116-14-3Relevant articles and documents
Booth et al.
, p. 529 (1967)
Infrared Laser Multiphoton Dissociation of CF2ClCH2Cl
Yano, T.,Ozaki, S.,Ogura, H.,Tschuikow-Roux, E.
, p. 1108 - 1116 (1985)
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.
CF3Br-H2 reaction in shock waves
Hidaka,Nakamura,Kawano
, p. 983 - 993 (1993)
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).
Zmbov et al.
, p. 5090 (1968)
Beveridge,Clark
, p. 601 (1968)
Multiphoton Excitation of trifluoroethene. Allene Production by Difluorovinylidine
Stachnik, Robert A.,Pimentel, George C.
, p. 2205 - 2210 (1984)
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.
Isothermal pyrolysis of iodomethanes in gases
Skorobogatov,Khripun,Rebrova
, p. 2641 - 2651 (2009)
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.
Highly selective photochemical synthesis of perfluoroalkyl bromides and iodides
Zhang,Zhang,Yang,Wang,Fuss,Weizbauer
, p. 153 - 168 (1998)
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.
Experimental and chemical kinetic study of the pyrolysis of trifluoroethane and the reaction of trifluoromethane with methane
Han, Wenfeng,Kennedy, Eric M.,Kundu, Sazal K.,MacKie, John C.,Adesina, Adesoji A.,Dlugogorski, Bogdan Z.
, p. 751 - 760 (2010)
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.
The reaction of C3F6 with dioxygen under IR laser initiation
Kuricheva,Dunyakhin,Timofeev,Zhitnev
, p. 45 - 49 (1999)
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.
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England,D.C.,Krespan,C.G.
, p. 816 - 819 (1968)
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Photochemistry of Anhydrides Part 5.-Photolysis of Perfluorosuccinic Anhydride
Stock, Colin J.,Whittle, Eric
, p. 503 - 511 (1980)
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.
Effects of NH3 on 13C-Selective Infrared Multiple Photon Decomposition of CF2HCl by a CO2 Laser
Sugita, Kyoko,Arai, Shigeyoshi
, p. 4217 - 4222 (1987)
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.
IR MATRIX ISOLATION SPECTRA OF SOME PERFLUORO ORGANIC FREE RADICALS PART III. n-C3F7 and iso-C3F7
Butler, R.,Snelson, A.
, p. 33 - 50 (1980)
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.
Lifshitz et al.
, p. 3050,3053 (1970)
Quantum yields and energy partitioning in the ultraviolet photodissociation of 1,2 dibromo-tetrafluoroethane (Halon-2402)
Zou, Peng,McGivern, W. Sean,Sorkhabi, Osman,Suits, Arthur G.,North, Simon W.
, p. 7149 - 7157 (2000)
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.
Conversion of CHF3 to CH2=CF2 via reaction with CH4 and CaBr2
Han, Wenfeng,Yu, Hai,Kennedy, Eric M.,Mackie, John C.,Dlugogorski, Bogdan Z.
, p. 5795 - 5799 (2008)
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.
COMPETITION AMONG COLLISIONAL DEACTIVATION, IONIZATION, AND DISSOCIATION IN THE MULTIPHOTON EXCITATION OF OCTAFLUOROCYCLOOCTATETRAENE
BelBruno, Joseph J.,Greenfield, Scott R.,Carl, Richard T.,Hughes, Russell P.
, p. 2480 - 2484 (1988)
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.
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Dalby
, p. 2297 (1964)
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Infrared Laser Induced Multiphoton Dissociation of Decafluorocyclopentane in a Concerted Pathway: Time-Resolved Evidence of :CF2 Formation
Chowdhury, P. K.,Rao, K. V. S. Rama,Mittal, J. P.
, p. 102 - 106 (1988)
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.
Perfluoroalkylation of ClGeEt3 with perfluoroalkyl bromides and iodides and P(NEt2)3
Bardin
, p. 1409 - 1413 (1993)
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.
Tetrafluoroethylene: A Convenient Laboratory Preparation
Hunadi, Ronald J.,Baum, Kurt
, p. 454 (1982)
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A carbon arc process for treatment of CF4 emissions
Chen, Daniel T.,David, Moses M.,Tiers, George V.D.,Schroepfer, Joseph N.
, p. 3237 - 3240 (1998)
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.
Mechanistic study of nucleophilic fluorination for the synthesis of fluorine-18 labeled fluoroform with high molar activity fromN-difluoromethyltriazolium triflate
Chai, Jin Young,Cha, Hyojin,Lee, Sung-Sik,Oh, Young-Ho,Lee, Sungyul,Chi, Dae Yoon
, p. 6099 - 6106 (2021)
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.
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Young,Murray
, p. 2814 (1948)
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Preparation method of hexafluoro-1, 3-butadiene
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Paragraph 0029-0030; 0032-0033; 0035-0036, (2021/04/14)
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.
Pentafluoroethylation of Arenediazonium Tetrafluoroborates Using On-Site Generated Tetrafluoroethylene
Xing, Bo,Li, Lingchun,Ni, Chuanfa,Hu, Jinbo
supporting information, p. 1131 - 1136 (2019/10/22)
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.
