摘要:

AbstractAn improved radical‐chain scheme of acetylene–chlorine mixture explosion initiated by small additions of oxygen is proposed. It includes among others the three‐body formation of chemically activated state (2) and describes the inhibiting effect of oxygen below the explosion

ISSN:0538-8066    

DOI:10.1002/kin.550150102

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe thermal reaction of hydrogen–butene‐2‐cismixtures has been studied in a static system at low extent of reaction around 500°C. Hydrogen does not affect the thermal reaction itself of the olefin, but gives rise to new stoichiometries of hydrogenolysis and hydrogenation, which are specified:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} {\rm H}_2 + cis - 2 - {\rm C}_4 {\rm H}_8 = {\rm CH}_4 + {\rm C}_3 {\rm H}_6 \\ {\rm H}_2 + cis - 2 - {\rm C}_4 {\rm H}_8 = {\rm H}_2 + 1 - {\rm C}_4 {\rm H}_8 \\{\rm H}_2 + cis - 2 - {\rm C}_4 {\rm H}_8 = n - {\rm C}_4 {\rm H}_{10} \\ \end{array} $$\end{document}The reaction is described in terms of a molecular and free‐radical mechanism. It is shown that the key process for the hydrogenolysis–hydrogenation reaction isand that the rate constant of this process can be determined from either propylene, or methane, or butene‐1 formations:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm k}_{{\rm 7'}} \simeq {\rm 10}^{{\rm 13}{\rm .1 - 24}{\rm .2/}\theta } \,{\rm cm}^{\rm 3} {\rm /mol} \cdot {\rm s} $$\end{document}with θ = 4.57 × 10−3Tkcal/mol. Other rate constants are estimated and agree with

ISSN:0538-8066    

DOI:10.1002/kin.550150103

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractRate constants and activation parameters for the acid‐catalyzed hydrolysis of eight ring‐substituted diazoacetophenones have been measured in three dioxan–water mixtures. An isokinetic relationship applies to the results obtained using a 50% dioxan–water mixture as solvent. Solvent and substituent effects are discussed together with some mechanistic aspects. Substituent constants are reported for the CO

ISSN:0538-8066    

DOI:10.1002/kin.550150104

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractRelative rate constants for the gas‐phase reactions of OH radicals with a series of bi‐ and tricyclic alkanes have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10−12cm3/molec·s, the rate constants obtained are (× 1012cm3/molec·s): bicyclo[2.2.1]heptane, 5.53 ± 0.15; bicyclo[2.2.2]octane, 14.8 ± 1.0; bicyclo[3.3.0]octane, 11.1 ± 0.6;cis‐bicyclo[4.3.0]nonane, 17.3 ± 1.3;trans‐bicyclo[4.3.0]nonane, 17.8 ± 1.3;cis‐bicyclo[4.4.0]decane, 20.1 ± 1.4;trans‐bicyclo[4.4.0]decane, 20.6 ± 1.2; tricyclo[5.2.1.02,6]decane, 11.4 ± 0.4; and tricyclo[3.3.1.13,7]decane, 23.2 ± 2.1. These data show that overall ring strain energies of ≲4–5 kcal mol−1have no significant effect on the rate constants, but that larger ring strain results in the rate constants being decreased, relative to those expected for the strain‐free molecules, by ratios which increase approximately exponen

ISSN:0538-8066    

DOI:10.1002/kin.550150105

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractRate constants for the reactions of O3and OH radicals with furan and thiophene have been determined at 298 ± 2 K. The rate constants obtained for the O3reactions were (2.42 ± 0.28) × 10−18cm3/molec·s for furan and<6 ×10−20cm3/molec·s for thiophene. The rate constants for the OH radical reactions, relative to a rate constant for the reaction of OH radicals withn‐hexane of (5.70 ± 0.09) × 10−12cm3/molec·s, were determined to be (4.01 ± 0.30) × 10−11cm3/molec·s for furan and (9.58 ± 0.38) × 10−12cm3/molec·s for thiophene. There are to date no reported rate constant data for the reactions of OH radicals with furan and thiophene or for the reaction of O3with furan. The data are compared and discussed with respect to those for other alkenes, dialkenes, and hete

ISSN:0538-8066    

DOI:10.1002/kin.550150106

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractIt is shown that, by deliberate activation of the reaction vessel, heterogeneous reaction at the wall can be made to dominate chain termination in a complex gas‐phase reaction. For a homogeneous process, characterized, as is often the case, by multiple terminations, this has the effect of simplifying the mechanism and allowing explicit solution of the relevant steady‐state equations so that the rate constants of some individual steps can be evaluated without assumption as to the values of those of others.The pyrolysis of propane, in the vicinity of 500°C, has been used as an example of this approach. Enhancement of the wall activity leads to the reactionproviding, almost exclusively, chain termination. As a result, rate constants for the initiation stepcan be directly determined. The results of this study provide the Arrhenius equation\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_1 (s^{ - 1}) = 16.71 \pm 0.54 - 83400 \pm 1950{\rm cal}/{\rm mol}/2.303RT $$\end{document}In combination with current thermochemical values this result givesk−1= 1013.40cm3/mol·s which, in turn, implies, via the geometric mean rule,kEt‐Et= 1012.9cm3/mol·s for ethyl–ethyl recombination, in good accord with the most recent determinations and compatible with the newly proposed value of the enthalpy of formation of ethyl.The first‐order wall constantk8has been evaluated ask8<104.2s−1. This appears to be the first occasion on which a wall constant has been evaluated from data for a high‐temperature co

ISSN:0538-8066    

DOI:10.1002/kin.550150107

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractRelative rate constants for the reaction of OH radicals with a series of α,β‐unsaturated carbonyls have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with propene of 2.52 × 10−11cm3/molec·s, the rate constants obtained are (× 1011cm3/molec·s: acrolein, 1.83 ± 0.13; crotonaldehyde, 3.50 ± 0.40; methacrolein, 2.85 ± 0.23; and methylvinylketone, 1.88 ± 0.14). These data, which are necessary input to chemical computer models of the NOx–air photooxidations of conjugated dialkenes, are discussed and compared with l

ISSN:0538-8066    

DOI:10.1002/kin.550150108

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

摘要:

AbstractThe initial rates of formation of the major products in the thermal reactions of ethylene at temperatures in the neighborhood of 800 K have been measured in the presence and absence of the additives neopentane and ethane. It has been shown that in the absence of the additive the main initiation process iswhile in the presence of neopentane and ethane the following additional initiation processes occur:From the ratios of the rates of formation of the major products in the presence and absence of the additive the ratioskN/k1andkE/k1were measured over the temperature range of 750–820 K. Taking values from the literature forkNandkE, the following value was obtained fork1:\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_1 ({\rm L}/{\rm mol} \cdot {\rm s}) = 11.27 \pm 0.6 - \frac{{64,200 \pm 2000}}{{2.3RT}} $$\end{document}Previous results using butene‐1 as additive were rexamined and shown to be consistent with this measurement. From this measurement the following values were derived: ΔHf(C2H3) = 63.4 ± 2 kcal/mol andD(C2H3H) = 103 k

ISSN:0538-8066    

DOI:10.1002/kin.550150109

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550150110

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550150101

出版商:John Wiley&Sons, Inc.    

年代:1983

数据来源: WILEY