12381-92-9Relevant articles and documents
Laptash, N. M.,Polyshchuk, S. A.
, p. 877 - 884 (1995)
Maneshkarimi, M.,Heydtmann, H.
, p. 182 - 186 (1995)
Absolute rate coefficients for F+H2 and F+D2 at T=295-765K
Heidner, R. F.,Bott, J. F.,Gardner, C. E.,Melzer, J. E.
, p. 4815 - 4821 (1980)
The rate coefficients of the F+H2 and F+D2 reactions must be accurately known over a wide temperature range if the HF and DF chemical lasers are to be properly modeled.Although the pulsed and cw chemical lasers operate at elevated temperatures (500 to 2000 K), no absolute rate data exist for T>400 K.Extension of the infrared multiphoton dissociation-infrared fluorescence technique permitted the following Arrhenius equations to be determined between 295 and 765 K: kF+H2=(1.3+/-0.25)*1014 exp; kF+D2=(6.4+/-2.2)*1013 exp; kF+H2/kF+D2=(2.1+/-0.8) exp.
Thermal decomposition of 2,2-bis(difluoroamino) propane studied by FTIR spectrometry and quantum chemical calculations: The primary dissociation kinetics and the mechanism for decomposition of the (CH3)2CNF2 radical
Park,Chakraborty,Jamindar,Xia,Lin,Bedford
, p. 101 - 111 (2002)
The kinetics of the thermal decomposition of 2,2-bis(difluoroamino) propane (BDFP) has been studied by pyrolysis/FTIR spectrometry at temperatures between 528 and 553 K using toluene as radical scavenger. The disappearance of BDFP was found to follow the first-order kinetics with the rate constant, k1 = 1016.0±0.7 exp[-(24200 ± 840)/T] s-1, which agrees closely with the expression obtained by Fokin et al. [Dokl. Akad. Nauk. 332 (1993) 735], k1 = 1015.60 exp(-23600/T) s-1. The measured large A-factor supports the earlier conclusion that the primary fragmentation process corresponds to the breaking of one of the two NF2 groups. The measured activation energy is also consistent with the predicted first C-N bond dissociation energy, 44-48 kcal/mol, by the hybrid density-functional theory and that evaluated by variational RRKM calculations fitting the observed rate constant, 47.9 kcal/mol. The 2-difluoroamino propyl radical, (CH3)2CNF2, was predicted to be thermally unstable, producing readily F atoms and HF molecules via the (CH3)2CFNF intermediate. The quantum-chemically predicted mechanisms for the fragmentation of (CH3)2C(NF2)2 and (CH3)2CNF2 agree with the product distribution reported by Ross and coworkers.
Brauner
, p. 68 - 68 (1882)
Runner, M. E.,Balog, G.,Kilpatrick, M.
, p. 5183 - 5186 (1956)
The rate of the F + H2 reaction at very low temperatures
Tizniti, Meryem,Le Picard, Sebastien D.,Lique, Francois,Berteloite, Coralie,Canosa, Andre,Alexander, Millard H.,Sims, Ian R.
, p. 141 - 145 (2014)
The prototypical F + H2 → HF + H reaction possesses a substantial energetic barrier (～800 K) and might therefore be expected to slow to a negligible rate at low temperatures. It is, however, the only source of interstellar HF, which has been detected in a wide range of cold (10-100 K) environments. In fact, the reaction does take place efficiently at low temperatures due to quantum-mechanical tunnelling. Rate constant measurements at such temperatures have essentially been limited to fast barrierless reactions, such as those between two radicals. Using uniform supersonic hydrogen flows we can now report direct experimental measurements of the rate of this reaction down to a temperature of 11 K, in remarkable agreement with state-of-the-art quantum reactive scattering calculations. The results will allow a stronger link to be made between observations of interstellar HF and the abundance of the most common interstellar molecule, H 2, and hence a more accurate estimation of the total mass of astronomical objects.
Brauner, B.
, p. 393 - 402 (1894)
Primary Energy Distribution in the Products of the Reaction F + HBr -> HF(ν') + Br
Aker, P. M.,Donaldson, D. J.,Sloan, J. J.
, p. 3110 - 3116 (1986)
It is shown that the title reaction creates HF with approximately the maximum vibrational and rotational excitation permitted by the exoergicity.Thus it appears to exhibit the same dynamics as the other members of the X + HY reaction family (X,Y halogen atoms).This result was obtained from a low-pressure infrared chemiluminescence experiment in which special procedures were introduced to show the absence of all gas-phase and surface energy transfer processes which might distort the measured distribution.
The nature of aqueous divalent xenon
Appelman, Evan H.
, p. 1268 - 1269 (1967)
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Infrared Chemiluminescence and Laser-Induced Fluorescence Studies of Energy Disposal by Reactions of F and Cl Atoms with H2S (D2S), H2Se, H2O (D2O), and CH3OH
Agrawalla, B. S.,Setser, D. W.
, p. 2450 - 2462 (1986)
The vibrational energy disposal to HF (DF), HCl (DCl), SH (SD), and CH3O and relative product formation rate constants were measured for the title reactions.The experiments were done in a fast-flow reactor with infrared emission and laser-induced fluorescence to observe nascent product state distributions for the diatomic hydride products.The CH3O vibrational and HF (DF) rotational distributions are partially relaxed, but the nascent distributions for these cases were estimated.Laser-induced fluorescence measurements showed that the SH, SD, and CH3O fragments received only 0.02-0.03 of the available energy.The v(HX)> values for group VI (group 16) hydrides, 0.45 (F + H2S), 0.44 (F + D2S), 0.48 (F + H2Se), 0.42 (F + D2O), 0.41 (Cl + H2Se), and 0.37 (Cl + D2S), are similar but distinctly smaller than for F and Cl atom reactions with group IV and VII (group 14 and 17) hydrides.The R(HX)> values, 0.18 (F + H2S), 0.19 (F + H2Se), and ca.0.14 (F + D2S), are typical for H-abstraction reactions with similar cross sections.The F + H2O/D2O systems were used to characterize the extent of secondary reactions in the fast-flow reactor.For high reagent concentrations and longer reaction times, S2 was observed in the F/Cl + H2S systems by LIF.
Stanko, V. I.,Kashin, A. N.,Beletskaya, I. P.
, p. 111 - 123 (1973)
Odenthal, R.-H.,Hoppe, R.
, p. 305 - 305 (1970)
Energy partitioning in atom-radical reactions: The reaction of F atoms with NH2
Donaldson, D. J.,Sloan, J. J.,Goddard, J. D.
, p. 4524 - 4536 (1985)
An extension of the low-pressure infrared chemiluminescence technique has allowed the measurement of energy partitioning in the atom/radical reactions: F + NH2->HF + NH, F + ND2->DF + ND.A complete numerical model of the experiment is described in detail including its parametrization.This model allows the unambiguous determination of the primary energy distribution of the above reactions.These reactions give inverted product energy distributions, in contrast to the isoelectronic F + OH->HF + O reaction.The inverted primary energy distribution for F + NH2/ND2 indicates a direct abstraction mechanism.Ab initio quantum chemical computations on some features of the relevant potential energy surfaces support this direct abstraction route.An energetically accessible transition state, having approximately zero barrier, is found on the triplet surface which directly correlates reagents and products.The geometry of this triplet transition state is also suggestive of strong HF vibrational excitation.Abstraction on the triplet surface provides an alternative pathway to reaction on the lowest singlet surface, which contains a deep potential energy well corresponding to NH2F.
Direct vs complex reaction dynamics for F+OH->HF+O
Sloan, J. J.,Watson, D. G.,Williamson, J. M.,Wright, James S.
, p. 1190 - 1200 (1981)
The exerogicity of the reaction F+H2O->HF+OH is sufficient to give HF(ν'1); howerver, arrested relaxation infrared chemiluminescence experiments on this system show emission from HF(ν'3).The higher vibrational levels are populated by the secondary reaction F(2P)+OH(2II)->HF(1Σ+)+O(3P).By a combination of SCF-Cl calculations and a rotated Morse curve fitting procedure, it is shown that barrier heights on triplet surfaces which correlate reactants and products of the secondary reaction are too high to provide a reaction path.Instead, the reaction proceeds on a singlet surface to produce an HOF complex, followed by rearrangement and a nonadiabatic transition to the triplet surface.An exit-channel barrier results from the surface crossing.The chemiluminescence data are shown to be in accord with this reaction mechanism.
Multi-emitter chemiluminescence in the solid-phase interaction of xenon difluoride with uranyl hydrogen phosphate
Ostakhov, Sergey S.,Masyagutova, Gul'shat A.,Mamykin, Alexander V.,Khursan, Sergey L.
, p. 405 - 406 (2016)
Chemiluminescence (CL) was found in the solid-phase interaction of xenon difluoride with uranyl hydrogen phosphate; the CL emitters are *Xe, UO22+ and the singlet oxygen dimole (1O2)2.
Chemiluminescence Mapping: Rate Constants for Formation and Relaxation in the F + HBr System
Feezel, L. L.,Tardy, D. C.
, p. 3124 - 3129 (1989)
The spectrally and time resolved chemiluminescence mapping technique is extended to isobaric conditions in which the atomic reactant is formed by the rapid multiphoton dissociation of SF6 designated as chemiluminescence mapping-laser pulse (CM-LP).Nascent
Rate constants, branching fractions, and energy disposal for the H+ClO and H+SF reactions
Wategaonkar, S. J.,Setser, D. W.
, p. 6223 - 6233 (1989)
The H+ClO and SF reactions have been isolated and studied by infrared chemiluminescence in a fast flow reactor.The OH product channel is favored over the HCl channel by a factor of 4.5 and the total rate constant is (7.7+/-1.9)*10-11 cm3 s-1 for the H+ClO reaction.Both sets of products are accessed from a bound singlet intermediate with HCl+O(3P) formed by a singlet-triplet surface crossing in the exit channel; the energy disposal is v(OH)>=0.45 and v(HCl)>=0.31.The H+SF reaction gives only HF+S(3P), but the energy disposal differs dramatically from the HCl channel of the ClO reaction.This difference arises from changes in the thermochemistry, which result in an earlier crossing to the HSF triplet surface followed by release of repulsive energy as the HF separates from the S(3P) atom.
Laser Induced Fluorescence Studies of the Reactions of NH(a1Δ) with NO and HCN
Hack, W.,Rathmann, K.
, p. 4155 - 4161 (1990)
The reactions of electronically excited imidogen NH(a1Δ) with NO and HCN have been studied at room temperature and low total pressures (20 mbar): NH(a) + NO --> products (1): NH(a) + HCN --> products (2).NH(a), produced by laser photolysis of HN3 at λL = 308nm, was detected directly by laser-induced fluorescence (LIF).Measurements of the rate constants were performed under pseudo-first-order conditions, i.e., >> a)>, whereby the time resolution resulted from the delay between the photolysis and the probe lasers.The following rate constants were measured at T = 298 K: k1 = 1.7*1013 cm3/(mol s); k2 = 2.1*1013 cm3/(mol s).Direct detection of the primary products NH(X), OH(X), NH2(X), CH2(a1A1), and CN(X) was performed by LIF.The contribution of physical quenching of NH(a) to form NH(X) for reactants NO and HCN was found to be 40percent and 4percent respectively.In reaction 1 OH and in reaction 2 CN were detected as chemical products.
Bagnall, K. W.,Brown, D.,Easey, J. F.
, (1968)
Rohrback, G. H.,Cady, G. H.
, p. 2603 - 2605 (1948)
A structural, mechanistic, and kinetic study of the dehydrofluorination of 1,1,1,3,3-pentafluoropropane in the absence of catalyst
Jia, Xiaoqing,Lu, Fengniu,Qing, Feiyao,Quan, Hengdao,Ren, Yangyang
, (2021)
The catalyst-free dehydrofluorination of 1,1,1,3,3-pentafluoropropane (HFC-245fa) was investigated both experimentally and theoretically to elucidate the mechanism and kinetics of the reaction. The experimental results demonstrated easier generation of E-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) than HFO-1234ze(Z) under the same reaction conditions within a temperature range of 500–700 °C. When analyzing the geometry, energetics, and kinetic modeling of the reaction at the B3LYP/6?311++G (d,p) level of theory, it was found that the thermodynamic stability of HFO-1234ze(E) is relatively higher than its isomer (HFO-1234ze(Z). Besides, the rate constants of HFO-1234ze(E) were always larger than those of HFO-1234ze(Z) at 400–2000 K, which agreed well with the higher selectivity of HFO-1234ze(E) in the synthetic experiment results. Our theoretical demonstration provides a reference to investigate the mechanism and kinetics of other analogous reactions.
Hsu et al.
, p. 121 (1978)
Absolute Rate Constant and Product Branching Fractions for the Reaction between F and C2H4 at T = 202-298 K
Nesbitt, Fred L.,Thorn Jr., R. Peyton,Payne Jr., Walter A.,Tardy
, p. 4470 - 4479 (1999)
The discharge-flow kinetic technique coupled to mass-spectrometric detection has been used to determine the variable-temperature dependence of the rate constant and product branching fractions for the reaction between F(2P) and C2H4 at P = 1 Torr nominal pressure (He). The reaction was studied at T = 202 and 236 K by monitoring the decay of C2H4 in the presence of a large excess of F(2P). The overall rate coefficients were determined to be k1(202 K) = (1.7 ± 0.4) x 10-10 cm3 molecule-1 s-1 and k1(236 K) = (2.1 ± 0.5) x 10-10 cm3 molecule-1 s-1 with the quoted uncertainty representing total errors. Further, the branching fractions for the two observed reaction channels F + C2H4 → C2H3 + HF (1a) and F + C2H4 → C2H3F + H (1b) were determined by quantitatively measuring the yield of C2H3F under conditions of excess C2H4. The stabilized adduct, C2H4F, was not detected at T = 202 K. The derived branching fractions were Γ1a(202 K) = 0.25 ± 0.09, Γ1b (202 K) = 0.75 ± 0.16, and Γ1a(236 K) = 0.27 ± 0.13, and Γ1b (236 K) = 0.73 ± 0.20, where the quoted uncertainty represents total errors. By inclusion of k1(298 K) = (3.0 ± 0.8) x 10-10 cm3 molecule-1 s-1, a revised value that used data from our previous study and Γ1a(298 K) = 0.35 ± 0.04 and Γ1b (298 K) = 0.65 ± 0.04 from a laser photolysis/photoionization mass spectrometry study, we obtain the Arrhenius expressions k1a(T) = (7.5 ± 4.0) x 10-10 exp[(-1.2 ± 0.3)/(RT)] and k1b(T) = (5.2 ± 1.0) x 10-10 exp[(-0.6 ± 0.1)/(RT)] in units of cm3 molecule-1 s-1 for k and in units of kcal mol-1 for activation energy. The quoted uncertainty represents total errors at 1σ precision errors plus 15% systematic errors. RRKM calculations have shown that the critical energy for H addition to C2H3F is less than 6 kcal mol-1 larger than that for the addition of F to C2H4 and that the competitive decomposition of chemically activated C2H4F radicals favor C-H bond rupture by a factor greater than 1000 over that for C-F bond rupture.
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Olah,Kuhn
, p. 6541,6544 (1958)
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Biochemical Characterization, Phytotoxic Effect and Antimicrobial Activity against Some Phytopathogens of New Gemifloxacin Schiff Base Metal Complexes
Mohamed, Amira A.,Elshafie, Hazem S.,Sadeek, Sadeek A.,Camele, Ippolito
, (2021/07/26)
String of Fe(III), Cu(II), Zn(II) and Zr(IV) complexes were synthesized with tetradentateamino Schiff base ligand derived by condensation of ethylene diamine with gemifloxacin. The novel Schiff base (4E,4′E)-4,4′-(ethane-1,2-diyldiazanylylidene)bis{7-[(4Z
Stabilization of a mixed iron vanadium based hexagonal tungsten bronze hydroxyfluoride HTB-(Fe0.55V0.45)F2.67(OH)0.33as a positive electrode for lithium-ion batteries
Grenèche, Jean-Marc,Hémon-Ribaud, Annie,Leblanc, Marc,Lemoine, Kévin,Lhoste, Jér?me,Maisonneuve, Vincent,Moury, Romain,Tarascon, Jean-Marie
, p. 8186 - 8193 (2020/07/10)
In our search for novel insertion compounds for Li-based batteries, we have identified a new mixed iron vanadium based Hexagonal Tungsten Bronze (HTB) type phase. Its synthesis involves two steps which consist first of preparing mixed metal hydrated fluoride Fe1.64V1.36F8(H2O)2 by a microwave assisted thermal process, followed by thermal treatment under air to obtain metastable HTB-(Fe0.55V0.45)F2.67(OH)0.33 hydroxyfluoride. 57Fe M?ssbauer spectrometry demonstrates the presence of oxidation states Fe2+ and Fe3+ in Fe1.64V1.36F8(H2O)2 as opposed to only Fe3+ in HTB-(Fe0.55V0.47)F2.67(OH)0.33. Moreover, the M?ssbauer spectra recorded at 77 K reveal that none of the compounds shows magnetic ordering owing to the presence of V3+ distributed over the crystallographic sites of Fe3+. Complementary X-ray spectroscopy and Rietveld refinement further confirm the successful synthesis of HTB-(Fe0.55V0.45)F2.67(OH)0.33. Electrochemically, the new HTB-(Fe0.55V0.45)F2.67(OH)0.33 shows a first discharge capacity of 181 mA h g-1 with 67percent of this capacity remaining upon cycling. Unlike HTB-FeF2.66(OH)0.34, the structure remains stable after the first discharge confirming the positive effect of vanadium in the HTB network. This journal is
