F:Flammable;
75-10-5Relevant academic research and scientific papers
Infrared laser-induced post-pulse dissociation of CF2HCl and CF2Cl2 under high pressure and fluence conditions
Strube,Wollbrandt,Rossberg,Linke
, p. 9478 - 9485 (1996)
The unimolecular decomposition of the halogenated methanes CF2HCl (one main channel) and CF2Cl2 (two main channels) in the focused beam of a pulsed CO2 laser under high pressure and fluence conditions (p = 100 Pa-2 kPa; Φ=5-200 J/cm2) was studied by a special laser-induced fluorescence (LIF) technique, permitting spatially resolved fragment concentration measurements in the focal region. Considerable amounts of CF2 product were formed after the end of the laser pulse. In the one-channel-dissociation case of CF2HCl LIF measurements of the CF2 yield distribution Y(z,r) can be related to the spatial distribution of the average absorbed energy in the parent molecules. Only part of the absorbed energy is consumed by multiphoton dissociation, while most reactant molecules remain highly vibrationally excited in the focus volume far into the double cone. Using the long-lived CF2 also as a probe for measuring the rotational, translational, and vibrational temperatures, the redistribution of the internal energy in the molecules and fragments involved is monitored. The post-pulse production of CF2 is shown to be caused by the energy pooling v-v transfer mechanism, while contributions of pyrolytic and gas dynamic processes are of little importance.
Convenient Preparation and Structure Determination of Air- and Moisture-Tolerant Difluoromethylborates
Yokawa, Akitaka,Ito, Shigekazu
, p. 3432 - 3436 (2020)
Convenient and reliable synthetic methods for difluoromethylborates have been established. The intermediary generated difluoromethylsilicate species from TMSCF2H (TMS=trimethylsilyl) and potassium tert-butoxide were allowed to react with pinBPh (Me4C2O2BPh) in the presence of 18-crown-6 to give the corresponding borate compound [pinB(Ph)CF2H]?K+(18-crown-6) as an air- and moisture-tolerant solid. The unambiguously determined crystal structure of [pinB(Ph)CF2H]?K+(18-crown-6) revealed that the difluoromethylborate unit partially coordinated on the potassium ion. Reaction of [pinB(Ph)CF2H]–K+(18-crown-6) with potassium difluoride (KHF2) in acetic acid enabled substitution of the pinacol unit and phenyl group with fluorides, and gave (difluoromethyl)trifluoroborate [F3BCF2H]–K+(18-crown-6) in a good yield. The crystal structure of air- and moisture-tolerant [F3BCF2H]–K+(18-crown-6), which would be a promising reagent for synthesis of various difluoromethylboron species, showed a polyrotaxane-like polymeric structure based on the K???F interactions between the K+(18-crown-6), CF2H, and BF3 units.
Capture of the Sulfur Monoxide-Hydroxyl Radical Complex
Chen, Changyun,Lu, Bo,Zhao, Xiaofang,Qian, Weiyu,Liu, Jie,Trabelsi, Tarek,Francisco, Joseph S.,Qin, Jie,Li, Jun,Wang, Lina,Zeng, Xiaoqing
supporting information, p. 2175 - 2179 (2020/03/03)
The elusive hydrogen-bonded sulfur monoxide-hydroxyl radical complex (?OH···OS), a missing intermediate in the atmospheric chemistry of SO2, was generated in the 266 nm laser photolysis of the sulfinyl radical HOSO?in cryogenic Ar-matrixes. In addition to the IR spectroscopic characterization with deuteration, its thermal conversion to HOSO?with an activation barrier of 0.33 ± 0.11 kcal mol-1 (calcd 0.32 kcal mol-1, CCSD(T)-F12a/AVTZ) in the temperature range of 15.0-21.0 K and a H/D kinetic isotope effect of 2.4 at 16.0 K have been observed.
Metallaphotoredox Difluoromethylation of Aryl Bromides
Bacauanu, Vlad,Cardinal, Sébastien,Yamauchi, Motoshi,Kondo, Masaru,Fernández, David F.,Remy, Richard,MacMillan, David W. C.
, p. 12543 - 12548 (2018/09/18)
Herein, we report a convenient and broadly applicable strategy for the difluoromethylation of aryl bromides by metallaphotoredox catalysis. Bromodifluoromethane, a simple and commercially available alkyl halide, is harnessed as an effective source of difluoromethyl radical by silyl-radical-mediated halogen abstraction. The merger of this fluoroalkyl electrophile activation pathway with a dual nickel/photoredox catalytic platform enables the difluoromethylation of a diverse array of aryl and heteroaryl bromides under mild conditions. The utility of this procedure is showcased in the late-stage functionalization of several drug analogues.
Nickel-Catalyzed Difluoromethylation of Arylboronic Acids with Bromodifluoromethane
Fu, Xia-Ping,Xiao, Yu-Lan,Zhang, Xingang
supporting information, p. 143 - 146 (2018/01/05)
Although bromodifluoromethane (BrCF2H) is a simple and readily available fluorine source, direct formation of difluoromethylated arenes with BrCF2H has not been reported. Herein, we describe an efficient method to access difluoromethylated arenes through a nickel-catalyzed difluoromethylation of arylboronic acids with BrCF2H. The reaction exhibits high efficiency, good functional group tolerance and broad substrate scope, thus providing an efficient route for applications in drug discovery and development. Preliminary mechanistic studies reveal that a difluoromethyl radical is involved in the reaction.
Selective reduction of a C–Cl bond in halomethanes with Et3GeH at nanoscopic Lewis acidic Aluminium fluoride
Mei?ner, Gisa,Feist, Michael,Braun, Thomas,Kemnitz, Erhard
, p. 234 - 241 (2017/09/12)
The selective activation of C–Cl bonds of hydrochlorofluoromethanes and chloromethanes at moderate reaction conditions using ACF in a combination with Et3GeH is presented. The reactions of the chloromethanes (CH3Cl, CH2Cl2, CHCl3 and CCl4) in the presence of Et3GeH and ACF as catalyst led to the activation of only one C–Cl bond resulting in the hydrodechlorination. Friedel-Crafts reactions with benzene as solvent are suppressed by Et3GeH. A selective hydrodechlorination of hydrochlorofluoromethanes was achieved, because a transformation of a C–F bond into a C–H bond by the combination of ACF with Et3GeH did not occur. Supporting PulseTA experiments illustrated the interaction between the solid catalyst and Et3GeH, the solvent benzene or CH2Cl2.
A tetrafluoroethylene in the product from the separation method of difluoromethane
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Paragraph 0020-0037, (2017/09/02)
The invention relates to a method for separation of difluoromethane from a tetrafluoroethylene product. The method is characterized by including the steps of: 1) extraction: introducing a difluoromethane containing tetrafluoroethylene product into an extraction tower, conducting extraction with an extraction agent, then recovering tetrafluoroethylene, and letting tetrafluoroethylene enter a stripping tower along with the extraction agent; 2) stripping: heating the stripping tower bottom, stripping difluoromethane out of the extraction agent, and recovering difluoromethane into a low pressure storage tank; and 3) membrane separation: subjecting the difluoromethane gas in the low pressure storage tank to membrane separation so as to obtain high purity difluoromethane gas. The separation method provided by the invention can realize the effective separation of tetrafluoroethylene and difluoromethane, on the one hand can reduce material waste, and on the other hand can reduce environmental pollution, thus having good social benefits.
Bis(difluoromethyl)trimethylsilicate Anion: A Key Intermediate in Nucleophilic Difluoromethylation of Enolizable Ketones with Me3SiCF2H
Chen, Dingben,Ni, Chuanfa,Zhao, Yanchuan,Cai, Xian,Li, Xinjin,Xiao, Pan,Hu, Jinbo
supporting information, p. 12632 - 12636 (2016/10/31)
A pentacoordinate bis(difluoromethyl)silicate anion, [Me3Si(CF2H)2]?, is observed for the first time by the activation of Me3SiCF2H with a nucleophilic alkali-metal salt and 18-crown-6. Further study on its reactivity by tuning the countercation effect led to the discovery and development of an efficient, catalytic nucleophilic difluoromethylation of enolizable ketones with Me3SiCF2H by using a combination of CsF and 18-crown-6 as the initiation system. Mechanistic investigations demonstrate that [(18-crown-6)Cs]+[Me3Si(CF2H)2]?is a key intermediate in this catalytic reaction.
METHOD FOR PRODUCING DIFLUOROMETHANE
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Paragraph 0121-0125, (2015/08/04)
A method for producing difluoromethane, including the catalytic reaction of dichloromethane with hydrogen fluoride in the liquid phase, in the presence of chlorine, and in the presence of an ionic liquid catalyst consisting of the product of the reaction of antimony pentachloride with an organic salt having the general formula X+A, where A is a halide anion or hexafluoroantimonate, and X+ is a quaternary ammonium cation, quarternary phosphonium or ternary sulfonium. Further, equipment suitable for implementing said method.
Xenon(IV)-carbon bond of [C6F5XeF2]+; Structural characterization and bonding of [C6F5XeF2][BF4], [C6F5XeF2][BF4]·2HF, and [C6F5XeF2][BF4]· n NCCH 3 (n = 1, 2); And the fluorinating properties of [C6F5XeF2][BF4]
Koppe, Karsten,Haner, Jamie,Mercier, Hlne P. A.,Frohn, Hermann-J.,Schrobilgen, Gary J.
, p. 11640 - 11661 (2015/01/16)
The [C6F5XeF2]+ cation is the only example of a XeIV-C bond, which had only been previously characterized as its [BF4]- salt in solution by multi-NMR spectroscopy. The [BF4]- salt and its new CH3CN and HF solvates, [C6F5XeF2][BF4]·1.5CH3CN and [C6F5XeF2][BF4]·2HF, have now been synthesized and fully characterized in the solid state by lowerature, single-crystal X-ray diffraction and Raman spectroscopy. Crystalline [C6F5XeF2][BF4] and [C6F5XeF2][BF4]·1.5CH3CN were obtained from CH3CN/CH2Cl2 solvent mixtures, and [C6F5XeF2][BF4]·2HF was obtained from anhydrous HF (aHF), where [C6F5XeF2][BF4]·1.5CH3CN is comprised of an equimolar mixture of [C6F5XeF2][BF4]·CH3CN and [C6F5XeF2][BF4]·2CH3CN. The crystal structures show that the [C6F5XeF2]+ cation has two short contacts with the F atoms of [BF4]- or with the F or N atoms of the solvent molecules, HF and CH3CN. The lowerature solid-state Raman spectra of [C6F5XeF2][BF4] and C6F5IF2 were assigned with the aid of quantum-chemical calculations. The bonding in [C6F5XeF2]+, C6F5IF2, [C6F5XeF2][BF4], [C6F5XeF2][BF4]·CH3CN, [C6F5XeF2][BF4]·2CH3CN, and [C6F5XeF2][BF4]·2HF was assessed with the aid of natural bond orbital analyses and molecular orbital calculations. The 129Xe, 19F, and 11B NMR spectra of [C6F5XeF2][BF4] in aHF are reported and compared with the 19F NMR spectrum of C6F5IF2, and all previously unreported J(129Xe-19F) and J(19F-19F) couplings were determined. The long-term solution stabilities of [C6F5XeF2][BF4] were investigated by 19F NMR spectroscopy and the oxidative fluorinating properties of [C6F5XeF2][BF4] were demonstrated by studies of its reactivity with K[C6F5BF3], Pn(C6F5)3 (Pn = P, As, or Bi), and C6F5X (X = Br or I).
