- 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 0026; 0028; 0031; 0033; 0036; 0038; 0041; 0043
(2019/01/22)
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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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experimental part
p. 1290 - 1295
(2011/01/04)
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- Process for activation of AIF3 based catalysts and process for isomerising hydrochlorofluorocarbons
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An activated AlF3 based catalyst is produced by treating a crude AlF3 for more than 5 hours with a gas stream at a temperature from 300°C to 450°C.
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- Synthesis and Diels-Alder cycloaddition reactions of [(2,2-dichloro-1- fluoroethenyl)sulfinyl] benzene and [(2-chloro-1,2-difluoro ethenyl)sulfinyl] benzene
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Synthesis of [(2,2-dichloro-1-fluoroethenyl)sulfinyl] benzene and [(2- chloro-1,2-difluoro ethenyl)sulfinyl] benzene and their Dieis-Alder cycloadditions with cyclopentadiene, furan and 1,3-diphenylisobenzofuran under thermal and microwave irradiation conditions are described. 2000 Elsevier Science Ltd.
- Sridhar, Madabhushi,Leela Krishna,Madhusudana Rao, Jampani
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p. 3539 - 3545
(2007/10/03)
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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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- Deuterium isotope studies of the hydrofluorination of chloroethenes over chromia catalysts
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The mechanism of the catalytic fluorination of chloroalkenes over a chromia catalyst has been investigated by examining the effects of substituting DF for HF as the fluorine source for reaction with tetrachloroethene and trichloroethene.At a temperature of 250 degC and a HF (DF)/alkene molar ratio of 4.2:1, the rate of conversion of tetrachloroethene is increased by using DF and there is a concomitant increase in the selectivity to some chlorofluoroalkanes and a decrease in the selectivity to chlorofluoroalkenes.The opposite behaviour observed for the halogenated alkenes and alkanes indicates that the alkenes are not important intermediates in the production of the alkanes by a series of hydrofluorination and dehydrochlorination reactions.For tetrachloroethene, the main reaction pathway to the alkanes is a direct chlorine/fluorine exchange over a heavily fluorinated chromia surface with minimal C-H/C-D cleavage of intermediates.Substitution of DF for HF causes no change in the product selectivities from reaction with trichloroethene over chromia catalysts.However, the presence of dideutero - and monodeutero - products shows that both chlorine/fluorine exchange and HF addition / HCl elimination pathways are occurring for the less-substituted alkene.
- Kavanagh, David M. C.,Ryan, T. Anthony,Mile, Brynmor
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p. 167 - 176
(2007/10/02)
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- Threshold Energies and Substituent Effects for Unimolecular Elimination of HCl (DCl) and HF (DF) from Chemically Activated CF2ClCH3 and CF2ClCD3
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Chemically activated CF2ClCH3-d0 and -d3 were prepared with 101 and 102 kcal/mol of internal energy, respectively, by the combination of CF2Cl with methyl-d0 and -d3 radicals at 300 K.The CF2ClCH3 reacts by loss of HCl and HF with rate constants of (2.5 +/- 0.4) x 109 and (0.10 +/- 0.02) x 109 s-1, respectively, a branching ratio of 25:1 in favor of HCl.The CF2ClCD3 has rate constants of (0.78 +/- 0.12) x 109 for loss of DCl and 0.033 +/- 0.005 x 109 sec-1 for loss of DF.The combined primary and secondary isotope effect was 3.2 +/- 0.9 for HCl/DCl elimination and 3.0 +/- 0.9 for loss of HF/DF.RRKM theory was used to model these unimolecular rate constants to determine the threshold energy barriers, E0's, for the four-centered elimination reactions.The E0's were 55 +/- 2 kcal/mol for dehydrochlorination and 69.5 +/- 2 kcal/mol for dehydrofluorination.These threshold barriers are in sharp disagreement with prediction based on trends in the E0's for a series of mono-, di-, and trisubstituted chloroethanes and a similar series of fluoroethanes.An analysis of the E0's for the chloroethanes, fluoroethanes, and chlorodifluoroethane suggests that the carbon-halogen bond in the transition state changes from a nearly neutral C-Cl bond for HCl loss to a C-F bond that has much greater charge separation when HF is eliminated.
- Jones, Yukari,Holmes, Bert E.,Duke, David W.,Tipton, Debbie L.
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p. 4957 - 4963
(2007/10/02)
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- STATE-DEPENDENT PHOTOCHEMISTRY OF HIGHLY FLUORINATED BICYCLOOCTA-2,4-DIENES
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A series of 1,2,3,4,5,6-hexafluorobicycloocta-2,4-dienes was subjected to direct irradiation with ultraviolet light and to triplet sensitization.While all of the dienes cyclized smoothly upon direct irradiation to tricyclo2,5>oct-3-enes, their behavior when triplet sensitized was strongly dependent upon the substituents in the 7- and 8-positions.Responses included no reaction, cyclization to tricyclooctene, and fragmentation to hexafluorobenzene plus olefin.Fragmentation occurred only when geminal chlorines were present at the 7-position.This observation is consistent with the view that the four-membered ring opens homolytically at the C6-C7 bond, and only if sufficient stabilization is available for a radical center at the 7-position.
- Roberts, Bryan E.,Goldman, Glenn D.,Lemal, David M.
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p. 353 - 360
(2007/10/02)
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The acrylic ester F2CCFCO2CD3 is prepared from a mixture of difluorotetrachloroethanes CFCI2CFCI2 and CF2CICCI. The dehalogenation of these Freons, followed by the addition of CFCI3 by means of AICI3 leads to a mixture of chlorofluoropropanes. The hydrolysis with oleum gives the acid chlorides which are then esterified by CD3OD. The dehalogenation of the mixture by the zinc stirred in oxalic acid enables isolation of the expected ester by distillation. This compound, the refractive index of which n20D=1.3667 does not show a major absorption in the near infra-red between 0.6 and 1.4 μm. Thus the corresponding polymer is likely to provide a good material for the core of optical fibers.
- Boutevin,Pietrasanta,Rousseau,Bosc
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p. 151 - 169
(2007/10/02)
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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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p. 3401 - 3409
(2007/10/02)
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