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  • 1985-1989  (118)
  • 1940-1944
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  • 1985  (118)
  • Physical Chemistry  (118)
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 601-612 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between nitric acid and thiocyanate has been studied both in batch and flow configurations. The batch reaction is autocatalytic with an induction period which is decreased by the addition of HNO2. At the nitric acid concentrations employed (1-10 M), a red NOSCNH+ intermediate is formed. The reaction in a flow reactor exhibits bistability. A model involving competitive reactions of SCN- and NOSCNH+ with NO2 is suggested, and computer simulations with this model give good agreement with both the batch and flow experiments.
    Additional Material: 3 Ill.
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  • 102
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 637-653 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of benzene has been investigated with a high-temperature alumina flow reactor in the temperature range of 950-1150 K at residence times of ca. 1 ms and pressures of ca. 400 mbar. Analysis of the reaction products at various stages of the reaction was carried out by direct expansion of the reacting gas yielding a molecular beam that was analyzed by a mass spectrometer. Product identification studies were made by comparing the results from the oxidations of C6H6 and C6D6. Besides the products found in previous studies a number of new oxygenated intermediate species were identified, namely benzoquinone, cyclopentadienone, acrolein, and a C4H4O species. In addition, some higher hydrocarbons have been found even at high oxygen excess. The role of the intermediates within the current ideas of the reaction mechanism is discussed.
    Additional Material: 4 Ill.
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  • 103
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 104
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 725-734 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Products of the reaction of OH radicals with 1-butene have been investigated in the presence of NO in one atmosphere of air at room temperature using gas chromatography and in situ long pathlength Fourier transform infrared absorption spectroscopy. The major product observed was propionaldehyde, with a formation yield (after allowing for its subsequent loss processes) of 0.94 ± 0.12. Minor yields of organic nitrates (RONO2) and of peroxypropionyl nitrate, a secondary product arising from propionaldehyde, were also observed. However, none of the products expected from the reactions subsequent to H-atom abstraction from 1-butene by OH radicals were observed, allowing an upper limit of 10% for this process to be derived. These data are compared with the available literature results and the implications are discussed.
    Additional Material: 2 Ill.
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  • 105
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 749-761 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the gas phase pyrolysis of dimethyl sulfide (DMS) was studied in a static system at 681-723 K by monitoring total pressure-time behavior. Analysis showed the pressure increase to follow DMS loss. The reaction follows two concurrent paths: with a slow, minor, secondary reaction: In a seasoned reactor the reaction follows a 3/2 order rate law with rate coefficient given by \documentclass{article}\pagestyle{empty}\begin{document}$$ \log [k({\rm L}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} /{\rm mol}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} {\rm s})] = 13.84 \pm 0.21 - (51.4 \pm 0.7)/\theta $$\end{document} with θ = 2.303 RT in kcal/mol. A free radical mechanism is proposed to account for the data and a theoretical rate coefficient is derived from independent data: \documentclass{article}\pagestyle{empty}\begin{document}$$\log [k({\rm L}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} /{\rm mol}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} {\rm s})] = 12.8 \pm 0.3 - (47 \pm 1.5)/\theta $$\end{document} which agrees well with the experimental one over the range studied. The reaction is initiated by Me2S → Me + MeS⋅ and propagated by metathetical radical attack on Me2S. C2H4 is formed by an isomerization reaction which may in part be due to a hot radical: Thermochemical data are listed, many from estimations, for both molecular and radical species of interest in the present system.
    Additional Material: 4 Tab.
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  • 106
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 107
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 108
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 257-264 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic study of the very low-pressure pyrolysis of ethylbenzene (I), 2-phenylethylamine (II), and N,N-dimethyl 2-phenylethylamine (III) above 900 K yields the heats of formation of aminomethyl (A) and N,N-dimethylaminomethyl (B) radicals: ΔHƒ, 300 K(A) = 30.3 and ΔHƒ, 300 K(B) = 27.5 kcal/mol. The difference of stabilization energies Es, (relative to methyl radicals): Δ = Es(B) - Es(A) = (2 ± 1) kcal/mol, conforms to similar effects in methyl substituted alkyl and amino free radicals.
    Additional Material: 1 Ill.
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  • 109
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 293-301 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The total rate constant for the reaction of Cl atoms with HO2NO2 was found to be less than 1.0 × 10-13 cm3 s-1 at 296 K by the discharge flow/resonance fluorescence technique. The reaction was also studied by the discharge flow/mass spectrometric technique. k1a + k1b was measured to be (3.4 ± 1.4) × 10-14 cm3 s-1 at 296 K. The reaction is too slow to be of any importance in stratospheric chemistry.
    Additional Material: 2 Ill.
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  • 110
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 315-326 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A flash photolysis-shock tube technique is described for making kinetic measurements at high temperature. Coupled with sensitive atomic resonance absorption detection, this method allows bimolecular rate constants for atom-molecule reactions to be measured directly under conditions free from kinetic complications. Experiments were performed in the reflected shock regime, and the temperature and density were calculated using ideal shock wave theory in this initial work. Results for the reaction of atomic hydrogen with ammonia are presented to illustrate the potential of the technique. The values of the Arrhenius rate parameters found in these experiments, 900 K ≤ T ≤ 1850 K, were A = (1.14 ± 0.12) × 10-10 cm3 molecule-1 s-1 and Ea = 13,216 ± 242 cal mol-1. This result gives rate constants that are about five times larger than those from previous studies. Although corrections for nonidealities in the reflected shock region are anticipated and under investigation, the expected changes will be relatively small and thus the large discrepancy noted here will remain.
    Additional Material: 5 Ill.
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  • 111
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash photolysis of dimethyl oxalate produced the radicals CH3, CH3O, and COOCH3. Thermally equilibrated methoxycarbonyl radicals did not decompose during radicalradical reactions in the presence of 40-torr cyclohexane in the temperature range 298-448 K. Cyclohexyl radicals were also generated during the flash photolysis of the reaction mixture. Rate coefficients of radical-radical reactions were calculated from the amounts of stable products determined by gas chromatography: CO, CO2, CH4, C2H4, C2H6, CH2O, CH3OH, CH3OCH3, HCOOCH3, CH3COOCH3, CH3OCOOCH3, CH3C6H11, and CH3OC6H11. Calculations were performed using an iterative computer integration program. Absolute values of rate coefficients were based on the rate coefficient of the reaction between methyl radicals, k1 = 2.7 × 1010 dm3 mol-1 s-1, measured with the same equipment. The rate coefficients for reactions (5)-(8) are: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} k_5 = (3.1 + 0.5) \times 10^{10} \,{\rm dm}^{\rm 3} \,{\rm mol}^{{\rm - 1}} \,{\rm s}^{{\rm - 1}} \\ k_6 = (2.1 + 0.2) \times 10^{10} \,{\rm dm}^{\rm 3} \,{\rm mol}^{{\rm - 1}} \,{\rm s}^{{\rm - 1}} \\ k_7 = (2.3 + 0.1) \times 10^{10} \,{\rm dm}^{\rm 3} \,{\rm mol}^{{\rm - 1}} \,{\rm s}^{{\rm - 1}} \\ \end{array} $$\end{document}
    Additional Material: 1 Ill.
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  • 112
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 113
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 525-534 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on an FTIR-product study of the photolysis of mixtures containing Br2—CH3CHO and Br2—CH3CHO—HCHO in 700 torr of N2, the rate constant for the reaction Br + CH3CHO → HBr + CH3CO was determined to be 3.7 × 10-12 cm3 molecule-1 s-1. In addition, the selective photochemical generation of Br at λ 〉 400 nm in mixtures containing Br2—CH3CHO—14NO2 (or 15NO2)—O2 was shown to serve as a quantitative preparation method for the corresponding nitrogen-isotope labeled CH3C(O)OONO2 (PAN). From the dark-decay rates of 15N-labeled PAN in large excess 14NO2, the rate constant for the unimolecular reaction CH3C(O)OO15NO2 → CH3C(O)OO + 15NO2 was measured to be 3.3 (±0.2) × 10-4 s-1 at 297 ± 0.5 K.
    Additional Material: 4 Ill.
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  • 114
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 535-546 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The alkyl nitrites, C2H5ONO, n-C3H7ONO, n-C4H9ONO, and i-C4H9ONO were photolyzed at 23°C in the presence of 15NO at 366-nm incident radiation. The quantum yields of the corresponding isotopically-enriched alkyl nitrites were measured by mass spectrometry. The results indicated that only part of the absorption leads to photodecomposition. The remainder forms an electronically excited state which isotopically exchanges with 15NO. The indicated reactions of the electronically excited state RONO*, are where k3/k2 = 0.50 ± 0.10, 0.62 ± 0.20, 0.42 ± 0.06, and 0.24 ± 0.03 torr, and that k2a/k2 = 1.0, 1.0, 0.64 ± 0.04, and 0.56 ± 0.03, respectively, for C2H5ONO, n-C3H7ONO, n-C4H9ONO, and i-C4H9ONO.
    Additional Material: 4 Ill.
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  • 115
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 573-582 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Recently, Atkinson et al. have developed a more sophisticated approach than simple additivity to determine group rate constants at room temperature for reactions of OH radicals with alkanes. In this article, use is made of reliable experimental data at room temperature and at 753 K to determine temperature coefficients for these reactions. Evidence based on experiment is cited in support of the expression k = AT1e-E/RT as a suitable quantitative expression for the variation of k with temperature between 300 and 1000 K for OH attack at any particular specific group in an alkane. Values are given for A and E for a number of groups found in both linear and branched alkanes. With highly branched alkanes, steric effects may limit the use of even the more sophisticated additivity approach used here. Use of the group values permits the calculation of both the overall rate constant for OH + alkane, the agreement with the limited amount of experimental data available being very good, and the proportions of each species of alkyl radical formed in the overall attack. Such information is vital to quantitative modeling of combustion processes currently being carried out extensively. The values given in the article are recommended for use over the temperature range 300-1000 K.
    Additional Material: 2 Ill.
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  • 116
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 583-590 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effective energy distribution of activated molecules at the time of reaction under soft collision conditions ƒ′(E, ω) is pressure dependent and therefore difficult to recover from unimolecular decomposition data obtained at different pressures. We show in this work that the part of this function restricted to the condition that the collision frequency ω has to be equal to the microscopic rate constant k(E) at the energy given ƒ″[E,ω = k(E)] is a reasonable approximation to the input energy distribution ƒ(E) for quite soft collisions. This function is not pressure dependent and then recoverable at least in principle and as a matter of fact is not conceptually far from the function that the already reported deconvolution methods based in physical approximations attempt to recover. The deconvolution methods have been checked under soft collision conditions. We have found that the input energy distribution is recovered with reasonable accuracy for energies transferred by collision 〈ΔE〉 above 5 kcal mol-1, conditions common in polyatomic systems.
    Additional Material: 4 Ill.
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  • 117
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the oxidation of naphthalene and phenanthrene by pyridinium fluorochromate, C5H5NHCrO3F, PFC, has been studied. The main product of the oxidation is the corresponding quinone. While each oxidation, studied in aqueous acetic acid (80-95%, v/v) medium, is first order with respect to the oxidant, the rate is almost independent of the substrate concentration. The reactions are catalyzed by acid, the acid-catalyzed reactions being very fast, which precluded determination of their order in acid medium. The kinetic isotope effect, kH/kD is 5.50 at 303 K for naphthalene. The reaction does not induce polymerization of acrylonitrile. The effects of temperature and solvent compositions were studied and activation parameters evaluated. Probable mechanisms are discussed.
    Additional Material: 5 Tab.
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  • 118
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 17 (1985), S. 1321-1331 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of liquid phase chlorination of methane in a difluorodichloromethane medium has been studied in a temperature interval of 293-150 K. The value of activation energy found for the hydrogen abstraction stage by a chlorine atom (E1) equals 14.2 ± 2.5 kJ/mol, with the processes of chlorine atoms recombination and the cage effect being taken into account. The method of competitive reactions has been employed to assess the constants of reaction of chlorine atoms (k1) with ethane, propane, hexane, ethylene, allyl bromide, allyl chloride, ethyl chloride, and cyclohexane in nonpolar solvents, viz. difluorodichloromethane and 1,2-dibromotetrafluoroethane. The values (k1) obtained in the liquid phaseare two to four orders lower than those in the gas phase, while the activation energy is 2-6 kJ/mol higher.
    Additional Material: 2 Ill.
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