3744-26-1Relevant academic research and scientific papers
FTIR and computational studies of gas-phase hydrogen atom abstraction kinetics by t-butoxy radical
Li, Shuping,Fan, Wai Yip
, p. 276 - 280 (2007/10/03)
By using Fourier-Transform Infrared (FTIR) absorption spectroscopy, rate coefficients in the range of 10-16 to 10-14 cm3 molecule-1 s-1 have been determined for the hydrogen atom abstraction reactions of several substrates including halogenated organic compounds and amines by t-butoxy radical generated from the uv photolysis of t-butyl nitrite in the gas phase. Arrhenius parameters for selected reactions have been measured in the temperature range 299-318 K. Transition states and activation barriers for such reactions have been computed with the help of Gaussian 03 software and found to match very well with the experimental values.
Homolytic dissociation of 1-substituted cyclohexa-2,5-diene-1-carboxylic acids: An EPR spectroscopic study of chain propagation
Jackson, Leon V.,Walton, John C.
, p. 1758 - 1764 (2007/10/03)
Hydrogen abstraction from 1-substituted cyclohexa-2,5-diene-1-carboxylic acids containing linear, branched and cyclic alkyl substituents, as well as allyl, propargyl (prop-2-ynyl), cyanomethyl and benzyl substituents, has been studied by EPR spectroscopy. For each carboxylic acid, EPR spectra of the corresponding cyclohexadienyl radicals were observed at lower temperatures, followed by spectra due to ejected carbon-centred radicals at higher temperatures. Rate constants, for release of the carbon-centred radicals from the cyclohexadienyl radicals, were determined from radical concentration measurements for the above range of substituents. The rate of cyclohexadienyl radical dissociation increased with branching in the 1-alkyl substituent and with electron delocalisation in the ejected carbon-centred radical; 3,5-and 2,6-dimethyl-substitution of the cyclohexadienyl ring led to reductions in the dissociation rate constants. Rate data for abstraction of bisallylic hydrogens from the cyclohexadienyl acids were also obtained for ethyl, n-propyl and isopropyl radicals. These results indicated a sharp drop in the rate of hydrogen abstraction as the degree of branching in the attacking radical increased. Small decreases in the hydrogen abstraction rate constants were observed for cyclohexadienes containing CO2R substituents.
Rate Constants for Halogen Atom Transfer from Representative α-Halocarbonyl Compounds to Primary Alkyl Radicals
Curran, Dennis P.,Bosch, Eric,Kaplan, Jere,Newcomb, Martin
, p. 1826 - 1831 (2007/10/02)
Rate constants for halogen atom transfer from diethyl methyliodomalonate (7a), iodoacetonitrile (7b), ethyl 2-methyl-2-iodopropanoate (7c), ethyl iodoacetate (7d), diethyl methylbromomalonate (7e), and ethyl bromoacetate (7f) to simple primary alkyl radicals have been studied by a variety of competition reactions.The Arrhenius functions for halogen atom transfer to the undecyl radical from halides 7d and 7f are log (kI, M-1 s-1) = 10.4 - 4.4/θ and log (kBr, M-1 s-1) = 10.4 - 8.2/θ, respectively.The rate constants for halogen atom transfer to a primaryradical from the series of compounds 7a-7f at 50 deg C are 1.8 x 109, 1.7 x 109, ca. 6 x 108, 2.6 x 107, 1.0 x 106, and 7.0 x 104 M-1 s-1, respectively.The kinetic values are useful for the planning of synthetic methods that incorporate an atom transfer-cyclization process.
Reaction of NO3 and N2O5 with Molecular Species of Possible Atmospheric Interest
Cantrell, C. A.,Davidson, J. A.,Shetter, R. E.,Anderson, B. A.,Calvert, J. G.
, p. 6017 - 6021 (2007/10/02)
The nitrate radical (NO3) has been shown to play an important role in nighttime tropospheric chemistry, particularly in polluted atmospheres.In order to understand more fully the role of NO3 in loss processes for various atmospheric species, a number of laboratory kinetic studies have been undertaken.Reported here are rate constant upper limits for the reaction of NO3 and N2O5 with HCl, ClNO, H2S, NH3, N2O, CH3CN, and CH4.Chemical reaction was observed in several of these systems (HCl, ClNO, H2S, and NH3), but possible heterogeneous (wall-catalyzed) reactions cannot be excluded.Possible mechanisms are presented for those cases where reaction occurred.In addition, studies of the reactions HCl + NO2, H2S + NO2, and Cl + HNO3 are also reported.The upper limits reported here rule out the reactions of NO3 or N2O5 in the gas phase as important removal processes for these species, but it is possible that the reaction of HCl with N2O5 catalyzed by aerosol surfaces may play an important role in linking the chemistry of the stratospheric odd nitrogen and odd chlorine cycles.
Spin Trapping of Radicals Formed during the Decomposition of Aromatic Diazonium Salts by Ultrasound
Rehorek, Detlef,Janzen, Edward G.
, p. 935 - 940 (2007/10/02)
The decomposition of aromatic diazonium compounds ArN2(+)X(-) (Ar = phenyl, 2,5-diethoxy-4-(N-morpholino)phenyl; X =BF4, PF6, B(C6H5)4, SCN, OCN, N3; 1a, 1c-f, 2b-f) by ultrasonic waves has been studied by e.s.r..The spin trapping technique has been shown to be a suitable method for the detection of free radical intermediates.
