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  • 1
    Electronic Resource
    Electronic Resource
    Role of 2-carboxyl substituent in the tautomerization between two equivalent enol forms of 3-hydroxyphenalenone (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 485-488 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The interconversion between two equivalent enol forms of 3-hydroxyphenalenone took place predominantly through a diketo form with a free energy of activation of ca 14 kcal mol-1 in DMSO solution determined by 125·8 MHz13C NMR measurement. On the other hand, the corresponding interconversion in 2-carboxy-3-hydroxyphenalenone was not frozen on the time scale of 13C NMR spectroscopy down to -60°C. This acceleration in the interconversion rate of the latter may be interpreted by a double proton switching between the hydrogen-bonded 2-carboxyl and 3-hydroxyenone moieties.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030712
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  • 2
    Electronic Resource
    Electronic Resource
    MO study of the possibility of a concerted mechanism in the pinacol rearrangement (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 737-745 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ab initio SCF-MO method was employed to examine the possibility of a reaction pathway without a carbocation intermediate in the pinacol rearrangement. The molecular geometries of the transition states were obtained for the 1,2-hydride shift together with H2O elimination, starting from the various methyl-substituted protonated 1,2-diols. It was found that the activation energies depend strongly on the substitutents. A comparison of the relative energies between β-hydroxycarbonium ions and the transition states of the concerted mechanism suggests that the stepwise mechanism is less favourable than the concerted path in each case.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610031107
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    High temperature pyrolysis of methane in shock waves. Rates for dissociative recombination reactions of methyl radicals and for propyne formation reaction (1990)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 22 (1990), S. 701-709 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of 2% CH4 and 5% CH4 diluted with Ar was studied using both a single-pulse and time-resolved spectroscopic methods over the temperature range 1400-2200 K and pressure range 2.3-3.7 atm. The rate constant expressions for dissociative recombination reactions of methyl radicals, CH3 + CH3 → C2H5 + H and CH3 + CH3 → C2H4 + H2, and for C3H4 formation reaction were investigated. The simulation results required considerably lower value than that reported for CH3 + CH3 → C2H4 + H2. Propyne formation was interpreted well by reaction C2H2 + CH3 → P-C3H4 + H with k = 6.2 × 1012 exp(-17 kcal/RT) cm3 mol-1 s-1.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550220706
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  • 4
    Electronic Resource
    Electronic Resource
    Shock tube and modeling study of propene pyrolysis (1992)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 24 (1992), S. 761-780 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of propene behind reflected shock waves with 1200 〈 T5 〈 1800 K and 1.6 × 10-5 〈 ρ5 〈 2.7 × 10-5 mol/cm3 was studied by IR laser kinetic absorption spectroscopy and gas-chromatographic analysis of reaction products. The present data together with earlier shock tube data were satisfactorily modeled with a 51-reaction mechanism. As the initial step of the reaction, three channels, C3H6 = CH3 + C2H3 (1), C3H6 = H + AC3H5 (2), and C3H6 = CH4 + C2H2 (3), were necessary to interpret all the experimental data. © John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550240902
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  • 5
    Electronic Resource
    Electronic Resource
    CF3Br—H2 reaction in shock waves (1993)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 25 (1993), S. 983-993 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CF3Br—H2 mixtures highly diluted with Ar were studied by using a time-resolved IR-emission of HBr and a gas-chromatography for reaction products. The temperature range covered was 1000-1600 K and the total pressure behind the reflected shock waves used was 1.2-2.6 atm. CF3H, C2F6, and C2F4 were produced and the yields of these products were determined as a function of temperature. The main product under our experimental conditions was CF3H. The mechanism and the rate constants of CF3Br—H2 reaction at high temperatures were discussed. The experimental data was satisfactorily modeled using a 14-reaction mechanism. Reaction (5) played an important role in the formation of CF3H together with reaction (4). The rate constant expression k5 = 2.2 × 1013 exp(-12 kcal/RT) cm3 mol-1 s-1 gave the best agreement between the calculated and observed results. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550251202
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal decomposition of vinylacetylene in shock waves (1992)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 24 (1992), S. 871-885 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of vinylacetylene (C4H4) was studied behind reflected shock waves using both a single-pulse method (reaction time between 0.8 and 3.3 ms) and a time-resolved UV-absorption method (230 nm). The studies were done over the temperature range of 1170-1690 K at the total pressure range of 1.3-2.3 atm. The mechanism was used to interpret both the early and late stages of vinylacetylene decomposition at the high temperatures. It was confirmed that C4H4 dissociation proceeded through the following three channels. The rate constant expression of reaction (1) was determined as k1 = 6.3 × 1013 exp(-87.1 kcal/RT) s-1. The rate constants of the succeeding reactions (chain reaction, C4H4 + H → i-C4H3 + H2 and C4H4 + H → C2H2 + C2H3 and decomposition reactions of free radicals, i-C4H3 + M → C4H2 + H + M) were confirmed or estimated. © John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550241005
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