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  • 1975-1979  (3)
  • 1970-1974
  • 1977  (3)
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  • 1975-1979  (3)
  • 1970-1974
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  • 1
    Electronic Resource
    Electronic Resource
    Steric factors in the gas-phase elimination of esters: The pyrolysis of 2,3-dimethyl-3-pentyl acetate (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 9 (1977), S. 379-385 
    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 decomposition of 2,3-dimethyl-3-pentyl acetate have been studied at a temperature range of 212-260°C and a pressure range of 30-300 mm Hg. The olefins produced are 2-ethyl-3-methyl-1-butene, 3,4-dimethyl-trans-2-pentene, 3,4-dimethyl-cis-2-pentene, and 2,3-dimethyl-2-pentene. The reaction is homogeneous, obeys first-order law, and the value of the rate constant is given by the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,k({\rm sec}^{- 1}) = (14.22 \pm 0.23) - (40,600 \pm 500)\,{\rm cal}/{\rm mol}/2.303RT $$\end{document} The directions of elimination and their corresponding partial rates are best explained in terms of purely steric factors.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550090307
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Substituent effects in the gas-phase eliminations of alpha;-substituted alkyl chlorides the pyrolyses of 2-chloro-3-methylbutane and pinacolyl chloride (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 9 (1977), S. 819-827 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase pyrolyses of 2-chloro-3-methylbutane and pinacolyl chloride in the temperature range of 345-390°C and pressure range of 60-220 mm Hg are homogeneous and unimolecular in a seasoned reaction vessel. The temperature dependence of the rate constants is given by the Arrhenius equations \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,k_{\rm 1} ({\rm sec}^{- 1}) = (13.80 \pm 0.24) - (49,700 \pm 700){\rm cal}/{\rm mol}/2.303RT $$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,k_{\rm 1} ({\rm sec}^{- 1}) = (12.99 \pm 0.09) - (47,200 \pm 250){\rm cal}/{\rm mol}/2.303RT $$\end{document} respectively. The Wagner-Meerwein rearrangement was not observed in these eliminations. Some correlations for the pyrolysis of α-substituted alkyl chlorides are presented and discussed. These facts are consistent with the heterolytic nature of the cyclic transition state mechanisms for these reactions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550090512
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Kinetics of the gas-phase elimination of isopropyl α-halo acetates and the taft correlation (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 9 (1977), S. 811-818 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gas-phase pyrolysis of three secondary acetates in the temperature range of 290-350°C and the pressure range of 40-236 mm Hg reveals a homogeneous first-order law and unimolecular elimination. The rate constants are given by the following Arrhenius equations: isopropyl fluoroacetate: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,k_{\rm 1} ({\rm sec}^{- 1}) = (12.83 \pm 0.53) - (43,700 \pm 1400){\rm cal}/{\rm mol}/2.303RT $$\end{document} isopropyl chloroacetate: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,k_{\rm 1} ({\rm sec}^{- 1}) = (12.63 \pm 0.33) - (42,800 \pm 900){\rm cal}/{\rm mol}/2.303RT $$\end{document} isopropyl iodoacetate: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log} \,k_1 ({\rm sec}^{- 1}) = (13.09 \pm 0.23) - (43,300 \pm 600){\rm cal}/{\rm mol}/2.303 RT $$\end{document}The differences in rates I 〉 Br 〉 Cl 〉 F apparently question previous assumptions where the pyrolyses of esters follow the same sequence as acid strength. The experimental data give a good correlation with σ* values, where ρ* = -1.85 at 330°C. Some kind of discrete bond polarization at the Cα—O bond of the acetate in the cyclic transition state seems to be involved in this type of reactions.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550090511
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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