F:Flammable;
75-10-5Relevant articles and documents
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.
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.
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.
