- INFRARED LASER INDUCED DECOMPOSITION OF HEXAFLUOROBENZENE AND SOME MONOSUBSTITUTED DERIVATIVES. INTERMEDIACY OF THE PENTAFLUOROPHENYL RADICAL.
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The infrared multiphoton laser induced reactions of hexafluorobenzene and related pentafluoro analogues (pentafluorobenzene, pentafluorochlorobenzene, pentafluorobromobenzene, and pentafluoroiodobenzene) have been investigated using a CO2 TEA laser.The study was carried out in order to define the decomposition products and to attempt to clarify their mode of formation.Thus, the products (relative yield, percent) of the irradiation of C6F6 (1027.3 cm-1; 0.73 J/cm2; 10 pulses; 25percent decomposition) were C2F4(64), C6F5CF3(28), C2F6(7), CF4(1) and that for C6F5H (949.4 cm-1; 0.80 J/cm2; 10 pulses; 25percent decomposition) was C2F4 and C6F5CF3.Increasing the number of pulses in the reaction with C6F6 decreased the amount of C2F4 and increased the amount of C6F5CF3 and C2F6 indicating secundary and tertiary reactions.Addition of halogen (X2, X = Cl, Br) to these reactions caused different products to be formed.Thus, the irradiation of a C6F6/Cl2 mixture (7.4/7 Torr; 1027.3 cm-1; 0.7 J/cm2; 35 pulses; 35percent reaction) afforded C6F5Cl(46); CF3Cl(24) and CF2Cl2(30).Irradiation of C6F5H/X2 mixtures afforded mainly C6F5X + HX.For example C6F5H/Br2 (10/40 Torr; 949.4 cm-1; 0.93 J/cm2; 10 pulses; 10percent reaction) gave C6F5Br and HBr exclusively.Irradiation of C6F5-X (X = Cl, Br, I) (977.2 cm-1; ca. 0.74 J/cm2; 200 pulses; 39-74percent reaction) gave C6F6 and a minor amount of decafluorobiphenyl , a radical combination product of the pentafluorophenyl radical (C6F5.).Increasing the fluence in these reactions gave similar products in most cases but in some instances increased the amount of C2F4 formed.The reactions and product distribution of the hydrogen substituted derivative (C6F5H) was examined in the presence of Br2 as a function of laser fluence and halogen concentration.It was found that the threshold for C6F5H decomposition was higher for the reaction involving Br2 (as compared with the reaction involving Cl2 or neat C6F5H).The presence of Br2 also decreased the amount of C6F5H that was decomposed, indicating a quenching process.The decomposition path with the lowest activation energie for these molecules is thought to be C6F5X -> C6F5. + X. and was accessible using a laser pulse with a fluence as low as 0.7 J/cm2.Using a higher laser fluence (ca. 1.2 J/cm2) di- and triatomic radicals were defined by spectroscopic identification of the and :CF2 species.These reactions are discussed in light of the formation of the C6F5. radical during a primary, laser induced, process.Subsequent decomposition to smaller fragments, combination with other radicals or scavenging by added reagents also takes place depending on the reaction conditions.
- Watanabe, Akio,Koga, Yoshinori,Sugawara, Ko-ichi,Takeo, Harutoshi,Fukuda, Kenzo,Matsumura, Chi
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- Infrared Laser Multiphoton Dissociation of CF2ClCH2Cl
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The infrared multiphoton decomposition (IRMPD) of CF2ClCH2Cl was studied with focusing geometry using the P(34) line of the 9.6-μm CO2 band (1033.6 cm-1).The principal reaction product is CF2CHCl.Other products of significance include CFClCHCl, CF2CH2, and CFCH.It is concluded that the primary processes of photodecomposition involve the molecular elimination of HCl and HF and, to a very minor extent, C-C bond rupture.The relative importance of the primary steps is approximately 1000:30:1, respectively.From a series of diagnostic experiments in the presence of hydrogen donors and D2, it is shown that CF2CH2 derives from the secondary photolysis of CF2CHCl.The decomposition yield, the HF/HCl ratio, and the CF2CH2/CF2CHCl ratio were investigated as a function of reactant and argon pressure, the latter serving as a buffer gas.From the dependence of the decomposition yield on pulse number at different pulse energies, E0, the specific rate of decomposition, b, was found to be proportional to b E01.8, the power dependence being somewhat higher than the standard 3/2 power law for focusing geometry.These phenomena are interpreted in terms of a simple geometric fluence model which includes contributions from collisionally induced reactions in the outermost (lower fluence) irradiated region.The nonresonant photodecomposition of C2H6 and C2H4 at 1033.6 cm-1 observed in auxiliary, diagnostic experiments is interpreted in terms of photosensitization processes.
- Yano, T.,Ozaki, S.,Ogura, H.,Tschuikow-Roux, E.
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- Difluorocarbene studied with threshold photoelectron spectroscopy (TPES): Measurement of the first adiabatic ionization energy (AIE) of CF2
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The first photoelectron band of difluorocarbene CF2, has been studied by threshold photoelectron (TPE) spectroscopy. CF2 was prepared by microwave discharge of a flowing mixture of hexafluoropropene, C3F6, and argon. A vibrationally resolved band was observed in which at least twenty-two components were observed. In the first PE band of CF2, the adiabatic ionization energy differs significantly from the vertical ionization energy because, for the ionization CF 2+ (X2A1)+e- ← CF2 (X1A1), there is an increase in the FCF bond angle (by ≈20°) and a decrease in the C-F bond length (by ≈ 0.7 A). The adiabatic component was not observed in the experimental TPE spectrum. However, on comparing this spectrum with an ab initio/Franck-Condon simulation of this band, using results from high-level ab initio calculations, the structure associated with the vibrational components could be assigned. This led to alignment of the experimental TPE spectrum and the computed Franck-Condon envelope, and a determination of the first adiabatic ionization energy of CF2 as (11.362± 0.005) eV. From the assignment of the vibrational structure, values were obtained for the harmonic and fundamental frequencies of the symmetric stretching mode (v1′) and symmetric bending mode (v2′) in CF2+ (X2A1).
- Innocenti, Fabrizio,Eypper, Marie,Lee, Edmond P. F.,Stranges, Stefano,Mok, Daniel K. W.,Chau, Foo-Tim,King, George C.,Dyke, John M.
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- CF3Br-H2 reaction in shock waves
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CF3Br-H2 mixtures highly diluted with Ar were studied by using a time-resolved IR-emission of HBr and a gas-chromatography for reaction products. The temperature range covered was 1000-1600 K and the total pressure behind the reflected shock waves used was 1. 2-2.6 atm. CF3H, C2F6, and C2F4 were produced and the yields of these products were determined as a function of temperature. The main product under our experimental conditions was CF3H. The mechanism and the rate constants of CF3Br--H2 reaction at high temperatures were discussed. The experimental data was satisfactorily modeled using a 14-reaction mechanism. Reaction (5) played an important role in the formation of CF3H together with reaction (4).
- Hidaka,Nakamura,Kawano
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- Infrared multiphoton dissociation of two perfluorobutenes
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Photofragment translational spectroscopy was used to examine the infrared multiphoton dissociation of octafluoro-1-butene and octafluoro-2-butene. The predominant unimolecular reaction in octafluoro-1-butene at moderate laser fluences is cleavage of a carbon-carbon single bond to give the products CF3 and C3F5. The two other reactions that take place are CF2 elimination and the formation of equal weight fragments with the chemical composition C2F4; both reactions take place via a diradical intermediate. Dissociation of octafluoro-1-butene to the resonance stabilized perfluoroallyl radical is suggested to account for the favoring of simple bond rupture. These three reaction pathways were also observed in octafluoro-2-butene dissociation, however, the branching fraction is different than from octafluoro-1-butene. In octafluoro-2-butene all three channels occur with roughly equal probability. The reactions involving CF2 loss and C2F4 formation in octafluoro-2-butene are thought to proceed through the same diradical intermediate as in octafluoro-1-butene, necessitating a 1,2-fluorine migration.
- Longfellow, Cheryl A.,Berrie, Cindy L.,Suits, Arthur G.,Lee, Yuan T.
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- Picosecond photofragment spectroscopy. IV. Dynamics of consecutive bond breakage in the reaction C2F4I2 -> C2F4 + 2I
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Picosecond photofragment spectroscopy of the ultraviolet (UV) photodissociation of 1,2-diiodotetrafluoroethane reveals consecutive breaking of the two C-I bonds.Spin-orbit excited (I*) atoms show a prompt rise, in agreement with a direct mode dissociation of the first bond.Ground-state (I) atoms show a biexponential buildup, one component being fast (1 ps) while the other component is slow (30-150 ps depending on total energy), characteristic of the second bond breaking.The transient behavior of I atoms changes with the available energy.These results are interpreted in terms of a two step model involving a weakly bound radical.Simulations of transient behavior of I atoms, based on estimated internal energy distributions from the primary step and a model for dissociation rates as a function of energy, suggest that surface crossings are relevant to the dynamics and that the quantum yield of I atoms varies with excitation energy.
- Khundkar, Lutfur R.,Zewail, Ahmed H.
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- Multiphoton Excitation of trifluoroethene. Allene Production by Difluorovinylidine
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Trifluorethene was excited with a high-power, pulsed CO2 laser, and the products were analyzed by mass and infrared spectroscopy.Mainly, this initiates αα elimination of HF to produce difluorovinylidine, CCF2.This species adds across the double bond of another parent molecule followed by deactivation or release of CF2 and carbon insertion to produce trifluoroallene and C2F4.In the presence of other olefins, C2H4, C2D4, and C2F4, multiphoton excitation of trifluoroethene forms respectively allene, perdeuterioallene, and perfluoroallene.In the presence of cyclopentadiene, carbon insertion seems to take place, but benzene is not formed.In these experiments, some olefin products show that when a vibrationally excited trifluoroethene molecule collides with another olefin, metathesis can take place, presumably through a cyclobutane intermediate.
- Stachnik, Robert A.,Pimentel, George C.
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- DEPENDENCE OF THE UNIMOLECULAR DISSOCIATION PRODUCTS ON THE FLUENCE OF THE CO2 LASER BEAM
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The dissociation products of CF2Cl2 irradiated in the line P20 at 9.17 μm with pulses of fluence as high as 60E4 J*m-2 depend on the pressure of the gas, giving rise to C2F4 only when the pressure is of the order of 2 mb.At remarkably lower fluence (2E4 J*m-2) this product appears however in a wide range of pressures. For CF2HCl, C2F4 is the only product that appears at fluences as high as 60E4 J*m-2).At lower fluences (2.5E4 J*m-2), less C2F4 is produced and another product, probably a halogenated derivative of butane, is obtained.
- Santos, M.,Hernandez-Vara, R.,Herreros, J. M.,Gonzales-Diaz, P. F.
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- Isothermal pyrolysis of iodomethanes in gases
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The fact was established that the pyrolysis of gaseous iodomethanes RI yields methane and non traces of recombination products R2. A pyrolysis mechanism was proposed and rate constants of limiting stages of the pyrolysis of iodomethane, trideuteroiodomethane, and diiodomethane over the range of 500-1500 K were determined. Pleiades Publishing, Ltd., 2009.
- Skorobogatov,Khripun,Rebrova
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- Highly selective photochemical synthesis of perfluoroalkyl bromides and iodides
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Highly fluorinated alkyl iodides are conveniently synthesized by telomerization of a fluoroalkyl-iodide, RI, with, e.g., C2F4. Normally, the reaction, often carried out in the liquid phase with a radical initiator, gives products with a broad distribution of molecular weights. In this work, we report a method that obtains selectively products of a desired molecular weight: this method is a photochemically induced reaction in the gas phase; the gas is circulated through a trap or a rectification still which continuously removes the heavier products, whereas the more volatile molecules return to the photoreactor. An analysis by rate equations shows which control parameters are important, and by a suitable choice of these parameters, we obtained a better selectivity for, e.g., C8F17I than previously. This method also works with BrC2F4Br instead of an iodide. In this case, we demonstrated in a small laboratory setup with simple low-pressure Hg lamps (5 × 30 W), a productivity of more than 0.5 kg/day. In the telomerization of CF3Br or HC2F4Br with C2F4 we found, however, a few percent of dibromide side products which are sometimes difficult to separate because of similar boiling points. For this case, it is better to synthesize the iodides instead, and then exchange the I for Br, if desired.
- Zhang,Zhang,Yang,Wang,Fuss,Weizbauer
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- Isolation, Characterization and Some Properties of Free Difluoroethyne, FCCF
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Difluoroethyne, FCCF 1, has been prepared by vacuum pyrolysis of perfluoro-1,2,3-triazine, isolated in pure form and characterized by 19F NMR and gas phase IR spectroscopy; its decomposition, with a half-life-time at 300 K and ca. 2.5 mbar of ca. 15 min, yields in the first step a polymer and :CF2, the latter either oligomerizing or reacting with 1 to form three different C3F4 isomers.
- Buerger, Hans,Sommer, Silvia
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- Experimental and chemical kinetic study of the pyrolysis of trifluoroethane and the reaction of trifluoromethane with methane
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A detailed reaction mechanism is developed and used to model experimental data on the pyrolysis of CHF3 and the non-oxidative gas-phase reaction of CHF3 with CH4 in an alumina tube reactor at temperatures between 873 and 1173 K and at atmospheric pressure. It was found that CHF3 can be converted into C2F4 during pyrolysis and CH2=CF2 via reaction with CH4. Other products generated include C3F6, CH 2F2, C2H3F, C2HF 3, C2H6, C2H2 and CHF2CHF2. The rate of CHF3 decomposition can be expressed as 5.2×1013[s-1]e -295[kJmol-1]/RT. During the pyrolysis of CHF3 and in the reaction of CHF3 with CH4, the initial steps in the reaction involve the decomposition of CHF3 and subsequent formation of CF2 difluorocarbene radical and HF. It is proposed that CH4 is activated by a series of chain reactions, initiated by H radicals. The NIST HFC and GRI-Mech mechanisms, with minor modifications, are able to obtain satisfactory agreement between modelling results and experimental data. With these modelling analyses, the reactions leading to the formation of major and minor products are fully elucidated.
- Han, Wenfeng,Kennedy, Eric M.,Kundu, Sazal K.,MacKie, John C.,Adesina, Adesoji A.,Dlugogorski, Bogdan Z.
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- Oxidation of hexafluoropropylene with oxygen to hexafluoropropylene oxide
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A method for pressure oxidation of hexafluoropropylene (HFP) with oxygen to hexafluoropropylene oxide (HFPO) has been presented. The oxidation was carried out in a periodically operated reactor. The influence of temperature, the nature of the solvent, and the molar ratio of HFP/O2 on the course of oxidation was investigated during the preliminary studies. The magnitudes describing the process were the conversion of HFP, the selectivity of transformation to HFPO in relation to HFP consumed, and the yield of HFPO in relation to the initial amount of HFP. The optimisation of the technological parameters of oxidation, temperature, HFP/O2 molar ratio, and the reaction time was performed by the application of a statistical experimental design method. The function describing the process was the yield of HFPO.
- Wroblewska, Agnieszka,Milchert, Eugeniusz,Meissner, Egbert
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- The reaction of C3F6 with dioxygen under IR laser initiation
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The mechanism of oxidation of C3F6 by molecular O2 under IR multiphoton excitation was studied. The activation energy of C3F6 oxidation was estimated from the dependence of the reagent conversion on the O2 pressure. The data obtained for the final reaction products, CF3CFO and CF2O, suggest the dioxetane mechanism of C3F6 oxidation.
- Kuricheva,Dunyakhin,Timofeev,Zhitnev
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- Shock-Tube Study of the Pyrolysis of the Halon Replacement Molecule CF3CHFCF3
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The kinetics of pyrolysis of CF3CHFCF3 have been studied in dilute mixtures (0.5 and 3 mol percent) in argon in a single-pulse shock tube over the temperature range of 1200-1500 K, residence times behind the reflected shock of between 650 and 850 μs, and pressures between 16 and 18 atm. Fluorinated products were quantified with gas chromatography and Fourier transform infrared spectroscopy; identification of unknown fluorocarbons and hydrofluorocarbons was performed with gas chromatography-mass spectrometry. The most significant products detected were C2F6, CF2=CHF, C2F4, C3F6, cyclo-C3F6, and CF3CHFCF2H. Traces of CF3H, CF4, C2F5H, C3F8, C4F6, and isomers of C4F8 were also identified. A detailed kinetic reaction scheme is presented to model the experimental reactant and product yield profiles as a function of temperature. The results of modeling showed that the major initiation reaction was the C-C bond fission reaction. The abstraction of the secondary H atom by F atoms was also predicted to be important, whereas 1,2-HF elimination was slower. From experiments and modeling, the following initiation rate constants were obtained: CF3CHFCF3 -> CF3 + CF3CHF (k37 = 1E15.9 exp(-355.6 kJ mol-1/RT) s-1), CF3CHFCF3 -> C3F6 + HF (k38 = 1E12.9 exp(-291.2 kJ mol-1/RT) s-1), and CF3CHFCF3 + F -> CF3CFCF3 + HF (k39 = 1E136 exp(-10.1 kJ mol-1/RT) cm3 mol-1 s-1).
- Hyenes, Robert G.,Mackie, John C.,Masri, Assaad R.
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- Silicon-substituted derivatives of trifluoro(trifluoromethyl)silane. Some chemistry of the silicon-iodine bond in a polyhalo system
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The fluoroiodosilane CF3SiF2I has been utilized to generate a series of compounds of formula CF3SiF2X, where X = Br, Cl, F, and OSiF2CF3; all but X = F are new compounds. Conversion of Si-I bonds to Si-X is effected by antimony(III) halides or, for oxygen, mercury(II) oxide. Each of the halodifluoro(trifluoromethyl)silanes undergoes pyrolytic decomposition at 100° to generate SiF3X and CF2, although the thermal decomposition of CF3SiF2I is quite complex. Each of the CF3SiF2X species (other than CF3SiF3) reacts with water vapor to generate CF3SiF3 and, for X = Br or I, CF2HX. The halodifluoromethanes evidently result from the reaction of CF2 with HX - the CF2 in turn resulting from the interaction of water vapor and CF3SiF3 at room temperature. Correlations of fluorine chemical shifts and directly bonded silicon-fluorine coupling constants between CF3SiF2X species and the corresponding SiF3X species are presented.
- Sharp, Kenneth G.
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- Photochemistry of Anhydrides Part 5.-Photolysis of Perfluorosuccinic Anhydride
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The photolysis of the vapour of perfluorosuccinic anhydride was studied at 22 and 199 deg C.The effective primary process is (C2F2O)2O+hυ -> CO+CO2+C2F4.The quantum yields of products are little affected by change of pressure but they decrease on increasing the pressure of anhydride or of added perfluoromethylcyclohexane.The results are compared with those for related fluoroanhydrides.
- Stock, Colin J.,Whittle, Eric
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- Real Time Optical Observation of Nascent Hexafluorobutadiene in the IR Multiphoton Dissociation of Decafluorocyclohexene
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Real time observation of retro-Diels-Alder dissociation of decafluorocyclohexene into tetrafluoroethylene and hexafluorobutadiene induced by transversely excited atmospheric pulsed CO2 laser is reported.The formation rate and the red-shifted absorption spectra of nascent hexafluorobutadiene suggest substantial internal energy incorporation, which appears to be sufficient for its undergoing electrolytic transformation to hexafluorocyclobutene at a rate corresponding to the decay kinetics.When the above IR multiphoton dissociation of decafluorocyclohexene occurs in presence of oxygen, UV light emission due to COF2* is observed.
- Chowdhury, Pradyot Kumar
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- Effects of NH3 on 13C-Selective Infrared Multiple Photon Decomposition of CF2HCl by a CO2 Laser
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The effects of NH3 on product yields and 13C enrichment factors have been examined for the IRMPD of CF2HCl using a CO2 TEA laser.The IRMPD of neat CF2HCl yields only C2F4 and HCl as final products.The addition of NH3 resulted in the formation of CF3H and NH4Cl in addition to C2F4, and enhanced significantly the decomposition of CF2HCl.The enrichment factors of 13C in C2F4 and CF3H decreased with increasing NH3, but the decreases were relatively small.The mechanism of the IRMPD in the presence of NH3 is discussed on the basis of the observed results.
- Sugita, Kyoko,Arai, Shigeyoshi
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- Glass Etching Initiated by Excimer Laser Photolysis of CF2Br2
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KrF and ArF excimer laser irradiation of glass surfaces immersed in gaseous CF2Br2 is found to induce etching.The etch mechanism is considered to be nonthermal on the basis of the small value of the glass absorption coefficient and wavelength variable etching experiments.The etch rate dependence on surface fluence is presented for three pressures.SEM photos reveal a rough surface morphology in the etched region that apparently is not a chemical effect but results solely from the laser irradiation.Photochemical and spectroscopic analysis of the irradiated gas provides evidence for CF2 and CF2Br as being major photolysis products.C2F4 was also found to cause etching at 248 and 193 nm.This is evidence that CF2, resulting from C2F4 photolysis, is alone capable of initiating glass etching in the presence of laser light.The paper concludes by discussing the observed inability of the CF3 releasing parent gases CF3Br and CF3I to significantly etch glass when irradiated in their appropriate absorption bands.
- Brannon, James H.
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- IR MATRIX ISOLATION SPECTRA OF SOME PERFLUORO ORGANIC FREE RADICALS PART III. n-C3F7 and iso-C3F7
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The perfluoro radicals n-C3F7 and iso-C3F7 have been prepared by pyrolyzing the corresponding iodides in a platinum effusion tube at temperatures between 450-550 deg C and isolated in argon matrices.By eliminating absorption bands attributed to known fluorine compounds and applying relative absorption band intensity correlations, several absorption bands have been assigned, some 30 to n-C3F7 and 29 to iso-C3F7, in the spectral range 2000-200 cm-1.A tentative vibrational assignment is presented for both species on the assumption of Cs symmetry.Some thermodynamic implications of the findings are also dicussed.
- Butler, R.,Snelson, A.
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- Multiphoton Chemistry of Perfluoropropene
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The multiphoton decomposition of perfluoropropene (C3F6) has been studied with parallel and focused beams of selected radiation from a CO2 laser.The predominant product for both geometries is C2F4, supporting the mechanism: C3F6 + nhν -> C2F4 + CF2; CF2 + CF2 -> C2F4.NO, 2,3-dimethylbutene, and 2,3-dimethylbutane have little effect on the decomposition whereas O2 changes both the yield and the nature of the products.Photolysis with parallel beams of 995- and 1004.3-cm+1 radiation gives highly selective decomposition of CF213CFCF3 over CF212CFCF3.The probabilities of decomposition, 13Pd, for 12Pd, for these two lines are reported as a function of initial C3F6 pressure from 0.2 to 10 torr.
- Nip, W. S.,Drouin, M.,Hackett, P. A.,Willis, C.
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- Infrared Multiphoton Decomposition of Hexafluorobenzene Investigated by Diode Laser Kinetic Spectroscopy: Detection of CF and CF2
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Infrared multiphoton decomposition of hexafluorobenzene (C6F6) was investigated by diode laser kinetic spectroscopy.Two transient species, CF and CF2, were detected, and the time evolution of their signals was observed.The signal of CF rose within 10 μs after a CO2 laser pulse and decreased with lifetime of about 200 μs, while that of CF2 rose slowly as CF decayed out.Final products observed by an FTIR spectrometer were mostly C2F4 and C6F5CF3.These experimental results suggested that CF was produced at the early stage of the reaction and that CF2 was produced by the reaction of CF with a certain fluorine-containing species and then decayedout through the dimerization and/or the reaction with C6F6.
- Sugawara, Ko-ichi,Watenabe, Akio,Koga, Yoshinori,Takeo, Harutoshi,Fukuda, Kenzo,et al.
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- Quantum yields and energy partitioning in the ultraviolet photodissociation of 1,2 dibromo-tetrafluoroethane (Halon-2402)
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The photofragment translational spectroscopy with vacuum ultraviolet ionization was used to investigate the photodissociation of 1,2 dibromo-tetrafluoroethane (Halon-2402) at 193 nm. The state-selected translational spectroscopy with resonance-enhanced multiphoton ionization was used to investigate the photodissociation of the compound at 193, 233, and 266 nm. The ultraviolet photodissociation was further studied by determining the product branch ratios, angular distributions, and translational energy distributions. A model was proposed to describe the wavelength-dependent bromine quantum yield. The implications of these products in upper atmosphere were studied.
- Zou, Peng,McGivern, W. Sean,Sorkhabi, Osman,Suits, Arthur G.,North, Simon W.
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- The Microwave Spectra, Electric Dipole Moment, and Molecular Structure of 1,1,2,2-Tetrafluorocyclopropane
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The microwave spectra of the normal, monodeuteriated, dideuteriated, and carbon-13 isotopic species of 1,1,2,2-tetrafluorocyclopropane heve been investigated and assigned in the region 26.5-40.0 GHz.The spectral assignments have yielded sufficient data to enable a complete determination of the molecular geometry in the frameworks of both the normal and dideuteriated isotopic species.The partial rs parameters in the framework of the normal isotopic species are r(C1C2) = 1.471(3) Angstroem, r(C3C1,2) = 1.497(10) Angstroem, r(C1,2F) = 1.344(40 Angstroem, r(C3H) = 1.088(5) Angstroem, θ(FC1,2F) = 109.9(4) deg and θ(HC3H) = 118.)(4) deg.The electric dipole moment is determined to be 2.16(3) D.The rotational spectra and symmetry of two low lying vibrational modes were assigned in the dideuteriated isotopic species.The frequencies of the modes were determined from relative intensity measurements to be 188(9) cm-1 for the symmetric (A) vibrational state and 178(13) cm-1 for the antisymmetric (B) vibrational state in accord with the previous vibrational assignments.All the ring bonds in 1,1,2,2-tetrafluorocyclopropane are found to shorten relative to cyclopropane with the greater reduction occurring in the C1-C2 bond.The FCF and HCH methylene angles, however, are larger in 1,1,2,2-tetrafluorocyclopropane than in 1,1-difluorocyclopropane.These results are related to structural trends established by several experimental and theoretical studies which examined the effect of fluorine substitution on the geometry of substituted cyclopropanes and oxiranes.
- Beauchamp, R. N.,Gillies, C. W.,Craig, N. C.
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- Conversion of CHF3 to CH2=CF2 via reaction with CH4 and CaBr2
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Reaction of CHF3 and CH4 over CaBr2 was investigated at 400-900°C as a potential route for transforming the highly potent greenhouse gas, CHF3, into the valuable product CH 2=CF2. The homogeneous reaction of CHF3 with CH4 was also studied to assist in understanding the chemistries involved. Compared to the gas phase reaction, the addition of CaBr2 as a reactant increases the conversion of CHF3 and CH4 significantly at low temperatures while to a lesser extent at higher temperatures. In the absence of CaBr2, besides the target product, CH2=CF2, a large amount of C2F4 forms. On addition of CaBr2, the rate of formation of C 2F4 drops dramatically to near zero, while the rate of formation of CH2=CF2 increases considerably at temperatures below 880°C. Experimental and theoretical studies suggest that CHF3 strongly interacts with CaBr2, resulting in the fluorination of CaBr2 to CaF2, the release of active Br species results in the selective formation of CBrF3. The subsequent reactions involving Br, methane, and CBrF3 play a major role in the observed enhanced yield of CH2=CF2.
- Han, Wenfeng,Yu, Hai,Kennedy, Eric M.,Mackie, John C.,Dlugogorski, Bogdan Z.
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- Shock wave studies of the pyrolysis of fluorocarbon oxygenates. I. The thermal dissociation of C3F6O and CF3COF
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The thermal decomposition of hexafluoropropylene oxide, C3F6O, to perfluoroacetyl fluoride, CF3COF, and CF2 has been studied in shock waves highly diluted in Ar between 630 and 1000 K. The measured rate constant k1 = 1.1 × 1014exp(-162(±4) kJ mol-1/RT) s-1 agrees well with literature data and modelling results. Using the reaction as a precursor, equimolar mixtures of CF3COF and CF2 were further heated. Combining experimental observations with theoretical modelling (on the CBS-QB3 and G4MP2 ab initio composite levels), CF3COF is shown to dissociate on two channels, either leading to CF2 + COF2 or to CF3 + FCO. By monitoring the CF2 signals, the branching ratio was determined between 1400 and 1900 K. The high pressure rate constants for the two channels were obtained from theoretical modelling as k5,∞(CF3COF → CF2 + COF2) = 7.1 × 1014exp(-320 kJ mol-1/RT) s-1 and k6,∞(CF3COF → CF3 + FCO) = 3.9 × 1015exp(-355 kJ mol-1/RT) s-1. The experimental results obtained at [Ar] ≈ 5 × 10-6 mol cm-3 were consistent with modelling results, showing that the reaction is in the falloff range of the unimolecular dissociation. The mechanism of secondary reactions following CF3COF dissociation has been analysed as well.
- Cobos,Hintzer,S?lter,Tellbach,Thaler,Troe
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- COMPETITION AMONG COLLISIONAL DEACTIVATION, IONIZATION, AND DISSOCIATION IN THE MULTIPHOTON EXCITATION OF OCTAFLUOROCYCLOOCTATETRAENE
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The gas-phase UV multiphoton induced chemistry and multiphoton ionization of octafluorocyclooctatetraene (OFCOT) have been examined as a function of laser pulse energy, laser wavelength, and background gas pressure.The production of hexafluorobenzene (HFB), tetrafluoroethylene (TFE), and tetrafluoromethane (TFM) as well as carbon has been observed.An intense fluorescence has also been recorded and attributed to the Swan bands of C2.The laser intensity dependent bulk kinetics of the OFCOT decomposition were found to be first order with a rate constant of 5.7 (+/-0.2)E3 s-1 at a (15 ns) pulse energy of 25 mJ and a sample pressure of 750 mTorr.Qualitative aspects of the photochemistry of HFB and TFE, under identical conditions, are also reported.The addition of N2 to the sample is shown to increase the rate of photolysis and decrease the MPI current.This observation is attributed to the competition between ionization and dissociation from the initially created valence state of the target molecule.The increase in the number of collisions results in a larger fraction of excited-state molecules undergoing relaxation to states which are either geometrically or energetically unfavorable with respect to ionization.The result, therefore, is an increase in the yield of the dissociation products.A simple kinetic rate equation model is in agreement with these observations.OFCOT appears to be a member of a unique group of large, organic molecules exhibiting this type of competition.
- BelBruno, Joseph J.,Greenfield, Scott R.,Carl, Richard T.,Hughes, Russell P.
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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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- Photodissociation of CF2Br2 at 248 nm: A Time-Resolved Absorption Study
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Photodissociation of CF2Br2 at 248 nm has been studied in the gas phase using time-resolved optical absorption spectroscopy.A transient absorption spectrum in the range of 200-320 nm with λmax ca. 260 nm is observed and has been assigned to the primary photodissociation product, the CF2Br radical.The absorption cross section of this radical at 260 nm has been found to be (1.05+/-0.2)x10-18 cm2 molecule-1.The rate constant for CF2Br dimerization is evaluated to be (3.0+/-0.6)x10-12 cm3 molecule-1 s-1.Laser fluence dependence in the secondary photodissociation of CF2Br radical is discussed.
- Vatsa, Rajesh Kumar,Kumar, Awadhesh,Naik, Prakash Dattatray,Rao, Kuchimanchi Venkata Subba Rama,Mittal, Jai Pal
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- Infrared Laser Induced Multiphoton Dissociation of Decafluorocyclopentane in a Concerted Pathway: Time-Resolved Evidence of :CF2 Formation
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The infrared multiphoton dissociation (IRMPD) of decafluorocyclopentane (DFCP) generates tetrafluoroethylene and difluorocarbene as the primary products.The :CF2 dimerizes to form C2F4; the kinetics of the reaction is followed by monitoring the disappearance of :CF2 absorption at 249 nm in real time after the CO2 laser pulse, with a rate constant k2=4.35E7 M-1s-1.The vibrational temperature associated with the nascent :CF2 is found to be 1100 K.The MPD yield of DFCP shows a strong fluence dependence, with a threshold of ca. 0.5 J/cm2 for the 10 R(40) CO2 laser line.The MPD spectra reveal two peaks, one 22 cm-1 red-shifted from the 989 cm-1 strong IR absorption band.Addition of SF6 decreases the MPD yield.
- Chowdhury, P. K.,Rao, K. V. S. Rama,Mittal, J. P.
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- Infrared Multiphoton-Induced Concerted :CF2 Elimination in Octafluorocyclopentene by a Pulsed CO2 Laser
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On infrared multiphoton excitation, octafluorocyclopentene (OFCP) undergoes a ring-opening reaction to give difluorocarbene and hexafluorobutadiene as unstable primary products which undergo further reactions; the former dimerizes to tetrafluoroethylene, and the latter isomerizes to its thermodynamically stable cyclic isomer.The multiphoton dissociation (MPD) yield of OFCP shows a strong fluence dependence, with a threshold of 0.3 J/cm2 for the 10R(32) line of the CO2 laser for inducing the reaction.Two characteristic peaks in the MPD spectra have been observed, both red-shifted from the ν20 ring deformation mode absorption peak of OFCP.Increase in pressure of OFCP or foreign gas addition has shown to deteriorate the MPD yield.
- Chowdhury, Pradyot K.,RAO, K. V. S. Rama,Mittal, J. P.
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- Perfluoroalkylation of ClGeEt3 with perfluoroalkyl bromides and iodides and P(NEt2)3
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RfGeEt3 were prepared by reaction of CF3Br, Cf3I or n-C4F9Br with P(NEt2)3 wheras Cf2Br-CF2Br underwent by debromination and tert-C4F9I gave only FGeEt3. Interaction of CCl4, ClGeEt3 and P(NEt2)3 led to formation of CCl3GeEt3.
- Bardin
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- A carbon arc process for treatment of CF4 emissions
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Light perfluorocarbons, such as carbon tetrafluoride, are produced or emitted from a variety of processes, including manufacture of aluminum and processing of semiconductor devices. At the same time, the long atmospheric lifetime and high global warming potential of such compounds makes them an environmental concern. A new process for the abatement of perfluorocarbon emissions using a carbon are plasma was investigated. In particular, the conversion of CF4 to C2F4 and higher fluorinated species, including poly(tetrafluoroethylene) (PTFE) was demonstrated. General features of the reaction chemistry are discussed, including primary reactions to form radicals and ions and secondary reactions to form C2F4 and higher compounds. The conversion efficiencies and products obtained in the reported experiments indicate potential applicability of the process for point source emission control of high global warming potential perfluorocarbons.
- Chen, Daniel T.,David, Moses M.,Tiers, George V.D.,Schroepfer, Joseph N.
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- Pulse-Duration Effects on Competitive Reactions in Infrared Multiple-Photon Decomposition of CH2ClCHClF and CHClFCHClF
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Vibrationally excited 1,2-dichlorofluoroethane and 1,2-dichloro-1,2-difluoroethane have been observed to dissociate competitively via two channels to form vibrationally excited HCl and HF.The fluence dependences of the branching ratio have been measured for both "short"-pulse (80-ns fwhm) and "long"-pulse (80-ns fwhm with 1-μs-fwhm tail) irradiations.The branching ratio shows not only fluence dependence but also pulse-duration dependence, that is, intensity dependence.When the reactant pressure is 1.0 Torr, collisional deactivation is expected to occur to a considerable extent under long-pulse irradiation while it can be ignored under short-pulse irradiation.The experimental results are interpreted by using the exact stochastic method based on the energy-grained master equations, which take into account collisional deactivation.
- Ishikawa, Yo-ichi,Sugita, Kyoko,Arai, Shigeyoshi
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- Mechanistic study of nucleophilic fluorination for the synthesis of fluorine-18 labeled fluoroform with high molar activity fromN-difluoromethyltriazolium triflate
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The synthesis of fluorine-18 labeled fluoroform with high molar activity has grown in importance for the development of fluorine-18 labeled aryl-CF3radiopharmaceuticals that are useful as diagnostic radiotracers for the powerful technique of positron emission tomography (PET). We designed a strategy of synthesizing fluorine-18 labeled fluoroform fromN1-difluoromethyl-N3-methyltriazolium triflate (1)viaSN2 fluorination without stable fluorine isotope scrambling. Fluoroform was generated at rt in 10 min by fluorination of the triazolium precursor with TBAF (6 equiv.). We propose three routes (a), (b), and (c) for this fluorination. Quantum chemical calculations have been carried out to elucidate the mechanism of experimentally observed nucleophilic attack of fluoride at difluoromethyl groupviaroute (a), notN3-methylviaroute (b).1H and19F NMR studies using deuterium source have been performed to examine the competition between SN2 fluorination (route (a)) and the formation of difluorocarbene (route (c)). The observed superiority of SN2 pathway to formation of difluorocarbene in the reaction of the precursor using CsF in (CD3CN/(CD3)3COD (17.8?:?1)) gives the possibility of preparing the fluorine-18 labeled fluoroform in high molar activity.
- Chai, Jin Young,Cha, Hyojin,Lee, Sung-Sik,Oh, Young-Ho,Lee, Sungyul,Chi, Dae Yoon
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- Fluorocarbene, fluoroolefin, and fluorocarbyne complexes of Rh
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The manuscript reports the synthesis, characterization, and analysis of electronic structure in a series of complexes of small perfluorocarbon ligands with the (PNP)Rh fragment (where PNP is a diarylamido/bis(phosphine) pincer ligand). Reactions of (PNP)Rh(TBE) as the source of (PNP)Rh with CHF3 and C2HF5 produced perfluoroalkylidene complexes (PNP)Rh═CF2 and (PNP)Rh═C(F)(CF3). (PNP)Rh═CF2 could also be obtained via the reaction of (PNP)Rh(TBE) with Me3SiCF3/CsF, with an admixture of (PNP)Rh(C2F4), where TBE = tert-butylethylene. Abstraction of fluoride from these neutral (PNP)RhCxFy complexes was successful, although only abstraction from (PNP)Rh═CF2 allowed unambiguous identification of the Rh product, [(PNP)Rh=CF]+. DFT computational studies allowed comparison of relative energies of (PNP)Rh(C2F4) and [(PNP)Rh(C2F3)]+ isomers as well as comparisons between the electronic structure of the ═CF2, C2F4, and =CF+ complexes and their hydrocarbon analogues.
- Pell, Christopher J.,Zhu, Yanjun,Huacuja, Rafael,Herbert, David E.,Hughes, Russell P.,Ozerov, Oleg V.
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- Preparation method of hexafluoro-1, 3-butadiene
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The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of hexafluoro-1, 3-butadiene. The method comprises the following steps: cracking R22 used as a raw material to prepare TFE, preparing TFE and Br2 according to a certain ratio under certain conditions to generate dibromotetrafluoroethane, and reacting dibromotetrafluoroethane with TFE at certain temperature under the conditions of zinc powder and a DMF-toluene combined solvent to prepare the hexafluoro-1, 3-butadiene. After the reaction, a gas phase sample is collected and analyzed by GC chromatography, and the proportion of hexafluoro-1, 3-butadiene accounts for more than 85%. The method has the advantages of simple and accessible raw materials, low price, simple and safe technical preparation process, high product yield and the like.
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Paragraph 0029-0030; 0032-0033; 0035-0036
(2021/04/14)
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- PROCESS FOR PRODUCING FLUORINE COMPOUND
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PROBLEM TO BE SOLVED: To provide a production process that can continuously produce 1,1,1,4,4,5,5,5-octafluoro-2-pentene (HFO1438 mzz) without using pure TFE having explosion risk. SOLUTION: Said production process comprises: a first step of pyrolyzing chlorodifluoromethane to yield a TFE crude product containing tetrafluoroethylene (TFE) and hydrogen chloride; a second step of subjecting the TFE crude product to hydrogen chloride removal, or hydrogen chloride removal and drying, to yield a TFE crude product from which hydrogen chloride is removed; and a third step of producing, in the presence of catalyst, HFO1438 mzz from the hydrogen chloride-removed TFE crude product and 1-3,3,3-tetrafluoropropene. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2020,JPOandINPIT
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Paragraph 0019-0026
(2020/03/05)
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- Pentafluoroethylation of Arenediazonium Tetrafluoroborates Using On-Site Generated Tetrafluoroethylene
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Copper-mediated pentafluoroethylation of arenediazonium tetrafluoroborates with tetrafluoroethylene (TFE) on-site generated from TMSCF3 has been developed as a new method to prepare pentafluoroethyl arenes. The active pentafluoroethylation reagent “CuC2F5” is pre-generated from CuSCN, TFE and CsF, and its generation and further reaction are strongly solvent-dependent. This pentafluoroethylation reaction represents the first example of Sandmeyer-type pentafluoroethylation, which exhibits good functional group tolerance and potential applications for the synthesis of complicated bioactive compounds.
- Xing, Bo,Li, Lingchun,Ni, Chuanfa,Hu, Jinbo
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supporting information
p. 1131 - 1136
(2019/10/22)
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- Direct defluorinative amidation-hydrolysis reaction of gem-difluoroalkenes with N,N-dimethylformamide, and primary and secondary amines
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A novel and efficient method for the synthesis of arylacetamides by the reactions of gem-difluoroalkenes with N,N-dialkylformamides, and primary and secondary amines with the assistance of KOtBu and water was developed.
- Wang, Biyun,Zhao, Xianghu,Liu, Qingyun,Cao, Song
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p. 8546 - 8552
(2018/12/01)
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- TMSCF3 as a Convenient Source of CF2=CF2 for Pentafluoroethylation, (Aryloxy)tetrafluoroethylation, and Tetrafluoroethylation
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A new method for the on-site preparation of tetrafluoroethylene (TFE) and a procedure for its efficient use in pentafluoroethylation by fluoride addition were developed by using a simple two-chamber system. The on-site preparation of TFE was accomplished by dimerization of difluorocarbene derived from (trifluoromethyl)trimethylsilane (TMSCF3) under mild conditions. Other fluoroalkylation reactions, such as (aryloxy)tetrafluoroethylation and tetrafluoroethylation processes, were also achieved using a similar approach. This work not only demonstrates a convenient and safe approach for the generation and use of TFE in academic laboratories, but also provides a new strategy for pentafluoroethylation.
- Li, Lingchun,Ni, Chuanfa,Xie, Qiqiang,Hu, Mingyou,Wang, Fei,Hu, Jinbo
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supporting information
p. 9971 - 9975
(2017/08/08)
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- Preparation of tetrafluoroethylene from the pyrolysis of pentafluoropropionate salts
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The use of tetrafluoroethylene (TFE) in academic institutions beyond a few millimoles has often been inhibited by the compound's inherent danger and general lack of commercial availability. On the other hand, TFE is prepared industrially on a rather large scale by a number of major fluorochemical companies via the pyrolysis of chlorodifluoromethane at high temperatures, yielding TFE and HCl. For a few years at The University of Alabama and Clemson University, we have been preparing TFE on a 100+-gram scale by the pyrolysis under dynamic vacuum of pentafluoropropionate salts, which can be obtained from the neutralization of pentafluoropropionic acid with a M(OH)n (where M?=?Li, Na, K, and Cs for n?=?1 and Mg, Ca, and Ba for n?=?2). Additionally, potassium pentafluoropropionate can be prepared from the reaction of potassium trimethylsilanolate and ethyl pentafluoropropionate. The pentafluoropropionate salts and their decomposition products have been characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC), nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry, Fourier transform-infrared (FTIR) spectrophotometry, scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDAX), X-ray diffraction (XRD), and single-crystal X-ray crystallography, where applicable. Typical yields of TFE obtained from pyrolysis of potassium pentafluoropropionate obtained from the acid-base neutralization method are >98%, while yields of TFE from the same salt prepared by the silanolate method from ethyl pentafluoropropionate are ca. 80%.
- Hercules, Daniel A.,Parrish, Cameron A.,Sayler, Todd S.,Tice, Kevin T.,Williams, Shane M.,Lowery, Lauren E.,Brady, Michael E.,Coward, Robert B.,Murphy, Justin A.,Hey, Trevyn A.,Scavuzzo, Anthony R.,Rummler, Lucy M.,Burns, Emory G.,Matsnev, Andrej V.,Fernandez, Richard E.,McMillen, Colin D.,Thrasher, Joseph S.
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p. 107 - 116
(2017/04/18)
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- Reaction system for preparing tetrafluoroethane-β-sultone and preparation method using the same
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The present invention relates to a reaction system for preparing tetrafluoroethane-andbeta;-sultone and to a preparation method using the same. By using the reaction system for preparing tetrafluoroethane-andbeta;-sultone and the preparation method using the same, tetrafluoroethane-andbeta;-sultone can be prepared safely and easily at a high yield and a high purity at normal temperature and normal pressure, rapid heat generation can be avoided and the risk of explosion in processes due to pressurization is reduced, so that the reaction system and the preparation method are usefully used to prepare energy-related materials such as fuel cell electrolytes and the like derived from tetrafluoroethane-andbeta;-sultone, and in particular, are usefully used to prepare fluorine-based ionomers.COPYRIGHT KIPO 2017
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Paragraph 0119-0121
(2017/12/27)
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- Gram-Scale Synthesis of Amines Bearing a gem-Difluorocyclopropane Moiety
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The synthesis of monocyclic, spirocyclic and fused bicyclic secondary amines bearing a gem-difluorocyclopropane moiety via difluorocyclopropanation of unsaturated N-Boc derivatives using the trifluoromethyl(trimethyl)silane/sodium iodide [CF3SiMe3-NaI] system is described. The relative order of the substrate reactivity is established. It is shown that for the reactive alkenes the standard reaction conditions can be used, whereas for the substrates with low reactivity, slow addition of the Ruppert–Prakash reagent is necessary. (Figure presented.).
- Nosik, Pavel S.,Gerasov, Andrii O.,Boiko, Rodion O.,Rusanov, Eduard,Ryabukhin, Sergey V.,Grygorenko, Oleksandr O.,Volochnyuk, Dmitriy M.
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p. 3126 - 3136
(2017/09/25)
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- Method for preparing fluorinated compound CH2F-R (R is H or CF3) through difluoromethane pyrolysis
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The invention discloses a method for preparing a fluorinated compound CH2F-R (R is H or CF3) through difluoromethane pyrolysis. According the method, the fluorinated compound is obtained through a gas-phase reaction between difluoromethane and CH4, NH3, H2O or H under the circumstance that no catalyst exists. The following reaction conditions of the method are achieved: the reaction pressure is 0.1-1.5 MPa; the reaction temperature is 700-1000 DEG C; the mole ratio of difluoromethane to any one or more of CH4, NH3, H2O and H is 1:(0-40); and the residence time is 0.1-50 s. The method disclosed by the invention has the advantages that the raw material, namely difluoromethane, is easy to obtain; no catalyst needs to use; the operation and the control are easy; and the experimental repeatability is high.
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Paragraph 0046-0049
(2017/05/18)
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- Shock wave studies of the pyrolysis of fluorocarbon oxygenates. II. the thermal dissociation of C4F8O
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The thermal decomposition of octafluorooxalane, C4F8O, to C2F4 + CF2 + COF2 has been studied in shock waves highly diluted in Ar between 1300 and 2200 K. The primary dissociation was shown to be followed by secondary dissociation of C2F4 and dimerization of CF2. The primary dissociation was found to be in its falloff range and falloff curves were constructed. The limiting low and high pressure rate constants were estimated and compared with modelling results. Quantum-chemical calculations identified possible reaction pathways, either leading directly to the final products of the reaction or passing through an open-chain CF2CF2CF2 intermediate which dissociates in a second step.
- Cobos,Hintzer,S?lter,Tellbach,Thaler,Troe
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p. 3159 - 3164
(2017/08/17)
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- A polyvinylidene fluoride preparation method and its catalyst preparation method
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The invention discloses a preparation method of vinylidene fluoride and a preparation method of a catalyst used by the same. The preparation method of vinylidene fluoride comprises the following steps: mixing methane, oxygen and fluoroform or monochlorodifluoromethane or the mixed gas of fluoroform and monochlorodifluoromethane at any ratio or the mixed gas of multiple gases including fluoroform and monochlorodifluoromethane; adding O2 at a certain proportion, and reacting at a temperature of 550-1,050 DEG C under a total pressure of 1-10bar and at an air speed of 50-10,000h; and reacting in the presence of a catalyst to generate vinylidene fluoride. According to the method disclosed by the invention, the vinylidene fluoride with relatively high added value is generated under a catalytic action from several waste fluoroform raw materials which are cheap or need forced treatment, has relatively high added value, and brings good economic and social benefits.
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Paragraph 0027-0030; 0056; 0057; 0058; 0059; 0060-0067
(2017/08/25)
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- Gas cracking reaction device and its application
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The invention provides a gas cracking reaction device and an application thereof. The device comprises a mixer, a gas preheater, a cracking device, a separator and a quench cooler. The device also comprises a powder temperature control heater. A powder outlet of the powder temperature control heater is arranged on the cracking device at the end close to the gas preheater and is communicated to the cracking device; the mixer, the gas preheater, the cracking device, the separator and the quench cooler are communicated in sequence through a pipeline; or the mixer, the gas preheater, the cracking device, the quench cooler and the separator are communicated in sequence through the pipeline. During a use process of the gas cracking reaction device, energy storing powder circulates in a cracking pipe, thereby playing a scouring role to clear away carbon deposition completely; the cracking pipe has no carbon deposition, so that temperature runaway phenomenon can be prevented; maintenance times can be reduced; and the service life of the cracking pipe can be prolonged. Besides, during the use process, the gas cracking reaction device can save energy, reduce side reactions and increase product yield.
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Paragraph 0046-0055
(2017/03/23)
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- At the same time, preparation of trifluoro-vinyl chloride and tetrafluoroethylene, and method
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The invention discloses a method for simultaneously preparing trifluorochloroethylene and tetrafluoroethylene. The method comprises the following steps: mixing monochlorodifluoromethane, dichlorofluoromethane and a diluent, performing copyrolysis reaction to generate pyrolysis gas, quickly cooling, washing by water and alkali in sequence, drying, compressing, rectifying and purifying to obtain trifluorochloroethylene and tetrafluoroethylene, wherein the molar ratio of monochlorodifluoromethane to dichlorofluoromethane is 1 to (1-4), the molar ratio of the diluent to the total amount of monochlorodifluoromethane and dichlorofluoromethane is 1 to (1-20), the reaction temperature is 500-1,200 DEG C, the reaction pressure is 0.1-1MPa, and the reaction retention time is 0.01-10 seconds. The method has the advantages of being simple in process, easy for industrialization and environment-friendly, and raw materials are easily available.
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Paragraph 0054; 0055
(2017/03/22)
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- 2, 3, 3, 3-tetrafluoropropene and 1,1-difluoro ethylene production method
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Provided is an economically advantageous method for producing industrially useful HFO-1234yf and VdF by a single-pass reaction accompanied by pyrolysis using readily available starting materials. Provided is a method for producing, from octafluorocyclobutane and chloromethane, 2,3,3,3-tetrafluoropropene and 1,1-difluoroethylene by a one-step reaction process that includes synthesis accompanied by pyrolysis.
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Paragraph 0044-0049
(2016/11/07)
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- METHOD FOR PRODUCING TETRAFLUOROETHYLENE AND/OR HEXAFLUOROPROPYLENE
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PROBLEM TO BE SOLVED: To provide a novel method for producing tetrafluoroethylene and/or hexafluoropropylene. SOLUTION: The method for producing tetrafluoroethylene and/or hexafluoropropylene comprises thermally decomposing a perfluoroalkane represented by the general formula (1) defined by CnF2n+2, where n represents an integer of 4-28.] COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0053-0054; 0058
(2016/11/09)
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- PRODUCTION METHOD FOR 2,3,3,3-TETRA-FLUOROPROPENE
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To provide an economically advantageous process for producing industrially useful HFO-1234yf efficiently and in a sufficiently controlled state by one reaction involving thermal decomposition, by using readily available raw material. A process for producing 2,3,3,3-tetrafluoropropene from a raw material composition containing chlorodifluoromethane and chloromethane, by a synthetic reaction involving thermal decomposition, which comprises (a) a step of supplying the chlorodifluoromethane and the chloromethane to a reactor, as preliminarily mixed or separately, in such amounts that the chloromethane would be in a ratio of from 0.01 to 3 mol to 1 mol of the chlorodifluoromethane, (b) a step of supplying a heat medium to the reactor, and (c) a step of bringing the heat medium in contact with the chlorodifluoromethane and the chloromethane in the reactor to form the 2,3,3,3-tetrafluoropropene.
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Paragraph 0084
(2015/02/02)
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- METHOD OF PRODUCING 2,3,3,3-TETRAFLUOROPROPENE AND 1,1-DIFLUOROETHYLENE
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PROBLEM TO BE SOLVED: To provide an economically advantageous method that produces industrially useful HFO-1234yf and VdF by a single reaction associated with heat decomposition by use of easily available raw material. SOLUTION: This invention provides a method of producing 2,3,3,3-tetrafluoropropene and 1,1-difluoroethylene by a synthetic reaction associated with heat decomposition from a raw material composition comprising octafluorocyclobutane and methane. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0050-0054; 0057; 0059
(2016/12/22)
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- Stepwise addition of difluorocarbene to a transition metal centre
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The Ruppert-Prakash reagent (Me3SiCF3) is used to introduce difluorocarbene (CF2) and tetrafluoroethylene (TFE) ligands to cobalt(i) metal centres, whereby the TFE ligand is generated via [2+1] cycloaddition between [Co]CF2 and CF2.
- Lee, Graham M.,Harrison, Daniel J.,Korobkov, Ilia,Tom Baker
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supporting information
p. 1128 - 1130
(2014/01/17)
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- Synthesis of tris- and tetrakis(pentafluoroethyl)silanes
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The synthesis and complete characterization of functional, highly Lewis acidic tris(pentafluoroethyl)silanes as well as tetrakis(perfluoroalkyl)silanes Si(C2F5)4 and Si(C2F 5)3CF3 by direct fluorination is described. The reaction of SiCl4 with LiC2F5 invariably affords (pentafluoroethyl)fluorosilicates. To avoid silicate formation by fluoride transfer from LiC2F5 the Lewis acidity of the silane has to be decreased by electron-donating substituents, such as dialkylamino groups. The easily accessible Si(C2F5) 3NEt2 is a valuable precursor for a series of tris(pentafluoroethyl)silanes. Special eFfects: functional and highly Lewis acidic tris(pentafluoroethyl)silanes as well as the tetrakis(perfluoroalkyl) silanes Si(C2F5)4 and Si(C2F 5)3CF3 are prepared. The two tetrakis species were formed in the direct fluorination of tris-(pentafluoroethyl)ethyl- and methylsilane. Si(C2F5)4 was characterized by X-ray crystallography (see figure).
- Steinhauer, Simon,Bader, Julia,Stammler, Hans-Georg,Ignat'Ev, Nikolai,Hoge, Berthold
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supporting information
p. 5206 - 5209
(2014/05/20)
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- PROCESS FOR MANUFACTURING PERFLUOROOLEFINS BY PYROLYSIS OF PERFLUOROCARBONS IN THE PRESENCE OF HYDROGEN
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A process is described of pyrolyzing at least one perfluorinated hydrocarbon, or a material containing at least one perfluorinated hydrocarbon, in the presence of hydrogen, to yield a reaction mixture containing difluorocarbene.
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Page/Page column 23-24
(2012/02/05)
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- 3-ALKOXY-1-PHENYLPYRAZOLE DERIVATIVE AND PEST CONTROL AGENT
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To provide pesticides such as insecticides, miticides and nematicides, which are excellent in the safety, pesticidal effects, residual effectiveness, etc., which further have infiltration, and which can be applied by soil treatment. A pesticide comprising a 3-alkoxy-1-phenyl-pyrazole derivative represented by the formula [I] or an agriculturally acceptable salt thereof as an active ingredient: wherein, for example, R1 is a C1 -C1 0 alkyl group or the like, R2 is a hydrogen atom or the like, R3 is a hydrogen atom or the like, and each of R4 , R5 , R6 and R8 which are independent of one another, is a hydrogen atom or the like, and R7 is a C2 -C4 haloalkylthio group or the like.
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Page/Page column 97
(2010/07/08)
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- PROCESS FOR PRODUCTION OF CARBONYL FLUORIDE
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The present invention provides a method for inexpensively, efficiently, safely, and continuously producing COF2, without using highly toxic raw materials such as phosgene or difficult-to-get raw materials, with no risk of explosion or the like. Tetrafluoroethylene gas and oxygen gas are introduced into a reactor, and they are then heated in a gas phase in the absence of nitrogen gas for reaction, so as to produce carbonyl fluoride. The reactor is preferably a tubular reaction tube. As such tetrafluoroethylene gas, unpurified or purified tetrafluoroethylene gas obtained by heating HCFC-22 gas for thermal decomposition can be used. According to the present invention, COF2 that is useful as cleaning gas for CVD devices (chemical vapor deposition method) can be inexpensively, efficiently, and safely produced.
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Page/Page column 9
(2010/08/07)
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- GASEOUS DIELECTRICS WITH LOW GLOBAL WARMING POTENTIALS
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A dielectric gaseous compound which exhibits the following properties: a boiling point in the range between about ?20° C. to about ?273° C.; non-ozone depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf0); a toxicity level such that when the dielectric gas leaks, the effective diluted concentration does not exceed its PEL; and a dielectric strength greater than air.
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- Activation of free-radical polyfluoroalkylation of organic substrates with freon BrCF2CF2Br using a system of organic base-electron transfer mediator
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A polyfluoroalkylation of pyrrole and phenols with freon BrCF2CF2Br using sulfur dioxide-substituted pyridine activating system proceeds at the aromatic nucleus by a free-radical mechanism. The essential influence of the basicity of the medium is demonstrated and discussed.
- Koshechko, Vyacheslav G.,Kiprianova, Lydiya A.,Kalinina, Ludmyla I.
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experimental part
p. 208 - 211
(2010/04/30)
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- Polyfluoroalkylation of pyrrole with 1,2-dibromotetrafluoroethane activated by sulfur dioxide
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A possibility of the homogeneous catalytic fluoroalkylation of pyrrole with Freon BrCF2CF2Br using a nitrous base-sulfur dioxide system was shown. The influence of pKa of bases on the occurrence of these processes was studied. The ion-radical mechanism of the processes was substantiated.
- Koshechko,Kiprianova,Kalinina
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experimental part
p. 577 - 580
(2011/02/17)
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- Catalytic pyrolysis of CHF3 over activated carbon and activated carbon supported potassium catalyst
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The catalytic activity of activated carbon (AC) and activated carbon supported potassium for the decomposition of CHF3 was investigated at temperatures between 873 and 1173 K and at a space velocity of 4300 h -1. It is found that activated carbon supported potassium shows high and relatively stable activity during the pyrolysis of CHF3 under the conditions studied. Compared with the gas phase reaction, the conversion of CHF3 increases by up to 10 times between 873 and 1123 K, with the major products being C2F4 and C3F6. Selectivities as high as 55% to C2F4 and 35% to C 3F6 are achieved under optimum conditions. The main byproduct HF readily reacts with K2O in the catalyst, converting the catalyst from K2O/AC into KF/AC. Selectivity to the major products remains relatively constant following this transformation.
- Han, Wenfeng,Kennedy, Eric M.,Liu, Huazhang,Li, Ying,Adesina, Adesoji A.,MacKie, John C.,Dlugogorski, Bogdan Z.
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scheme or table
p. 698 - 703
(2010/09/12)
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- Depolymerization of Fluoropolymers
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A process for depolymerizing fluoropolymers includes continuously feeding a solid fluoropolymer, in particulate form, into a horizontal cylindrical first reaction zone. The fluoropolymer particles enter the first reaction zone at one end. Within the first reaction zone, a central axle from which protrudes at least one paddle, continuously rotates. The rotating paddle serves to advance the fluoropolymer particles along the reaction zone while agitating them. As the fluoropolymer particles pass along the reaction zone, they are subjected to an elevated temperature, thereby depolymerizing the fluoropolymer into a fluoro-containing compound-rich gas phase. A residual solids phase is withdrawn at the other end of the first reaction zone, as is the gas phase. Optionally, the gas phase is passed through a second reaction zone which is also at an elevated temperature. The gas phase is quenched, thereby to recover the fluoro-containing compounds as gaseous products.
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Page/Page column 4-5
(2009/06/27)
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- Capturing transient structures in the elimination reaction of haloalkane in solution by transient X-ray diffraction
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This Communication reports simultaneous tracking of structural and kinetic information for the photoinduced elimination reaction of 1,2-diiodotetrafluoroethane in solution by transient X-ray diffraction. The transient structure of ·CF2CF2I is determined to be a classical mixture whereas ·CH2CH2I is bridged. Compared with the gas phase reaction, the secondary dissociation of ·CF2CF2I into C2F4 and I is slowed down by a factor of 6 in solution. Transient X-ray diffraction offers a complementary method for capturing transient structures in solution which might be invisible or optically silent in time-resolved optical spectroscopy. Copyright
- Jae, Hyuk Lee,Tae, Kyu Kim,Kim, Joonghan,Kong, Qingyu,Cammarata, Marco,Lorenc, Maciej,Wulff, Michael,Ihee, Hyotcherl
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p. 5834 - 5835
(2008/09/20)
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- Cyclization processes in pyrolysis of perfluorooxaalkanedicarboxylic acid derivatives
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Formation of cyclic structures under the conditions of pyrolytic decarboxylation of perfluorooxaalkanedicarboxylic acids was studied.
- Lebedev,Berenblit,Starobin
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-
- Simultaneous conversion of CHClF2 and CH3Br to CH2CF2
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Gas phase reaction of CHClF2 with CH3Br in an alumina tube reactor at 773-1123 K as a function of various input ratios of CH3Br to CHClF2 is presented. The major products detected include C2F4, CH2CF2, and CH4. Minor products include CH3Cl, CHF3, C2H4, C2H2, CH2CF-CF3, and C2H3F. The reaction produces a high yield of CH2CF2 (53% based on CHClF2 feed) at 1123 K and an input molar ratio of CH3Br to CHClF2 of 1.8, suggesting that the reaction potentially can be developed as a process to convert two ozone depleting substances (CHClF2 and CH3Br) to a highly valuable chemical, CH2CF2. The reaction of CHClF2 with CH3Cl and CH3I was also investigated under similar reaction conditions, to assist in understanding the reaction chemistry involved in the reaction of CHClF2 with CH3Br.
- Yu, Hai,Kennedy, Eric M.,Mackie, John C.,Dlugogorski, Bogdan Z.
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p. 2003 - 2006
(2008/02/04)
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- Insertion reactions of difluorocarbene generated by pyrolysis of hexafluoropropene oxide to O-H bond
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ROCHF2-type fluorinated ethers were synthesized by the reaction of hexafluoropropene oxide (HFPO) with alcohol or phenol. In this reaction, although the insertion reaction of difluorocarbene to OH bond and the nucleophilic attack of alcohol or
- Mizukado, Junji,Matsukawa, Yasuhisa,Quan, Heng-Dao,Tamura, Masanori,Sekiya, Akira
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p. 373 - 377
(2007/10/03)
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- PYROLYSIS PROCESS
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The present invention relates to the pyrolysis of hydrochlorofluorocarbons to form fluoromonomers such as tetrafluoroethylene, the pyrolysis being carried out in a reaction zone lined with nickel and mechanically supported by a jacket of other corrosion resistant metal, the nickel lining providing an improved yield of valuable reaction products.
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Page/Page column 4-5
(2008/06/13)
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- Pyrolytic decarboxylation of some derivatives of perfluorinated mono- and dicarboxylic acids
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Pathways of pyrolysis of perfluorinated carboxylic acids are considered in relation to the structure of the acids and reaction conditions. The reaction mechanism is discussed.
- Lebedev,Berenblit,Starobin,Gubanov
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p. 1640 - 1645
(2007/10/03)
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- Materials and methods for the conversion of hydrofluorocarbons
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Methods and materials are disclosed for the recovery of valuable hydrofluorocarbons and subsequent conversion to environmentally inert compounds. More specifically methods and materials are provided for recovering hydrofluorocarbons such as HFC-227, HFC-236, HFC-245, HFC-125, HFC-134, HFC-143, HFC-152, HFC-32, HFC-23 and their respective isomers. Processes are provided for converting hydrofluorocarbons such as these to fluoromonomer precursors such as CFC-217, CFC-216, CFC-215, CFC-115, CFC-114, CFC-113, CFC-112, HCFC-22, CFC-12, CFC-13 and their respective isomers. Materials, methods and schemes are provided for the conversion of these fluoromonomer precursors to fluoromonomers such as HFP, PFP, TFP, TFE, and VDF.
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- METHOD OF A SIMULTANEOUS PREPARATION OF HEXAFLUOROPROPYLENE AND OCTAFLUOROCYCLOBUTANE
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A method of simultaneous and selective perpararation of hexafluoropropylene and octafluorocyclebutane comprising the steps of: (a) thermally decomposing difluorochloromethane to obtain tetrafluoroethylene and then supplying the resulting tetrafluoroethylene into a bed reactor equipped with a distributor for supplying steam; and (b) supplying steam into a flow of tetrafluoroethylene supplied into the fluidized bed reactor, through a distributor for supplying steam at a certain molar ratio of tetrafluoroethylene/stream, and then performing dimerization of tetrafluoroethylene in the fluidized bed reactor under an atmospheric pressure.
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- CONVERSION OF FLUOROCARBONS
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A process is disclosed for the conversion of fluorocarbons into fluorinated unsaturated compounds useful as monomers or other chemical precursors, such as C2H2F2. The process comprises reacting a hydrocarbon feed (20) and a fluorocarbon feed (10) in a high temperature reactor (26), at sufficiently high temperature and sufficiently short resident time to form a reaction product mixture (28) having the fluorinated unsaturated compound as the major reaction product, and cooling (18) to a temperature sufficiently low to inhibit polymerisation of the unsaturated compound. The reaction product may then be processed by removal of higher molecular weight compounds (35) and acids (32) and optionally separated (44) into product components.
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Page column 7-10
(2008/06/13)
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- NOVEL FLUOROPOLYMER, RESIST COMPOSITIONS CONTAINING THE SAME, AND NOVEL FLUOROMONOMERS
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There is provided a fluorine-containing copolymer having an aliphatic monocyclic structure in the polymer trunk chain which has a number average molecular weight of from 500 to 1,000,000 and is represented by the formula (Ma):- (M1) - (M2a) - (N) - in which the structural unit M1 is a structural unit derived from an ethylenic monomer having 2 or 3 carbon atoms and at least one fluorine atom, the structural unit M2a is at least one structural unit which introduces an aliphatic monocyclic structure in the polymer trunk chain and is represented by the formula (a): wherein R1 is at least one hydrocarbon group selected from the group consisting of a divalent hydrocarbon group having 1 to 8 carbon atoms and constituting a ring which may be further substituted with a hydrocarbon group or a fluorine-containing alkyl group and a divalent hydrocarbon group having ether bond which has the sum of carbon atoms and oxygen atoms of 2 to 8, constitutes a ring and may be further substituted with a hydrocarbon group or a fluorine-containing alkyl group; R2 is an alkylene group which has 1 to 3 carbon atoms and constitutes a ring; R3 and R4 are the same or different and each is a divalent alkylene group which has 1 or 2 carbon atoms and constitutes a ring; n1, n2 and n3 are the same or different and each is 0 or 1, the structural unit N is a structural unit derived from a monomer copolymerizable with the monomers to introduce the structural units M1 and M2a, and the structural units M1, M2a and N are contained in amounts of from 1 to 99 % by mole, from 1 to 99 % by mole and from 0 to 98 % by mole, respectively. The fluorine-containing polymer possesses excellent dry etching resistance and transparency in a vacuum ultraviolet region.
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- Simultaneous preparation of tetrafluoroethylene and hexafluoropropylene
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The present invention relates to a process for simultaneously preparing tetrafluoroethylene and hexafluoropropylene by the pyrolysis of difluorochloromethane mixed in the molar ratio of super-heated steam/pre-heated difluorochloromethane ([H2O]/[R22]) of 5-10 under the conditions such as a temperature of 730° C. to 760° C. and a residence time of 0.01 to 0.2 seconds, where the unreacted R22 and produced HFP are recycled and controlled to have an appropriate molar ratio of HFP/R22 of 0.01 to 0.1 in order to obtain a high yield of HFP. Thus, the pyrolysis process of the present invention is efficient for preparing TFE and HFP, which are essential monomers in fluorinated resin industry.
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- Fluorine chemistry - Wittig based synthesis of volatile organofluorine compounds
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A simple and practical method has been developed for the synthesis and characterization of several interesting classes of volatile organofluorine compounds from fluorophosphonium salts via their in situ generated corresponding ylides. The fluorinated phosphonium ylides react with hexafluoroacetone in DMF to generate perfluoroisobutylene, whereas in the presence of bromine or iodine containing electrophiles, tetrafluoroethylene, perfluoro-2-butene, perfluorocyclobutane, and 1H-heptafluoropropane are obtained.
- Bhadury, Pinaki S.,Singh, Sapna,Sharma, Mamta,Palit, Meehir,Jaiswal, Devendra K.
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p. 1186 - 1191
(2007/10/03)
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- PROCESS FOR PRODUCING FLUOROMONOMER
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Processes for producing a fluoromonomer from a fluoropolymer, among which one that can be carried out more simply is a process wherein thermal decomposition of a fluoropolymer is preformed by means of a rotary kiln (5) so as to produce a fluoromonomer, the process comprising feeding a fluoropolymer and steam (3) into a rotary kiln and heating the fluoropolymer.
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- Pyrolyses of chlorodifluoromethane and trifluoromethane in the presence of hydrogen. Mechanism and optimization of reaction conditions
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When CHC1F2 and CHF3 are subjected to high-temperature, gas-phase flow pyrolysis in the presence of H2, they are converted, via a free radical chain mechanism, to CH2F2, CHF2CHF2, and CF3CH2F in good yield. Optimal conditions for pyrolysis of CHC1F2 involve a high conversion (92%) at 650 °C with an observed yield of products = 18, 17, and 28%, respectively, whereas optimal conditions for CHF3 involve a low conversion (24%) at 775 °C, but a higher yield of products (26, 6, and 39%, respectively).
- Romelaer,Kruger,Baker,Dolbier Jr.
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p. 6767 - 6772
(2007/10/03)
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