reducing the content of the unsaturated compound contained in said crude product and a distillation step.
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Page/Page column 10-16
(2008/06/13)
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- A study of trichloroethylene hydrofluorination using a kinetic model
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The kinetic features of catalytic hydrofluorination of trichloroethylene and 2-chloro-1,1,1-trifluoroethane on chromium fluoride/magnesium fluoride catalyst were studied. The effect of pressure and addition of various components of the reaction mixture at the reactor inlet was studied using the developed model.
- Dmitriev,Trukshin,Smykalov
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p. 771 - 776
(2007/10/03)
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- Synthesis of trifluoroethyl ethers from 2,2,2-trifluoroethyl chloride (HCFC-133a) in high temperature aqueous medium
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Treatment of 2,2,2-trifluoroethyl chloride (HCFC-133a) with alcohols (phenols) and aqueous KOH in autoclave at 240-280 C gives the corresponding 2,2,2-trifluoroethyl (2-chloro-1,1-difluoroethyl) ethers in good yields.
- Wu, Kai,Chen, Qing-Yun
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- Preparation of 1,1,1,2-tetrafluoroethane by the vapor-phase catalytic reaction of 1,1,1-trifluoro-2-chloroethane with anhydrous hydrogen fluoride
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1,1,1,2-Tetrafluoroethane was prepared in 97% selectivity by the vapor-phase catalytic reaction of 1,1,1-trifluoro-2-chloroethane with anhydrous hydrogen fluoride (AHF) over a metal fluoride catalyst (CrF3 and CoF2) supported on porous aluminum fluoride (PAF). The relationship between the crystalline phase transition of porous aluminum fluoride and temperature from 100 to 640°C was investigated by X-ray diffraction.
- Quan, Heng-Dao,Yang, Hui-E,Li, Zhong,Ren, Jian-Zhang,Li, Hui-Li
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p. 193 - 199
(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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- 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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- Synthetic utility of HCFC-123 (2,2-dichloro-1,1,1-trifluoroethane): the reaction between HCFC-123 and aldehydes using zinc
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HCFC-123 (2,2-dichloro-1,1,1-trifluoroethane) reacted with zinc and aldehydes to afford predominantly either 1-substituted 2-chloro-3,3-difluoro-2-propen-1-ols or 1-substituted 2,2-dichloro-3,3,3-trifluoro-1-propanols.The reactions proceeded via 1,1-dichloro-2,2,2-trifluoroethylzinc chloride as an organozinc intermediate. - Keywords: 2,2-Dichloro-1,1,1-trifluoroethane; Reaction; Aldehydes; Zinc; 1,1-Dichloro-2,2,2-trifluoroethylzinc chloride
- Tamura, Masanori,Sekiya, Akira
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p. 119 - 122
(2007/10/02)
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- Process for the purification of chlorofluorohydrocarbons
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The invention relates to a process for removing olefinic impurities from hydrogen-containing chlorofluorohydrocarbons (HCFCs) in which the contaminated HCFCs are passed in the gas phase at 200° to 400° C. over a zeolite.
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- Unimolecular Rate Constants for Chemically Activated 1,1,1-Trifluoro-2-chloroethane: A Competitive Three-Channel System
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Chemically activated CF3CH2Cl was prepared with 97.5 kcal/mol of internal energy by the combination of CF3 and CH2Cl radicals.The total unimolecular decomposition rate constant was measured by using two internal standard methods and the average was (7.5 +/- 2.61.5) * 106 s-1.The rate constant for four-centered elimination of HF was measured as (2.8 +/- 0.1) * 106 s-1, for C-Cl bond homolysis the rate constant was (0.8 +/- 5.60.1) * 106 s-1, and by difference the three-centered HCl elimination rate constant was (3.9 +/- 2.63.0) * 106 s-1.These rate constants were compared to predictions from RRKM theory, and threshold energies were assigned for loss of HF (76 kcal/mol), for C-Cl-bond rupture (83 kcal/mol), and for HCl elimination (72 kcal/mol).Product distributions from three activation methods (chemical, multiphoton laser, and thermal) were analyzed to develop a self-consistent view of this complex reaction system.
- Rakestraw, David, J.,Holmes, Bert E.
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p. 3968 - 3975
(2007/10/02)
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- COLLISIONAL ENERGY TRANSFER IN THE THREE-CHANNEL THERMAL DECOMPOSITION OF 1-CHLORO-2,2,3,3-TERTAFLUOROCYCLOBUTANE
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The three-channel thermal decomposition of 1-chloro-2,2,3,3-tetrafluorocyclobutane has been investigated over the temperature range 915-1255 K by using the technique of very low pressure pyrolysis (VLPP).The three individual channels are the elimination of hydrogen chloride, the formation of 1,1-difluoroethylene and 1-chloro-2,2-difluoroethylene.Extrapolated high-pressure rate coefficients (s-1) for the separate channels are 1E(13.2+/-0.3)exp(-271 +/- 8 kJ mol-1/RT), 1E(15.3+/-0.3)exp(-287 +/- 8 kJ mol-1/RT), and 1E(15.3 +/- 0.3)exp(-287 +/- 8 kJ mol-1/RT), respectively, which are consistent with previous studies of related compounds and the predicted effects of chloro and fluoro substitution.With the technique of pressure-dependent VLPP, the average downward energy transferred from the reactant to the bath gas upon collision, (ΔEdown), has been obtained for the bath gases Ne, Kr, CO2, CH4, CF4, C2H4, and CH2CF2 at ca. 1048 K.The values (cm-1) are 445 (Ne), ca. 500 (Kr), 735 (CO2), 665 (CH4), 1370 (CF4), 920 (C2H4), and 1190 (CH2CF2).The data are found to be insensitive to the choice of the energy-transfer probability function (four functions were tested).A comparison is made between the (ΔEdown) values for the bath gases CF4 and CH2CF2 with those for CH4 and C2H4, respectively, with a discussion of the effect of resonance.
- Staker, Warren S.,King, Keith D.
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p. 1805 - 1812
(2007/10/02)
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- Electron Transfer Reactions in Organic Chemistry. XIV. The Reactivities of Some Polyhaloalkanes toward the Outer-Sphere Electron Transfer Reductants Co(II)sepulchrate2+ and Co(II)W12O407-
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Rates were measured for the title reactions in CH3CN/H2O buffered at pH ca.7 at 20 or 50 deg C.The following order of reactivity toward Co(II)W12O407- was found: CBr4 > (CBrCl2)2 > CBr2Cl2 > C2Cl6 > CBrCl3 > CF3CHClBr > CHBr3 > CCl4.Only CBr4, (CBrCl2)2, CBr2Cl2 and CBrCl3 gave measurable rates of reaction with Co(II)sepulchrate2+, and with the same order of reactivity as above.Four these four substrates, a plot of log kET2+ had a slope close to 1.Qualitative product studies for the reactions with Co(II)W12O407- showed that the polyhalomethanes generally reacted by losing their heaviest halogen, while polyhaloethanes formed ethylenes by losing their havies halogen on each carbon atom.For some of the reactions, the intermediate radical formed in the first step could be trapped by N-t-butyl-α-phenylnitrone.The resulting spin adducts were detected by ESR spectroscopy.It is agrued that the rate constant difference between CBr4 and CBrCl3 supports the notion of a very short-lived intermediate anion radical.
- Eberson, Lennart,Ekstroem, Mikael
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p. 113 - 121
(2007/10/02)
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- COMPETITION BETWEEN HYDROGEN FLUORIDE AND HYDROGEN CHLORIDE MOLECULAR ELIMINATION CHANNELS IN THE INFRARED MULTIPLE-PHOTON DECOMPOSITION OF 1,2-DICHLORO-1,1-DIFLUOROETHANE.
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Time-resolved infrared emission spectra have been measured in the infrared multiple-photon decomposition of CClF//2CH//2Cl. The spectra were composed of emissions attributable to vibrationally excited HF* and HCl*. The emission yield of HF* increased rapidly with an increase in the fluence, while the yield of HCl* showed a maximum at 20 J cm** minus **2. These results suggest that the HF and HCl molecular elimination channels compete with each other in the unimolecular decomposition of highly vibrationally excited parent molecules. The stochastic trajectory calculations provided a satisfactory description of the fluence dependences of the HF and HCl yields observed here for CClF//2CH//2Cl and previously for CHClFCHClF.
- Ishikawa,Arai
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p. 681 - 686
(2007/10/02)
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