摘要:

AbstractThe total decomposition rates of the chemically activated alkanesn‐butane,n‐pentane, isopentane, and neohexane were measured using an internal comparison technique. Chemical activation was by the CH insertion reaction of excited singlet‐state methylene radicals. A total of ten rate constants ranging from 4.6 × 105to 2.3 × 107sec−1were measured for these alkanes at different excitation energies. These rates correlate via RRKM theory calculations with thermalA‐factors in the range of 1016.1to 1017.1sec−1for free rotoractivated complex models and in the range of 1016.4to 1017.8sec−1for vibrator‐activated complex models. It was found that high critical energies for decomposition, “tight” radical models, and activated complex models with free internal rotations were required to correlate the decomposition rates of these alkanes with estimated alkyl radical recombination rates. The correlation is just barely possible even for these favorable extremes, indicating that there may be a basic discrepancy between the recombination rate and decompositio

ISSN:0538-8066    

DOI:10.1002/kin.550040102

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe rate of the isotope exchange reaction between iron(II) and iron(III) perchlorates has been measured in a solvent mixture containing a 3:2 mole ratio of water to dimethyl sulfoxide over the temperature range from 25° to −98°C. In this temperature range, the reactants can diffuse together faster than they can undergo isotope exchange. The activation enthalpy and entropy for the acid‐independent reaction were 6.0 ± 1.2 kcal/mole and −38 ± 17 cal/deg mole, respectively. Below −22°C, the acid‐dependent exchange reaction did not contribute significantly to the exchange. In liquid media at −112° and −117°C and in a solid glass at −136°C, no isotope exchange was observed over the period of a calculated half‐life for the reaction. At these temperatures, the rate at which the reactants diffuse together is slower than the calculated rate of isotope exchange. In a solid glass at −196°C, no isotope exchange was observed

ISSN:0538-8066    

DOI:10.1002/kin.550040103

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe pyrolyses of trimethylethylene and tetramethylethylene have been investigated in the presence and absence of nitric oxide. It appears that apart from a unimolecular split, e.g.,a disproportionation reaction such asmay play an important role in initiation. Nitric oxide had no effect on H2production, which is probably a molecular process. There was similar behavior of both compounds in the presence of NO, indicating that the olefinic hydrogen atom does not play a decisive role. Other aspects of the mechanisms are discussed.

ISSN:0538-8066    

DOI:10.1002/kin.550040104

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe 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 forkf:\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 forK,\documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }K{\rm (atm}^{ - {\rm 1}} {\rm)} = - \frac{{45.4}}{{2.3R}} + \frac{{20700}}{{2.3RT}}$$\end{docume

ISSN:0538-8066    

DOI:10.1002/kin.550040105

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractDichloromethane, chlorofluoromethane, and dichlorofluoromethane have been brominated competitively with each other and with chloroform and methyl chloride. Using the literature values for the rates of bromination of these latter two compounds, the rate constants for the three former compounds have been determined:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} k_2 ({\rm CH}_{\rm 2} {\rm Cl}_{\rm 2} {\rm)} = (9.77 \pm 1.44) \times 10^9 \exp (- 10,860 \pm 480{\rm cal}/RT) \\ k_2 ({\rm CH}_{\rm 2} {\rm F Cl)} = (7.76 \pm 1.59) \times 10^{10} \exp (- 14,800 \pm 800{\rm cal}/RT) \\ k_2 ({\rm CHF Cl}_{\rm 2} {\rm)} = (1.05 \pm 1.48) \times 10^{10} \exp (- 13,300 \pm 570{\rm cal}/RT) \\ \end{array}$$\end{document}whereRis taken to be 1.987 cal deg−1mol−1(1 cal = 4.186

ISSN:0538-8066    

DOI:10.1002/kin.550040106

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractC2F5radicals were generated in the presence of benzene vapor by the reaction\documentclass{article}\pagestyle{empty}\begin{document}$$({\rm C}_{\rm 2} {\rm F}_{\rm 5} {\rm CO})_2 {\rm O} + hv \to {\rm CO} + {\rm CO}_2 + 2{\rm C}_{\rm 2} {\rm F}_5 $$\end{document}The radicals react with the benzene by addition and pseudo H abstractionThe rate constantkaddfor the addition reaction (7) is given by\documentclass{article}\pagestyle{empty}\begin{document}$$\log k_{add} /k_{c^{1/2} } {\rm cm}^{{\rm 3/2}} {\rm mole}^{ - 1/2} \sec ^{ - 1/2} = (4.49 \pm 0.10) - (4210 \pm 150)/\theta $$\end{document}where θ = 2.303RTcal/mole andkcis the rate constant for combination of C2F5radicals. The addition becomes reversible above 110°C. The reactions of CF3and C2F5radicals with benzene vapor are compare

ISSN:0538-8066    

DOI:10.1002/kin.550040107

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe rate of decomposition of allyl iodide has been measured from 742plusmn;K to 1068±K and from 169 to 1429 torr using a shock tube method in which the disappearance of allyl iodide and the appearance of iodine are followed simultaneously. The kinetics are first order in allyl iodide and probably are slightly dependent upon total pressure. Mathematical modeling shows that they are compatible with a mechanism consisting of three reactions:The experiments yield the rate constantk1, the high‐pressure limiting value of which is found to be\documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} k_\infty (\sec ^{ - 1}) = (14.45 \pm 0.4) - (42.8 \pm 2.4{\rm kcal})/2.3RT$$\end{document}in reasonable agreement with that predicted using the methods of Benson and O'Neal [

ISSN:0538-8066    

DOI:10.1002/kin.550040108

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe kinetics of the reaction of O + CH3OCH3were investigated using fast‐flow apparatus equipped with ESR and mass‐spectrometric detection. The concentration of O(3P) atoms to CH3OCH3was varied over an unusually large range. The rate constant for reaction\documentclass{article}\pagestyle{empty}\begin{document}$${\rm O} + {\rm CH}_{\rm 3} {\rm OCH}_3 \to {\rm OH} + {\rm CH}_{\rm 2} {\rm OCH}_{\rm 3} $$\end{document}was found to bek= (5.0 ± 1.0) × 1012exp [(−2850 ± 200/RT)] cm3mole−1sec−1. The reaction O + CH3OH was studied using ESR detection. Based on an assumed stoichiometry of two oxygen atoms consumed per molecule of CH3OH which reacts, we obtain a value ofk= (1.70 ± 0.66) × 1012exp [(−2,280 ± 200/RT)] cm3mole−1sec−1for the reaction\documentclass{article}\pagestyle{empty}\begin{document}$${\rm O} + {\rm CH}_{\rm 3} {\rm OH} \to {\rm OH} + {\rm CH}_{\rm 2} {\rm OH}$$\end{document}The results obtained in this study are compared with the results from other workers on these reactions. The observation of essentially equal activation energies in these two reactions is indicative of approximately equal CH bond strengths in CH3OCH3and CH3OH. This is in agreement with recent measurements

ISSN:0538-8066    

DOI:10.1002/kin.550040109

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe gas‐phase reaction kinetics of 1,1,2‐trimethylcyclopropane have been studied in the temperature range of 700–755°K. First‐order unimolecular rate constants for over‐all reactant disappearance fit the Arrhenius equation\documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }k_0 {\rm (sec}^{ - {\rm 1}} {\rm)} = {\rm 14}{\rm .47} - \frac{{61.08 \pm 0.51}}{\theta }$$\end{document}Reaction products and the relative rates of their formation are found to be reasonably consistent with the biradical

ISSN:0538-8066    

DOI:10.1002/kin.550040110

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550040101

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY