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  • 1975-1979  (115)
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  • 1979  (115)
  • Physical Chemistry  (115)
  • 101
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 813-819 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A kinetic study of the oxidation of allyl alcohol by potassium hexacyanoferrate (III) in the presence of palladium (II) chloride is reported. The reaction was observed by measuring the disappearance of the potassium hexacyanoferrate (III) spectrophotometrically. The reaction is first order with respect to allyl alcohol and palladium (II) chloride, inverse second order with respect to [Cl-], and zero order with respect to potassium hexacyanoferrate (III). The rate is found to increase linearly with hydroxyl ion concentration.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 102
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 453-460 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of ground-state oxygen atoms with carbonothioicdichloride, carbonothioicdifluoride, and tetrafluoro-1,3-dithietane have been studied in a crossed molecular jet reactor in order to determine the initial reaction products and in a fast-flow reactor in order to determine their overall rate constants at temperatures between 250 and 500 K. These rate constants arek(O + C2CS) =(3.09 ± 0.54) × 10-11 exp(+115 ± 106 cal/mol/RT),k(O + F2CS) = (1.22 ± 0.19) × 10-11 exp(-747 ± 95 cal/mol/RT), andk(O + F4C2S2) = (2.36 ± 0.52) × 10-11 exp(-1700 ± 128 cal/mol/RT) cm3/molec·sec. The detected reaction products and their rate constants indicate that the primary reaction mechanism is the electrophilic addition of the oxygen atom to the sulfur atom contained in the reactant molecule to form an energy-rich adduct which then decomposes by C-S bond cleavage.
    Additional Material: 1 Ill.
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  • 103
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 951-967 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photochemistry of azo-n-propane is investigated at 366 nm up to 1 atm pressure, and over a range of temperature from 50 to 190°C. Some additional experiments with azoethane at room temperature and azoisopropane at 180 and 190°C are also reported. From a consideration of the pressure dependence of the quantum yields for photodissociation a generalized mechanism is proposed which accounts for the known experimental observations in acyclic azoalkane photochemistry. These observations include the extensive photoisomerization data which were previously obtained for azoisopropane. In the mechanistic scheme dissociation at low pressures is believed to occur mainly from S1v and T1v, the vibrationally excited and randomized first excited singlet and triplet states. At high pressures and low temperatures (≤100°C) the major dissociation channel is probably a nonrandom S1 state. In direct or singlet sensitized photolysis isomerization occurs predominatly at high pressure and is postulated to occur by internal conversion from S10, the thermalized singlet, to the ground state. During the process partitioning to the cis or trans isomer is equally probable. In triplet sensitized photolysis isomerization occurs via intersystem crossing from T1to the ground state. At elevated temperatures (〉150°C) dissociation from S10, which has a significant activation energy, can compete with return to the ground state.
    Additional Material: 9 Ill.
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  • 104
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 543-557 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The products of the heterogeneous reactions of chlorine atoms and chlorine oxide radicals with acid coated Pyrex walls have been directly determined for the first time. Contrary to the usual assumption that chlorine atoms recombine to form Cl2, we find that the major product is HCl, with small amounts of perchlorate also formed. Similarly, ClO radicals form HCl rather than Cl2. The source of hydrogen for these reactions is probably the water always found in this type of vacuum system. These results may change the interpretation of flow tube experiments with chlorine atoms. Application to the H + HCl reaction is discussed as an example.
    Additional Material: 4 Ill.
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  • 105
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 995-1005 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intrinsic spectral and kinetic parameters have been measured for the ethyl radical, which was formed in the gas phase by the flash photolysis of azoethane. Absolute values of the extinction coefficient ε(λ) were derived from complementary measurements of the yield of nitrogen and the absorbance of an equivalent concentration of the ethyl radical. The absorption spectrum is broad, structureless, and comparatively weak; ε(247) = 4.8 × 102 l/mol·cm at the maximum, and the oscillator strength is (9.1 ± 0.5) × 10-3. This is in good qualitative agreement with a spectrum obtained independently using the technique of molecular modulation spectrometry.The biomolecular reactions of mutual interaction were the only significant reactions of the ethyl radical in this system; kinetic analysis of the second-order decline of the absorbance during the dark period yielded a value of k/ε(λ) for each experiment. The rate constant for mutual interaction was evaluated from the product of corresponding measurements of k/ε(λ) and ε(λ) individual values are independent of the wavelength of measurement, and the mean value is k = (1.40 ± 0.27) × 1010 l/mol·sec. The rate constant for mutual combination was derived with the aid of product analysis as k2 = (1.24 ± 0.23) × 1010 l/mol·sec; it stands in close agreement with the set of “high” values obtained by direct measurement using a variety of methods.
    Additional Material: 1 Ill.
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  • 106
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1055-1069 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1-Methylallyl, 1,1-dimethylallyl, 1,2-dimethylallyl, 1,3-dimethylallyl, 1,1,2-trimethylallyl, and 1-ethylallyl radicals have been generated in the gas phase at 20 ± 1°C by addition of H atoms, formed by Hg(63P1) photosensitization of H2, to appropriate dienes. Their combination reactions with ethyl radicals have been studied and the relative reactivities of the reaction centers in each allylic radical determined. Similar measurements have been made for some combination reactions of n-propyl, i-propyl, and t-butyl with 1-methylallyl and 1,1,2-trimethylallyl radicals. The more substituted reaction centers are found to be the less reactive. In addition the self-combination and disproportionation of 1-methylallyl radicals has been investigated, as has cross disproportionation of each allylic radical with ethyl. The results establish a general pattern of reactivity for these radicals, which is interpreted primarily in terms of the effects of steric interaction during reaction.
    Additional Material: 4 Ill.
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  • 107
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1045-1053 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using dimethyl peroxide as a thermal source of methoxy radicals overthe temperature range of 110-160°C, and the combination of methoxy radicals and nitrogen dioxide as a reference reaction: a value was determined of the rate constant for the reaction of methoxy radicals with oxygen: is independent of nitrogen dioxide or oxygen concentration and added inert gas (carbon tetrafluoride). No heterogeneous effects were detected. The value of k4 is given by the expression \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log }k_4 {\rm = 9}{\rm .0} \pm {\rm 0}{\rm .6 - 4}{\rm .8 } \pm {\rm 1}{\rm .1/}\theta {\rm (M}^{{\rm - 1}} \cdot \sec ^{ - 1}) $$\end{document} In terms of atmospheric chemistry, this corresponds to a value of 105.6 M-1·sec-1 at 298 K. Extrapolation to temperatures where the combustion of organic compounds has been studied (813 K) produces a value of 107.7 M-1·sec-1 for k4. Under these conditions, reaction (4) competes with hydrogen abstraction or disproportionation reactions of the methoxy radical and its decomposition (3): In particular k3 is in the falloff region under these conditions. It is concluded that reaction (4) takes place as the result of a bimolecular collision process rather than via the formation of a cyclic complex.
    Additional Material: 1 Ill.
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  • 108
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1097-1108 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A portable program package, MACKSIM, for mass action chemical kinetics simulation, is discussed. As these kinetics are readily expressed in explicit mathematical terms, such a package contains two major and distinct modules, the numerical analysis and the user interface. For the first, MACKSIM uses the latest proven developments incorporating sparse matrix techniques in the backward difference predictor corrector methods originated by Gear for the integration of stiff ordinary differential equations, and thus requires minimal computing time to solve large systems of equations. For the second, the program provides a flexible interface which permits simple specification and variation of reactions, requires no special character input, and has no limit on the number of reactions or species involved other than that imposed by the size of the computer. The technology of these components is discussed briefly, the use of the package for standard reactions is illustrated, and current applications are mentioned.
    Additional Material: 3 Ill.
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  • 109
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1109-1130 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrolytic decay of carbon diselenide was monitored by ultraviolet absorption spectroscopy in reflected shock waves in the temperature range of 1600-2600°K. The temperature dependence of the absorption coefficient of CSe2 at 2308 Å was determined and was used to provide kinetic information along with a deconvolution procedure which accounted for and removed systematic distortions of the fast time-resolved absorbance profile. For temperatures of 1600-2600°K and argon densities of 1.5-7.0 × 10-5 mol/cm3 dilute (1.0-9.0 × 10-9 mol/cm3) CSe2 pyrolyzed with measured first-order decay rates in the range of log10 k1 (sec-1) = 3.0-5.7; at midrange (2100°K and 4.3 × 10-5 mol/cm3 in Ar) k1 ≈ 3 × 104 sec-1. The decay probably occurs via a unimolecular low-pressure process, first order in both CSe2 and Ar, for which k2 ± 109 cm3/mol·sec at 2100°K. The deconvoluted data yield Arrhenius activation energies of 53.2 kcal/mol under second-order treatment, but the activation energy is less reliable than the general magnitude of the rate constant. A comparison of CSe2 with other molecules which are isoelectronic in their valence shells (CO2, CS2, OCS, and N2O) is made.
    Additional Material: 13 Ill.
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  • 110
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1137-1162 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitivity/uncertainty analysis is performed on a mechanism describing the chemistry of the polluted troposphere. General features of the photochemical reaction system are outlined together with an assessment of the uncertainties associated with the formulations of mechanistic details and rate data. The combined effects of sensitivity and uncertainty are determined using the Fourier amplitude sensitivity test (FAST) method. The results of this analysis identify the key parameters influencing the chemistry of NO2, O3, and PAN. Based on these findings, a series of recommendations are made for future experimental kinetic studies.
    Additional Material: 8 Ill.
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  • 111
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1197-1209 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Linear free-energy (LFE) correlations for gas phase O(3P) and OH addition and abstraction reactions with a number of organic compounds have been established using existing room-temperature rate constants evaluated from the literature. Addition reaction rate constant correlations with ionization potential and abstraction reaction rate constant correlations with bond dissociation energies are examined and compared to the LFE approach. Using multiple regression analysis, empirical linear equations are derived and used to predict rate constants for reactions of O(3P) and OH with a number of organic molecules. The use of LFE room-temperature rate predictions permits chemical modeling efforts to be extended to compounds where experimental determinations of rate coefficients are lacking and also serves as a useful tool in evaluation of experimental rate measurements.
    Additional Material: 6 Ill.
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  • 112
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 113
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1263-1269 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The gamma-radiation-induced free-radical chain reactions in liquid CCl4—C2Cl4—c—C6H12 mixtures were studied in the temperature range of 363-448°K. The main products in this system are chloroform, hexachloropropene and chlorocyclohexane. These products are formed via reactions (1)-(5): with G values (molec/100 eV) of the order of magnitude of 102 and 103 at the lowest and highest temperatures, respectively. Values of k2/k1 were determined from the product distribution. In turn, these values gave the following Arrhenius expression for k2/k1 (θ = 2.303RT, in kcal/mol): \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log }\,k_2 /k_1 = ( - 1.21 + 0.10) + (1.59 \pm 0.27)/\theta $$\end{document} From this result and the previously determined Arrhenius parameters of reaction (1), k2 is found to be given by \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log }\,k_2 (1/{\rm mol} \cdot {\rm sec) = 7}{\rm .58 - 9}{\rm .49/}\theta $$\end{document}.
    Additional Material: 1 Ill.
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  • 114
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1301-1301 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No. Abstract.
    Type of Medium: Electronic Resource
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  • 115
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 1287-1296 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the gas-phase thermal isomerization between trans- and cis-1,2-bis(trifluoromethyl)-1,2,3,3-tetrafluorocyclopropane as well as their decomposition to trans- and cis-perfluoro-2-butene, respectively, and CF2, was studied in the temperature range of 473-533°K, with an initial pressure of reactant of 1.5 to 7.0 Torr. Some runs were also made with the addition of SF6 as an inert gas up to a total pressure of 100 Torr. The reactions are first order and homogeneous. The rate constants for the geometrical isomerization fit the following Arrhenius relations: \documentclass{article}\pagestyle{empty}\begin{document}$$ {{\log {k}_{{trans}\to {cis}}}\mathord{\left/{\vphantom {{\log {k}_{{trans}\to {cis}}}{(\sec ^{ - 1})}}}\right.\kern-\nulldelimiterspace}{(\sec ^{ - 1})}}{ = }{{{(15}{.15}\pm{0}{.16)-(44,487}\pm{ 374)}}\mathord{\left/ {\vphantom {{{(15}{.15} \pm{0}{.16) - (44,487 }\pm { 374)}}{4.576{ }T}}} \right.\kern-\nulldelimiterspace} {4.576{ }T}} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ {{\log {k}_{{trans}\to {cis}}}\mathord{\left/{\vphantom {{\log {k}_{{trans}\to {cis}}}{(\sec ^{ - 1})}}}\right.\kern-\nulldelimiterspace} {(\sec ^{ - 1})}}{ = }{{{(15}{.35} \pm {0}{.19) - (43,419 } \pm { 428)}} \mathord{\left/ {\vphantom {{{(15}{.35} \pm {0}{.19) - (43,419 } \pm { 428)}} {4.576{ }T}}} \right. \kern-\nulldelimiterspace} {4.576{ }T}} $$\end{document} and the corresponding equations for the decomposition of the trans and cis-cyclopropane are \documentclass{article}\pagestyle{empty}\begin{document}$$ {{\log {k}_{{trans}}} \mathord{\left/ {\vphantom {{\log {k}_{{trans}}} {(\sec ^{ - 1})}}} \right. \kern-\nulldelimiterspace} {(\sec ^{ - 1})}}{ = }{{{(15}{.14} \pm {0}{.28) - (46,700} \pm { 652)}} \mathord{\left/ {\vphantom {{{(15}{.14} \pm {0}{.28) - (46,700 } \pm { 652)}} {4.576{ }T}}} \right. \kern-\nulldelimiterspace} {4.576{ }T}} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ {{\log {k}_{{cis}}} \mathord{\left/ {\vphantom {{\log {k}_{{cis}} } {(\sec ^{ - 1})}}} \right. \kern-\nulldelimiterspace} {(\sec ^{ - 1})}}{ = }{{{(15}{.39} \pm {0}{.26) - (46,639} \pm { 598)}} \mathord{\left/ {\vphantom {{{(15}{.39} \pm {0}{.26) -(46,639 } \pm { 598)}} {4.576{ }T}}} \right. \kern-\nulldelimiterspace} {4.576{ }T}} $$\end{document}.
    Additional Material: 3 Ill.
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