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  • Artikel: DFG Deutsche Nationallizenzen  (57)
  • 1970-1974  (57)
  • Physical Chemistry  (57)
  • 1
    Digitale Medien
    Digitale Medien
    The pyrolysis of neopentane at small extents of reaction (1971)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 197-213 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pyrolysis of neopentane, at small extents of reaction, was studied by gas chromatography, in Pyrex reaction vessels between 450° and 530°C and in the initial pressure range 25-200 mm Hg. At initial time, this thermal decomposition can be essentially represented by a homogeneous long-chain radical mechanism. The rate constant of the unimolecular initiation process is approximately given by the expression \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm 0} \simeq 10^{13} {\rm exp}\left({\frac{{50,000}}{{RT}}} \right){\rm mole}^{- {\rm 1/2}} {\rm .ml}^{- {\rm 1/2}} {\rm .s}^{- {\rm 1}}$$\end{document} The initial rate constant of the global reaction (order 3/2) is nearly equal to \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm 1} + 10^{16.8} {\rm exp}\left({\frac{{82,000}}{{RT}}} \right){\rm s}^{- {\rm 1}}$$\end{document} This reaction is strongly inhibited by propene or isobutene and self-inhibited by the isobutene formed; an interpretation of all these inhibition phenomena of the neopentane pyrolysis is proposed. Our observations and conclusions, which have been summarized in communications during 1968 and 1969, are compared to those of other authors, particularly to the recent ones of Purnell and colleagues [13] and of Taylor and colleagues [14], [15].
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550030302
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  • 2
    Digitale Medien
    Digitale Medien
    Kinetics of the thermal gas phase reactions of 1,2-epoxy-2-methylpropane (1971)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 443-452 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the gas phase decomposition of 1,2-epoxy-2-methylpropane has been studied over the temperature range 377°-436°C at pressures between 5.3 and 61.6 torr. Isomerization reactions to give isobutyraldehyde, isopropenyl methyl ether, and 2-methyl-prop-2-en-l-ol account for over 95% of the epoxide decomposition. These isomerizations are homogeneous first-order, nonradical processes: \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} k({\rm isobutyraldehyde)} = {\rm 10}^{{\rm 13}{\rm .32} \pm {\rm 0}{\rm .18}} \exp (- 52720 \pm 570/1.987T)\sec ^{- 1} \\ {\rm}k({\rm isopropenyl methyl ether)} = {\rm 10}^{{\rm 13}{\rm .55} \pm {\rm 0}{\rm .47}} \exp (- 56140 \pm 1460/1.987T)\sec ^{- 1} \\ {\rm}k({\rm 2 - methyl - prop - 2 - en - l - ol)} = {\rm 10}^{{\rm 11}{\rm .53} \pm {\rm 0}{\rm .67}} \exp (- 49680 \pm 2080/1.987T)\sec ^{- 1} \\ \end{array}$$\end{document}
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550030506
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  • 3
    Digitale Medien
    Digitale Medien
    Liquid-phase hydrogen abstraction from chlorinated ethanes by chlorine atoms (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 5 (1973), S. 539-543 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The hydrogen abstraction from the chlorinated ethanes by chlorine atoms has been investigated in the liquid phase. Rate constants relative to that for hydrogen abstraction from chloroform have been measured between 267° and 333°K using a competition technique. The results are compared with gas-phase data.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550050404
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  • 4
    Digitale Medien
    Digitale Medien
    Kinetics of the formation of cyclobutane from ethylene (1972)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 61-68 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate of the thermal reaction of ethylene to form cyclobutane has been measured over the temperature range 723°-786°K and at pressures between 300 and 1300 torr. The equilibrium constant for the system \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$${\rm 2C}_{\rm 2} {\rm H}_{\rm 4}\mathop {\leftrightharpoons}\limits_{kf}^{kr} c - {\rm C}_{\rm 4} {\rm H}_{\rm 8}$$\end{document} was calculated both from the initial rate data and from measurements of the equilibrium concentration of cyclobutane. Agreement with the reported thermodynamic quantities for cyclobutane was satisfactory. The initial rate data gave the following epxression for kf: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }k_f {\rm (1}{\rm .mole}^{ - {\rm 1}} {\rm sec}^{ - {\rm 1}} {\rm)} = {\rm 7}{\rm .84} - \frac{{43800}}{{2.3RT}}$$\end{document} while the measurements of the equilibrium concentration of cyclobutane gave the expression for K, \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }K{\rm (atm}^{ - {\rm 1}} {\rm)} = - \frac{{45.4}}{{2.3R}} + \frac{{20700}}{{2.3RT}}$$\end{document}.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550040105
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  • 5
    Digitale Medien
    Digitale Medien
    A kinetic study of the reactions of the hydrogen atom with the cyclohexadiene isomers in the gas phase (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 337-357 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Absolute values of the rate constants for the reaction of hydrogen atoms with cyclic olefins in the gas phase have been measured in a discharge-flow system under 3.5, 16, and 22 torr Ar at 23°C. The attenuation of hydrogen atom concentration in the reaction tube in the presence of a large excess of olefin was measured with an ESR spectrometer, and the products were analyzed by gas chromatography. Cyclic C6 hydrocarbons were the only significant products obtained when the hydrogen atom concentration was 2.6 × 10-10 mole/1., the olefin concentration was in the range of 9 to 22 × 10-8 mole/1., and the pressure was 16 torr Ar. The values for the rate constants for reaction with cyclohexadiene-1,3, cyclohexadiene-1,4, and cyclohexene are, respectively, (9 ± 2) × 108, (12 ± 1) × 108, and (6 ± 1) × 108 l./mole-sec, and they are not changed significantly by a sixfold change in total pressure. The fraction of the total interaction that proceeds by addition is 84% in the cyclohexadiene-1,3 system, but only 18% in the cyclohexadiene-1,4 system, and the cyclohexadienyl radical is therefore the dominant radical species in the latter system. The pattern of interaction between the hydrogen atom and the cyclohexadienyl radical was determined, and comprises 65% of disproportionation, and 13% and 23% of combination to yield cyclohexadiene-1,3 and cyclohexadiene-1,4, respectively. These results are consistent with the general patterns of reactivity emerging from studies of the reactions between free radicals and olefins in related systems.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550060305
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  • 6
    Digitale Medien
    Digitale Medien
    The solvent-jump relaxation method using continuous flowThis paper was abstracted from the Ph.D. dissertation submitted by M. M. Wong to the University of Georgia. Presented in part at the 165th National Meeting of the American Chemical Society, Dallas, Texas, 1973 (1974)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 6 (1974), S. 687-692 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A step perturbation (concentration-jump or solvent-jump) relaxation method is described for studying the rates of fast reactions, using nontransient observation in a steadystate flow system. Therelaxation time is determined from a single measurement of an integrated relaxation amplitude. Remeasurement of the rate of dimerization of aqueous rhodamine B is reported.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550060506
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  • 7
    Digitale Medien
    Digitale Medien
    Very low-pressure pyrolysis. VIII. The decomposition of Di-t-amyl peroxideThis work was supported in part by Contract No. F44620-71-C-0103 with the Air Force Office of Scientific Research. (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 5 (1973), S. 55-65 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The very low-pressure pyrolysis (VLPP) technique has been applied to the pyrolysis of di-t-amyl peroxide (DTAP) over the temperature range 523-633°K. VLPP yields a low-pressure rate constant, kuni The conversion of kuni to k∞ which must be made to calculate the Arrhenius parameters, is accomplished via the RRKM theory. The transition state model used in the RRKM calculations was based on a transition state model which accurately reproduced the VLPP data for di-t-butyl peroxide for which the Arrhenius parameters are well known. For the decomposition of DTAP it was found that log k∞(300°K) = 15.8 - 36.4/θ, where θ = 2.303RT, in kcal/mole, and the units of k∞, are sec-1.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550050106
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  • 8
    Digitale Medien
    Digitale Medien
    The very low-pressure dehydrogenation of cis-2-butene. The activation energy for 1,4-H2 elimination (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 5 (1973), S. 991-1000 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Pyrolysis of cis-butene-2 under conditions of very low pressure (VLPP) has been studied in the range of 1100-1300°K. The principal products are butadiene and H2, obtained in a unimolecular reaction. A competing reaction to form butene-l accounts for from 10% to 40% of the overall decomposition over the range. Using a «tight» model for the transition state and RRKM theory yields a high-pressure, unimolecular rate constant for the 1,4-H2 elimination of \documentclass{article}\pagestyle{empty}\begin{document}$$ \log \,k\left( {{\rm s}^{ - 1} } \right) = \left( {13.0 \pm 0.6} \right) - {{\left( {65 \pm 2} \right)} \mathord{\left/ {\vphantom {{\left( {65 \pm 2} \right)} \theta }} \right. \kern-\nulldelimiterspace} \theta } $$\end{document} where θ = 2.303RT in kcal/mol. There is some surface reaction of butadiene at these temperatures to yield H2 + nonvolatile residue. Butene-l proceeds to decompose irreversibly to allyl + methyl radicals which have been observed directly. Comparison with related reactions leads to the conclusion that orbital symmetry-forbidden, 1,2-H2 elimination from saturated organic compounds will have activation energies too high to observe.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550050608
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  • 9
    Digitale Medien
    Digitale Medien
    The self-inhibited pyrolysis of isobutane (1973)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 5 (1973), S. 1007-1021 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pyrolysis of isobutane was investigated in the ranges of 770° to 855°K and 20 to 150 Torr at up to 4% decomposition. The reaction is homogeneous and strongly self-inhibited. A simple Rice-Herzfeld chain terminated by the recombination of methyl radicals is proposed for the initial, uninhibited reaction. Self-inhibition is due to abstraction of hydrogen atoms from product isobutene giving resonance-stabilized 2-methylallyl radicals which participate in termination reactions. The reaction chains are shown to be long. It is suggested that a previously published rate constant for the initiation reaction (1)\documentclass{article}\pagestyle{empty}\begin{document}$$ i - C_4 H_{10} \to CH_3 + i - C_3 H_7 $$\end{document} is incorrect and the value k1 = 1016.8 exp (-81700 cal mol-1/RT)s-1 is recommended. The values of the rate constants for the reactions (4i) \documentclass{article}\pagestyle{empty}\begin{document}$$ CH_3 + i - C_4 H_{10} \to CH_3 + i - C_4 H_9 $$\end{document} (4t) \documentclass{article}\pagestyle{empty}\begin{document}$$ CH_3 + i - C_4 H_{10} \to CH_4 + t - C_4 H_9 $$\end{document} (8) \documentclass{article}\pagestyle{empty}\begin{document}$$ CH_3 + i - C_4 H_8 \to CH_4 + 2 - methylallyl $$\end{document} are estimated to be \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{4i} = 10^{13.16} \exp (- 16300calmol^{ - 1} /RT)cm^3 mol^{ - 1} s^{ - 1} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{4t} = 10^{12.51} \exp (- 12900calmol^{ - 1} /RT)cm^3 mol^{ - 1} s^{ - 1} $$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{8} = 10^{14.05} \exp (- 17600calmol^{ - 1} /RT)cm^3 mol^{ - 1} s^{ - 1} $$\end{document} From a recalculation of previously published data on the pyrolysis of isobutane at lower temperatures and higher pressures, the value k11c, = 109.6 cm3 mol-1 s-1 is obtained for the rate constant of recombination of t-butyl. A calculation which is independent of any assumed rate constants or thermochemistry shows that the predominant chain termination reaction is the recombination of two methyl radicals in the conditions of the present work and the recombination of two t-butyl radicals in those of our previous study at lower temperatures and higher pressures.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550050610
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  • 10
    Digitale Medien
    Digitale Medien
    The thermal isomerization of cyclobutenes. XVI. 1,2-bis(trimethylsiloxy)cyclobutene (1971)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 85-88 
    Details
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas phase thermal isomerization of 1,2-bis(trimethylsiloxy)cyclobutene has been studied in the temperature range 172°-204°C. The reaction is homogeneous, kinetically first order, and yields 2,3-bis(trimethylsiloxy)buta-1,3-diene as the only product. The rate constants fit the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {k = 10^{13.509 \pm 0.120} \exp \left( {{{ - 148,920 \pm 1060\,{\rm J}\,{\rm mole}^{ - 1} } \mathord{\left/ {\vphantom {{ - 148,920 \pm 1060\,{\rm J}\,{\rm mole}^{ - 1} } {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right)\sec ^{ - 1} } \hfill \\ {\left[ {k = 10^{13.509 \pm 0.120} \exp \left( {{{ - 35,590 \pm 250\,{\rm cal mole}^{ - 1} } \mathord{\left/ {\vphantom {{ - 35,590 \pm 250\,{\rm cal mole}^{ - 1} } {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right)\sec ^{ - 1} } \right]} \hfill \\ \end{array}$$\end{document} These results, taken with those obtained previously, demonstrate the insensitivity of the kinetics of the reaction to the nature of the groups substituted on the 1- and/or 2-positions of the cyclobutene ring.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/kin.550030107
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