1630-77-9Relevant academic research and scientific papers
Gas-phase reaction of CCl2F2 (CFC-12) with methane.
Uddin, Md Azhar,Kennedy, Eric M,Dlugogorski, Bogdan Z
, p. 1189 - 1191 (2003)
Gas-phase reaction of CFC-12 (CCl2F2) with methane was carried out in a plug flow reactor over the temperature range of 873-1123 K. The major organic halocarbons formed during the reaction were C2F4, C2H2F2, CHClF2, CH3Cl, C3H2F6 and CCl3F. The formation of all products except C2H2F2 decreased with temperature, while the selectivity to C2H2F2 (difluoroethylene) increased with temperature and reached approximately 80% at 1123 K. Under these reaction conditions, methane acts as hydrogen and carbon source, resulting in the formation of an unsaturated C2 hydrofluorocarbon from two C1 precursors.
Selective Copper Complex-Catalyzed Hydrodefluorination of Fluoroalkenes and Allyl Fluorides: A Tale of Two Mechanisms
Andrella, Nicholas O.,Xu, Nancy,Gabidullin, Bulat M.,Ehm, Christian,Baker, R. Tom
, p. 11506 - 11521 (2019)
The transition to more economically friendly small-chain fluorinated groups is leading to a resurgence in the synthesis and reactivity of fluoroalkenes. One versatile method to obtain a variety of commercially relevant hydrofluoroalkenes involves the catalytic hydrodefluorination (HDF) of fluoroalkenes using silanes. In this work it is shown that copper hydride complexes of tertiary phosphorus ligands (L) can be tuned to achieve selective multiple HDF of fluoroalkenes. In one example, HDF of the hexafluoropropene dimer affords a single isomer of heptafluoro-2-methylpentene in which five fluorines have been selectively replaced with hydrogens. DFT computational studies suggest a distinct HDF mechanisms for L2CuH (bidentate or bulky monodentate phosphines) and L3CuH (small cone angle monodentate phosphines) catalysts, allowing for stereocontrol of the HDF of trifluoroethylene.
High-resolution FTIR study of the v2 fundamental of cis-CHF=CHF
Visinoni,Giorgianni,Baldan,Nivellini
, p. 4242 - 4246 (2001)
The high-resolution FTIR spectrum at room temperature of cis-1,2-difluoroethylene has been analyzed in the v2 fundamental region from 1670 to 1760 cm-1. This vibration of A1 symmetry, corresponding to the C=C stretching, gives rise to a strong b-type band approximately centered at 1719 cm-1. The rovibrational analysis led to the assignment of many transitions in the P, Q and R branches with J′ ≤ 70, Ka′ ≤ 30, Kc′ ≤ 69. From a simultaneous fit of the ground state combination differences coming from the present work and the previously analyzed v4 and v10 fundamentals, together with a few literature microwave data, a set of ground state parameters, including all the quartic and four new sextic centrifugal distortion coefficients, was derived. Using the Watson's A-reduction Hamiltonian in the Ir representation, from the final fit of about 3600 assigned transitions, accurate rovibrational constants for the upper state were obtained with a standard deviation of about 8 × 10-4 cm-1.
Vacuum Ultraviolet Photochemistry of Fluoroethene and 1,1-Difluoroethene
Sirkin, Eric R.,Pimentel, George C.
, p. 1833 - 1840 (1984)
Products from the broad-band vacuum ultraviolet photolysis of CH2CHF and CH2CF2 were collected by using a novel gas collection technique and analyzed by using gas chromatography.The primary route of decay for both parents is through α-β elimination of HF.Primary branching ratios for HF elimination, F atom ejection, and HH elimination from CH2CHF were determined: 0.82, 0.13, and 0.05, respectively.The technique does not permit detection of single H atom ejection.The ratio of (C2F2H3) stabilization by He vs. decomposition, formed by the addition of F to CH2CHF, is 0.029 +/- 0.004 torr-1.The lifetime of the excited complex is approximately a factor of 5 longer relative to other related systems.A less detailed study of excited-CH2CF2 decay indicates similar trends.
FLUOROOLEFIN PRODUCTION METHOD
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Paragraph 0047-0049, (2021/03/13)
The present disclosure provides a method for producing fluoroolefin represented by formula (1): CX1X2═CX3X4, wherein X1, X2, X3, and X4 are the same or different, and represent a hydrogen atom or a fluorine atom, with high selectivity. Specifically, the present disclosure is a method for producing fluoroolefin represented by formula (1), wherein the method includes the step of performing dehydrofluorination by bringing a fluorocarbon represented by formula (2): CX1X2FCX3X4H, wherein X1, X2, X3, and X4 are as defined above, into contact with a base, and the dehydrofluorination step is performed in the liquid phase at a temperature of ?70° C. or higher to less than 120° C.
Rare Earth Metal Catalyzed C–F Bond Activation
Jaeger, Alma D.,Lentz, Dieter
supporting information, p. 1229 - 1233 (2018/11/24)
Cp3Ln (Ln = Ce, Nd, Sm, Er, Yb) are applied as precatalysts in the presence of LiAlH4 for the C–F bond activation of hexafluoropropene, 1,1,3,3,3-pentafluoropropene, trifluoropropene, chlorotrifluoroethene, and octafluorotoluene. 100 % conversion and TONs up to 155 could be observed for the hydrodefluorination reaction (HDF). For chlorotrifluoroethene hydrodefluorination occurs with high chemoselectivity favoring the C–F bond activation versus C–Cl bond activation.
Organocatalytic C?F Bond Activation with Alanes
Jaeger, Alma D.,Ehm, Christian,Lentz, Dieter
supporting information, p. 6769 - 6777 (2018/04/02)
Hydrodefluorination reactions (HDF) of per- and polyfluorinated olefins and arenes by cheap aluminum alkyl hydrides in non-coordinating solvents can be catalyzed by O and N donors. TONs with respect to the organocatalysts of up to 87 have been observed. Depending on substrate and concentration, high selectivities can be achieved. For the prototypical hexafluoropropene, however, low selectivities are observed (E/Z≈2). DFT studies show that the preferred HDF mechanism for this substrate in the presence of donor solvents proceeds from the dimer Me4Al2(μ-H)2?THF by nucleophilic vinylic substitution (SNV)-like transition states with low selectivity and without formation of an intermediate, not via hydrometallation or σ-bond metathesis. In the absence of donor solvents, hydrometallation is preferred but this is associated with inaccessibly high activation barriers at low temperatures. Donor solvents activate the aluminum hydride bond, lower the barrier for HDF significantly, and switch the product preference from Z to E. The exact nature of the donor has only a minimal influence on the selectivity at low concentrations, as the donor is located far away from the active center in the transition states. The mechanism changes at higher donor concentrations and proceeds from Me2AlH?THF via SNV and formation of a stable intermediate, from which elimination is unselective, which results in a loss of selectivity.
The preparation of HCF2CdX and HCF2ZnX via direct insertion into the carbon halogen bond of CF2HY (Y = Br, I)
Burton, Donald J.,Hartgraves, Greg A.
, p. 1198 - 1215 (2008/02/08)
The difluoromethylcadmium and zinc reagents have been prepared in DMF via direct insertion of Cd0 into the carbon halogen bond of CF2HY (Y = Br, I). These reagents are stable at 65-75 °C and exhibit prolonged stability and activity at room temperature. Metathesis of the difluoromethylcadmium reagents with Cu(I)X (X = Br, Cl) at -55 °C rapidly produces difluoromethylcopper. The copper reagent is significantly less stable than the cadmium or zinc reagent and rapidly decomposes at room temperature. The difluoromethylcadmium and copper reagents exhibit good reactivity with allylic halides, propargylic derivatives and 1-iodoalkynes to provide good yields of the corresponding difluoromethylalkenes, difluoromethylallenes and difluoromethyl-2-alkynes. Alkylation is successful only with reactive alkyl halides. Generally, the difluoromethylcopper reagent is more reactive than the difluoromethylcadmium reagent and generally exhibits higher regioselectivity in reactions that can occur by either α- or γ-attack.
Stereoselective preparation of (Z)-α,β-difluorostyrenes
Davis, Charles R.,Burton, Donald J.
, p. 7237 - 7240 (2007/10/03)
Substituted aromatic iodides couple with (E)-HFC = CFZnI, under mild conditions, in the presence of catalytic Pd(PPh3)4 in DMF to give the title compounds in good yield.
Pulse-Duration Effects on Competitive Reactions in Infrared Multiple-Photon Decomposition of CH2ClCHClF and CHClFCHClF
Ishikawa, Yo-ichi,Sugita, Kyoko,Arai, Shigeyoshi
, p. 5067 - 5071 (2007/10/02)
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.
