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  • 1970-1974  (289)
  • Physical Chemistry  (289)
  • 201
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 207-227 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The quantum yields of phosphorescence (Φp) of biacetyl have been determined in pure biacetyl, biacetyl-SO2, and biacetyl-c-C6H12 mixtures in experiments using bands of radiation centered at 3450, 3650, 3880, and 4348 Å. It has been shown that the unexpected effect of gas concentration on the quantum yields of the sulfur dioxide triplet-sensitized phosphorescence of biacetyl resulted largely from the significant destruction of biacetyl triplets at the wall of the cell. The kinetics of the variation of Φp with [Ac2], wavelength of the absorbed light, and added gases provide new estimates of the energy relations and the rate constants for the decomposition reaction of vibrationally rich biacetyl molecules in the first excited singlet state (1Ac2
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 202
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 235-242 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A comparative study of the kinetics of the N-nitrosation of sulfanilamide by cyclohexyl nitrite and by nitrous acid has been made, using an automated technique. The results indicate that a common nitrosating species is effective in analogous reactions involving cyclohexyl nitrite or nitrous acid. The N-nitrosation reaction has been followed spectrophotometrically by coupling the diazotized product with 1-naphthol. Under certain conditions a competitive reaction takes place in which coupling occurs with unreacted sulfanilamide.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
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  • 203
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 243-247 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 204
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 249-252 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 205
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 253-253 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 206
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 207
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 255-264 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An analysis of the atmospheric observations of O2(1δg) in the dayglow and twilight confirms the crude experimental assessments of Brown [1] and the conclusions that can be made from recent work of Westenberg, Roscoe, and DeHaas [2] that the reaction \documentclass{article}\pagestyle{empty}\begin{document}$${\rm H} + {\rm O}_{\rm 2} (^1 \Delta g) \to {\rm OH} + {\rm O}$$\end{document} is relatively slow, much slower than was expected or can be explained easily in theoretical terms. Using a value for the concentration of atomic hydrogen at 85 km, an upper limit rate of 3×10-13 cm3 molecule-1 sec-1 would be compatible with current atmospheric models. An evaluation of the available data for the rates of several reactions involving ground state or electronically excited species, for which the values are reasonably well established, is included to better analyze the general effects of an electronically excited reactant. This further illustrates the unusual slowness of the H + O2(1Δg) reaction.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 208
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 273-276 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Values of the rate constants for allyl-radical abstraction from toluene and allyl-radical recombination have been recalculated in the light of recent data on butene-1 decomposition. The rate of recombination is in good agreement with that found by Van den Bergh and Callear [13] and the cross-combination ratio for the allyl + methyl system has a “normal” value of almost 4. It is concluded that allyl radicals behave like alkyl radicals in respect of their rates of reaction with other radicals.
    Materialart: Digitale Medien
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  • 209
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 210
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 211
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 395-403 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of C2F5 radicals with H2S \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {(2)} & {{\rm C}_{\rm 2} {\rm H}_{\rm 5} + {\rm H}_{\rm 2} {\rm S} \to {\rm C}_{\rm 2} {\rm F}_{\rm 5} {\rm H} + {\rm HS}} & {k_H } \\ \end{array}$$\end{document} was studied over the range 1°-123°C using C2F5 radicals generated by photolysis of perfluoropropionic anhydride. The rate constant kH for reaction (2) is given by \documentclass{article}\pagestyle{empty}\begin{document}$$\log {\rm }k_H ({\rm cm}^{\rm 3} {\rm mole}^{ - 1} \sec ^{ - 1}) = (11.70 \pm 0.19) - (4260 \pm 290)/\theta$$\end{document} where θ = 2.303RT/cal mole-1. The relevance of this result to conflicting published data on the analogous reaction between CF3 radicals and H2S is discussed. It is concluded that there is little difference in the Arrhenius parameters for reaction of CF3 and C2F5 radicals with H2S.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 212
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 405-416 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A metathetical reaction between carbon tetrachloride and toluene to give benzyl chloride and chloroform occurs at temperatures above 200°C (k = 4.8 × 1010 e-32,900/RT cc mole-1sec-1). The reaction does not involve free radicals, as is shown by the kinetic behavior of the system, by the lack of effect of added free-radical chain inhibitors, and by the absence of the expected chain termination product, hexachloroethane. The reaction is one of a general type between carbon tetrachloride and alkanes or alkylaromatics, but at the temperatures required it is often obscured by dehydrohalogenation of the product to the highly reactive olefin. At high temperatures, benzyl chloride reacts with toluene to give bibenzyl and hydrogen chloride, apparently also by a metathetical reaction. The transition state is postulated to be four-center, in which the carbon-chlorine and carbon-hydrogen bonds are broken and reformed: The experimental preexponential factor is in good agreement with that calculated from transition-state theory.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 213
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 449-461 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the “a” and “b” band emissions arising from the 1Σg+ ← 3Ou and 1Σg+ ← 3lu transitions of the diatomic mercury molecule at λmax ∼ 4850 Å and 3350 Å, respectively, have been studied at low concentrations of mercury in the presence of N2, C2H6, C3H8, and N2O. Rate constant values have been obtained for the following reactions of the excimer molecule: Hg2(3lu) + N2 → Hg2(3Ou) + N2 and Hg2(3Ou) + RH → Hg2(1Σg+) + RH, where RH = C2H6 or C3H8. From a consideration of the detailed kinetics of band emissions, it was also possible to derive rate constants for the quenching reactions of Hg(3P0) atoms. These values are in reasonable agreement with those obtained previously from monitoring atom concentrations directly by 4047 Å absorbiometry.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 214
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 463-477 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The self-radiolysis of CO2 in excess tritium (3H2) has been studied at pressures of 0.1 to 1.0 atm, temperatures of -80° to +100°C, and in the presence of added H2O, He, or Ar. The primary products of decomposition are CO and 3H2O. Secondary products are C3H4, C23H4, and a white polymer. The rates of disappearance of CO2 and formation of products and G-;values were measured. The disappearance of CO2 initially obeys first-order kinetics, then slows down with time at a rate depending upon the initial pressure of 3H2. The initial rates are proportional to pressures of CO2 and 3H2. They are independent of temperature, decreased by addition of H2O vapor, and increased by addition of He or Ar. The proposed mechanism of decomposition of CO2 and formation of products involves ionization of CO2 followed by dissociative recombination forming CO and O. Then the O reacts with a hydrogen-containing species forming OH and H2O, and a back reaction forms CO2 from CO and OH.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 215
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 216
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constants (kuni) for the first-order disappearance of the title molecules have been determined under VLPP conditions. The kuni are not the rate constants of ultimate interest since they reflect the fact that energy transfer competes with the chemical decomposition. Use of the Rice-Ramsperger-Kassel-(Marcus) [RRK(M)] theory allows the determination of the high-pressure rate constants (kα), if the mode of decomposition is known. The heats of formation of the radicals NH2, CH3NH, and (CH3)2N are known. These values should be usable for prediction of the activation energy for N—N bond homolysis in the hydrazines. Measured rate constants for UDMH and TMH bear this out, but the rate constant for MMH does not. This and other evidence lead to the conclusion that MMH decomposes via molecular concerted elimination of NH3 and H2 not and by N—N bond scission. The following values are preferred from this work (θ = 2.303RT in kcal/mole). Mode of decomposition is N - N bond scission unless noted otherwise in parenthesis: \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{ll} \underline{{{{\rm Molecule}}}}& \underline{{{{\rm log }k_\infty /\sec ^{ - 1} (298^\circ {\rm K})}}}\\ {{{{\rm MMH}}}}&{{{13.2{\rm - }54/\theta (- {\rm NH}_{\rm 3});}}}\\ {} & {13.5{\rm - }57/\theta (- {\rm H}_{\rm 2})} \\ {{\rm UDMH}} & {17.0{\rm - }63/\theta } \\ {{\rm SDMH}} & {{\rm 13}{\rm .5 - 57/}\theta {\rm (} - {\rm H}_{\rm 2} {\rm)}} \\ {{\rm TMH}} & {{\rm 17}{\rm .4 - 54/}\theta } \\\end{array}$$\end{document}.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 217
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Products of the radical reactions arising from t-Bu2O2, CF3I, and CH3I at 146°C in the vapor phase have been measured over a 33-fold range of CH3I/CH3I ratios and shown to be governed by the rapidly established equilibrium \documentclass{article}\pagestyle{empty}\begin{document}$${\rm Me} \cdot + {\rm CF}_{\rm 3} {\rm I}\mathop {{\rm \rightleftharpoons}}\limits^K {\rm MeI} + {\rm CF}_{\rm 3} \cdot$$\end{document} Together with K estimated by thermochemical methods, the results yield, for the rate of recombination for CF3· radicals, kr = 109.7 ± 0.5 M-1 sec-1.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
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  • 218
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 513-520 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 219
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas phase iodination of cyclobutane was studied spectrophotometrically in a static system over the temperature range 589° to 662°K. The early stage of the reaction was found to correspond to the general mechanism \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} {\rm RH} + {\rm I} \cdot \mathop {{\rm \rightleftharpoons}}\limits^1 {\rm R} \cdot + {\rm HI} \\ {\rm R} \cdot + {\rm I}_{\rm 2} \mathop {{\rm \rightleftharpoons}}\limits^2 {\rm R} - {\rm I} + {\rm I} \cdot \\ \end{array}$$\end{document} where the Arrenius parameters describing k1 are given by log k1/M-1 sec-1 = 11.66 ± 0.11 - 26.83 ± .31/θ, θ = 2.303RT in kcal/mole. The measured value of E1, together with the fact that E-1 = 1 ± 1 kcal/mole, provides ΔHf,2980(c-C4H7.) = 51.14 ± 1.0 kcal/mole, and the corresponding bond dissociation energy, D(c-C4H7—H) = 96.8 ± 1.0 kcal/mole. A bond dissociation energy of 1.8 kcal/mole higher than that for a normal secondary C—H bond corresponds to one half of the extra strain energy in cyclobutene compared to cyclobutane and is in excellent agreement with the recent value of Whittle, determined in a completely different system. Estimates of ΔHf0 and entropy of cyclobutyl iodide are in very good agreement with the equilibrium constant K12 deduced from the kinetic data. Also in good agreement with estimates of Arrhenius parameters is the rate of HI elimination from cyclobutyl iodide.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 220
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 49-60 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pyrolyses of trimethylethylene and tetramethylethylene have been investigated in the presence and absence of nitric oxide. It appears that apart from a unimolecular split, e.g., a disproportionation reaction such as may play an important role in initiation. Nitric oxide had no effect on H2 production, which is probably a molecular process. There was similar behavior of both compounds in the presence of NO, indicating that the olefinic hydrogen atom does not play a decisive role. Other aspects of the mechanisms are discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 221
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The total decomposition rates of the chemically activated alkanes n-butane, n-pentane, isopentane, and neohexane were measured using an internal comparison technique. Chemical activation was by the C—H insertion reaction of excited singlet-state methylene radicals. A total of ten rate constants ranging from 4.6 × 105 to 2.3 × 107 sec-1 were measured for these alkanes at different excitation energies. These rates correlate via RRKM theory calculations with thermal A-factors in the range of 1016.1 to 1017.1 sec-1 for free rotoractivated complex models and in the range of 1016.4 to 1017.8 sec-1 for vibrator-activated complex models. It was found that high critical energies for decomposition, “tight” radical models, and activated complex models with free internal rotations were required to correlate the decomposition rates of these alkanes with estimated alkyl radical recombination rates. The correlation is just barely possible even for these favorable extremes, indicating that there may be a basic discrepancy between the recombination rate and decomposition rate data for alkanes.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 222
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 61-68 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate of the thermal reaction of ethylene to form cyclobutane has been measured over the temperature range 723°-786°K and at pressures between 300 and 1300 torr. The equilibrium constant for the system \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$${\rm 2C}_{\rm 2} {\rm H}_{\rm 4}\mathop {\leftrightharpoons}\limits_{kf}^{kr} c - {\rm C}_{\rm 4} {\rm H}_{\rm 8}$$\end{document} was calculated both from the initial rate data and from measurements of the equilibrium concentration of cyclobutane. Agreement with the reported thermodynamic quantities for cyclobutane was satisfactory. The initial rate data gave the following epxression for kf: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }k_f {\rm (1}{\rm .mole}^{ - {\rm 1}} {\rm sec}^{ - {\rm 1}} {\rm)} = {\rm 7}{\rm .84} - \frac{{43800}}{{2.3RT}}$$\end{document} while the measurements of the equilibrium concentration of cyclobutane gave the expression for K, \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }K{\rm (atm}^{ - {\rm 1}} {\rm)} = - \frac{{45.4}}{{2.3R}} + \frac{{20700}}{{2.3RT}}$$\end{document}.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 223
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 87-102 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate of decomposition of allyl iodide has been measured from 742plusmn;K to 1068±K and from 169 to 1429 torr using a shock tube method in which the disappearance of allyl iodide and the appearance of iodine are followed simultaneously. The kinetics are first order in allyl iodide and probably are slightly dependent upon total pressure. Mathematical modeling shows that they are compatible with a mechanism consisting of three reactions: The experiments yield the rate constant k1, the high-pressure limiting value of which is found to be \documentclass{article}\pagestyle{empty}\begin{document}$$\log _{10} k_\infty (\sec ^{ - 1}) = (14.45 \pm 0.4) - (42.8 \pm 2.4{\rm kcal})/2.3RT$$\end{document} in reasonable agreement with that predicted using the methods of Benson and O'Neal [1].
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 224
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dichloromethane, chlorofluoromethane, and dichlorofluoromethane have been brominated competitively with each other and with chloroform and methyl chloride. Using the literature values for the rates of bromination of these latter two compounds, the rate constants for the three former compounds have been determined: \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} k_2 ({\rm CH}_{\rm 2} {\rm Cl}_{\rm 2} {\rm)} = (9.77 \pm 1.44) \times 10^9 \exp (- 10,860 \pm 480{\rm cal}/RT) \\ k_2 ({\rm CH}_{\rm 2} {\rm F Cl)} = (7.76 \pm 1.59) \times 10^{10} \exp (- 14,800 \pm 800{\rm cal}/RT) \\ k_2 ({\rm CHF Cl}_{\rm 2} {\rm)} = (1.05 \pm 1.48) \times 10^{10} \exp (- 13,300 \pm 570{\rm cal}/RT) \\ \end{array}$$\end{document} where R is taken to be 1.987 cal deg-1 mol-1 (1 cal = 4.186 J).
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 225
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 79-86 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: C2F5 radicals were generated in the presence of benzene vapor by the reaction \documentclass{article}\pagestyle{empty}\begin{document}$$({\rm C}_{\rm 2} {\rm F}_{\rm 5} {\rm CO})_2 {\rm O} + hv \to {\rm CO} + {\rm CO}_2 + 2{\rm C}_{\rm 2} {\rm F}_5 $$\end{document} The radicals react with the benzene by addition and pseudo H abstraction The rate constant kadd for the addition reaction (7) is given by \documentclass{article}\pagestyle{empty}\begin{document}$$\log k_{add} /k_{c^{1/2} } {\rm cm}^{{\rm 3/2}} {\rm mole}^{ - 1/2} \sec ^{ - 1/2} = (4.49 \pm 0.10) - (4210 \pm 150)/\theta $$\end{document} where θ = 2.303RT cal/mole and kc is the rate constant for combination of C2F5 radicals. The addition becomes reversible above 110°C. The reactions of CF3 and C2F5 radicals with benzene vapor are compared.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 226
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 103-116 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the reaction of O + CH3OCH3 were investigated using fast-flow apparatus equipped with ESR and mass-spectrometric detection. The concentration of O(3P) atoms to CH3OCH3 was varied over an unusually large range. The rate constant for reaction \documentclass{article}\pagestyle{empty}\begin{document}$${\rm O} + {\rm CH}_{\rm 3} {\rm OCH}_3 \to {\rm OH} + {\rm CH}_{\rm 2} {\rm OCH}_{\rm 3} $$\end{document} was found to be k = (5.0 ± 1.0) × 1012 exp [(-2850 ± 200/RT)] cm3 mole-1 sec-1. The reaction O + CH3OH was studied using ESR detection. Based on an assumed stoichiometry of two oxygen atoms consumed per molecule of CH3OH which reacts, we obtain a value of k = (1.70 ± 0.66) × 1012 exp [(-2,280 ± 200/RT)] cm3 mole-1 sec-1 for the reaction \documentclass{article}\pagestyle{empty}\begin{document}$${\rm O} + {\rm CH}_{\rm 3} {\rm OH} \to {\rm OH} + {\rm CH}_{\rm 2} {\rm OH}$$\end{document} The results obtained in this study are compared with the results from other workers on these reactions. The observation of essentially equal activation energies in these two reactions is indicative of approximately equal C—H bond strengths in CH3OCH3 and CH3OH. This is in agreement with recent measurements of these bond energies.
    Zusätzliches Material: 4 Ill.
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  • 227
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 228
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 117-126 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas-phase reaction kinetics of 1,1,2-trimethylcyclopropane have been studied in the temperature range of 700-755°K. First-order unimolecular rate constants for over-all reactant disappearance fit the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }k_0 {\rm (sec}^{ - {\rm 1}} {\rm)} = {\rm 14}{\rm .47} - \frac{{61.08 \pm 0.51}}{\theta }$$\end{document} Reaction products and the relative rates of their formation are found to be reasonably consistent with the biradical mechanism.
    Zusätzliches Material: 4 Tab.
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  • 229
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 383-394 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Absolute rate constants for the reaction of S(3P) with ethylene were measured over an ethylene concentration range of 7, a total pressure of 50 to 400 torr, and a flash intensity range of 10. At 298°K, the bimolecular rate constant was found to be invariant over this range of variables and had a measured value of 4.96 × 10-13 cm3 molec-1 s-1. Over the temperature range of 218° to 442°K, the rate data could be fit to a simple Arrhenius equation of the form \documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = (7.13 \pm 0.74) \times 10^{ - 12} {\rm exp}\left({\frac{{{\rm - 1}{\rm .58} \pm {\rm 0}{\rm .08 kcal/mole}}}{{RT}}} \right)$$\end{document} Units are cm3 molec-1 s-1. The dependence of the measured value of k1 on the concentration of the reaction product ethylene episulfide is discussed.
    Zusätzliches Material: 2 Ill.
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  • 230
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 497-512 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The method of chemical difference was utilized to accurately determine the relative importance of all the reaction steps in the direct photolysis of N2O at 2139 Å (25° and 250°C) and 1849 Å (25° C), as well as in the Hg6(1P1)-sensitized photolysis of N2O at 1849 Å (25°C). In all cases, the primary process is predominantly, if not exclusively, \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {{\rm (1)}} & {{\rm N}_{\rm 2} {\rm O} + hv{\rm or H}_{\rm g} 6(^1 P_1) \to {\rm N}_{\rm 2} + {\rm O(}^{\rm 1} D{\rm)}} \\\end{array}$$\end{document} Experiments with trace amounts of C3H6 added showed a slight, but not significant, difference in product ratios (N2 and O2). From these experiments the quantum yield of O(3P) from all possible sources was estimated as 0.02 ± 0.02. Experiments with excess N2 at 1849 Å indicated that O(1S) was not produced in the direct photolysis. The O(1S) yield is probably zero, and certainly 〈0.05. The O(1D) atom can react with N2O via \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} \begin{array}{*{20}c} {{\rm (2)}} & {{\rm O(}^{\rm 1} D{\rm)} + {\rm N}_{\rm 2} {\rm O} \to {\rm N}_{\rm 2} + {\rm O}_2 } \\\end{array} \\ \begin{array}{*{20}c} {{\rm (3)}} & {{\rm O(}^{\rm 1} D{\rm)} + {\rm N}_{\rm 2} {\rm O} \to 2{\rm NO}} \\\end{array} \\ \end{array}$$\end{document} The ratio k2/k3 was found to be 0.69 ± 0.05 in all cases. When combined with other data from our laboratory, the average value is 0.65 ± 0.07. This represents the value for translationally energetic O(1D) atoms. When excess He was added to remove the excess translational energy, k2/k3 rose to 0.83 ± 0.06, which is in reasonable agreement with the value of 1.01 ± 0.06 found in another laboratory. We conclude that for O(1D) atoms with no excess thermal energy, k2/k3 = 0.90 ± 0.10.
    Zusätzliches Material: 4 Tab.
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  • 231
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 521-527 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Rate constants for the reactions of atomic oxygen (O3P) with C2H3F, C2H3Cl, C2H3Br, 1,1-C2H2F2, and 1,2-C2H2F2 have been measured at 307°K using a discharge-flow system coupled to a mass spectrometer. The rate constants for these reactions are (in units of 1011 cm3 mole-1 s-1) 2.63 ± 0.38, 5.22 ± 0.24, 4.90 ± 0.34, 2.19 ± 0.18, and 2.70 ± 0.34, respectively. For some of these reactions, the product carbonyl halides were identified.
    Zusätzliches Material: 1 Ill.
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  • 232
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 541-545 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Pyrolysis of (CF3)2C(OH)CH2CH=CH2, the reverse of the reaction between perfluoroacetone and propene, has been studied in the gas phase between 475° and 598°K. Even at 573°K, the unimolecular reaction rate constant appears to be in its pressure-independent region at 20.0 torr pressure. In a quartz vessel, the decomposition is homogeneous. The specific unimolecular rate constant is \documentclass{article}\pagestyle{empty}\begin{document}$$k = T^{1/2} 10[^{(10.3 \pm 0.10) - (\frac{{40300 \pm 300}}{{4.575T}})}]\sec ^{ - 1}$$\end{document} where the limits are for one standard deviation. Combining these results with the previously reported results on the reverse reaction, the equilibrium constant for the reaction \documentclass{article}\pagestyle{empty}\begin{document}$${\rm C}_{\rm 3} {\rm H}_{\rm 6} + {\rm CF}_{\rm 3} {\rm COCF}_{\rm 3} {\rm \rightleftharpoons(CF}_{\rm 3} {\rm)}_{\rm 2} {\rm C(OH)CH}_{\rm 2} {\rm CH = CH}_{\rm 2}$$\end{document} is \documentclass{article}\pagestyle{empty}\begin{document}$$k_p = 10[^{(1/4.575)(-34.0 \pm 1.0) + (\frac{{18700 \pm 400}}{T})}]atm^{ - 1}$$\end{document} It is noteworthy that in the temperature range of the study of the forward reaction (448° to 573°K), the percentage of back reaction in the times of the experiments varies from less than 0.1 to 1.5. Using group additivities and the above ΔH0, ΔHf0 of (CF3)2CO is calculated to be -325.2 kcal/mole at 600°K and the average C—C bond is 42.0 kcal/mole.
    Zusätzliches Material: 1 Tab.
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  • 233
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 234
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 591-637 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An e×tensive table is given of the Kassel integral \documentclass{article}\pagestyle{empty}\begin{document}$$I(S,B,D) = \Gamma \mathop {(S)}\limits^1 \int_0^\infty {\frac{{x^{S - 1} e^{ - x} dx}}{{1 + 10^D \left({\frac{x}{{B + x}}} \right)^{S - 1} }}}$$\end{document} that occurs in the Rice-Ramsperger-Kassel theory of unimolecular gas reactions.
    Zusätzliches Material: 5 Ill.
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  • 235
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 639-644 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Electron transfer involving triplet molecules of anthraquinone sulfonates has been studied by flash photolysis. It was revealed that semiquinone radicals were formed in one-electron oxidation of carbonate anions. Absorption spectra and the kinetics of decay transients in aqueous and aqueous-alcoholic solutions have been studied.
    Zusätzliches Material: 3 Ill.
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  • 236
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 645-655 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermal decompositions of 1-chloro-1-fluoroethane and 1-chloro-1,1-difluorethane at atmospheric pressure have been studied in the temperature range 500-600°C in a flow system. The dehydrochlorinations are homogenous in a carbonaceous reactor and unimolecular. The rate constants are given by \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm I} = 10^{13.94 \pm 0.05} \exp (- 57,015 \pm 200/RT)^{\sec - 1}$$\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$$k_{{\rm II}} = 10^{14.35 \pm 0.12} \exp (- 60,200 \pm 500/RT)^{\sec - 1}$$\end{document} The criteria for molecular or chain processes in thermal dehydrochlorinations are discussed.
    Zusätzliches Material: 4 Ill.
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  • 237
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 4 (1972), S. 575-589 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of NO2 with C2F4 was studied at 30°, 68°, 114°, and 157°C by in situ monitoring the infrared absorption bands of the products. The major primary products of the reaction are O2NCF2CFO and FNO. Smaller amounts of CF2O (and presumably NO) are also produced. There was no evidence for other primary products, though they may have been produced in minor amounts. The rate laws for the production of both O2NCF2CFO and CF2O are first order in both [NO2] and [C2F4]. CF2O production is at least partly heterogeneous as demonstrated by packing the quartz reaction vessel with Pyrex beads and by using a Monel cell. The homogeneous rate constant obtained from the high-temperature results gives a rate constant of 3.4 × 108 exp (minus;17000/RT) M-1sec-1 for CF2O production. Actually these Arrhenius parameters represent lower limits, since the heterogeneous reaction may still be playing a significant role. The production rate of O2NCF2CFO is not much affected by changing the nature of the surface or the surface to volume ratio. However the reaction may be heterogeneous, since the rate constant for its formation of 1.3 × 104 e×p (-7500/RT) M-1sec-1 has an abnormally low pree×ponential factor. E×periments in the presence of NO indicate that the mechanism for O2NCF2CFO formatlon is \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} \begin{array}{*{20}c} {(11)} & {{\rm NO}_{\rm 2} + {\rm C}_{\rm 2} {\rm F}_{\rm 4} \to {\rm O}_{\rm 2} {\rm NCF}_{\rm 2} {\rm CF}_{\rm 2} } \\ \end{array} \\ \begin{array}{*{20}c} {(12)} & {{\rm O}_{\rm 2} + {\rm NCF}_{\rm 2} {\rm CF}_{\rm 2} + {\rm NO}_{\rm 2} \to {\rm O}_{\rm 2} {\rm NCF}_{\rm 2} {\rm CFO} + {\rm FNO}} \\ \end{array} \\ \end{array}$$\end{document} The intermediate can also react with NO: \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {(13)} & {{\rm O}_{\rm 2} {\rm NCF}_{\rm 2} {\rm CF}_{\rm 2} + {\rm NO} \to {\rm O}_{\rm 2} {\rm NCF}_{\rm 2} {\rm CF}_{\rm 2} {\rm NO}} \\ \end{array}$$\end{document} with k13/k12 = 1.3.
    Zusätzliches Material: 6 Ill.
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  • 238
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rates and products of the reactions of ozone with acetylene, methylacetylene, dimethylacetylene, and ethylacetylene have been studied in a long-path infrared cell at 21 ± 1°C. The gas phase reaction gives products formed by cleavage of the carbon-carbon triple bond. A mechanism is proposed that involves formation of a short-lived acid anhydride intermediate, which is energized by virtue of the reaction exothermicity and undergoes unimolecular decomposition. Formation of an α-dicarbonyl was observed in every case, but there is evidence that a side reaction on the walls accounted for that product. The general relationship between alkyne and alkene ozonation is discussed. The rate measurements showed that, unlike the alkenes, the rate of alkyne ozonation is not greatly affected by substitution with simple alkyl groups. The rate constant for C2H2 agrees with earlier work and thus provides additional support for the previously derived high A-factor for acetylene ozonation relative to alkenes.
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  • 239
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 240
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 197-213 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The pyrolysis of neopentane, at small extents of reaction, was studied by gas chromatography, in Pyrex reaction vessels between 450° and 530°C and in the initial pressure range 25-200 mm Hg. At initial time, this thermal decomposition can be essentially represented by a homogeneous long-chain radical mechanism. The rate constant of the unimolecular initiation process is approximately given by the expression \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm 0} \simeq 10^{13} {\rm exp}\left({\frac{{50,000}}{{RT}}} \right){\rm mole}^{- {\rm 1/2}} {\rm .ml}^{- {\rm 1/2}} {\rm .s}^{- {\rm 1}}$$\end{document} The initial rate constant of the global reaction (order 3/2) is nearly equal to \documentclass{article}\pagestyle{empty}\begin{document}$$k_{\rm 1} + 10^{16.8} {\rm exp}\left({\frac{{82,000}}{{RT}}} \right){\rm s}^{- {\rm 1}}$$\end{document} This reaction is strongly inhibited by propene or isobutene and self-inhibited by the isobutene formed; an interpretation of all these inhibition phenomena of the neopentane pyrolysis is proposed. Our observations and conclusions, which have been summarized in communications during 1968 and 1969, are compared to those of other authors, particularly to the recent ones of Purnell and colleagues [13] and of Taylor and colleagues [14], [15].
    Zusätzliches Material: 7 Ill.
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  • 241
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 491-499 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Methods of linear algebra are applied to (a) the problem of determining whether detailed balancing for some or all stages of a chemical process is implicit from the existence of steady state for some or all of the chemical species involved, and (b) the formulation of general concentration-type equilibrium relationships solely from kinetic considerations and the assumption of full detailed balancing.
    Zusätzliches Material: 1 Ill.
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  • 242
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 501-508 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ozone was photolyzed at room temperature in the presence of N2O at 2537 Å and 2288 Å to produce O(1D) atoms. These atoms can react with either O3 or N2O via From the quantum yield of N2, the relative rate constants k6a/k6 and k2/k6 could be obtained, where k6 + k6a + k6b. The former rate constant ratio was found to be 0.37 ± 0.03 at 2537 Å and 0.33 ± 0.03 at 2288 Å, in good agreement with an earlier report from our laboratory. The ratio k2/k6 was found to be 2.6 at 2537 Å, but 4.1 at 2288 Å. The difference in the two numbers, if real, may reflect differences in reactivity due to different amounts of excess translational energy in the O(1D) atom at the two wavelengths.
    Zusätzliches Material: 3 Ill.
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  • 243
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 553-554 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 244
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 523-534 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Disproportionation-combination ratios have been obtained for small alkyl radicals produced in the mercury-photosensitized hydrogenation of ethylene, propylene, butene-1, butene-2, and isobutene. For conditions favoring thermalized radicals, kd/kc (ethyl, ethyl) = 0.14, kd/kc (isopropyl, isopropyl) = 0.69, kd/kc (isopropyl, n-propyl) = 0.41, kd/kc (2-butyl, 2-butyl) = 0.77, kd/kc (2-butyl, n-butyl) = 0.45, and kd/kc (t-butyl, t-butyl) = 3.1. The results are consistent with kd/kc (n-propyl, n-propyl) = 0.15 and kd/kc (n-butyl, n-butyl) = 0.14. The general agreement between these disproportionation-combination ratios and those obtained where photolytic radical sources have been used indicates that under appropriate conditions, H atom addition to olefins is a suitable source for the study of thermalized alkyl radicals and may be especially useful for larger alkyl radicals for which clean photolytic precursors are not available.
    Zusätzliches Material: 4 Ill.
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  • 245
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 535-551 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The disproportionation-combination reactions of radicals 4,4-dimethylpentyl-2 and 2,4-dimethylpentyl-2, produced by collisional stabilization of the respective chemically activated species, have been studied at 298°K, with and without getter radicals. Use of getters t-C4H9 and C2H5 with 4,4-dimethylpentyl-2, and of iso-C3H7 with 2,4-dimethylpentyl-2 yielded disproportionation-combination ratios ω for parent-getter and t-C4H9-C2H5 cross reactions, and for the mutual reaction of t-C4H9 radicals. The unstabilized hot radicals decompose, and these experiments also yielded values for the high-pressure rate constant ka∞ of 1.70 × 108sec-1 and 2.11 × 107sec-1 for 4,4-dimethylpentyl-2 and 2,4-dimethylpentyl-2, respectively. The results, compared to those for other large alkyl radical systems obtained earlier, suggest that steric effects influence the accessibility of H atoms for transfer.
    Zusätzliches Material: 1 Ill.
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  • 246
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas phase reactions of PhCOOCH3 with I2 and Br2 were studied spectrophotometrically in a static system over the temperature ranges 344-359° and 246-303°, respectively. For each system the initial rate was first order in PhCOOCH3 and half order in halogen as the concentration of PhCOOCH3 was varied from 1.4 to 15.2 torr, that of I2 from 6.2 to 26.4 torr, and that of Br2 from 3.0 to 13.6 torr. The rate-determining step is the extraction of a methoxyl hydrogen atom: Empirical assignment of A-factors for k1 lead to \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log(k}_{\rm 1} {\rm /M}^{- {\rm 1}} {\rm sec}^{- {\rm 1}} {\rm) = (11}{\rm .5} \pm {\rm 0}{\rm .3)} - (29.9 \pm 0.8)/\theta $$\end{document} for the I2 system, and to \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log(k}_{\rm 1} {\rm /M}^{- {\rm 1}} {\rm sec}^{- {\rm 1}} {\rm)} = {\rm (11}{\rm .3} \pm {\rm 0}{\rm .3)} - (14.6 \pm 0.8)/\theta $$\end{document}for the Br2 system, where φ = 2.303RT in kcal/mole. Combined with the assumption that E-1 = 1 ± 1 kcal/mole and 2 ± 1 kcal/mole for HI and HBr, respectively, DH2980 (PhCOOCH2—H) calculated from the two systems shows excellent agreement at 100.2 ± 1.3 kcal/mole and 100.1 ± 1.3 kcal/mole. Using a value of δHf,2980 (PhCOOMe) = -65.6 ± 1.5 kcal/mole obtained from group additivity estimates, δHf,2980 (PhCOOCH2) is calculated to be -16.7 ± 2.0 kcal/mole. Unimolecular decomposition of the Ph(CO)O°CH2 radical was also observed: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Ph}\left( {{\rm CO}} \right){\rm O\dot CH}_{\rm 2} \mathop {\hbox to 20pt{\rightarrowfill}}\limits^3 {\rm Ph\dot CO} + {\rm H}_{\rm 2} {\rm CO} $$\end{document} with a rate constant equal to \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log(}k_{\rm 3} {\rm /sec}^{- {\rm 1}} {\rm)} = {\rm (15} \pm {\rm 0}{\rm .5)} - (26 \pm 3)/\theta $$\end{document} The abnormally high methoxyl C—H bond strength is discussed in relation to the bonding in ethers, alkanes, and esters.
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  • 247
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A critical evaluation of the rates of the dissociation and recombination reactions of fluorine and chlorine is given. Data are presented graphically and in tabular form. The effect of various third bodies is discussed. Rate expressions for specified temperature ranges are recommended, while comparison with theoretical values obtained from the Benson and Fueno theory is made where applicable.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 248
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 69-84 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The photolysis of 1,1,3,3-tetrafluoroacetone has been reinvestigated as a source of CHF2 radicals at temperatures up to 578°K, and the following rate constant ratio was determined for the reactions θ= 2.303 RT in kcal/mole. 1,1-Difluoro- and 1,1,3,3-tetrafluoroacetone were photolyzed in the presence of tetramethylsilane, and Arrhenius parameters were measured for the hydrogen abstraction reactions: R + Me4Si → RH + Me3SiCH2 TextRT(°K)E (kcal/mole)log A (mole-1cc sec-1)log k (500°K) (mole-1cc sec-1)CH2F473-58612.00 ± 0.3011.68 ± 0.126.44CHF2416-52610.18 ± 0.3311.65 ± 0.157.21By comparing with previous data on the CH3 and CF3 reactions, the activation energies were interpreted in terms of the enthalpy changes for the reactions and a polar effect operative between the attacking fluoromethyl radicals and the substrate which tends to reduce the activation energy progressively as the fluorine content of the radical increases. This polar effect, which decreases the activation energy for hydrogen abstraction from SiMe4 along the series CH3, CH2F, CHF2, and CF3, is in marked contrast to the polar repulsion between the fluorinated radicals and SiHCl3 which was tentatively proposed to explain the increase in activation energy observed in the same series of reactions with SiHCl3.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 249
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 89-96 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Long-chain chlorine-photosensitized oxidation has been observed in the gas phase at about 355°K for 1,1,2,2- and 1,1,1,2-C2H2Cl4, C2HCl5, and C2Cl4 but not for C2H6, 1,2-C2H4Cl2, 1,1,1-C2H3Cl3, C2H4, and 1,2-C2H2Cl2. This is shown to depend on the exothermicity of the dissociation of the chloroethoxy radicals which must be involved in each reaction system.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
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  • 250
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 251
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 85-88 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas phase thermal isomerization of 1,2-bis(trimethylsiloxy)cyclobutene has been studied in the temperature range 172°-204°C. The reaction is homogeneous, kinetically first order, and yields 2,3-bis(trimethylsiloxy)buta-1,3-diene as the only product. The rate constants fit the Arrhenius equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {k = 10^{13.509 \pm 0.120} \exp \left( {{{ - 148,920 \pm 1060\,{\rm J}\,{\rm mole}^{ - 1} } \mathord{\left/ {\vphantom {{ - 148,920 \pm 1060\,{\rm J}\,{\rm mole}^{ - 1} } {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right)\sec ^{ - 1} } \hfill \\ {\left[ {k = 10^{13.509 \pm 0.120} \exp \left( {{{ - 35,590 \pm 250\,{\rm cal mole}^{ - 1} } \mathord{\left/ {\vphantom {{ - 35,590 \pm 250\,{\rm cal mole}^{ - 1} } {RT}}} \right. \kern-\nulldelimiterspace} {RT}}} \right)\sec ^{ - 1} } \right]} \hfill \\ \end{array}$$\end{document} These results, taken with those obtained previously, demonstrate the insensitivity of the kinetics of the reaction to the nature of the groups substituted on the 1- and/or 2-positions of the cyclobutene ring.
    Zusätzliches Material: 1 Tab.
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  • 252
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 269-282 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The photolysis of pure N2O, N2O and N2, and N2O and C3H6 mixtures at 1470 Å and room temperature has been studied to determine the relative importance of the primary processes. The results are where φ{O(1D)} = 0.515 represents both the O(1D) produced in the primary act and that produced by collisional quenching of O(1S); φ{N2(3Σ)} = 0.084 represents only that portion of N2(3φ) which dissociates N2O on deactivation; and φ{O(1S)} = 0.38 - ±{N(2D)} represents only that portion of O(1S) which enters into chemical reaction with N2O. If the reaction of O(1S) with N2O yields only N2 and O2 as products, which seems likely from potential-energy curve considerations then ±{O(1S)} = 0.135 ± 0.06 and φ{N(2D)} = 0.245 ± 0.06. Young and coworkers [4] have found from spectroscopic observations that the total quantum yield of O(1S) is about 0.5. Thus it can be concluded that collisional removal of O(1S) by N2O yields mainly O(1D) with chemical reaction being less important. Furthermore, most of the O(1D) is produced this way, and the true primary yield of O(1D) is about 0.15. The metastable N(2D) is not deactivated by N2O, but is removed by chemical reaction to produce N2 and NO. The results further indicate that N2(3Σ) dissociates N2O at least 80% of the time during quenching. The relative efficiency of N2O compared to N2 is about 2 for the removal of O(1D). O(1S) is removed about 90 times as efficiently by C3H6 as by N2O.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 253
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 283-289 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas phase photolysis of CCl4 in the presence of several alkanes has been used to obtain Arrhenius parameters for the abstraction of hydrogen atoms by the CCl3 radical: The following log k4 values were obtained: TextRHlog k4c-C5H10,\documentclass{article}\pagestyle{empty}\begin{document}$$12.00 \pm 0.21 - \frac{{10,700 \pm 400}}{{2.3RT}}$$\end{document}n-C6H14\documentclass{article}\pagestyle{empty}\begin{document}$$11.81 \pm 0.18 - \frac{{10,800 \pm 300}}{{2.3RT}}$$\end{document}2,3-Dimethylbutane\documentclass{article}\pagestyle{empty}\begin{document}$$10.88 \pm 0.11 - \frac{{8,200 \pm 200}}{{2.3RT}}$$\end{document}c-C7H14\documentclass{article}\pagestyle{empty}\begin{document}$$12.07 \pm 0.43 - \frac{{9,900 \pm 800}}{{2.3RT}}$$\end{document}Methylcyclohexane\documentclass{article}\pagestyle{empty}\begin{document}$$11.75 \pm 0.26 - \frac{{9,900 \pm 500}}{{2.3RT}}$$\end{document}c-C8H16\documentclass{article}\pagestyle{empty}\begin{document}$$12.11 \pm 0.29 - \frac{{9,600 \pm 500}}{{2.3RT}}$$\end{document}The results are compared to those for CH3 and CF3 radicals.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 254
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 255
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 293-305 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The photolysis of CD2CO at 313 nm in the presence of neopentane was carried out over the temperature range 576-706 K. Analysis of the products and isotopic analysis of the methanes demonstrate abstraction of H from neopentane and D from CD2CO by methylene. The relative kinetics of abstraction of H and D have been measured over the temperature range, and the absolute value for the collision yield of the abstraction of H from neopentane by CD2 at 653 K has been been estimated to be about 1.5 × 1011 mole-1 cm3 sec-1, a value 103 times larger than the corresponding reaction of CH3.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 256
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 307-317 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Hydrogen abstraction from boron trimethyl has been studied using the abstracting radicals CF3 and CD3, from the photolysis of the corresponding ketones over the temperature range of 150° to 300°C. The following Arrhenius parameters were obtained: \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} {\rm (CD}_{\rm 3} {\rm + BME}_{\rm 3} {\rm); log }A{\rm = 11}{\rm .8, }E{\rm = 9}{\rm .98 kcal/mole} \\ {\rm (CF}_{\rm 3} {\rm + BMe}_{\rm 3} {\rm); log }A{\rm = 11}{\rm .6, }E{\rm = 6}{\rm .59 kcal/mole} \\ \end{array}$$\end{document} The difference ECD3 - ECF3 in the case of BMe3 is considered due, in part, to polar effects. An exchange reaction is proposed for both CF3 and CD3 in collisions with BMe3: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm R} + {\rm B}({\rm Me})_3 \to {\rm Me} + {\rm RBMe}_2$$\end{document} Radical combination of CF3 and CH2BMe2 leads to a hot molecule which undergoes a β-fluoro rearrangement elimination process, or a stabilized molecule which can thermally decompose:
    Zusätzliches Material: 1 Ill.
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  • 257
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 319-341 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The mercury-photosensitized oxidation of CO was studied at 275°C over a wide range of [O2]/[CO] ratios in the absence and presence of the oxygen atom scavenger 2-trifluoromethylpropene (TMP) and at 25°C at low [O2]/[CO] ratios in the presence of TMP. By following the quantum yield of CO2 production, Φ {CO2}, as a function of the [O2]/[CO] ratio, the reactions of vibrationally excited CO (v υ 9) and electronically excited O2, probably in the c1Σ-u state, were studied. At low [O2]/[CO] ratios the predominant reactions are of vibrationally excited CO (v υ 9). Relative rate constants for chemical reaction versus deactivation of CO (v υ 9) were obtained. At higher [O2]/[CO] ratios, the principal reactions are of electronically excited O2. Relative rate constants for chemical reactions and deactivation of this electronically excited O2 with CO, O2, and TMP were obtained. From the effect of total pressure on Φ {CO2}, it is proposed that an intermediate CO3 is formed in the reaction of electronically excited O2 with CO.
    Zusätzliches Material: 7 Ill.
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  • 258
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 343-357 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Rate constants for the tri-n-butyltin radical (Sn ·) induced decomposition of a number of peroxides have been measured in benzene at 10°C. The values range from ∼100 M-1 sec-1 for di-t-butyl peroxide to 2.6 × 107 M-1 sec-1 for di-t-butyl diperoxyisophthalate. The majority of the peroxides, including diethyl peroxide, diacetyl peroxide, and t-butyl peracetate, have rate constants of ∼105 M-1 sec-1. It is shown that di-n-alkyl disulfides are ten times as reactive toward Sn · as di-n-alkyl peroxides, although the exothermicities of these reactions are ∼15 and ∼39 kcal/mole, respectively. The enhanced reactivity of the disulfides is attributed to the easier formation of an intermediate or transition state with 9 electrons around sulfur, compared with an analogous species with 9 electrons around oxygen.The following bond strengths (kcal/mole) have been estimated: D[Sn—OR] = 77; D[Sn—H] = 82; D[Sn—SR] = 83; and D[Sn—OC(O)R] = 86, where R = alkyl. Rate constants for reaction of Sn · with some benzyl esters have also been measured. It has been found that t-butoxy radicals can add to benzene and abstract hydrogen from benzene at ambient temperatures.
    Zusätzliches Material: 3 Tab.
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  • 259
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 375-376 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 260
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate of the gas phase reaction \documentclass{article}\pagestyle{empty}\begin{document}$$\Delta - {\rm CH}_{\rm 2} - {\rm I + I} \cdot {\rightleftharpoons}\Delta - {\rm CH}_{\rm 2} \cdot + {\rm I}_{\rm 2}$$\end{document} has been measured spectrophotometrically over the range 480°-550°K. The rate constant fits the equation \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}k{\rm (M}^{- {\rm 1}} {\rm sec}^{- {\rm 1}} {\rm)} = {\rm (11}{\rm .4} \pm {\rm 0}{\rm .1)} - (16.8 \pm 0.2)/\theta$$\end{document} where θ = 2.303RT in kcal/mole. This result, together with the assumption that the activation energy for the back reaction is 0 ± 1 kcal/mole, allows calculation of DH0298 (Δ—CH2—H) = 97.4 ± 1.6 kcal/mole and ΔH0f 298 (Δ—CH2·) = 51.1 ± 1.6 kcal/mole. These values correspond to a stabilization energy of 0.4 ± 1.6 kcal/mole in the cyclopropylcarbinyl radical.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 261
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 379-380 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 262
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 377-378 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 263
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 264
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 381-383 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 265
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 395-410 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The orientation of addition of H atoms to the asymmetric olefins propylene, butene-1, and isobutene has been determined as a function of atom concentration, olefin concentration, hydrogen pressure, total pressure, and olefin conversion. Conditions have been determined for which complicating secondary processes are believed to be unimportant. The percentage of nonterminal addition is 5.7, 5.7, and 0.48 for propylene, butene-1, and isobutene, respectively. From these data activation energy differences between nonterminal and terminal addition of 1.7 and 3.2 kcal/mole for the linear olefins and isobutene, respectively, may be calculated. For D atom addition to propylene, a small isotope effect was observed, nonterminal addition being 5.4%. These observations are consistent with a predominantly free radical or electroneutral character for H atoms.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 266
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In 1958, Bartlett and Hiatt [1] suggested that the number of bonds which are rotationally “frozen” at the transition state for decomposition of peresters can be determined from the magnitude of the values of ΔH
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 267
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 411-426 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The decomposition rate constant of i-PrI under conditions of very low-pressure pyrolysis (VLPP) is completely consistent with the well-known high-pressure Arrhenius parameters and the RRK(M) theory. The decomposition of n-PrI under the same conditions proceeds via two pathways, the anti-Markownikoff dehydroiodination and C—I bond scission. The data, analyzed by taking into account the mutual interaction of the two pathways, is completely consistent with the known Arrhenius parameters for the bond scission step and, when combined with a reasonable A-factor, yields an activation energy for HI elimination which is as predicted for these semi-ion pair transition states.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 268
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 427-441 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the thermal elimination of HF from 1,2-difluoroethane \documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_{\rm 2} {\rm FCH}_2 {\rm F} \to {\rm CH}_{\rm 2} = {\rm CHF} + {\rm HF}$$\end{document} have been studied in a static system over the temperature range 734-820°K. The reaction was shown to be first order and homogeneous, with a rate constant of \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log }k_2 ({\rm s}^{- {\rm 1}} {\rm)} = {\rm 13}{\rm .39} \pm {\rm 0}{\rm .2} - (62.9 \pm 0.9)/\theta$$\end{document} where θ = 2.303RT in kcal/mole. The A-factor falls within the normal range for such reactions and is in line with transition state theory; the activation energy is similarly consistent with an estimate based on data for the analogous reactions of ethyl fluoride and other alkyl halides. The above activation energy has been compared with values of the critical energy calculated from data on the decomposition of chemically activated 1,2-difluoroethane by the RRKM theory and the bond dissociation energy, D(CH2F—CH2F) = 88 ± 2 kcal/mole, derived. It follows from thermochemistry that ΔHf0(CH2F) = -7.8 and D(CH2F—H) = 101 ± 2 kcal/mole. Bond dissociation energies in fluoromethanes and fluoroethanes are discussed.
    Zusätzliches Material: 4 Ill.
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  • 269
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 443-452 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The kinetics of the gas phase decomposition of 1,2-epoxy-2-methylpropane has been studied over the temperature range 377°-436°C at pressures between 5.3 and 61.6 torr. Isomerization reactions to give isobutyraldehyde, isopropenyl methyl ether, and 2-methyl-prop-2-en-l-ol account for over 95% of the epoxide decomposition. These isomerizations are homogeneous first-order, nonradical processes: \documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} k({\rm isobutyraldehyde)} = {\rm 10}^{{\rm 13}{\rm .32} \pm {\rm 0}{\rm .18}} \exp (- 52720 \pm 570/1.987T)\sec ^{- 1} \\ {\rm}k({\rm isopropenyl methyl ether)} = {\rm 10}^{{\rm 13}{\rm .55} \pm {\rm 0}{\rm .47}} \exp (- 56140 \pm 1460/1.987T)\sec ^{- 1} \\ {\rm}k({\rm 2 - methyl - prop - 2 - en - l - ol)} = {\rm 10}^{{\rm 11}{\rm .53} \pm {\rm 0}{\rm .67}} \exp (- 49680 \pm 2080/1.987T)\sec ^{- 1} \\ \end{array}$$\end{document}
    Zusätzliches Material: 3 Ill.
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  • 270
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 271
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971) 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 272
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 15-23 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: During methane oxidation initiated by nitric acid or nitrogen dioxide, it is possible to observe, under certain conditions of temperature, initiator content, and flow rates, the formation of an adiabatic “temperature peak.” Because the maximum temperature of the peak does not exceed the initial temperature of the reactor by more than 220°C, the recorded temperature-increase curves were used for a kinetic interpretation. The obtained kinetic parameters (overall n and E) agree with the values reported in the literature for isothermal methane oxidation and suggest that the overall mechanism does not change in the conditions of “temperature peak.”
    Zusätzliches Material: 8 Ill.
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  • 273
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 25-37 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A study of the structural isomerization rate of chemically activated 1,1-dimethylcyclopropane from singlet methylene addition to the double bond of isobutene is reported. Singlet methylenes were produced from the 4358- and 3660-Å photolysis of diazomethane in the presence of added oxygen. Theoretical rates calculated via RRKM theory are in excellent agreement with experiment for calculations utilizing activated complex structures and critical energies consistent with known thermal Arrhenius parameters, and excitation energies consistent with previous determinations of ΔHf00(CH2) + E*(CH2) = 116.1 and 112.6 kcal/mole for diazomethane photolyses at 3660 and 4358 Å, respectively.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 274
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 1-14 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The photolyses of 1,3-difluoro- and 1,1,3,3-tetrafluoroacetone have been reinvestigated as sources of fluoromethyl radicals, and the following rate constant ratios were determined θ= 2.303 RT in kcal/mole. The results are in substantial agreement with the original investigations. The photolyses of the fluoroacetones were used as sources of CH2F and CHF2 radicals, and the following Arrhenius parameters were obtained for the hydrogen abstraction reactions R + SiHCl3 → RH + SiCl3: TextRT(°K)E (kcal/mole)log A (mole-1 cc sec-1)log k (400°K) (mole-1 cc sec-1)CH2F335-4436.06 ± 0.1510.79 ± 0.087.48 CHF2CHF2334-4426.82 ± 0.0911.32 ± 0.057.59The rates of reactions of CH2F and CHF2 radicals toward hydrogen abstraction from SiHCl3 are an order of magnitude lower than the corresponding rates for the CH3, C2H5, and CF3 radicals as a result of increased activation energies for the CH2F and CHF2 reactions. The interpretation of the results is hindered by a lack of accurate thermochemical data on the radicals. The activation energies, as they stand, can be rationalized in terms of a polar repulsion between SiHCl3 and the radicals, increasing regularly and leading to a progressive increase in activation energy with increasing fluorine substitution in the radical. This interpretation is consistent with the estimates D(CH2F—H) ∝ D(CHF2—H) ∝ 97 kcal/mole. On the other hand, there is some indication, from the spread of A-factors in the series of fluoromethyl radicals reacting with SiHCl3, that internal compensation of Arrhenius parameters is occurring in some of the reactions; and when this is taken into account, the interpretation of activation energies is more difficult.
    Zusätzliches Material: 3 Ill.
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  • 275
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 97-104 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A simple model involving random displacements of particles in a cubic lattice is used to evaluate the importance of primary and secondary recombination in cage processes and leads to estimates of the lifetime of cage pehnomena. However, it is pointed out that all such models, and treatments which attempt to relate processes at the molecular level with bulk viscosity or diffusion constants, are inherently qualitative since they ignore the important correlation between motions of neighboring molecules.
    Zusätzliches Material: 2 Ill.
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  • 276
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 105-125 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A critical examination has been made of some aspects of the thermal decomposition of ethane and the reverse recombination reaction. The experimental Arrhenius A-factors for ethane are, in general, smaller than those which are calculated from thermodynamic quantities together with the observed rate constants for methyl recombination. Theoretical calculations also illustrate a discrepancy between the experimental work on recombination and decomposition. The experimental shapes of k/kα falloff curves and the pressure region of falloff are compared with the predictions of RRKM theory for various models.
    Zusätzliches Material: 2 Ill.
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  • 277
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constant for the combination of 1,1-dichloro-2,2,2-trifluoroethyl radicals in the gas phase has been measured by applying the rotating sector technique to the 1,1,1-trichloro-2,2,2-trifluoroethane-cyclohexane photochemical system. The combination rate constant, k5, was found to be 6.6 × 1012 cc mole-1 sec-1. Arrhenius parameters for the reaction, are given by the expression log k4 = 11.81 - (9700/2.3RT).
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 278
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate constant for the combination of trichloromethyl radicals in the gas phase has been measured by applying the rotating sector technique to the gas phase carbon tetrachloride-cyclohexane photochemical system. A temperature-independent rate constant, k5, of 3.9 ± 1.0 × 1012 cc mole-1 sec-1 was found. Arrhenius parameters for the reaction \documentclass{article}\pagestyle{empty}\begin{document}$${\rm CCl}_{\rm 3} + c - {\rm C}_{\rm 6} {\rm H}_{{\rm 12}} \mathop {\hbox to 30pt{\rightarrowfill}}\limits^{k_4 } {\rm CHCl}_{\rm 3} + c - {\rm C}_{\rm 6} {\rm H}_{{\rm 11}} $$\end{document} were found to be given by the expression log k4 = 11.79 - (10,700/2.3 RT).
    Zusätzliches Material: 4 Ill.
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  • 279
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 145-153 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of OH with acetylene was studied in a discharge flow system at room temperature. OH was generated by the reaction of atomic hydrogen with NO2 and was monitored throughout the reaction using ESR spectroscopy. Mass-spectrometric analysis of the reaction products yielded the following results: (1) less than 3 molecules of OH were consumed, and less than 2 molecules of H2O were formed for every molecule of acetylene that reacted; (2) CO was identified as the major carbon-containing product; (3) NO, formed in the generation of OH, reacted with a reaction intermediate to give among other products N2O. These observations placed severe limitations on the choice of a reaction mechanism. A mechanism containing the reaction OH + C2H2 → HC2O + H2 better accounted for the experimental results than one involving the abstraction reaction OH + C2H2 → C2H + H2O. The rate constant for the initial reaction was measured as 1.9 ± 0.6 × 10-13 cm3 molecule-1 sec-1.
    Zusätzliches Material: 1 Ill.
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  • 280
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 155-160 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The addition of methyl radicals to hexafluoropropylene has been studied over the temperature range 81°-203°C using a mass-balance technique involving the photolysis of biacetyl in the presence of hexafluoropropylene-isobutane mixtures. For the reaction \documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_{\rm 3} + {\rm C}_3 {\rm F}_6 \to {\rm CH}_3 {\rm C}_{\rm 3} {\rm F}_6$$\end{document} the rate constant is given by the equation \documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}k{\rm (in mole}^{- {\rm 1}} {\rm cm}^{\rm 3} {\rm sec}^{- {\rm 1}} {\rm) = (12}{\rm .04} \pm {\rm 0}{\rm .06)} - \frac{{6200 \pm 110}}{{2.303RT}}$$\end{document} The result suggests that methyl radicals are very unselective in their behavior reacting with tetrafluoroethylene and hexafluoropropylene at similar rates. This is in marked contrast to the behavior of oxygen atoms with these olefins.
    Zusätzliches Material: 1 Ill.
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  • 281
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 187-193 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The Pyrolysis of ethyl formate has been carried out in the temperature range 557°-630° and the rate expression k = 1012.34 e-48,100±500/RT sec-1 was obtained, in agreement with the prediction of O'Neal and Benson [1]. Calculated Arrhenius A-factors and experimental rate constants have been used to obtain the activation energies for the decomposition of the following compounds by the six-center molecular mechanism (in kcal/mole): 2-pentanone 59; methoxyacetone, 58; 2,4-pentanedione, 51; methyl butyrate, ≥ 70; 1-heptene, 54, and 4-methyl-1-hexene, 54-55.
    Zusätzliches Material: 1 Tab.
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  • 282
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 175-186 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: By monitoring the relative concentrations of mercury 3P0 atoms using absorption photometry, absolute rate constants have been measured for the excimer-forming reaction Hg (3P0) + Hg + N2 → Hg2* + N2 and for the quenching of Hg (3P0) atoms by ethane, propane, deuterated propanes, and nitrous oxide.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 283
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 223-235 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In dissociation experiments of H2O2 under shock wave conditions, the spectra of H2O2 and HO2 have been observed in the UV at 2200 ≤ 2800 Å. By the use of these spectra the H2O2 decomposition in the presence of H2 and CO at 870 ≤ T ≤ 1000°K has been analyzed. It was found that in this temperature range, in contrast to low temperature behavior, reactions of H atoms with H2O2 and with HO2 are equally important. The rate of the reaction H + H2O2 ← HO2 + H2 was estimated in comparison with the rate of the reaction between H and HO2. Good agreement between calculated and measured concentration profiles of HO2 and H2O2 was obtained.
    Zusätzliches Material: 5 Ill.
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  • 284
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 215-222 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The vibrational excitation of HF occurring behind incident shock waves has been studied in the temperature range of 1400°K to 4100°K. The extent of excitation was determined as a function of time by continuously monitoring the emission intensity from the 1-0 band of HF centered at 2.5 μ. The data were interpreted in terms of the process \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm HF}(0) + {\rm M = HF(1)} + {\rm M} $$\end{document} and gave a value of \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm (}\tau \rho {\rm)}\begin{array}{*{20}c} {{\rm - 1}} \\ {{\rm HF}} \\ \end{array}{\rm = 10}^{{\rm 9}{\rm .2} \pm 0.1} \exp \left({\frac{{- 64 \pm 4}}{{T^{1/3}}}} \right)atm^{- 1} \sec ^{- 1} $$\end{document} for M = HF. The corresponding result for (τp)-1Ar was found to be insignificant in comparison to this result. Data were also obtained for the effect of F atoms upon the relaxation rate, i.e., it was found that \documentclass{article}\pagestyle{empty}\begin{document}$$ {{\left( {\tau p} \right)_{{\rm HP}} } \mathord{\left/ {\vphantom {{\left( {\tau p} \right)_{{\rm HP}} } {\left( {\tau p} \right)_{\rm F} \sim 18 \pm 1}}} \right. \kern-\nulldelimiterspace} {\left( {\tau p} \right)_{\rm F} \sim 18 \pm 1}} $$\end{document}
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 285
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The rate of the reaction of cyclopentadiene with iodine has been followed spectrophotometrically over the temperature range 171.7° to 276.5°C. The reaction first proceeds almost to the point of equilibrium with cyclopentadienyl iodide and HI, although the final products are fulvalene and HI. Equilibrium constants obtained are those predicted by bond additivity. A third-law value of δH0f 298 (c-C5H5I,g) = 49 kcal/mole is obtained. Rate studies of the reaction up to the iodide equilibrium, yield values for the rate constant . Uncertainty in the Arrhenius parameters, as well as doubts as to the applicability of the usual assumption that E3 = 1 ± 1 kcal/mole, make difficult an evaluation of total cyclopentadienyl stabilization energy (TSE) from these data. However, the value is probably 15 〈 TSE 〈 20.
    Zusätzliches Material: 2 Ill.
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  • 286
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 467-482 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The competitive reactions between 2-trifluoromethylpropene (TMP) and OCS for O(3P) atoms were studied between 300° and 523°K, using the mercury-senstitized photolysis of N2O as a source of O(3P). From the known value for the rate constant of the O(3P) + TMP reaction, k3 was found to be 1.6 × 10-11 exp (-4500/RT) cm3/particle-sec, where reaction (3) is \documentclass{article}\pagestyle{empty}\begin{document}$${\rm (3) O(}^{\rm 3} {\rm P)} + {\rm OCS} \to {\rm CO} + {\rm SO}$$\end{document}Mixtures of O3 and OCS were photolyzed at 197°, 228°, 273°, and 299°K with radiation above 4300 Å to produce O(3P) from the photolysis of O3, and thus study the competition between reaction (3) and \documentclass{article}\pagestyle{empty}\begin{document}$${\rm (1)O(}^{\rm 3} {\rm P)} + {\rm O}_{\rm 3} \to 2{\rm O}_{\rm 2}$$\end{document} From the above value of k3, k1 could be computed. When combined with all the previous data, the best espression for k1 is k1 = 1.2 × 10-11 exp (-4300/RT) cm3/particle-sec.
    Zusätzliches Material: 6 Ill.
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  • 287
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An experimental study of the decomposition kinetics of chemically activated 2-methyl-l-butene and 3-methyl-l-butene produced from photolysis of diazomethane-isobutene-neopentane-oxygen mixtures is reported. The experimental rate constants for 3-methyl-l-butene decomposition were 1.74 ± 0.44 × 108 sec-1 and 1.01 ± 0.25 × 108 sec-1 at 3660 and 4358 Å, respectively. 2-Methyl-l-butene experimental decomposition rate constants were found to be 5.94 ± 0.59 × 107 sec-1 at 3660 Å and 3.42 ± 0.34 × 107 sec-1 at 4358 Å. Activated complex structures giving Arrhenius A-factors calculated from absolute rate theory of 1016.6 ± 0.5 sec-1 for 3-methyl-l-butene and 1016.2 ± 0.4 sec-1 for 2-methyl-l-butene, both calculated at 1000°K, were required to fit RRKM theory calculated rate constants to the experimental rate constants at reasonable E0 and E* values. Corrected calculations (adjusted E0 values) on previous results for 2-pentene decomposition gave an Arrhenius A-factor of 1016.45 ± 0.35 sec-1 at 1000°K. The predicted A-factors for these three alkene decompositions giving resonance-stabilized methylully radicals are in good internal agreement. The fact that these A-factors are only slightly less than those for related alkane decompositions indicates that methylallylic resonance in the decomposition products leads to only a small amount of tightening in the corresponding activated complexes. This tightening is a significantly smaller factor than the large reduction in the critical energy due to resonance stabilization.
    Zusätzliches Material: 1 Ill.
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  • 288
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 483-489 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The gas phase photolysis of CF3CCl3 in the presence of several alkanes has been used to obtain Arrhenius parameters for the abstraction of hydrogen atoms by the CF3CCl2 radical: \documentclass{article}\pagestyle{empty}\begin{document}$${\rm CF}_{\rm 3} {\rm CCl}_2 + {\rm RH} \to {\rm CF}_{\rm 3} {\rm CCl}_2 {\rm H} + {\rm R}$$\end{document}Activation energies of 9.6 and 8.0 kcal/mole are found for abstraction from secondary and tertiary C-H bonds, respectively. The Arrhenius parameters are compared to those for CCl3 and CF3 radicals.
    Zusätzliches Material: 1 Ill.
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  • 289
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    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 3 (1971), S. 249-268 
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The high-temperature reaction between sulfur dioxide and acetylene in an excess of argon was studied in a 1-in. i.d. single-pulse shock tube. Mixtures ranging from 1.81% to 5.40% SO2 and 1.60% to 4.90% C2H2 were heated to reflected shock temperatures of 1550°-2150°K, for dwell times of about 0.6 msec and gas dynamically quenched. Total reaction densities were 0.89 to 5.4 × 10-2 moles/1. The reaction products were analyzed by gas chromatography. A technique was developed for separating Ar, C2H4, C2H2, SO2, CO, CO2, H2S, COS, and CS2. The major products of the reaction are CO, H2, CS2, and sulfur. The products observed were compared with those predicted on the assumption that equilibrium was attained. Several preliminary experiments were carried out with ethylene-sulfur dioxide mixtures, and the results indicated that for this combination the sulfur dioxide probably reacted with the acetylene generated from the decomposition of the ethylene, rather than directly with the ethylene. The rate of decline in the sulfur dioxide content in C2H2-SO2 mixtures was found to be approximately second order (total) and can be empirically represented by \documentclass{article}\pagestyle{empty}\begin{document}$$- \Delta ({\rm SO}_2)/\Delta t = 3.1 \times 10^{10} T^{1/2} \exp (- 40,800/RT)[{\rm Ar}]^{0.83} [{\rm SO}_{\rm 2}]^{0.87} [{\rm C}_2 {\rm H}_{\rm 2}]^{0.25} {\rm mole cm}^{{\rm - 3}} \sec ^{ - 1}$$\end{document}A mechanism is proposed to account for the overall reaction kinetics.
    Zusätzliches Material: 9 Ill.
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