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  • 1990-1994
  • 1980-1984  (123)
  • 1981  (123)
  • Physical Chemistry  (123)
  • Nuclear reactions
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 135-148 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate of the cerium (IV) oxidation of p-chloromandelic acid has been studied in perchlorate media at an ionic strength of 1.50 mol/dm3 by the stopped-flow technique and in H2SO4—MHSO4 (M+ = Li+, Na+, K+) and H2SO4—MClO4 (M+ = H+, Li+, Na+) mixtures at constant total electrolyte concentrations of 1.00 and 2.00 mol/dm3 using the conventional spectrophotometric method. In perchlorate media the kinetic data indicate the formation of two intermediate complexes between cerium (IV) and the organic substrate, but only one is significantly involved in the intramolecular electron-transfer process. The oxidation rate is markedly lower in sulfate media, where two reaction paths have been found to contribute to the overall redox reaction. The univalent cations examined exhibit negative specific effects upon the overall oxidation rate increasing in the order H+ 〈 Li+ 〈 Na+ 〈 K+. Activation parameters have been also estimated.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 231-243 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The spectrum of the intermediate product ascribed to nitrosopentane has been detected in the photolysis of the SO2-pentane (RH)-NO mixture. This result has been interpreted in terms of the radical mechanism by assuming the H-atom abstraction from RH by the excited SO2 molecules to be the primary act. The contribution of the singlet and triplet SO2 states to the product formation rate and the ratio of the singlet-to-triplet rate constants have been evaluated. At NO pressures above 5 torr, the product formation rate significantly deviates from the Stern-Volmer dependence.
    Additional Material: 9 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 325-332 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction Cl + H2CO → HCl + HCO has been studied at 295 K. Chlorine atoms were produced via the infrared laser induced dissociation of CCl3F, using a pulsed CO2 TEA laser. Using HCl infrared chemiluminescence as the diagnostic, we find the rate constant to be 7.4 ± 0.7 × 10-11 cm3/molecule sec, in good agreement with several recent studies. An evaluation of TEA laser photolysis as a technique for the generation of chlorine atoms is made, and the relationship of this experiment to recent theories of infrared laser induced chemistry is discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 385-401 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the reaction have been investigated in H2SO4 medium under different conditions. The observed bimolecular rate constant kobs, has been found to depend on [H+]-0.55 and to increase with the initial concentration ratio of the reactants R0 = [H2O2]0/[U (IV)]0 above 0.49. The activation energy of the overall reaction has been determined as 13.79 and 14.3 kcal/mol at R0 = 1 and 0.35, respectively. Consistent with experimental data, a detailed reaction mechanism has been proposed where the hydrolytic reaction (4) followed by the rate-controlling reaction (10) and subsequent fast reactions of U (V) and OH radicals are involved: A kinetic expression has been derived from which a graphical evaluation of (kK4)-1 and k-1 has been made at R0 = 1 as (12.30 ± 0.09) × 10-3 M min, (6.23 ± 2.19) × 10-4 M min; and at R0 = 0.35 as (12.63 ± 2.13) × 10-3 M min, (8.32 ± 6.62) × 10-4 M min, respectively. Indications of some participation of a chain reactionat R0 = 1 have been obtained without affecting thesecond-order kinetics as observed.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 433-444 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No reliable rate constant is available for the self-reaction of tert-;butoxy radicals. We have set up a competition between hydrogen abstraction and self-reaction of tert-butoxy radicals in a flash photolysis electron spin resonance study to extract this information. Experimental values of hydrogen abstraction product radical concentrations under various hydrogen donor concentrations were then compared with theoretically calculated values with different values of 2k4 to obtain the best fit. Hydrogen donors such as cyclopentane, anisole, methyl tert-butyl ether, and methanol were chosen for the study. A value of (1.3 ± 0.5) × 109M-1 sec-1 for the rate constant of the self-reaction of tert-butoxy radicals has been determined at 293°K.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 481-495 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of ethane has been reinvestigated using the single pulse, reflected shock technique. Reflected shock temperatures were corrected for boundary layer-induced nonidealities using the thermal decomposition of cyclohexene as a kinetic standard. The rate constant for the reaction was calculated from the rate of formation of methane under conditions of very low extent of reaction, over a temperature range of 1000-1241 K. Ethane compositions of 1% and 3% in argon at total reaction pressures of 3 and 9 atm were used, and a small pressure dependence of k1 was observed.An RRKM model is described which gives excellent agreement with this and other recent dissociation and recombination rate constant data in light of a recent revision to the thermochemistry of the methyl radical. In the range of 1000-1300 K an RRKM extrapolated k1∞ is given by the expression, log k1∞ = 17.2 - 91,000/2.3RT, while at 298 K the calculation gives log k-1∞ (l/mol sec) = 10.44, where k-1∞ is calculated from k1∞ and the equilibrium constant.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 503-514 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title reaction has been investigated in the temperature range of 494-545 K. During the early stages of reaction the only observed products were silyl iodide and hydrogen iodide. Initial rates were found to obey the rate law over a wide range of initial iodine and monosilane pressures. Secondary reactions, most probably of SiH3I with I2, became more important as the reaction progressed. However, provided [SiH4]0/[I2]0 〉 20, these secondary processes had a negligible effect on the kinetics, and an integrated rate expression could be used. These kinetics are consistent with an iodine atom abstraction chain mechanism, and for the step has been deduced. From this the bond dissociation energy D(SiH3—H) = 378 ± 5 kJ/mol (90 kcal/mol) is obtained. The kinetic and thermochemical implications of this value, especially to the pyrolysis of monosilane, are discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 591-601 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that A factors for atom fissions in polyatomics can be reliably estimated by an improved version of the restricted free rotor model (RFRM). No adjustable parameters are used in the evaluation of A factors for the dissociation of the RO—F bond (R: NO2, SF5, CF3, FSO2), and the authors' predictions are compared with high-pressure kinetic data for these reactions. In the case of O2NOF, for which full spectroscopic information is available, RFRM reproduces the observed value Am well within a factor of 2. Similar agreement is reached for F5SOF and FO2SOF, assigning reasonable limits to their —OF torsional frequencies. For F3COF, Am and the calculated back reaction rate constant, which is independent of the model, are both much too small to be plausible, suggesting falloff effects rather than a failure of RFRM.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 627-638 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(trifluoromethyl) peroxide is readily dissociated by multiple infrared photon excitation at CO2 laser wavelengths. The primary dissociation product is CF3O; approximately 85% of the nascent radicals are further dissociated in the laser field to form CF2O and F. The F atoms then react with the remaining CF3O to produce CF3OF. The formation of CF3OF is strongly inhibited by addition of HI, which reacts preferentially with the F atoms.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 695-705 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The acid-catalyzed enolization of acetone in the presence of bromine is found to be catalyzed by the anionic micelles of sodium dodecyl sulfate. The rate acceleration expected on the basis of lowering of activation energy is largely nullified by the decrease in the entropy of activation, leading to a very small rate enhancement, i.e., kψ/k0 = 1.2 at 30°C. The binding constant for the micelle-substrate complex is determined. The micellar rate enhancement is the same, irrespective of the halogen used, chlorine, bromine, or iodine.
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  • 13
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With a continuous jet-stirred tank reactor operating at small space time (0.05-1.2 s) the kinetics of the formation of six minor products (ethane, isobutane, butene-1, 2,3-dimethyl-butane, 4-methylpentene-1, and 1,5-hexadiene) are studied during the pyrolysis of propane, at small extents of reaction and over the temperature range of 600-780°C. The experimental results are in agreement with the free radical mechanism proposed by Jezequel, Baronnet, and Niclause for this reaction. They show that the two most important termination processes are The measured rates of formation of the minor products are consistent with the quasi-identical values estimated by Jezequel and co-workers (between 475 and 505°C) and by Allara and Edelson (between 510 and 560°C) for kinetic parameters (A1 ≃ 1016.65 s-1 and E1 ≃ 84.7 kcal/mole) of the chain initiation process
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 39-58 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A small tubular reactor having an inner diameter of 1-2 mm andused as the source in a molecular beam apparatus is described in detail. This arrangement allows the study of fast reactions with reaction times smaller than 1 msec. The preexplosive reaction phase between F2 and H2 and CH4, respectively, is investigated to find out the initiation reactions. In the F2/H2 reaction, initiation is brought about by heterogeneous generation of F atoms or some other surface reaction. Evidence is also obtained for chain branching reactions. In the F2/CH4 case the dominant initiation reaction is the homogeneous reaction CH4 + F2 → CH3 + HF + F. The rate constant for the reaction between 300 and 400 K is 1012.3±0.3 exp[-47 ± 8 kJ/mol/RT] cm3/mol sec. The analysis of the experimental data also yields the rate constant for the propagation reaction CH3 + F2 → CH3 F + F, which is 1012.3±0.3 exp[-4.6 ±2.1 kJ/mol/RT] cm3/mol sec.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 321-322 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 463-471 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of thermal decomposition of ethyl, isopropyl, and t-butyl trifluoroacetates have been studied in the gas phase. In each case initial decomposition follows the normal ester route to give an olefin and trifluoroacetic acid, and elimination of hydrogen fluoride does not occur. However, trifluoroacetic acid is thermally unstable at ethyl and isopropyl ester decomposition temperatures, and further products result, including those from the difluorocarbene produced by decomposing trifluoroacetic acid. Placing a CF3 group at an ester's γ carbon increases the polarity of its transition state and decreases its thermal stability. The activation energies of the ethyl and isopropyl esters are lowered by 3.8 and 4.7 kcal/mol compared to the corresponding acetates, and the primary decomposition kinetics, which are homogeneous and of the first order, are expressed by α-Methylation enhances the reactivity of the trifluoroacetates, and the t-butyl ester, the transition state for which is sufficiently polar for heterogeneous decomposition to occur, shows signs of thermal instability at room temperature. The equilibrium was also investigated and gave ΔH° = +13,580 cal/mol and ΔS° = +31.07 gibbs/mol in the forward direction. The results obtained extend and support the known structure-rate correlations in the gas-phase elimination of esters.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 445-462 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal unimolecular decomposition of ethylbenzene, isopropylbenzene, and tert-butylbenzene was studied using the very-low-pressure pyrolysis (VLPP) technique. Each reactant decomposed by way of β C—C bond homolysis, producing methyl radicals and benzyl or benzylic-type radicals. RRKM calculations show that the observed rate constants, when combined with thermochemical estimates, are consistent with the following high-pressure rate expressions: \documentclass{article}\pagestyle{empty}\begin{document}$ \log k(\sec ^{ - 1}) = 15.3 - (72.7/{\rm \theta)} $\end{document} for ethylbenzene between 1053 and 1234 K, \documentclass{article}\pagestyle{empty}\begin{document}$ \log k(\sec ^{ - 1}) = 15.8 - (71.3/{\rm \theta)} $\end{document} for isopropylbenzene between 971 and 1151 K, and \documentclass{article}\pagestyle{empty}\begin{document}$ \log k(\sec ^{ - 1}) = 15.9 - (69.1/{\rm \theta)} $\end{document} for tert-butylbenzene between 929 and 1157 K, where θ (kcal/mol) = 2.303RT. Resulting activation energies combined with heat capacity and heat of formation data led to the following dissociation enthalpies and enthalpies of formation at 298 K: DH° (øCH(CH3)—CH3) = 73.8 kcal/mol, ΔHf° (øÇCH(CH3)) = 39.6 kcal/mol, DH° (øC(CH3)2—CH3) = 72.9 kcal/mol, and ΔHf° (øÇ(CH3)2) = 32.4 kcal/mol. Derived high-pressure rate constants are in good accord with results of lower temperature toluene- and aniline-carrier experiments.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 149-172 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Overall and detailed kinetic descriptions of the pyrolysis of C3H8 have been proposed as a result of a turbulent flow reactor investigation in the temperature range of 1110-1235 K and at atmospheric pressure. The overall reaction was described by a first-order rate expression with an activation energy of 58.65 kcal/mol and a preexponential factor of 3.2 × 1012 sec-1. This expression agrees with previously reported rate data. In addition, a kinetic mechanism involving 13 chemical species and 32 elementary reactions has been postulated to describe the kinetics. Experimental data from the present flow reactor experiments and from static vessel and shock tube experiments reported in the literature were used to verify the mechanism. Agreement over the temperature range of 800-1400 K and over the pressure range of 0.1-8.5 atm was obtained by adjusting three rate constants. Previously reported values for these rate constants appear to require reexamination. The reactions in question are the following: The sum of the rate constants for reactions (2a) and (2b) and the rate constant for reaction (23) are best represented by \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{2a} + k_{2b} = 10^{- 0.1} T^4 \exp (-8300/{\rm RT}){\rm cm}^3 /{\rm mol}\;{\rm sec} $$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{23} = 10^{14.55} \exp (-14,340/{\rm RT}){\rm cm}^3 /{\rm mol}\;{\rm sec} $$\end{document} which differ with the expressions in the literature.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 209-217 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By measuring the rates of decay of ozone in a large excess of reactant, second-order rate constants have been obtained for the reactions of ozone with ethene, propene, but-1-ene, trans-but-2-ene, isobutene, hex-1-ene, cyclopentene, cyclohexene, isoprene, vinyl fluoride, 1,1-difluoroethene, cis-1,2-difluoroethene, trans-1,2-difluoroethene, trifluoroethene, tetrafluoroethene, and 2,5—dihydrofuran. The reactions have been studied in synthetic air at atmospheric pressure and at temperatures of 294 and 260 K. The rate constants and Arrhenius parameters are discussed in relation to existing kinetic data on ozone-alkene reactions.
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  • 21
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of the unimolecular decomposition of 4-methylpent-2-yne (M2P) and 4,4-dimethylpent-2-yne (DM2P) have been carried out over the temperature range of 903-1246 K using the technique of very-low pressure pyrolysis (VLPP). The primary reaction for both compounds is fission of the C—C bond adjacent to the acetylenic group producing the resonance-stabilized methyl-substituted propargyl radicals, CH3C≡ĊH(CH3) from M2P and CH3C≡CĊ(CH3)2 from DM2P. RRKM calculations were performed in conjunction with both vibrational and hindered rotational models for the transition state. Employing the usual assumption of unit efficiency for gas-wall collisions, the results show that only the rotational model with a temperature-dependent hindrance parameter gives a proper fit to the VLPP data over the entire experimental temperature range. The high-pressure Arrhenius parameters at 1100 K are given by the rate expressions log k2 (sec-1) = (16.2 ± 0.3) - (74.4 ± 1.5)/θ for M2P and log k3 (sec-1) = (16.4 ± 0.3) - (71.4 ± 1.5)/θ for DM2P where θ = 2.303RT kcal/mol. The A factors were assigned from the results of recent shock-tube studies of related alkynes. Inclusion of a decrease in gas-wall collision efficiency with temperature would lower both activation energies by ∼1 kcal/mol. The critical energies together with the assumption of zero activation energy for recombination of the product radicals at 0 K lead to DH0[CH3CCCH(CH3)—CH3] = 76.7 ± 1.5, ΔHf0[CH3CCCH(CH3)] = 65.2 ± 2.3, DH0[CH3CCCH(CH3)—H] = 87.3 ± 2.7, DH0[CH3CCC(CH3)2—CH3] = 72.5 ± 1.5, ΔHf0[CH3CCĊ(CH3)2] = 53.0 ± 2.3, and DH0[CH3CCC(CH3)2—H] = 82.3 ± 2.7, where all quantities are in kcal/mol at 300 K. The resonance stabilization energies of the 1,3-dimethylpropargyl and 1,1,3-trimethylpropargyl radicals are 7.7 ± 2.9 and 9.7 ± 2.9 kcal/mol at 300 K. Comparison with results obtained previously for other propargylic radicals indicates that methyl substituents on both the radical center and the terminal carbon atom have little effect on the propargyl resonance energy.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 283-293 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is assumed that A∞ in the limiting high-pressure unimolecular rate constant expression k∞ = A∞ exp(-Ea∞/kT) is given by A∞ = A″∞eBkT. The test case is the decomposition butane → 2 ethyl, where a negative B reproduces the temperature dependence of A∞ about as well as the previously considered power law A∞ = A′∞(kT)n. It is shown that the term eBkT modifies significantly the high-temperature falloff of the general-pressure rate constant kuni and its various derivatives, and admits of a fairly simple interpretation in terms of Benson's restricted rotor theory. On physical grounds, the exponential law appears more reasonable than the power law.
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  • 23
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 323-323 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 24
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 333-365 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Models for the energy profile along the reaction coordinate are utilized to determine the barrier's height and location as a function of ΔG. These form the basis for structure-reactivity correlations and afford a unified formulation for various postulates in the field of physical organic chemistry. Current experimental evidence is examined for the resulting correlations, and some of their applications as an aid to the chemical kineticist are presented.
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  • 25
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 411-416 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The entropy of activation for the hydrolysis of pentaphenoxyphosphorane in 25% aqueous dioxane is -188 J/mol deg. The enthalpy of activation is 22.5 kJ/mol, which is small for the relatively slow reaction. This suggests that the reaction is a multistep process having a preliminary equilibrium with a negative heat of reaction. This conclusion is supported by the results obtained for the hydrolysis of C6H5[OCH(CF3)2]2. A kinetic isotope effect kH2O/kD2O of 3.46 was found for the latter reaction. Orders in water were obtained, and a mechanism of hydrolysis is proposed.
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  • 26
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 497-501 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A competitive reaction study for two isoelectronic peroxides (peroxodisulfate S2O82- and peroxodiphosphate P2O84-) interacting with the free radical ·Clpar;CH3)2OH is described. The radical formation is initiated by photolysis, the amounts of peroxide remaining analyzed volumetrically. It is found that persulfate reacts with the organic radical over 100 times more rapidly than does perphosphate. Mechanistic consequences in relation to previous work are briefly discussed.
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  • 27
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 13 (1981), S. 527-541 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The decay of photochemically generated tert-butyl radicals in methylcyclopentane solutions containing chloroform is studied by time-resolved ESR spectroscopy. In the pure solvent it perfectly follows the second-order rate law for radical self-termination. Increasing chloroform concentrations cause increasing admixture of a pseudo-first-order decay from which the rate constant of the title reaction is obtained. For 273 K ≦ T ≦ 323 K, \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,{\rm k(}M^{{\rm - 1}}\sec ^{ - 1}) = (8.41 \pm 0.14) - \frac{{8.12 \pm 0.18}}{\theta } $$\end{document} where θ = 2.303RT kcal/mol. CIDNP studies of the reaction mechanism and NMR product yields show H and Cl abstractions to occur with the temperature-independent ratio kH/kCl = 1.4 ± 0.1. The results point to polar effects in the transfer reactions of tert-butyl. The potential of time-resolved ESR spectroscopy in studies of first- and pseudo-first-order reaction rates is discussed.
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  • 28
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    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 29
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    International Journal of Chemical Kinetics 13 (1981), S. 615-625 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The decomposition of cyclobutyl chloride following multiple infraredphoton excitation has been investigated. The primary photolysis products are butadiene, from elimination of HCl, and ethylene and vinyl chloride, fromring scission. The vinyl chloride undergoes secondary decomposition to acetylene and HCl. In addition to these products, known from thermal VLPP experiments, we also find 1-butene, which may arise from a higher energy C—Cl homolysis channel. Collisions with either reactant molecules oradded buffer gas lead to cooling of the laser-produced vibrational energy distributions. The average amount of energy removed per collision is 15-20 kcal/mol for self-collisions and 2-4 kcal/mol with argon.
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  • 30
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    International Journal of Chemical Kinetics 13 (1981), S. 667-675 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The absolute rate constant for the reaction of methyl radicals with ozone has been measured as a function of temperature. Small concentrations of CH3 were generated by flash photolyzing CH3NO2 at 193 nm with an ArF laser. A photoionization mass spectrometer was used to follow the rate of decay of CH3 at various ozone concentrations. The resulting rate constants could be fit by the expressions \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 = (5.4 \pm 1.5) \times 10^{ - 12} \exp [(- 216 \pm 80)/T]{\rm cm}^3 /{\rm molec}\,{\rm s} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 = (2.6 \pm 0.7) \times 10^{ - 12} {\rm (T/300)}^{{\rm 0}{\rm .71} \pm {\rm 0}{\rm .34}} {\rm cm}^3 /{\rm molec}\,{\rm s} $$\end{document} over the temperature range of 243-384 K. These rate constants can be modeled by simple transition state theory using reasonable parameters for the activated complex. Use of this rate constant shows that less than 1% of the methyl radicals formed in the stratosphere react with ozone.
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  • 31
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    International Journal of Chemical Kinetics 13 (1981), S. 693-693 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 32
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    International Journal of Chemical Kinetics 13 (1981), S. 707-728 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction C2H5 + O2 → C2H5O2 in glassy methanol-d4 and the H-atom abstraction by CH3, C2H5, and n-C4H9 radicals in C2H5OH + C2D5OH and CD3CH2OH + C2D5OH glassy mixtures have been studied by electron spin resonance. The analysis of the dependence of the reaction rates on the concentration of O2 (oxidation) and C2H5OH, CD3CH2OH (H-atom abstraction) has shown that the √t law is not conditioned by the existence of regions characterized by different rate constants.
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  • 33
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    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 34
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    International Journal of Chemical Kinetics 13 (1981), S. 799-815 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: H atoms react with C2H5SSC2H5 to give C2H5SH as the sole retrievable product with φ = 2.32 at 25°C and 2.84 at 145°C. The primary reaction is postulated to be H + C2H5SSC2H5 ← C2H5SH + C2H5S with k1 = (4.73 ± 0.64) × 1013 exp [-(1710 ± 69)/RT] cm3/mol·s relative to the rate constant of the H + C2H4 ← C2H5 reaction. The high value of the entropy of activation suggests the presence of partial hydrogen bonding in diethyldisulfide which is broken in the transition state.Ethylmethyldisulfide reacts similarly: H + C2H5SSCH3 ← C2H5SH + CH3S or CH3SH + C2H5S. The thiyl radicals propagate a chain of radical exchange reactions forming the symmetrical disulfides with exposure-time-dependent quantum yields. The overall kinetics conform to a 16-step mechanism from which the rate constants of the elementary reactions could be established by computer modeling. Thiyl radicals react considerably more slowly with disulfides than H atoms.
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  • 35
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    International Journal of Chemical Kinetics 13 (1981), S. 873-881 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CFBr radicals produced by the reaction of atomic oxygen with F2CCFBr were monitored in a discharge flow system by fluorescence excited at 424 nm. The rate coefficients for reactions of the CFBr radicals were measured between 298 and 358 K, and the following values were obtained in units of cm3/molec·s: O2 〈 2 × 10-16 at 353 K; NO 〈 10-14 at 298 K; F2CCFBr 〈 10-15 at 298 K; Cl2 (1.9 ± 0.6) × 10-12 exp(-762 ± 92/T) Br2 (1.4 ± 0.3) × 10-12 exp(-533 ± 62/T).
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  • 36
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    International Journal of Chemical Kinetics 13 (1981), S. 865-872 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Consideration of current information on the dependence of the electron transfer rate on the radial separation distance and on the reactants′ radial distribution function suggests for adiabatic transfers a frequency factor closer to 1012M-1 s-1 than to 1011M-1 s-1. One effect is to raise the λ values estimated from self-exchange rate constants, and to extend thereby the range of ΔG°'s in which the “inverted region′” is masked by a diffusion-controlled reaction rate.
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  • 37
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    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 38
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    International Journal of Chemical Kinetics 13 (1981), S. 125-133 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new method of theoretical prediction of the kinetic rate constants of fast chemical reactions in solutions is presented. It takes into account the effect of finite diffusive displacements of the reacting molecules. The approach is based on the solution of the steady-state Fokker-Planck equation by the moments method of Grad developed in the theory of coagulation of aerosol particles. A comparison of the predicted rate constants with the experimental data provided by Schuh and Fischer for the self-reaction of tert-butyl radicals in n-alkanes shows a good correspondence.
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  • 39
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    International Journal of Chemical Kinetics 13 (1981), S. 317-320 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 40
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    International Journal of Chemical Kinetics 13 (1981), S. 303-316 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate of the reverse reaction of the system has been measured in the range of 584-604 K from a study of the azomethane sensitized pyrolysis of isobutane. Assuming the published value for the rate constant of recombination of t-butyl we obtain \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_{{\rm - 1}} (\sec ^{- 1}) = 14.67 - 39.4\,{\rm kcal}/{\rm mol}/(2.3{\rm RT}) $$\end{document} Combination with our published data for k1 permits the evaluation \documentclass{article}\pagestyle{empty}\begin{document}$$ \log K_1 ({\rm atm}^{ - 1}) = 7.94\,\,{\rm at}\,\,600{\rm K} $$\end{document}We have modified a previously published structural model of t-butyl by the inclusion of a barrier to free rotation of the methyl groups in order to calculate values of the entropy and enthalpy of t-butyl as a function of temperature. Using standard data for H and for i-C4H8 we obtain \documentclass{article}\pagestyle{empty}\begin{document}$$ \Delta H_ f^\circ(t - {\rm butyl},\,300\,{\rm K})({\rm kcal}/{\rm mol}) = 10.6 \pm 0.5 $$\end{document}We have obtained other, independent values of this quantity by a reworking of published data using our new calculations of the entropy and enthalpy of t-butyl. There is substantial agreement between the different values with one exception, namely, that derived from published data on the equilibrium \documentclass{article}\pagestyle{empty}\begin{document}$$ i - {\rm C}_{\rm 4} {\rm H}_{{\rm 10}} + {\rm I}\rightleftharpoons t{-} {\rm C}_4 {\rm H}_9 + {\rm HI} $$\end{document} which is significantly lower than the other values.We conclude that the value \documentclass{article}\pagestyle{empty}\begin{document}$$ \Delta H_ f^\circ(t - {\rm butyl},\,300\,{\rm K})({\rm kcal}/{\rm mol}) = 10.5 \pm 1.0 $$\end{document}obtained from the present work and a reworking of published data which involves the use of experimental data on t-butyl recombination is incompatible with the result based on iodination data.
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  • 41
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    International Journal of Chemical Kinetics 13 (1981), S. 403-410 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rates of pyrolysis of 4-chloro-2-butanone in the gas phase have been determined in a static system seasoned with the products of decomposition of allyl bromide. The reaction is catalyzed by hydrogen chloride. Under maximum catalysis of HCl, the kinetics were found to be of order 1.5 in the substrate suggesting that a complex elimination is involved. The reaction, when maximally inhibited with propene, appears to undergo a unimolecular elimination and follows a first-order law kinetics. The products are methylvinyl ketone and hydrogen chloride. The kinetics have been measured over the temperature range of 402.0-424.4°C.The rate coefficients are given by the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$ \log k_1 (\sec ^{ - 1}) = (13.67 \pm 0.69) - (225.2 \pm 8.6)\,{\rm kj}/{\rm mol}/2.303RT\angle $\end{document}. Thepyrolysis of 4-chloro-2-butanone is 31 times greater in rate than that of ethyl chloride at 440°C. This large difference in rate may be attributed to the -M effect of the acetyl substituent in the pyrolysis of the former halo compound.
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  • 42
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    International Journal of Chemical Kinetics 13 (1981), S. 7-21 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of gaseous neopentyl bromide to 2-methyl-2-butene, 2-methyl-1-butene, and hydrogen bromide was studied under conditions of maximal inhibition by cyclohexene over the temperature range of 389-444°C. This reaction was shown to beconsistent with a first-order homogeneous molecular process, with Arrhenius parameters of E = 247 ± 5 kJ/mol and log A (sec-1) = 14.2 ± 0.3. Examination of the uninhibited reaction showed it to be a radical process, simpler than that with neopentyl chloride, there being only one propagation step, thedissociation of the γ-radical to 1,1-dimethylcyclopropane and a bromine atom.
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  • 43
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    International Journal of Chemical Kinetics 13 (1981), S. 69-84 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of O(3P) atoms with propanehas been studied at temperatures near 300 K by using a discharge flow system. Oxygen atoms were generated in the absence of molecular oxygen by the reaction N + NO → N2 + O, nitrogen atoms having been generated in a microwave discharge. Rate constants for the reaction were measured in two ways, either by measurement of O-atom decay in the presence of excess propane or by measuring the change in propane concentration after an appropriate time in the presence of an excess of oxygen atoms. The two methods were in good agreement, and the mean rate constant at 306 K is given by \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 = (4.7 \pm 0.8) \times 10^6 {\rm dm}^3 /{\rm mol}\;\sec $$\end{document} A study of the products of the reaction under conditions corresponding to complete removal of oxygen atoms has shown that an important product of the reaction in the early stages is propene. This is difficult to explain interms of a mechanism involving alkoxy radicals similar to that which has been proposed for some other O(3P)-hydrocarbon reactions. An alternative mechanism is proposed in terms of successive hydrogen abstraction reactions.
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  • 44
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    International Journal of Chemical Kinetics 13 (1981), S. 119-123 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactivity of amines towards tert-butoxy radicals depends upon the amine ionization potential and the solvent, indicating that polar structures contribute to the reactivity of these compounds. Nevertheless, the dependence with the amine potential is smaller than the one obtained for the quenching of carbonyl excited states by amines and other factors as the strength of the broken hydrogen bond and steric hindrance are also significant in determining the rate of the process.
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  • 45
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    International Journal of Chemical Kinetics 13 (1981), S. 741-753 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of the thermal decomposition of an acetylene-ethane-d6 mixture indicates that the rate constant for hydrogen abstraction from acetylene by methyl is more than 20 times less than for abstraction from ethane. Isotopic exchange is initiated by a rapid reaction between product D atoms and C2H2. A series of experiments involving the reactions of a D2-acetylene mixture indicated that a molecular exchange process was also occurring, and it was shown that d[C2HD]/dt = k[D2]0.7[C2H2]0.3, effective activation energy = 15.8 kcal/mol. This mechanism made an insignificant contribution to isotope exchange in C2H2-C2D6 mixtures.
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  • 46
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    International Journal of Chemical Kinetics 13 (1981), S. 817-831 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl nitrate decomposition is accompanied by self-heating. Using very fine thermocouples, direct measurements of excess temperatures have been made to establish the intensity and extent of self-heating in nonisothermal reaction. The measurements are displayed as contourlines of equal degrees of temperature excess on the pressure-temperature ignition diagram.A twofold kinetic investigation has been made of the overall reaction. One part concentrates on achieving isothermal conditions and full characterization of intermediate products. It uses mass-spectrometric analyses both to establish stoichiometry throughout decomposition and to validate velocity constant measurements derived from continuous pressure-time records. The best value for E = 151 ± 3 kJ/mol is about 10 kJ/mol less than previously.The other part deliberately invades the nonisothermal region to test the qualitative and quantitative predictions of theory (1) that uncorrected reaction orders and activation energies will exceed their isothermal values, (2) that their relative excess (δn/n, δE/E) will be about the same, and (3) that they will be dependent in a simple and predictable way on the reduced excess central temperature.
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  • 47
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    International Journal of Chemical Kinetics 13 (1981), S. 785-786 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 48
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    International Journal of Chemical Kinetics 13 (1981), S. 787-788 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 49
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    International Journal of Chemical Kinetics 13 (1981), S. 833-844 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Arrhenius parameters for the decomposition reactions of various alkoxy radicals are evaluated. The recommended values for tert-butoxy radical decomposition reaction are log A (s-1) = 14.1, Ea = 15.3 kcal/mol. The parameters give reasonably self-consistent results with related rate constants, product distributions of hydrocarbon oxidation reactions, and the values reported in different laboratories in different environments.A reworking of data by Batt et al. on RO + NO and RO + NO2 leads to a lowering of his A factors for these reactions by a factor of 5. It also leads to a similar lowering of the A factors for RO decompositions. The intrinsic activation energies E for the addition of alkyl radicals R to the carbonyl group are not only found to be a function of the exothermicity of reaction, but they are also dependent on the nucleophilicity of the alkyl radicals. For each radical R (Me, Et, i-Pr) the data can be fit to an Evans-Polanyi plot E = a + b (δH), where a uniform slope b = 0.58 can be found for all R. The intercepts a are then found to decrease nearly linearly with the decreasing ionization potential of R, namely, a = 2.1 [IP] - 6.2 (kcal/mol), with the ionization potential given in electron volts.
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  • 50
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    International Journal of Chemical Kinetics 13 (1981), S. 1-6 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Chloro-2-methylpent-2-ene decomposes at temperatures of 370-420°C with initial pressures from 61to 158 torr to yield hydrogen chloride and a mixture of methylpentadiene isomers. In a static system, with seasoned vessel and propene inhibitor, the reaction is homogeneous, unimolecular, and of the first order. The rate coefficient is expressed by the following Arrhenius equation: log k (sec-1) = (13.43 ± 0.30) - (215.0 ± 3.7) kJ/mol/2.303RT. The result ofthe present work additionally supports the participation of the neighboringaliphatic olefinic double bond in the rate of HCl elimination of alkenyl chlorides in the gas phase. Moreover, it also confirms the three-membered conformation as the most favored structure for anchimeric assistance.
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  • 51
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    International Journal of Chemical Kinetics 13 (1981), S. 59-67 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mixture of Br2 + HBr + C2F5I was photolyzed in the vapor phase. The reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Br + C}_{\rm 2} {\rm F}_{\rm 5} {\rm I} \to {\rm IBr + C}_{\rm 2} {\rm F}_{\rm 5} $$\end{document} forms C2F5 radicals which are removed by Competitive studies over the range of 74-146°C gave ratios of k10/k9, and these were combined with values obtained previously by different methods at higher temperatures upto 515°C to give \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log(}k_{10} /k_9) = (- 0.47 \pm 0.03) - (12,500 \pm 300)/\theta $$\end{document} where θ = 2.303RT J/mol. A value is assigned to the activation energy E10, and this, with other data, leads to \documentclass{article}\pagestyle{empty}\begin{document}$$ D{\rm (C}_{\rm 2} {\rm F}_{\rm 5} - {\rm H}) = 429.8 \pm 2.1{\rm KJ}/{\rm mol} $$\end{document} at 25°C. This result is in excellent agreement with two previous independent determinations.
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  • 52
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    International Journal of Chemical Kinetics 13 (1981), S. 97-107 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stoichiometric and, in most cases, absolute rates of coupling of a series of m- and p-substituted benzenediazonium ions with 2,3-dihydroxynaphthalene-6-sulfonate ion (1) have been determined (i) at pH 5.6 (when one OH group is partly monoionized) and (ii) at pH 9.9 (when one OH group is completely ionized and the second slightly so). The rates at both pH values correlate with the σ+ parameter (except for the most reactive ArN2+ at pH 9.9) and the contributions of the two reactive forms of the coupler evaluated. Detailed pH dependences of the coupling rate of the p-chlorobenzenediazonium ion with (1) reveal a strong interaction between (1) and the borate ion, which strongly influences the coupling rate. Coupling rates have also been measured for both diazonium ions and couplers of importance in the diazo reprographic process.
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  • 53
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    International Journal of Chemical Kinetics 13 (1981), S. 187-197 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rates of several novel elementary reactions involving ClO, BrO and SO free radicals in their ground states were studied in a discharge-flow system at 295 K, using mass spectrometry. The rate constant k2 was determined from the decay of SO radicals in the presence of excess ClO radicals: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm SO} + {\rm ClO} \to {\rm SO}_{\rm 2} + {\rm Cl;}} & {k_{\rm 2} = (2.3{\rm } \pm {\rm 0}{\rm .6}) \times 10^{ - 11} {\rm cm}^3 \sec ^{ - 1} } \\ \end{array}$$ \end{document}The SO + OClO overall reaction has a complex mechanism, with the primary step having a rate constant k5 equal to (1.9 ± 0.7) × 10-12 cm3 sec-1: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm SO} + {\rm OClO } \to {\rm SO}_{\rm 2} + {\rm ClO} $$\end{document}A lower limit for the rate constant of the rapid reaction of SO radicals with BrO radicals was determined: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm SO} + {\rm BrO} \to {\rm SO}_{\rm 2} + {\rm Br;}} & {k_{17} } \\ \end{array} \ge 4 \times 10^{ - 11} {\rm cm}^3 \sec ^{ - 1} $$\end{document}
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  • 54
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gamma radiation-induced free radical chain reactions in liquid mixtures of BrCH2CN, eyelohexane (RH), and haloalkanes (XCCl3) were studied. The kinetics of hydrogen and chlorine atom abstraction from CHCl3, CH3CCl3, CH2ClCCl3, CHCl2CCl3, CF3CCl3, C2Cl6, CCl3CN, and CCl4 by CH2CN radicals were investigated by a competitive method. The reactions investigated were Rate constant ratios k3/k2, k5/k6, k7/k2, and k3/k7 were determined at 180°C. In the CCl4—RH—BrCH2CN system k3/k2 was determined in the temperature range of 100-180°C, yielding log k2 k3 = -0.11 ± 0.2 -(3.34 ± 0.39/θ): where θ = 2.3RT in kcal/mol. The value E2—E3 was combined with existing data on E3 to yield E2(CCl4) = 17.57 kcal/mol. The reactivity trend of CH2CN is compared with that of R radicals. It is shown that in spite of a difference of about four orders of magnitude in kCl values, the reactive cyclohexyl radical is somewhat more selective than CH2CN. It is proposed that the relative reactivities log[k2(XCCl3)/k2(CH3CCl3)] can be correlated in terms of a dual-parameter Taft equation which takes into account both resonance and inductive substituent effects.
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  • 55
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    International Journal of Chemical Kinetics 13 (1981), S. 295-301 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The overall rate constant for hydrogen-atom addition to isobutene has been measured in the temperature range of 298-563 K in a flow discharge system coupled to a quadrupole mass spectrometer. Previously published results allow the determination of \documentclass{article}\pagestyle{empty}\begin{document}$$ \log {\rm }k_1 ({\rm cm}^3 /{\rm mol\,\, sec}) = 13.59 \pm 0.11 - 1.79 \pm 0.19\,\,{\rm kcal/mol/(2}{\rm .3}RT{\rm)} $$\end{document} where the error limits are 95% confidence limits.
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  • 56
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    International Journal of Chemical Kinetics 13 (1981), S. 555-564 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of acid catalyzed decomposition of peroxodisulfate, (S2O82-) in aqueous perchlorate medium involves the hydrolysis of the species H2S2O8 and HS2O8- and the homolysis of the species H2S2O8, HS2O8- and S2O82- at the O—O bond. The overall rate law when 1.4M 〉 [HClO4] 〉 0.1M is \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{ - d[{\rm S}_{\rm 2}{\rm O}_8^{2 - }]}}{{dt}}\, = \,k_0 [{\rm S}_{\rm 2}{\rm O}_8^{2 - }]\, + \,k' [{\rm S}_{\rm 2}{\rm O}_8^{2 - }][{\rm H}+]\, + \,k{''}[{\rm S}_{\rm 2}{\rm O}_8^{2 - }][{\rm H}+]^2 $$\end{document}The constants k′ and k″ contain the hydrolysis and homolysis rate constants of HS2O8- and H2S2O8, respectively. With added Ag(I), the acid catalyzed and Ag(I) catalyzed reactions take place independently. Ag(I) catalyzed decomposition appears to involve the species AgS2O8- (aq).
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  • 57
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    International Journal of Chemical Kinetics 13 (1981), S. 543-554 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photolysis of C2H5I in a glassy salt matrix (5M, 7.5M, 10M) of aqueous LiCl at 77 K with light of λ = 254 nm has been conducted, product analysis being by ESR and UV spectroscopy. The electrolytic medium causes the ionization of product HI, and I- concentrations can be continuously determined. During photolysis [I-] is less than the amount of C2H5I decomposed. But after photolysis thaw-freeze cycling is accompanied by progressive growth in [I-] until the yield matches the C2H5I loss, the quantum yields being 0.26, 0.20, and 0.17 for the three LiCl solutions, respectively. The quantum yield of unionized HI is unchanged, however, at around 0.36, the overall change being due to a fall in the extent to which the HI is ionized in the direct photolysis (ø = 0.22, 0.16, and 0.11). It is proposed that this is a consequence of the density increase of matrix packing as the LiCl concentration is increased so that fewer HI are in contact with the aqueous medium and cage recombination is favored.The results establish that the primary reaction is essentially exclusive: and that substantial aggregates of C2H5I exist within which HI are caged and cannot be ionized. The direct reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 2}{\rm H}_{\rm 5}{\rm I}+ h\nu \to {\rm C}_{\rm 2}{\rm H}_5^. + {\rm I}^. $$\end{document} occurs only to a trivial extent, ø; = 10-4, C2H5 arising virtually totally via \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm C}_{\rm 2}{\rm H}_{\rm 4}+ {\rm H}^. \to {\rm C}_{\rm 2}{\rm H}_5^. $$\end{document}
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  • 58
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    International Journal of Chemical Kinetics 13 (1981), S. 577-589 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis kinetics of 4,4-dimethylpent-2-yl acetate, in a static system and in a vessel seasoned with allyl bromide, have been studied in the temperature range of 300-350°C and the pressure range of 48-211 torr. The olefin products were 4,4-dimethylpent-1-ene, cis-4,4-dimethylpent-2-ene, and trans-4,4-dimethylpent-2-ene. The rate coefficient for the homogeneous unimolecular elimination of this ester is given by the following Arrhenius equation: log k(sec-1) = (12.87 ± 0.31) - (181.2 ± 3.4)kJ/mol/2.303RT. The direction of elimination of this acetate has been found to proceed to the formation of the corresponding olefin by kinetic control. The present data, together with other pyrolysis work subject to kinetic control, imply that the direction of elimination of bulky alkyl esters is determined by steric hindrance in the eclipsed cis conformation. However, further analyses reveal that if a series of esters are compared, in the case of a gradual increase of alkyl branching when adjacent to a hydrogen atom (alkyl-H interactions), the rate was determined by steric acceleration, owing to the crowding effect at the highly substituted carbon atom. Otherwise if this gradual alkyl increase in size happened to be adjacent to another alkyl substituent (alkyl-alkyl interactions), the rate was affected by steric hindrance of the eclipsed cis conformation.
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  • 59
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    International Journal of Chemical Kinetics 13 (1981), S. 651-665 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For H-atom abstraction reactions by HO radicals it has been shown that If Di is taken as the C—H bond dissociation enthalpy at 298 K, then a = 0.323 and D0is obtained from the empirical formula \documentclass{article}\pagestyle{empty}\begin{document}$$ D_0 ^{ - 1} = 1.062 \times 10^{ - 2} + 3.52 \times 10^{ - 6} T $$\end{document} where D0 is in kcal/mol and T is in K. Thisrelationship is valid for T between 200 and 400 K. Finally empiricalrelationships are given to help estimate Di.
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  • 60
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    International Journal of Chemical Kinetics 13 (1981), S. 677-691 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bimolecular rate constant for the title reaction has been measured by very-low-pressure reactor techniques at 233 〈 T K 〈 338. The equilibrium constant has also been measured between 253 and 338 K. Our rate constants are in excellent agreement with recent measurements using very different techniques and reaction conditions, and the general agreement probably makes this one of the most accurately measured rateconstants. Transition state models of the reaction rule out a bent TS in favor of a TS with colinear Cl···H···C bonds. The curvature at higher temperatures (〉350 K) is quantitatively accounted for by transition state theory analysis. Tunneling is shown not to play a role. The measured values of K1 allow an experimental value of S° (CH3) to be fixed to only ±2.4 e.u. However, using known values of S° for all species gives ΔH°f298(CH3.) = 35.1 plusmn; 0.1 kcal/mol in excellent agreement with other measured values.
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  • 61
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    International Journal of Chemical Kinetics 13 (1981), S. 735-740 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of NOx-air irradiations, with trace amounts of propane and propene present to monitor OH radical concentrations, have been carried out in a 5800-L evacuable environmental chamber to investigate radical levels and sources during such irradiations. The data obtained show conclusively that unknown radical sources are present, and that photolysis of initial nitrous acid can be, at best, only a minor source of radicals after ∼30-60 min of irradiation.
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  • 62
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    International Journal of Chemical Kinetics 13 (1981), S. 755-770 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of cyclopentyl cyanide has been investigated in the temperature range of 905-1143 K using both conventional stirred-flow reactor and very low-pressure pyrolysis (VLPP) techniques. The results from both techniques are consistent. The main primary processes are HCN elimination to form cyclopentene: and ring fragmentation to form vinyl cyanide plus propylene and ethylene plus cyanopropenes: Under the experimental conditions cyclopentene undergoes further decomposition to cyclopentadiene plus hydrogen. There is evidence for conversion of some of the reactant to a solid residue, presumably polymer. From the stirred-flow reactor results the following Arrhenius expressions were obtained: log k1(s-1) = (12.8 ± 0.3) - (65.6 ± 1.3)/θ and log k2(s-1) = (16.0 ± 0.3) - (80.0 ± 1.1)/θ, where θ = 2.303RT kcal/mol. Application of RRKM theory shows that the VLPP experimental rate constants are consistent with high-pressure Arrhenius parameters given by log k1(s-1) = (12.8 ± 0.3) - (67.8 ± 2.5)/θ for HCN elimination, and log k4(s-1) = (16.3 ± 0.3) - (80.1 ± 2.0)/θ for the sum of the ring fragmentation pathways. The rate parameters for HCN elimination are in good agreement with previous VLPP studies of alkyl cyanides and with theoretical predictions. The difference in activation energies for the ring opening of cyclopentane and cyclopentyl cyanide is reasonably close to the established value for the cyano stabilization energy. This supports the assumption of a biradical mechanism.
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  • 63
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    International Journal of Chemical Kinetics 13 (1981) 
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    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 64
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    International Journal of Chemical Kinetics 13 (1981), S. 23-38 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics and mechanism of the free-radical chain dechlorination of C2Cl6, C2Cl5H, and sym-C2Cl4H2 in Et3SiH wereinvestigated over a wide temperature range. The propagation step of the dechlorination of chloroethanes (C2Clx H6-x) proceeds by the following reactions: Analysis of the temperature dependence of product formation gave the Arrhenius expressions for k4/k3 which in turn were utilized for the estimation of the absolute Arrhenius parameters for hydrogen abstraction from Et3SiH. Our results show that the values of Eabs are lower in Et3SiH than in c-C6H12 by about 2-3 kcal/mol, while the A factors are almost equal. In competitive studies k2 was determined versus Br abstraction from n-C5H11Br. The relative Arrhenius parameters determined by this method show that variations in both A factors and activationenergies are responsible for the reactivity trends observed in the Cl transfer reactions of Et3Si radicals.
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  • 65
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    International Journal of Chemical Kinetics 13 (1981), S. 85-96 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of oxidation of dimethyl, dipropyl, and diphenyl sulfides by pyridinium chloro chromate in chlorobenzene-nitrobenzene mixtures are reported. The rate data show Michaelis-Menten behavior. The oxidation process is catalyzed by the organic acids like dichloro and trichloro acetic acids. The rate-determining step appears to be a unimolecular decomposition of a complex of the reactants.
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  • 66
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    International Journal of Chemical Kinetics 13 (1981), S. 111-118 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constants of peroxy radical recombination in the oxidation of 1-methyl-3-phenylindan, 1,3-dimethyl-3-phenylindan, and 1,1-dimethyl-3-phenylindan were measured using the nonstationary-state technique. A cooxidation method was applied to obtain the reactivities of these compounds with respect to α-phenylethyl peroxy radicals.
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  • 67
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    International Journal of Chemical Kinetics 13 (1981), S. 173-186 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two-parameter equation correlations are reported for radical reactions of aromatic compounds. In these correlations polar and resonance substituent constants identical with the substituent constants of aliphatic compounds were used. The equations correlate the rate constants for H abstraction reactions and for the addition of a variety of free radicals to the ortho-, meta-, and para-substituted aromatic compounds. Besides, they correlate parameters of the spectra for substituted aromatic radicals. The correlations show that the effects of para substituents on the reactions studied are nearly entirely resonance effects, whereas for the meta- and ortho-substituted compounds polar (inductive) effects become essential. Application of the two-parameter correlations permits also to determine the structure of transition states (σ or π-complex) in free-radical reactions.
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  • 68
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    International Journal of Chemical Kinetics 13 (1981), S. 199-207 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Results on the oxidation of N3- by Br2 in neutral and acid media are presented. The rate of the reaction is found to be proportional to [N3-] and [Br2]. The gaseous product of oxidation is found to be pure nitrogen. The stoichiometry of the reaction is \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Br}_2 + 2{\rm N}_{\rm 3}^ - \to 2{\rm Br}^ - + 3{\rm N}_{\rm 2} {\rm ([N}_{\rm 3}^ -]) 〉 [{\rm Br}_2] $$\end{document} The reaction shows a positive salt effect. It is found that the addition of Br- stabilizes the complex BrN3, which decomposes into Br- and N2: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm Br}_2 + {\rm N}_{\rm 3}^ - \rightleftharpoons {\rm BrN}_{\rm 3} + {\rm Br}^ - } \\ {{\rm BrN}_3 + {\rm N}_{\rm 3}^ - \to {\rm Br}^ - + 3{\rm N}_{\rm 2} } \\ \end{array} $$\end{document} The spectroscopic measurements also support the kinetic observation. The equilibrium constant K, the rate constants and the thermodynamic parameters were calculated. It is observed that H+ ion inhibits the reaction. The mechanism is discussed in terms of the kinetic results.
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  • 69
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    International Journal of Chemical Kinetics 13 (1981), S. 245-254 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal unimolecular decomposition of pent-1-yne has been investigated over the temperature range of 923-1154 K using the technique of very low-pressure pyrolysis (VLPP). Under the experimental conditions the reaction proceeds predominantly via a molecular retro-ene pathway to yield allene and ethylene. There was some evidence for the occurrence of the higher energy C3—C4 bond fission pathway at the high end of the temperature range. Interpretation of the data with the aid of RRKM theory and taking into account a decrease in gas-wall collision efficiency with temperature yields the following high-pressure rate constant expression for the retro-ene pathway: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k(\sec ^{ - 1}) = (12.8 \pm 0.4) - (57.0 \pm 2.0)/\theta $$\end{document} at 1100 K where θ = 2.303 RT kcal/mol and the A factor was assigned from the results of shock-tube studies of similar molecules. These rate parameters are independent of the inclusion of the bond fission pathway in the RRKM calculations. The results are compared with previous data on the retro-ene decomposition of alkynes.
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  • 70
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    International Journal of Chemical Kinetics 13 (1981), S. 273-282 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal unimolecular decomposition of hex-1-yne has been investigated over the temperature range of 903-1153 K using the technique of very low-pressure pyrolysis (VLPP). The reaction proceeds via the competitive pathways of C3—C4 fission and molecular retro-ene decomposition, with the latter being the major pathway under the experimental conditions. RRKM calculations, generalized to take into account two competing pathways, show that the experimental unimolecular rate constants are consistent with the high-pressure Arrhenius parameters at 1100 K given by \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k(\sec ^{ - 1}) = (12.7 \pm 0.4) - (56.4 \pm 1.0)/\theta \;\;\;\hbox{for retro-ene} $$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k(\sec ^{ - 1}) = (15.9 \pm 0.3) - (70.7 \pm 2.0)/\theta \;\;{\rm for}\;{\rm C} {-} {\rm C}\,{\rm fission} $$\end{document} where θ = 2.303 RT kcal/mol and the A factors were assigned from the results of recent shock-tube studies of hex-1-yne and related alkynes. The results for C—C fission are consistent with previous VLPP and shock-tube determinations of the propargyl resonance energy, and the parameters for the molecular pathway are consistent with systematic trends for the retro-ene decomposition of unsaturated hydrocarbons.
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  • 71
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    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 72
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    International Journal of Chemical Kinetics 13 (1981), S. 367-384 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The flash photolysis of azo-n-propane and of azoisopropane has been studied by kinetic spectroscopy. Transient absorption spectra in theregion of 220-260 nm have been assigned to the n-propyl and isopropyl radicals. For the n-propyl radical, ∊max = 744 ± 39 l/mol cm at 245 nm and the rate constants for the mutual reactions were measured to be kc = (1.0 ± 0.1) × 1010 l/mol sec (combination) and kd = (1.9 ± 0.2) × 109 l/mol sec (disproportionation). For the isopropyl radical, ∊max = 1280 ± 110 l/mol cm at 238 nm, with kc = (7.7 ± 1.6) × 109 l/mol sec and kd = (5.0 ± 1.2) × 109 l/mol secThe rate constant for the dissociation of the vibrationally excited triplet state of the azopropanes into radicals was measured from the variation in the quantum yield of radicals with pressure. For azo-n-propane kdT = (6.6 ± 1.3) × 107 sec-1, and for azoisopropane kdT = (1.6 ± 0.4) × 108 sec-1. Collisional deactivation of the vibrationally excited singlet and triplet states was found to occur on every collision for n-pentane; but nitrogen and argon were inefficient with a rate constant of 1.1 × 1010 l/mol sec.Spectra observed in the region of 220-260 and 370-400 nm areattributed to the cis isomers of the parent trans-azopropanes. These are formed, as permanent products, in increasing amounts as the pressure is increased.
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  • 73
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    International Journal of Chemical Kinetics 13 (1981), S. 427-432 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions have been studied competitively over the range of 28-182°C by photolysis of mixtures of Cl2 + C2F5I+ CH4. We obtain \documentclass{article}\pagestyle{empty}\begin{document}$$ \log {\rm }k_1 /k_2 = (0.96 \pm 0.06) + (1210 + 440)/\theta $$\end{document} where θ = 2.303RT J/mol. The use of published data on reaction (2) leads to log (k1cm3/mol sec) = (13.96 ± 0.2) - (11,500 ± 2000)/θ.
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  • 74
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants and activation parameters for the isotopic exchange reactions between (PhO)2PSCl and M36Cl (M = Me4N+, Et4N+, n-Bu4N+, Et3HN+, EtH3N+, Li+) in acetonitrile were measured in order to find the effect of the cation nature onthe kinetics of the reaction. The rate constants measured for a range of concentrations of Et3HN36Cl, EtH3N36Cl, and Li36Cl were analyzed using the Acree equation. The equivalent conductance of LiCl in acetonitrile was determined. The nature of the cation has no effect on the mechanism of the reaction. The cation changes only the experimental rate constant proportionally to the dissociation degree of the salt. Smaller values of the rate constant and smaller activation parameters ΔH
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  • 75
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    International Journal of Chemical Kinetics 13 (1981), S. 473-480 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Cl-transfer reaction between CFCl3 and c-C6H11 radicals (R) was studied in liquid cyclohexane (RH). The Arrhenius parameters for Cl abstraction were determined in the RH-CFCl3 system versus the termination reaction between cyclohexyl radicals and competitively versus addition to C2Cl4 in the RH-CFCl3-C2Cl4 system. The two sets of results are in very good agreement and give the following Arrhenius expression for the reaction R + CFCL3 → RCl + CFCl2 (2): \documentclass{article}\pagestyle{empty}\begin{document}$$ \log {\rm }k_2 (1/{\rm mol\, sec}) = 8.95 - 7.79/\theta $$\end{document} where θ = 2.303RT in kcal/mol. Comparison with Cl-transfer data of other chloromethanes and chloroethanes shows that an increase in the C—Cl bond dissociation energy is the main cause of the reduced reactivity of CFCl3. Based on a previously developed correlation, D(CFCl2 — Cl) is estimated to be equal to 74.4 kcal/mol.
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  • 76
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    International Journal of Chemical Kinetics 13 (1981), S. 515-515 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 77
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    International Journal of Chemical Kinetics 13 (1981), S. 517-526 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of gamma-radiation induced free radicals reactions in carbon tetrachloride solutions of cyclohexane, cyclooctane and cyclododecane were studied in the range of 27-190°C. The activation energies found were in the order c—C6H12 〉 c—C12H24 〉 c—C8H16, which was explained as due to their ring strain which has the same order. The following log k1 was obtained using the known Arrhenius parameters for CCl3 radical recombination:
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  • 78
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    International Journal of Chemical Kinetics 13 (1981), S. 565-575 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Detailed measurements on the kinetics and stoichiometry of the oxidation of N-methylformamide and N,N-dimethylformamide by aquosilver (II) ions are reported. Four AgaqII ions are consumed for each amide, and the reaction is first order in [AgaqII] and first order in [amide]. The reaction is inversely dependent on acidity in the range of 1.5-5.0M HClO4. The oxidation rate is independent of [AgI] and ionic strength. The proposed reaction mechanism and activation parameters are compared with those found for the oxidation of amides by other oxidants such as cobalt(III) and manganese(III).
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  • 79
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    International Journal of Chemical Kinetics 13 (1981), S. 603-613 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A special method of electrodialysis has been developed for investigation of the kinetics and mechanism of polymerization reactions involving ions. The ionic composition of homogeneous systems such as Cp2TiRClAlRCl2, RTiCl3 + AlRCl2, Ti(OR)4 + AlR3, and (RLi)n has been studied. The composition of catalytically active ions has been determined. Using the regularities of “open” systems, the methods of determining the carbocation reactivity under electrodialysis conditions havebeen worked out. The impulse electrodialysis method has been suggested for studying ionic polymerization kinetics and evaluating the rate constants ofion reactions with the monomer and gegenion.
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  • 80
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    International Journal of Chemical Kinetics 13 (1981), S. 639-649 
    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 CF3O3CF3 has been investigated in the pressure range of 15-599 torr at temperatures between 59.8 and 90.3°C and also in the presence of CO between 42 and 7°C. The reaction is homogeneous. In the absence of CO the only reaction products are CF3O2CF3 and O2. The rate of reaction is strictly proportional to the trioxide pressure, and is not affected by the total pressure, the presence of inert gases, and oxygen. \documentclass{article}\pagestyle{empty}\begin{document}$$ -\frac{{d[{\rm CF}_{\rm 3} {\rm O}_{\rm 3} {\rm CF}_{\rm 3}]}}{{dt}} = 2\frac{{dp}}{{dt}} = k[{\rm CF}_{\rm 3} {\rm O}_{\rm 3}{\rm CF}_{\rm 3}] $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k = 2.25 \pm 0.18 \times 10^{15} \exp (- 30,530 \pm 130\,{\rm cal}/RT)s^{ - 1} $$\end{document}The following mechanism explains the experimental results: In the presence of CO there appear CO2, (CF3OCO)2, and CF3O2C(O)OCF3 as products. With increasing temperature the amount of peroxicarbonate decreases, while the amounts of oxalate and CO2 increase. The rate of decomposition of the trioxide above a limiting pressure of about 10 torr CO is strictly first order and independent of CO pressure, total pressure, and the pressure of the products. \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm CF}_{\rm 3} {\rm O}_{\rm 3} {\rm CF}_3]}}{{dt}} = k*[{\rm CF}_{\rm 3} {\rm O}_{\rm 3} {\rm CF}_{\rm 3}] $$\end{document} The addition of larger amounts of O2 to the CO containing system chaqnges the course of the reaction.
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  • 81
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    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 82
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    International Journal of Chemical Kinetics 13 (1981), S. 729-733 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of the title compound has been studied in the gas phase in the temperature range of 584-634 K. The decomposition was found to be a first-order homogeneous process yielding 2-methylbuta-1,3-diene and formaldehyde. The rate constants obtained at 11 temperatures within the quoted range fitted the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}k/({\rm s}^{ - 1}) = 14.619 \pm 0.030 - (209.48 \pm 0.35)\,{\rm kJ}\,{\rm mol}^{ - 1} /RT\,\ln \,10 $$\end{document} The decomposition is probably unimolecular and concerted.
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  • 83
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    International Journal of Chemical Kinetics 13 (1981), S. 771-783 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of hydrogen abstraction from cyclohexene by CCl3 radicals were studied in CCl4 solution as a function of cyclohexene concentration and temperature in the range of 26-140°C. The CCl3 radicals were produced both by radiolysis of CCl4 and by photolysis of CCl3Br. The rate constant for the reaction was found to be given by the equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k1(M^{ - 1} s^{ - 1}) = 7.64 - 6.36/\theta $$\end{document} where θ = 2.303 RT kcal/mol. This activation energy leads to C—H bond strength for the allylic hydrogen of 85 ± 1 kcal/mol, which means a resonance stabilization energy of 11 ± 1.5 kcal/mol for the C-C6H11 radical.
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  • 84
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    International Journal of Chemical Kinetics 13 (1981), S. 789-798 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An approximate analytical solution of relaxation in a low-pressure system with exponential transition probabilities is given for vibrational-rotational energy transfer in the dissociation of diatomics. The main assumption is that the rotational degrees of freedom are in thermal equilibrium at all times, and that the barrier to dissociation in the vibrational-rotational plane is linear and asymmetric. The theory is applied to high-temperature dissociations of N2, Br2, and CO in excess argon, with satisfactory agreement with available experimental data.
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  • 85
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    International Journal of Chemical Kinetics 13 (1981), S. 845-854 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A preliminary report is given of relative reactive cross sections for four abstraction reactions H + H′Br ← HH′ + Br with attacking atom (A) H or D, and atom under attack (B) H or D. The pattern of reactive cross sections, as obtained in a crossed molecular beam experiment at a collision energy ET = 7 kcal/mol, indicates Sr(D,H) ≤ Sr(D,D) 〉 Sr(H,H) 〉 Sr(H,D). The atoms in parentheses are A and B. We describe a three-dimensional classical trajectory (CT) study on a potential-energy surface proposed in 1969 by Parr and Kuppermann (PK); the CT results are in fair accord with experiment. It is suggested that (D,H) has the largest cross section because it exhibits the most favorable relative timing of A approach to BC rotation. On the basis of CT it appears that the same sequence of cross sections and the same rationale may be applied to the exchange reactions H + BrH′ ← HBr + H′.
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  • 86
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    International Journal of Chemical Kinetics 13 (1981), S. 883-895 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of formation of primary products from cumene cracking over a partially exchanged LaNaY catalyst have been studied at 400, 450, and 500°C. It has been found that in both the fully and the partially exchanged LaNaY zeolite catalysts the nature of active sites is the same. The higher activity of the fully exchanged catalyst is attributed to a higher concentration of the active sites. It has also been found that an increase in exchange level leads to an increase in the number of both Bronsted and Lewis active sites, but in somewhat different proportions. A comparatively slight increase in the decay rate constant is observed over the same increase in the level of exchange.
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  • 87
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    International Journal of Chemical Kinetics 13 (1981), S. 897-911 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The initial rates of formation of the major products in the thermal reactions of ethylene at temperatures in the neighborhood of 750 K have been measured in the presence and absence of the additive butene-1. It has been shown that this ratio of rates is related to the ratio of rate constants for the two initiation processes: The ratio k′1/k1 has been measured over the temperature range of 700-773 K and may be expressed as (R = 1.987 cal/mol deg) log k′1k1(mol/L) = 2.8 - 4400/2.3RT. Assuming a value for k′1 of log k′1 (s-1) = 16 - 71,500/2.3RT, the value of k1 may be expressed as log k1(L/mol) = 13.2 - 67,000/2.3RT. The values for the frequency factor and activation energy for reaction (1) are discussed in relation to the heat of formation of the vinyl radical, and it is concluded that reaction (1) is the main initiation process in the thermal decomposition of ethylene under the present conditions.
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  • 88
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    International Journal of Chemical Kinetics 13 (1981), S. 913-923 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cell membranes consist of lipid bilayers in which proteins are embedded. Many cell functions are carried out at the cell boundary which interface with water. Here we describe the response to an anesthetic of a lipid bilayer and of an enzyme separately. While both systems are markedly affected by anesthetics at appropriately high concentrations, the result at the clinical concentrations seems best explained as principally an effect on the protein somewhat accentuated by its presence in the lipid bilayer. Thus the lipoprotein complex seems to have the properties of the protein alone, except with somewhat greater induced sensitivity due to the lipid matrix in which it is immersed.
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  • 89
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    International Journal of Chemical Kinetics 13 (1981), S. 945-956 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A phase-shift method has been used to determine the rate constant for the reaction of ground state oxygen atoms with HCl over the temperature range of 330-600 K. Oxygen atoms were generated by modulated mercury photosensitized decomposition of N2O, and monitored by the chemiluminescence from their reaction with NO. After correction for diffusion of oxygen atoms from the viewing zone, the rate constants can be represented by the Arrhenius equation k1 = (3.06 ± 1.43) × 1012 exp[(-3160 ± 184)/T] cm3/mol·s. The indicated uncertainties are 95% confidence limits for 15 degrees of freedom. Also, the third-body efficiency of HCl relative to N2O in the reaction O + NO + M ← NO2 + M was determined to be 1.9 ± 0.2 over the temperature range of 298-360 K.
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  • 90
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    International Journal of Chemical Kinetics 13 (1981), S. 925-944 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experiments are described in which the kinetics of cathodic hydrogen evolution from the unhydrated H3O+ ion in pure CF3SO3- H3O+ are compared with those from an aqueous solution of CF3SO3H where the proton is mainly in a fully hydrated state as H9O4+. From the acid hydrate, which exists mainly as the ionic compound CF3SO3-H3O+, rates of H2 evolution at Ni, Pt, and Hg electrodes, measured at a given overpotential or expressed as exchange current densities, are between about 3.5 and 20 times slower than those from the same electrolyte in dilute (1.0M) aqueous solution. Allowing for the concentration differences in these two types of system and double-layer effects, the rate constants are between about 9.4 and 216 times smaller for the reaction from H3O+ than from H9O4+ at the above electrodes.The evaluation of apparent heats of activation for H2 evolution from the two types of proton sources allows ratios of real frequency factors to be calculated for discharge from H3O+ and H9O4+. These data have a bearing on the theoretical conclusions regarding proton discharge mechanisms and show that frequency factor effects can be as important as activation energy differences in determining the rates of proton discharge from different proton sources.The results are discussed in terms of current ideas about electron and proton transfer in electrochemical reactions, the state of hydration of H+, and the role of discharge from paired CF3SO3- and H3O+ ions. In particular, the molecular mechanics of discharge of the proton from the molecular ion H3O+ can be different from that from the fully hydrated H+ ion where many more HO- vibrational and librational modes can be involved in the process of activation of the H9O4+ entity.
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  • 91
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    International Journal of Chemical Kinetics 13 (1981) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 92
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    International Journal of Chemical Kinetics 13 (1981), S. 957-975 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quasi-classical trajectory calculations have been performed on the H + O2 system. Significant reaction probabilities are obtained when the initial energy is in rotation or vibration, or a combination of the two, but not when the initial energy is in translation. The opacity function shows a bimodal dependence on the impact parameter, with a small peak at 0.9 Å 〈 b 〈 1.5 Å and a very prominent peak at 2.5 Å 〈 b 〈 3.3 Å. The product scattering angles and product energy distributions also depend on b and to a limited extent on the initial energy distribution.The observations can be largely interpreted in terms of the nature of the motion on the potential energy surface, while the effects of rotational energy on the reaction follow qualitatively from statistical phase-space theory.
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  • 93
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    International Journal of Chemical Kinetics 13 (1981), S. 977-999 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nascent vibrational energy distributions of the HF† formed in the reactions of a series of partially fluorinated alkanes (RFH; RF = CH2F, CHF2, CF3, C2F5, C3F7, and C7F15) with electronically excited oxygen atoms O(21D2) have been determined by measuring the appearance times of stimulated emissions from various vibration-rotation transitions in a grating-tuned optical cavity. The vibrational energy contents of the HF formed in these reactions were found to be considerably greater than statistically expected. These reactions are believed to occur via vibrationally excited short-lived α;-fluorinated alcohols (RFOH†), formed by insertion of the O(21D2) atoms into C—H bonds. The observation of nonstatistical energy partitioning in the above reactions is in clear contrast to the result obtained from the O(21D2) + CF3CH3 reaction that produces the β-fluorinated alcohol CF3CH2OH, from which the HF product carries a near statistical vibrational energy distribution. A mechanism for HF† formation in these very exothermic reactions is presented.
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  • 94
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    International Journal of Chemical Kinetics 13 (1981), S. 1001-1010 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of oxidation of thiosulfate to tetrathionate by trans-dihydroxotetraoxoosmate(VIII) in aqueous alkaline media have been studied. The oxidation follows a rate expression \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm Os(VIII})]}}{{dt}} = k3{\rm K}_{OS} {\rm K}_2 [{\rm S}_2 {\rm O}_3^{2 - }][{\rm Os(VIII})](1 + {\rm K}_{os} {\rm K}_2 [{\rm S}_2 {\rm O}_3^{2 - }])^{ - 1} $$\end{document} where KOs is the formation constant of trans-dihydroxotetraoxoosmate (VIII), and K2 and k3, respectively, represent the formation constants of the intermediate complex involving Os(VIII) and S2O32- and its decomposition constant. The KOs, K2, and k3 values have been computed to be (19.5 ± 3) dm3/mol, (6.12 ± 0.5) and (3.32 ± 0.3) × 10-1 dm3/mol s at 303 K, and I = 0.32 mol/dm3, respectively. The rate law is consistent with a mechanism envisaging the equilibrium formation of an intermediate complex involving Os(VIII) and S2O32-, followed by a rate-determining decomposition of the complex with concomitant electron transfer.
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  • 95
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    International Journal of Chemical Kinetics 13 (1981), S. 1011-1028 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between C2H5 and O2 at 295 K has been studied with a flow reactor sampled by a mass spectrometer. With helium as the carrier gas the rate coefficient was found to increase from (1.2 ± 0.3) × 10-12 to (3.6 ± 0.9) × 10-12 cm3/s as [He] was increased from 2 × 1016 to 3.4 × 1017 cm-3. The importance of has been determined from a knowledge of the initial C2H5 concentration together with a measurement of the C2H4 produced in reaction (5). F, the fraction of the C2H5 radicals removed by path (5), was found to decrease from 0.15 to 0.06 as [He] increased from 2 × 1016 to 3.4 × 1017 cm-3. The rate coefficient for reaction (5) was found to be independent of [He] and to have a value of (2.1 ± 0.5) × 10-13 cm3/s. The variation in F reflects the fact that k1b increases as [He] increases. These observations are taken as evidence for a direct mechanism for C2H4 production and a collision-stabilized route for C2H5O2 formation. Calculations indicate that the high-pressure limit for reaction (1b) is ∼4.4 × 10-12 cm3/s and that in the polluted troposphere the branching ratio for reactions (1b) and (5) will be ∼l20.
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  • 96
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    International Journal of Chemical Kinetics 13 (1981), S. 1029-1040 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the cerium(IV) oxidation of p-nitro and p-methoxymandelic acids have been investigated in H2SO4-MHSO4 (M+ = Li+, Na+, K+) and H2SO4-MClO4 (M+ = H+, Na+) mixtures at a constant total electrolyte concentration of 2.00 mol/dm3. The oxidation of p+nitromandelic acid proceeds through two [H+]-independent paths, as was also observed for some substituted mandelic acids studied previously. The kinetic behavior of the p-methoxy derivative differs from that of the other mandelic acids in that (1) the oxidation occurs via two [H+]-dependent paths, (2) the reaction rate is anomalously high, (3) the activation enthalpy and entropy of the overall process are markedly lower. It provides strong support to the suggestion that a different mechanism is operative. The substituent effects and the reaction mechanism are discussed.
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  • 97
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    International Journal of Chemical Kinetics 13 (1981), S. 1041-1050 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash photolysis of CH3CHO and H2CO in the presence of NO has been investigated by the intracavity laser spectroscopy technique. The decay of HNO formed by the reaction HCO + NO → HNO + CO was studied at NO pressures of 6.8-380 torr. At low NO pressure HNO was found to decay by the reaction HNO + HNO → N2O + H2O. The rate constant of this reaction was determined to be k1 = (1.5 ± 0.8) × 10-15 cm3/s. At high NO pressure the reaction HNO + NO → products was more important, and its rate constant was measured to be k2 = (5 ± 1.5) × 10-19 cm3/s. NO2 was detected as one of the products of this reaction. Alternative mechanisms for this reaction are discussed.
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  • 98
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    International Journal of Chemical Kinetics 13 (1981), S. 1051-1070 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theory of collisional energy transfer based on microcanonical relaxation in the limit of infinitesimal collision lifetimes is developed. In distinction to the recently formulated ergodic collision theory the potential energy is now frozen due to the short time scale, and only kinetic energy is available for redistribution. As a consequence, the rate of energy transfer is decreased, and agreement with experimentally based estimates generally improved.
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  • 99
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    International Journal of Chemical Kinetics 13 (1981), S. 1071-1083 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of hot hydrogen atoms originating from 253.7- and 228.8-nm photolyses of hydrogen sulfide with 1-butene was investigated. Of the hydrogen atoms undergoing addition a substantial part undergoes it in a first collision (37 and 48% at 253.7 and 228.8 nm, respectively) yielding highly excited butyl radicals. The ratio of nonterminal to terminal addition is 0.5 and practically does not depend on the energy of the hydrogen atoms over the range of 15-33 kcal/mol. Comparing the results of 229- and 254-nm photolyses of hydrogen sulfide with those of 313- and 334-nm photolyses of hydrogen iodide with the use of the decomposition rate constants of n-butyl radicals calculated by the RRKM methods, the conclusion is reached that the hydrogen atom from H2S photodissociation has 90-95% of the available energy.
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  • 100
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    International Journal of Chemical Kinetics 13 (1981), S. 1101-1103 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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