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  • 1
    Electronic Resource
    Electronic Resource
    The oxidation of cerous ions by bromate ions comparison of experimental data with computer calculations (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 9 (1977), S. 841-862 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of cerous ions by bromate ions in sulfuric acid medium was followed spectrophotometrically under various experimental conditions. The results were compared to the calculated predictions on the basis of a mechanism suggested by R. M. Noyes and collaborators. The computations were done by solving the complete set of the kinetic differential equations. The results of the computations show that the proposed mechanism explains adequately most of our and previous experimental data. In particular, the mechanism predicts the main features of the reaction, namely, the induction and the fast and slow reaction periods which occur during the oxidation.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550090514
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of oxidation of dimethyl sulfoxide by chloramine-T in aqueous solution (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 261-273 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of oxidation of dimethyl sulfoxide (DMSO) by chloramine-T (CAT) is studied in HClO4 and NaOH media with OsO4 as a catalyst in the latter medium. In acid medium, the rate law is -d [CAT]/dt = k [CAT][DMSO][H+]. Alkali retards the reaction and the rate law takes the form -d [CAT]/dt = k [CAT][DMSO][OsO4]/[NaOH], but is reduced to -d [CAT]/dt = k [CAT][DMSO] at higher alkali concentrations. The reaction is subjected to changes in (a) ionic strength, (b) concentrations of added neutral salts, (c) concentrations of added reaction product, (d) dielectric constant, and (e) solvent isotope effect, and the subsequent effects on the reaction rate are studied.The reaction mechanism in acid medium assumes an electrophilic attack by the free acid RNHCl (CAT′) at the sulfur site in DMSO, forming a reaction intermediate which subsequently decomposes to dimethyl sulfone on hydrolysis. Formation of a cyclic complex between RNHCl and OsO4 which interacts with the substrate in a slow step explains the observed results in alkaline medium. The simplification of the rate equation at higher alkali concentrations is attributed to a direct reaction between chloramine-T and the substrate.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110304
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  • 3
    Electronic Resource
    Electronic Resource
    A model for explosions during carbon monoxide oxidationPaper 32 in the Series Oscillations in Chemical Systems. For Paper 31 see [1]. (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 821-841 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During the oxidation of carbon monoxide containing a trace of water, ten well-known atomic and molecular species can be identified as of potential significance. All conceivable reactions of these species in their ground electronic states were considered, and rate constants for all those that are of potential importance are either known or can be estimated with considerable confidence. For compositions and temperatures of experimental interest an isothermal system goes to a single steady state that is stable to perturbation and will neither explode nor oscillate. These steady-state computations also predict that as the temperature is raised above about 1000 K most of the water is converted to H, OH, and HO2 radicals. Under such conditions, exothermic reactions would be so rapid that strong thermal gradients would develop in any real system of plausible dimensions. A simple model based on these calculations predicts explosion limits consistent with those observed experimentally. Simultaneous behavior in time and in space must be calculated in detail before it is clear whether or not this model based on ground electronic states can model the oscillations that are sometimes observed in this system.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110803
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  • 4
    Electronic Resource
    Electronic Resource
    Estimating the positions of transition states from experimental data (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 853-865 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure is suggested to estimate the positions of a transition state (TS) along the reaction coordinate in reaction series involving several radical reactions. It is based on the dependence between experimental activation energies U± and heat effects Q. Taking into account the shift of a TS position, the following relation between these quantities is obtained: U± -; U0± = A (Q - Q0)2 + B(Q - Q0). The subscript 0 indicates the standard reference reaction. For three series, namely, the hydrogen abstraction from hydrocarbon substrates by radicals CH3·, CF·3, and Br·, the bond lengths characterizing the TS reaction center are evaluated. The TS positions appear to vary significantly in the reaction series, which accounts for significant changes in the experimentally observed activation volumes. The derivation of the Hammond rule and the range of its validity for the series with polar and steric substituent effects are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110805
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  • 5
    Electronic Resource
    Electronic Resource
    Hydroxyl radical measurements in a photochemical reactor by laser-induced fluorescence (1976)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 8 (1976), S. 765-776 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Measurements of hydroxyl radical (HO) concentrations in ambient air by the technique of laser-induced fluorescence have been recently reported. The present study was undertaken to provide an independent test of the validity of those measurements. A photochemical reactor was used to provide a source of HO, and the concentration of HO in the reactor was determined by the laser-induced fluorescence technique. The HO concentration was also deduced from measured hydrocarbon decay rates in the reactor. There was agreement between the HO concentrations obtained by these two different methods, thus providing further validation of the fluorescence method. Some studies of HO fluorescence efficiency as well as of possible interferences with the fluorescence measurements are reported.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550080511
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  • 6
    Electronic Resource
    Electronic Resource
    Evidence for production of the hydroxycarbonyl radical in the decomposition of formic acid on platinum (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 445-449 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formic acid molecules highly diluted in argon were passed through a clean platinum screen at 420-730 K and condensed onto an 8-K CsI window. The well-known decomposition products, CO2, CO, and H2O, were observed in the infrared spectra of the resulting matrices. In addition, new absorptions which are attributed to the OCOH free radical were also observed. Experiments with partially deuterated formic acids confirmed that the carbon-hydrogen bond of the formic acid was lost in the formation of the new intermediate species. The activation energy for CO2 production, Ea = 3.5 ± 0.2 kcal/mol, was determined by monitoring its appearance rate at several different catalyst temperatures.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110409
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  • 7
    Electronic Resource
    Electronic Resource
    Homogeneous decomposition of vinyl ethers. The heat of formation of ethanal-2-yl (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 715-730 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal unimolecular decomposition of three vinylethers has been studied in a VLPP apparatus. The high-pressure rate constant for the retro-ene reaction of ethylvinylether was fit by log k (sec-1) = (11.47 + 0.25) - (43.4 ± 1.0)/2.303 RT at 〈T〉 = 900 K and that of t - butylvinylether by log k (sec-1) = (12.00 ± 0.27) - (38.4 ± 1.0)/2.303 RT at 〈T〉 = 800 K. No evidence for the competition of the higher energy homolytic bond-fission process could be obtained from the experimental data. The rate constant compatible with the C—O bond scission reaction in the case of benzylvinylether was log k (sec-1) = (16.63 ± 0.30) - (53.74 ± 1.0)/2.303 RT at 〈T〉 = 750 K. Together with ΔHf,3000(benzyl·) = 47.0 kcal/mol, the activation energy for this reaction results in ΔHf,3000(CH2CHO) = +3.0 ± 2.0 kcal/mol and a corresponding resonance stabilization energy of 3.2 ± 2.0 kcal/mol for 2-ethanalyl radical.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110705
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal hydrocracking of indan. Effects of the hydrogen pressure on thekinetics and Arrhenius parameters (1975)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 351-362 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the thermal hydrocracking of indan were investigatedin a high-pressure flow reactor at temperatures from 470 to 530°C, total pressures of up to 300 atm, and molar ratios from 3 to 40. The effect of the hydrogen pressure was reflected especially in a change of the experimental rate equations for the formation of toluene from rT=k [indan]0.5 [hydrogen] to rT=k′ [indan] 0.75[hydrogen]0.75 with hydrogen partial pressureincreasing from 73 to 230 atm. The rate equation of n-propylbenzene remained constant at rPr=k″ [indan] [hydrogen]1.5. Simultaneously the Arrheniusparameters of toluene changed significantly, while those of n-propylbenzene remained unchanged.The observed effect of the hydrogen pressure is explained as a change inthe rates of the intermediate reactions; it provides an excellent agreementbetween the theoretical and experimental data. It was found that the steady-state concentration of the hydrogen atoms, which act as chain carriers in the thermal hydrocracking, was much smaller than the thermodynamic equilibrium concentrations
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550070305
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  • 9
    Electronic Resource
    Electronic Resource
    An absolute measurement of the rate constant for ethyl radical combination (1976)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 8 (1976), S. 381-387 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An absolute value of kr of ethyl radicals at 860 ± 17°K of 4.5 × 109 M-1·sec-1 was determined under VLPP conditions, where the value of kr/kr∞ should be about 1/2. Thus kr∞(M-1·sec-1) ∼ 1010 at 860°K. An error of as much as a factor of 2 in kr would be surprising, but possible.The value of 1010M-1·sec-1 seems to be a factor of from 2 to 5 too high to be compatible with extensive data on the reverse reaction and the accepted thermochemistry. Changes in the heat of formation and entropy of the ethyl radical can change the situation somewhat, but even these changes when applied to the work of Hiatt and Benson [3] indicate that ethyl combination should be ∼ 109.3 M-1·sec-1. More work is necessary if a better value is desired.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550080305
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamics of a conformational change in aqueous 18-crown-6 by an ultrasonic absorption method (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 10 (1978), S. 471-487 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A temperature dependence study of the ultrasonic amplitudes, velocities, and relaxation times for a presumed conformational transition of noncomplexed aqueous 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) is discussed. At all temperatures a single relaxation was observed within a 15-255-MHz frequency range. The equilibrium constant for the presumed conformational transition \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CR}_1 \mathop \rightleftarrows\limits^{K_{12} } {\rm CR}_2 $\end{document} was determined to be K21 = (2 ± 2) × 10-2. The activation parameters are ΔH21≠ = 10.2 ± 1.0 kcal/mol, ΔS21≠ = 7.7 ± 0.2 cal/(mol·deg), ΔH12≠ = 7.4 ± 1.0 kcal/mol, and ΔS12≠ = 7.7 ± 0.2 cal/(mol·deg), while the thermodynamic enthalpy and entropy were found to be -2.6 ± 1.0 kcal/mol and 0 ± 0.2 cal/(mol·deg), respectively. The rate constants at 25.0°C for the presumed conformational transition are k21 = (1.0 ± 0.3) × 107 sec-1 and k12 = (6.2 ± 0.2) × 108 sec-1.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550100506
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