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  • Physical Chemistry  (197)
  • Wiley-Blackwell  (197)
  • Annual Reviews
  • Periodicals Archive Online (PAO)
  • 1975-1979  (197)
  • 1970-1974
  • 1979  (115)
  • 1975  (82)
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  • Wiley-Blackwell  (197)
  • Annual Reviews
  • Periodicals Archive Online (PAO)
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  • 1975-1979  (197)
  • 1970-1974
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 1-13 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The temperature dependence of the vibration-vibration energy transfer between the v3 mode of N2O and the first vibrational level of CO was determined over a range of 780 to 1400°K using a shock tube. Several mixtures of CO-N2O were tested, diluted in 95% Ar. The Landau-Teller plot of the vibration-vibration relaxation times has a least squares line of \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}_{{\rm 10}} p\tau _{{\rm VV}} = 2.69T^{ - 1/3} - 1.70 $$\end{document} where pτvv is in atm ·μsec and T in °K. The measured kinetic reaction was determined to be \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm N}_{\rm 2} {\rm O(001) + CO(O)} \to {\rm N}_{\rm 2} {\rm O}(000) + {\rm CO(1) + 81cm}^{{\rm - 1}} $$\end{document} The transfer probabilities for this process were found to vary directly with temperature.
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  • 2
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The activation energy parameters for the reaction of PdX42- (X=Cl-, Br-) in aqueous halide acid solution with thiourea (tu) and selenourea (seu) have been determined. High rates of reaction parallel low enthalpies and appreciable negative entropy of activation. The rate law in each case simplifies to kobs=k[L] where L=tu or seu, and only ligand-dependent rate constants are observed at 25°C. The ligand-dependent rate constants for the first identifiable step in the PdCl42- + X system is (9.1±0.1) × 103 M-1 sec-1 and (4.5±0.1) × 104 M-1 sec-1 for X=tu and seu, respectively, while for the PdBr42- + X system it is (2.0±0.1) × 104 M-1 sec-1 and (9.0±0.1) × 104 M-1 sec-1 for X=tu and seu, respectively.
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  • 3
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 125-142 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed shock-tube investigation of the ignition in H2 + Cl2 + Ar mixtures in a shock tube is presented, and the mechanism of the reaction is discussed. Ignition delay times were determined from pressure and heat flux measurements behind reflected shock waves. The induction times measured ranged between 35 and 2100 μsec over the temperature range of 830-1260°K. The experimental results of close to seventy tests can be correlated by the relationship \documentclass{article}\pagestyle{empty}\begin{document}$$ t_{{\rm ig}} = 10^{ - 12.73} \exp (18.75 \times 10^3 /RT) \cdot [{\rm Cl}_{\rm 2}]^{ - 0.66} [{\rm H}_{\rm 2}]^{ - 0.60} [{\rm Ar]}^{{\rm 0}{\rm .40 }} \,\sec. $$\end{document} where the concentrations are expressed in mole/cm3. The above relationship served as a basis for a computer modeling of the ignition delay times. Ten calculations, simulating typical laboratory experiments, were run by the computer for each reaction scheme and the obtained temperature and composition dependence of the induction times were compared with the ones observed experimentally. A reaction scheme based on a simple exothermal chain propagation could not reproduce the experimental relationship. When the energy branching reaction HCl*(ν) + Cl2 → (HCl3) → HCl + Cl + Cl was added to the reaction scheme, a much better agreement with the experiment was obtained. It is believed that the above reaction does take place and that it is the main supplier of atoms to the system.
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  • 4
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 205-214 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spectrophotometric methods have been used to obtain rate laws and rate parameters for the following reactions: with ka, kb, Ea, Eb having the values 85±5 l./mole · s, 5.7±0.2 s-1 (both at 298.2°K), and 56±4 and 66±2 kJ/mole, respectively. with kc=0.106±0.004 l./mole ·s at 298.2°K and Ec=67±2 kJ/mole. with kd=(3.06 ±; 0.15) × 10-3 l./mole ·s at 298.2°K and Ed=66±2 kJ/mole.Mechanisms for these reactions are discussed and compared with previous work.
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  • 5
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 249-272 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of decarbonylation of [Ir(CO)(dp)2]Cl and [IrCl(CO)2(Ph3P)2] has been studied in different solvents, at temperatures between -25° and +70°C, by means of reactors of defined fluid dynamics which allow a separation to be made between “physical” and “chemical” rate constants. Chemical rate constants have been found to depend markedly on the diffusion coefficients of carbon monoxide in the various solvents. The process of decarbonylation has been described, for both reactions, by the sequence: structural isomerization, characterized by a very low preexponential factor, decomposition of the less stable isomer against the solvent's barrier, and diffusion of carbon monoxide to the gas-liquid interface. The kinetic problems involved in the determination of rate constants and their implications have been emphasized.
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  • 6
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975), S. 287-300 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The overall photobromination reactions \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Br}_{\rm 2} + {\rm R}_{\rm F} {\rm I} \to {\rm IBr} + {\rm R}_{\rm F} {\rm Br} $$\end{document} have been studied using a competitive technique. Relative Arrhenius parameters were obtained for the rate-determining step These were placed on an absolute basis using previous-absolute values of A and E for RFI=CF3I. The activation energies were used to calculate bond dissociation energies D(R—I) with the following results: TextRF-E16D(RF-I)(kcal/mole)CF3I10.852.6C2F5I8.850.6n-C3F7I7.449.2i-C3F7I7.549.2n-C4F9I6.748.4E16 from [1]The D(RF-I) are compared with related D(R—I) and it is concluded that for a given alkyl group RH and the corresponding perfuloroalkyl group RF, D(RH-I) 〉 D(RF-I) whereas it has previously been found that D(RH-X;) 〈 D(RF-X) where X is not iodine.
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  • 7
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    International Journal of Chemical Kinetics 7 (1975), S. 341-349 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rates of reaction of t-BuOOK, t-BuOK, n-BuOOK, and p-MeC6H4OKwith p-nitrophenyl diphenylphosphinate 1 and with p-nitrophenyl benzoate 2 have been measured in toluene both in the absence and in the presence of crown polyether dicyclohexyl-18-crown-6 3a. The rates of nucleophilic displacementon 1 by HOO-, t-BuOO-, and some “nonalpha” oxyanions in water have also been determined. Solvent transfer from water to toluene results in increasing the nucleophilic reactivity of the t-butyl hydroperoxide anion. Rate ratios QQa are given which allow one to estimate the enhanced reactivity of t-BuOO- (an α-nucleophile) compared to oxygen nucleophiles of comparable base strength toward 1 and 2. These are for substrate 1, Qα (water) ≃ 6.5 and Qα (toluene) ≃ 2.7; for substrate 2, Qα (water) ≃ 5.5 and Qα (toluene) ≃ 5. The hypothesis is advanced that solvation is not a major factor in determining the α-effect of the t-butylhydroperoxide anion.
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  • 8
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    International Journal of Chemical Kinetics 7 (1975), S. 633-636 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 9
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    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 7 (1975) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 10
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    International Journal of Chemical Kinetics 7 (1975), S. 463-471 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A consecutive single-route reaction is considered. When two (groups of) steps compete in controlling the overall reaction rate, there exists a general rule that the earlier step in the flow of the overall reaction tends to be rate-determining with the increase of the reaction affinity. The latter may, however, be distributed more or less evenly to both steps.
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  • 11
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    International Journal of Chemical Kinetics 7 (1975), S. 479-507 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanisms of the pyrolyses of the n-alkanes C3H8, n-C4H10, and n-C5H12 at temperatures between 390 and 560°C have been studied by the construction and evaluation of sets of several hundred reactions. Rate parameter values were assigned using literature data and calculated estimates. Time-dependent numerical solutions were computed for the experimental conditions of several rate and product studies reported in the literature. The comparisons of these a priori computations with experiment show excellent agreement for propane and agreement for butane and pentane within the estimated error limits of the assigned rate parameters. These results demonstrate that the general “state of knowledge” of the mechanism of alkane pyrolysis, namely, the reactions and their rate parameters, is such that reasonable a priori predictions of experimental results can be made. Discussions of the major stepwise processes in the pyrolyses are presented, and the importance of allyl radicals in termination is demonstrated.
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  • 12
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    International Journal of Chemical Kinetics 7 (1975), S. 547-555 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The decomposition rate of chemically activated ethyltrimethylgermane from the reaction 1CH2 + (CH3)4Ge, where 1CH2 was produced from diazomethane photolysis at 3660 Å, is 8.6 × 105 sec-1. This result combined with RRKM theory and critical energy estimates yields an Arrhenius A factor of log[A (sec-1)/methyl] = 14.7 ± 0.8 for methyl rupture from germanium.Log A values for methyl rupture from carbon, silicon, and germanium linearly correlate with the vibrational-rotational entropies of the corresponding tetramethyls. Extrapolation predicts log[A (sec-1)/methyl] = 14.4 and 14.3 for methyl rupture from tin and lead, respectively.
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  • 13
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    International Journal of Chemical Kinetics 7 (1975), S. 625-631 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The addition of methoxy radicals to several olefins has been studied by a competitive method at 127°C in gas phase. The thermal decomposition of dimethyl peroxide was used as methoxy radical source. The rate of addition to the double bond was measured relative to the oxidation of carbon monoxide. For the addition to ethylene it was obtained that \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{{\rm add}} = \left({3.7 \pm 0.8} \right) \times 10^4 M^{ - 1} \cdot {\rm s}^{{\rm - 1}} $$\end{document} This rate constant is similar to the one shown by methyl radicals under similar conditions. From the relative rate of addition to several chlorinated and fluorinated olefins it can be concluded that methoxy radicals show very little “electrophilic” character.
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  • 14
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    International Journal of Chemical Kinetics 11 (1979), S. 103-104 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 15
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    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
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  • 16
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    International Journal of Chemical Kinetics 11 (1979), S. 109-115 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of 2-dimethylaminoethyl chloride in the temperature range of 360-400°C and the pressure range of 60-271 mmHg is a homogeneous, unimolecular, first-order reaction giving dimethylvinyl amine and hydrogen chloride. 2-Methoxyethyl chloride pyrolysis in the temperature range of 450-490°C and the pressure range of 53-110 mmHg by a similar unimolecular, first-order reaction yields methylvinyl ether and hydrogen chloride. These reactions were carried out in a seasoned reaction vessel and in the presence of a propene inhibitor. The methylvinyl ether decomposes slowly into other products at the temperature of pyrolysis. The rate constants are given by the Arrhenius equations(a) 2-dimethylaminoethyl chloride: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k(\sec ^{ - 1}) = (13.22 \pm 0.17) - (203.7 \pm 2.1)kJ/mol/2.303RT $$\end{document}(b) 2-methoxyethyl chloride: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k(\sec ^{ - 1}) = (14.06 \pm 0.53) - (244.7 \pm 7.1)kJ/mol/2.303RT $$\end{document}The effects of polar β substituents in the 2 position of ethyl chloride are discussed in terms of anchimeric assistance and electron-withdrawing deactivation in these elimination reactions. The present results are consistent with the heterolytic nature of the four-centered cyclic transition state for the gas-phase pyrolysis of alkyl halides.
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  • 17
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    International Journal of Chemical Kinetics 11 (1979), S. 131-145 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction\documentclass{article}\pagestyle{empty}\begin{document}$ CH\left({CH_3 } \right)\left({COOH} \right)_2 + I_2 \rightleftharpoons CI(CH_3)\left({COOH} \right)_2 + H^ + + I^ - $\end{document} was followed spectrophotometrically at 353 nm and 470 nm at 25°C under various conditions of pH and methylmalonic acid concentration. The equilibrium constant for the reaction is 0.11 ± 0.02. An iterative technique was used to integrate postulated rate equations. Agreement between experimental and calculated absorbance versus time curves was generally better than 0.005 A (approximately 5% of maximum) at both wavelengths for a mechanism where the rate-determining step is formation of an enolate (k = 1.63 Θ 10-4 ± 0.03 Θ 10-4 sec-1). The enolate may be rapidly transformed to the enol or enol carboxylate anion depending on the pH. All three forms are rapidly iodinated. The mechanism of general base catalysis is supported by rate increases proportional to base concentration in buffer solutions. The bases, acetate ion, chloracetate ion, sulfate ion, dichloracetate ion, and water, follow a Brønsted relationship with β = 0.7.
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  • 18
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    International Journal of Chemical Kinetics 11 (1979), S. 165-173 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of oxidation of glycine, alanine, phenylalanine, serine threonine, aspartic, and glutamic acid by acid permanganate were investigated to elucidate the mechanism of the reactions. The rate law was found to be \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{ - d[Mn\left({VII} \right)]}}{{dt}} = k_0 [a\min oacid][Mn\left({VII} \right)] $$\end{document} The reactions were found to be acid catalyzed, and the kinetic data indicate the participation of the water molecules in the rate-determining step as a proton-abstracting agent from the substrate, as per Bunnett's hypothesis. As Ag+ was found to catalyze these reactions, the oxidation of glycine and glutamic acid was studied, and the rate law was found to be \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{ - d\ln [Mn\left({VII} \right)]}}{{dt}} = \frac{{Kk_c^{''} [a\min oacid][Ag^ +]}}{{1 + K[a\min oacid] = K[Ag^ +]}}$$\end{document} A probable mechanism consistent with the observed results is discussed.
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  • 19
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    International Journal of Chemical Kinetics 11 (1979), S. 117-124 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The competitive photochlorination and chlorine photosensitized dehydrochlorination of 1,1,1,2-C2H2Cl4 have been studied over the temperature range of 349.4-404.5 K after less than 1% conversion. The results are discussed and a value of \documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_{4A} (\sec ^{ - 1}) = (11.6\pm 0.6) - (16,400\pm 1000)/4.58T $$\end{document} is proposed for the reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm CCl}_{\rm 3} {\rm CHCl}\mathop \to \limits^{(4{\rm A)}} {\rm CCl}_{\rm 2} {\rm CHCl + Cl} $$\end{document} This result, combined with existing thermochemical data, indicates that there is no evidence of an activation energy for the addition of a Cl atom on the most chlorinated carbon in trichloroethylene: in that case the selectivity of the addition of Cl on the less chlorinated carbon should not depend on temperature.
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  • 20
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    International Journal of Chemical Kinetics 11 (1979), S. 125-130 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lifetime data have been obtained for the decay of SO2(3B1 0,0,0) at 25°C over the pressure range of 1-762 torr. The 3B1 state was populated by direct absorption to eliminate any possible complications in interpretation due to the participation of excited-singlet manifolds. At pressures greater than about 10 torr, the measured lifetimes are longer than predicted from low-pressure Stern-Volmer parameters. This deviation can be interpreted in terms of Freed's theory on collisionally induced intersystem crossing and provides unequivocal evidence to support earlier speculations that the lengthening of the lifetimes at high pressures is due to saturation in depopulation of the 3B1 state.
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  • 21
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    International Journal of Chemical Kinetics 11 (1979), S. 155-164 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Our previous mechanistic model for the Belousov-Zhabotinsky reaction has been revised to include a more realistic set of reactions for the oxidation pathways of the organic intermediates. A few other rate constants have also been modified to include new information. The revised mechanism reproduces the essential experimental observations, although the periods of oscillation are somewhat too long and oscillations cease at malonic acid concentrations about ten times greater than the observed lower limit. However, the essential features of the mechanism are clearly understood.
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  • 22
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    International Journal of Chemical Kinetics 11 (1979) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 23
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    International Journal of Chemical Kinetics 11 (1979), S. 219-237 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photolysis was investigated at 313 nm wavelength, 253-529 K temperatures, and 4 × 10-11-2 × 10-9 mol·photon/cm2·sec light intensities by determining the quantum yields of 20 reaction products. Primary quantum yields for the seven primary processes and rate constant ratios, rate constants, and Arrhenius parameters for secondary processes were derived on the basis of the suggested reaction scheme. The dependence of the quantum yields of the four major primary processes on experimental conditions was established.
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  • 24
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    International Journal of Chemical Kinetics 11 (1979), S. 261-273 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of oxidation of dimethyl sulfoxide (DMSO) by chloramine-T (CAT) is studied in HClO4 and NaOH media with OsO4 as a catalyst in the latter medium. In acid medium, the rate law is -d [CAT]/dt = k [CAT][DMSO][H+]. Alkali retards the reaction and the rate law takes the form -d [CAT]/dt = k [CAT][DMSO][OsO4]/[NaOH], but is reduced to -d [CAT]/dt = k [CAT][DMSO] at higher alkali concentrations. The reaction is subjected to changes in (a) ionic strength, (b) concentrations of added neutral salts, (c) concentrations of added reaction product, (d) dielectric constant, and (e) solvent isotope effect, and the subsequent effects on the reaction rate are studied.The reaction mechanism in acid medium assumes an electrophilic attack by the free acid RNHCl (CAT′) at the sulfur site in DMSO, forming a reaction intermediate which subsequently decomposes to dimethyl sulfone on hydrolysis. Formation of a cyclic complex between RNHCl and OsO4 which interacts with the substrate in a slow step explains the observed results in alkaline medium. The simplification of the rate equation at higher alkali concentrations is attributed to a direct reaction between chloramine-T and the substrate.
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  • 25
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    International Journal of Chemical Kinetics 11 (1979), S. 495-509 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constant for the bimolecular combination of trichloromethyl radicals in methanol is determined as a function of temperature by steady-state kinetics and electron-spin resonance with modulated radical initiation. The rate constant is in accord with the Smoluchowski equation and indicates a diffusion-controlled radical termination. The temperature dependence of the rate constant for the electron-transfer reaction between hydroxymethyl radicals and carbon tetrachloride in methanol is determined, and is found to disagree with predictions of the Marcus theory. This disagreement is tentatively ascribed to the structure of the transition state.
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  • 26
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    International Journal of Chemical Kinetics 11 (1979), S. 821-841 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: During the oxidation of carbon monoxide containing a trace of water, ten well-known atomic and molecular species can be identified as of potential significance. All conceivable reactions of these species in their ground electronic states were considered, and rate constants for all those that are of potential importance are either known or can be estimated with considerable confidence. For compositions and temperatures of experimental interest an isothermal system goes to a single steady state that is stable to perturbation and will neither explode nor oscillate. These steady-state computations also predict that as the temperature is raised above about 1000 K most of the water is converted to H, OH, and HO2 radicals. Under such conditions, exothermic reactions would be so rapid that strong thermal gradients would develop in any real system of plausible dimensions. A simple model based on these calculations predicts explosion limits consistent with those observed experimentally. Simultaneous behavior in time and in space must be calculated in detail before it is clear whether or not this model based on ground electronic states can model the oscillations that are sometimes observed in this system.
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  • 27
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    International Journal of Chemical Kinetics 11 (1979), S. 853-865 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure is suggested to estimate the positions of a transition state (TS) along the reaction coordinate in reaction series involving several radical reactions. It is based on the dependence between experimental activation energies U± and heat effects Q. Taking into account the shift of a TS position, the following relation between these quantities is obtained: U± -; U0± = A (Q - Q0)2 + B(Q - Q0). The subscript 0 indicates the standard reference reaction. For three series, namely, the hydrogen abstraction from hydrocarbon substrates by radicals CH3·, CF·3, and Br·, the bond lengths characterizing the TS reaction center are evaluated. The TS positions appear to vary significantly in the reaction series, which accounts for significant changes in the experimentally observed activation volumes. The derivation of the Hammond rule and the range of its validity for the series with polar and steric substituent effects are discussed.
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    International Journal of Chemical Kinetics 11 (1979), S. 899-906 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of chlorine transfer from CH2Cl2, CHCl3, CCl4, and CCl3CN to the triethylsilyl radical was studied in the liquid phase by a competitive method. Br abstraction from 1-bromopentane was used as a reference. The following Arrhenius parameters were determined:where the error limits are two standard deviations (2σ). Based on these results, the observed reactivity trends in the chlorine transfer reactions of Et3Si radicals appear to primarily reflect the variation in entropy of activation rather than in activation energies.
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  • 29
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    International Journal of Chemical Kinetics 11 (1979), S. 649-664 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mutual combination reaction is proposed as the rate-limiting step in the removal of ClO radicals at moderate pressures. The third--order rate constants measured at room temperature were k1(Ar) = 3.51 ± 0.14 × 109 l2/mol2·ec; k1(He) ≈ 2.8 × 109 l2/mol2·sec, and k1(O2) ≈ 7.9 × 109 l2/mol2·sec. There is also an independent second-order reaction for which k3 ≈ 8 × 106 l/mol·sec. A new absorption spectrum has been observed in the ultraviolet and attributed to Cl2O2. The extinction coefficient for Cl2O2 has been measured at six wavelengths, and, between 292 and 232 nm, it increases from 0.4 × 103 to 2.9 × 103 l/mol·cm. In the presence of the chlorine atom scavengers OClO or Cl2O, Cl2O2 exists in equilibrium with ClO. The equilibrium constant Ke1 = 3.1 ± 0.1 × 106 l/mol at 298 K, and, with ΔS10 estimated to be -133 ± 11 J/K·mol, ΔH10 = -69 ± 3 kJ/mol and ΔHf0(Cl2O2) = 136 ± 3 kJ/mol.
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    International Journal of Chemical Kinetics 11 (1979), S. 665-683 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relations of quantum and kinetic isotope effects are investigated using the exact quantum corrections to the collision and activated complex theories. The latter are computed for the collinear three-atomic reaction H2 + H → H + H2 and the related isotopic reactions using realistic potential energy surfaces. Taking into account the bent configurations of the collision complex H-H-H gives a very good agreement between the quantum collision theory and the experimental data for the absolute values and the isotopic ratios of rate constants. Classical trajectory calculations yield considerably lower results.
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    International Journal of Chemical Kinetics 11 (1979) 
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    Keywords: Chemistry ; Physical Chemistry
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  • 32
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    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.
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    International Journal of Chemical Kinetics 11 (1979), S. 511-527 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of methyl radicals with CCl4 and CCl3Br have been reinvestigated in the gas phase over a wide range of temperatures and pressures using both the photolysis of acetone and the pyrolysis of di-tertiary butyl peroxide (dtBP) as the methyl radical sources. The results are in essential agreement with previous work; however, these new studies provide evidence that at higher pressures the major source of HCl in the reactions is due to methyl radical attack on CH3CCl3, formed via the combination of methyl and trichloromethyl radicals.From these investigations Arrhenius parameters for the reactions have been determined: \documentclass{article}\pagestyle{empty}\begin{document}$$ k_2 = 10^{8.8 \pm 0.3} {\rm exp - }\left({\frac{{{\rm 10}{\rm .1} \pm {\rm 0}{\rm .5}\,{\rm kcal}}}{{RT}}} \right)1/{\rm mol} \cdot {\rm sec} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{15} { } = { 10}^{8.1 \pm {0}{.3}} { exp - }\left({\frac{{{3}{.5 } \pm { 0}{.5 kcal}}}{{RT}}} \right){ 1/mol} \cdot {sec} $$\end{document}Pyrolysis of dtBP in the presence of relatively high-pressure mixtures of CCl4 and CCl3Br resulted in no enhanced methane formation, since, under these conditions, the only termination product is C2Cl6, and the HCl precursor CH3CCl3 is not formed. A competitive technique has been used in which dtBP was pyrolysed in the gas phase in the presence of high-pressure mixtures of CCl3Br and a chloromethane. Arrhenius parameters were obtained for the reactions and the results were used to provide information on the importance of polar effects for hydrogen abstraction from halogenated methanes.
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    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.
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  • 35
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    International Journal of Chemical Kinetics 11 (1979), S. 561-567 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of gas-phase elimination of 3-methyl-1-butyl acetate and 3,3-dimethyl-1-butyl acetate into acetic acid and the corresponding substituted butenes have been measured over the temperature range of 360-420°C and the pressure range of 63-250 Torr. The reactions are homogeneous in both clean and seasoned vessels, obey first-order law, and are unimolecular. The temperature dependence of the rate constants is given by the Arrhenius equation3-methyl-1-butyl acetate: \documentclass{article}\pagestyle{empty}\begin{document}$$ {log k(sec}^{{ - 1}} {) = (12}{.73 } \pm { 0}{.29) - (202}{.5 } \pm { 3}{.8) kJ/mol/2}{.303}RT $$\end{document}3,3-dimethyl-1-butyl acetate: \documentclass{article}\pagestyle{empty}\begin{document}$$ {log k(sec}^{{ - 1}} {) = (12}{.34 } \pm { 0}{.35) - (194}{.1 } \pm { 4}{.2) kJ/mol/2}{.303}RT $$\end{document} The points in a plot of log (k/k0) of β-alkyl and several β-substituted ethyl acetates against Es values appear aligned in an approximate linear relationship. These results may be interpreted as a consequence of steric effects, namely, steric accelerations.
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    International Journal of Chemical Kinetics 11 (1979), S. 595-604 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using the technique of CO2 laser photosensitized decomposition, ethane and propane decomposition was investigated in relation to energy transfer from an SF6 photosensitizer to the hydrocarbon. The end products appearing in the course of irradiation are similar to those formed during classical thermal pyrolysis. The energy transfer from SF6 to the hydrocarbon is closely related to hydrocarbon decomposition. A similar overall kinetic behavior for the two alcanes allows the use of a general diffusional kinetic treatment, provided pressure, intensity, and duration of irradiation are well defined.
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    International Journal of Chemical Kinetics 11 (1979), S. 635-648 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants for the reaction HO2 + NO2(+ M) = HO2NO2(+ M) have been obtained from direct observations of the HO2 radical using the technique of molecular modulation ultraviolet spectrometry. HO2 was generated by periodic photolysis of Cl2 in the presence of excess H2 and O2, and k1 was determined from the measured concentrations and lifetime of HO2 with NO2 present. k1 increased with pressure in the range of 40-600 Torr, and a simple energy transfer model gave the following limiting second- and third-order rate constants at 283 K: k1∞ = 1.5 ± 0.5 × 10-12 cm3/molec·sec and k1III = 2.5 ± 0.5 × 10-31 cm6/molec·sec. The ultraviolet absorption spectrum of peroxynitric acid was also recorded in the range of 195-265 nm; it showed a broad feature with a maximum at 200 nm, σmax = 4.4 × 10-18 cm2.
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    International Journal of Chemical Kinetics 11 (1979), S. 613-619 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decomposition of SF5O3SF5 has been investigated between 5 and 25°C. In the presence of sufficient high pressures of O2 the only products formed are SF5O2SF5 and O2: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm SF}_5 {\rm O}_3 {\rm SF}_5 { } \to { SF}_{5} {O}_{2} {SF}_{5} { + (}{\raise0.5ex\hbox{$\scriptstyle {1}$} \kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle {2}$}}{) O}_{2} {, }\Delta n{ = }{\raise0.5ex\hbox{$\scriptstyle {1}$} \kern-0.1em/\kern-0.15em \lower0.25ex\hbox{$\scriptstyle 2$}} $$\end{document} The reaction is homogeneous. Its rate is strictly first order with respect to the trioxide pressure and independent of the total pressure of the reaction products and of oxygen above a certain limiting pressure: \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{{\rm d}[{\rm SF}_5 {\rm O}_3 {\rm SF}_5 ]}}{{{\rm dt}}}{ = + }\frac{{{\rm d}[{\rm SF}_5 {\rm O}_2 {\rm SF}_5 ]}}{{{\rm dt}}}{ = 2}\frac{{{dp}}}{{{\rm dt}}}{ = k[SF}_{5} {O}_{3} {SF}_{5} {]} $$\end{document} The experimental results can be explained with the following mechanism: In the presence of O2 〉 100 Torr the concentration of SF5 is insignificantly small. Therefore reactions (5) and (6) do not have to be considered any more, and steps (2) and (2′) will be of no importance. From reactions (1)-(4) it follows: \documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm SF}_{\rm 5} {\rm O}_{\rm 3} {\rm SF}_{\rm 5} ]}}{{dt}} = + \frac{{d[{\rm SF}_{\rm 5} {\rm O}_{\rm 2} {\rm SF}_{\rm 5} ]}}{{dt}} = k_1 \frac{{[{\rm SF}_{\rm 5} {\rm O}_{\rm 3} {\rm SF}_{\rm 5} ]}}{{1 + k'_1 (1/2k_3 k_4 )^{1/2} }}k({\rm sec}^{{\rm - 1}}) = k_1 /\left[ {1 + k'_1 \left({\frac{1}{{2k_3 k_4 }}} \right)^{1/2} } \right] = 10^{16.06 \pm 0.37} {\rm exp( - 26,000} \pm {\rm 500}\,{\rm cal)/1}{\rm .987 }T $$\end{document}The numerical value of the factor [1 + (k′12/2k3k4)1/2] is small. It can be estimated that E3 ≃ 2 ± 1 kcal; therefore, E - E1 ≤ 1 kcal, and D (SF5O—O2SF5) = (26 - 1) ± 1.0 kcal.
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    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.
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    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.
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    Keywords: Chemistry ; Physical Chemistry
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    Topics: Chemistry and Pharmacology
    Notes: The electron transfer step of the reduction of Mn(acac)3 and Co(acac)3 by Fe(II) in acetonitrile is preceded by the one-ended dissociation of an acac ligand and the formation of a binuclear bridged complex. After the electron transfer has taken place through the bridging ligand, the complex dissociates into the products M(acac)2 (M = Mn, Co) and Fe(acac)2+. These primary reaction products could not be identified, since the transfer of acac from M(acac)2 to Fe(acac)2+ is too rapid, producing ultimately Fe(acac)3 and M2+. The M(III)-oxygen cleavage is accelerated by M(acac)2. Furthermore, the dissociation of the binuclear intermediate is catalyzed by the M(acac)3 reactant. Mn(acac)3 is reduced more than a thousand times faster than Co(acac)3.
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    International Journal of Chemical Kinetics 11 (1979) 
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    Keywords: Chemistry ; Physical Chemistry
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    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}.
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    International Journal of Chemical Kinetics 7 (1975) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal of Chemical Kinetics 7 (1975), S. 33-37 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present study reports the measurement of the V-V energy transfer rates for the CO*—COS system in the temperature range of 195 to 370°K. The measured rates exhibit a slight inverse temperature dependence. The experimental results are compared to prediction based on a model of long-range dipole-dipole interactions between colliding molecules. The effect of single quantum rotational transitions is compared to that of multiquantum rotational transitions.
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    International Journal of Chemical Kinetics 7 (1975), S. 77-86 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electronically excited tin atoms Sn(51D2), 1.068 eV above the 53P0 ground state, have been generated by the pulsed irradiation of tin tetramethyl and monitored photoelectrically in absorption by time-resolved attenuation of atomic resonance radiation at λ=285.06 nm [Sn((5d3F20) ← (5p2 1D2))]. Deactivation rate constants are reported for the quenching of Sn(51D2) with a range of collision partners and the resulting data are compared with those for analogous states within group IV, namely, C(21D2) and Pb(61D2). The data are discussed in terms of correlations based on both the weak and strong spin orbit coupling approximations.
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    International Journal of Chemical Kinetics 7 (1975), S. 661-677 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of acetylene by water vapor was studied behind the reflected shock in a single-pulse shock tube. Computer simulation experiments reproduced the experimental results in the temperature range of 1500 to 2000°K. The kinetic scheme suggested here involves three major processes, (1) production of hydrogen atoms by the sequence of reactions which lead from acetylene to carbon; (2) production of OH radicals, mainly by the reaction H + H2O → H2 + OH, and (3) fast oxidation of the acetylene and other C/H species by the available oxidants in the system. The experimental results of methane oxidation suggest that methane is converted to acetylene prior to its oxidation. The implication of the experimental results to processes occurring in planetary atmospheres as a result of thunder shock waves is briefly discussed.
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    International Journal of Chemical Kinetics 7 (1975), S. 443-451 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equilibrium quotients for the formation of Co(NH3)5Cl2+ from Co(NH3)5OH23+ and Cl- were 3.74±0.25 M-1 and 6.07±0.54 M-1 at 45.0°C in 10:1 mole ratio water: dimethyl sulfoxide and in 25 w/w % aqueous ethanol, respectively, and those forthe formation of the ion pair Co(NH3)5OH23+ . Cl- were 1.21±0.20 M-1 and 1.58±0.17 M-1, respectively, in the same solvents. The aquation and anation rateconstants were determined at 45.0°C for these two solvents over the range of chloride-ion concentrations 0.0 ≤ [Cl-] ≤ 0.9 M. The aquation rate constant was essentially independent of chloride-ion concentration in each solvent over this range. The inverse of the pseudo-first-order anation rate constant was linearly dependent on the inverse of the chloride-ion concentration in each solvent. The least squares relationships between (1/kan) and (1/[Cl-]) gave intercepts and ratios of intercept to slope which were analyzed interms of Id and D mechanisms. It was concluded that the data were not satisfied by a D mechanism, but that they were consistent with an Id mechanism.
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    International Journal of Chemical Kinetics 7 (1975), S. 535-546 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between a hydroquinone aqueous solution and manganese dioxide has been investigated by electron paramagnetic resonance spectroscopy. A very stable p-benzosemiquinone anion is formed when an aqueous solution of hydroquinone is passed through a column of manganese dioxide. The kinetics for the reaction between hydroquinone and manganese dioxide follow the equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{dC}}{{d\left({W/F} \right)}} = k_1 ^0 \left({A_0 - C} \right) - k_2 ^0 C $$\end{document} where A0 is the initial concentration of hydroquinone, C is the concentration of p-benzosemiquinone anions, W is the amount of manganese dioxide, F is the feed rate of a hydroquinone aqueous solution, and k10 and k20 are constants; k10 = 3.1 × 10-2 (cm3/g MnO2· min), k20 = 3.2 (cm3/g MnO2·min).A mechanism for the reaction is proposed such that Mn(IV) in manganese dioxide is reduced to Mn(II) with hydroquinone from which the semiquinone anion is formed via a neutral semiquinone. The formation of semiquinone anions from several substituted hydroquinones is also discussed.
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    International Journal of Chemical Kinetics 7 (1975), S. 575-587 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Solvent-solute interactions in the peroxyacid oxidations are believed to be specific rather than electrostatic in nature. The kinetic solvent effects reported for the oxidations of organic sulfides, olefins, acetylenes, nitrosobenzenes, thioketones, and aryl sulfines reveal that in each case the rates are fast in nonbasic solvents (e.g., benzene, nitrobenzene, and halogenated hydrocarbons) relative to those in basic solvents such as DMF, dioxane, and alcohols. The rates in CF3CH2OH and aqueous or partially aqueous media are again higher than those in the basic solvents. This remakably similar pattern of sensitivity of rates to changes in the solvent nature appears to be characteristic of these oxidations as demonstrated by the existence of linear free-energy relationship. The behavior is best understood in terms of cyclic transition states for these oxidations in which charge separation is avoided by intra- or intermolecular hydrogen bonding depending on the nature of the solvent. Solvent effects on sulfoxide oxidation and on oxidations by hydrogen peroxide and t-butylhydroperoxide are also briefly discussed.
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    International Journal of Chemical Kinetics 7 (1975), S. 637-638 
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    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal of Chemical Kinetics 7 (1975), S. 679-688 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of tetrafluorohydrazine has been studied from 578 to 791°K. The stoichiometry has been established as \documentclass{article}\pagestyle{empty}\begin{document}$$ 6{\rm NF}_{\rm 2} \to 4{\rm NF}_{\rm 3} + {\rm N}_{\rm 2} $$\end{document} Reaction rates have been measured and the effects of surface area, inert gas pressure, and nitric oxide have been examined. The rate-determining step proposed is \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2NF}_{\rm 2} \to {\rm NF}_{\rm 3} + {\rm NF} $$\end{document} and the general rate expression obtained for this is \documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 = 10^{9.0 \pm 0.4} \exp {{ - 36,950 \pm 500} \mathord{\left/ {\vphantom {{ - 36,950 \pm 500} {RTM^{ - 1} \cdot \sec ^{ - 1} }}} \right. \kern-\nulldelimiterspace} {RTM^{ - 1} \cdot \sec ^{ - 1} }} $$\end{document}
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  • 53
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The high-pressure absolute rate constants for the decomposition of nitrosobenzene and pentafluoronitrosobenzene were determined using the very-low-pressure pyrolysis (VLPP) technique.Bond dissociation energies of DH0(C6H5—NO) = 51.5 ± 1 kcal/mole and DH0 (C6F5—NO) = 50.5 ± 1 kcal/mole could be deduced if the radical combination rate constant is set at log kr(M-1·sec-1) = 10.0 ± 0.5 for both systems and the activation energy for combination is taken as 0 kcal/mole at 298°K. δHf0(C6H5NO), δHf0(C6F5NO), and δHf0(C6F5) could be estimated from our kinetic data and group additivity. The values are 48.1 ± 1, -160 ± 2, and - 130.9 ± 2 kcal/mole, respectively. C-X bond dissociation energies of several perfluorinated phenyl compounds, DH0(C6F5-X), were obtained from the reported values of δHf0(C6F5X) and our estimated δHf0(C6F5) [X = H, CH3, NO, Cl, F, CF3, I, and OH].
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  • 54
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    International Journal of Chemical Kinetics 7 (1975), S. 785-795 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of chlorine atom abstraction from trichloromethyl groups of the haloethanes (XCCl3), CF3CCl3, CH3CCl3, C2Cl6, C2Cl5H, and CH2ClCCl3, by radiolytically generated cyclohexyl radicals was studied in the liquid phase by a competitive method. The chlorine atom abstraction data were put on an absolute basis by comparing the rates of the metathetical reactions with the known rate of addition of cyclohexyl radicals to C2Cl4.The following Arrhenius parameters were obtained: The error limits are the standard deviations from least mean square Arrhenius plots. It is shown that the neighboring group effect on the rate of chlorine atom abstraction from the trichloromethyl groups can be correlated with Taft polar substituent constants.
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  • 55
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    International Journal of Chemical Kinetics 7 (1975) 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 56
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The homogeneous exchange reaction between tetradeutero methane and ammonia was studied behind reflected shocks in a single-pulse shock tube over the temperature range of 1300-1800°K. The rate of production of CD3H at the early stages of the reaction in mixtures ranging between 1-4.5% NH3 and 1-4.3% CD4 in argon is given by d[CD3H]/dt=kb [CD4]0[NH3]0, where kb=8 × 1016 exp (-65.3 × 103/RT) cm3/mole·sec. This activation energy is considerably lower than the one that may be expected on the basis of a pure free radical mechanism. It is rationalized by C2D6 impurities in the methane. No clear answer can be obtained regarding the role of a four-center intermediate in this reaction.
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  • 57
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    International Journal of Chemical Kinetics 7 (1975), S. 879-894 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The specific decomposition rates of chemically activated methylcyclobutane produced from CH2(1A1) reaction with cyclobutane have been determined. CH2(1A1)was produced from ketene photolyses at 3340 and 3130 Å and from diazomethane photolyses at 4358 and 3660 Å. Comparisons of the excitation energies of the methylcyclobutane, determined by RRKM theory calculations, and the experimental results for the ketene systems, with thermochemically predicted maximum excitation energies, favor an Arrhenius A factor in the range of 5 × 1015 to 1 × 1016 sec-1 for methylcyclobutane. This result is consistent with (1) the comparison of RRKM theory calculations and the experimental unimolecular falloff for methylcyclobutane, (2) the comparison of experimental A factors for cyclobutane and other alkylcyclobutane decompositions, and (3) two out of three reported experimental A factors for methylcyclobutane. An analysis of these and previous results leads to a value of the CH2(1A1) ↔ CH2(3B1) energy splitting of 9±3 kcal/mole.
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  • 58
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    International Journal of Chemical Kinetics 7 (1975), S. 973-979 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal decompositions of ethyl chloride, iso propyl chloride, and tertiary butyl chloride were studied in a static system in the pressure range of 0.1-300 torr. The following Arrhenius equations for the high-pressure limit were obtained: The pressure dependence of the first-order rate constant (falloff) for these three unimolecular dehydrochlorination reactions, starting with approximately equal kω values, by proper choice of temperature, is shifted to lower pressures with increasing molecular size:
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  • 59
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    International Journal of Chemical Kinetics 11 (1979), S. 339-341 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Absract.
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  • 60
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    International Journal of Chemical Kinetics 11 (1979), S. 357-374 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate, equilibrium, and thermodynamic data for reaction (1) of 2,6-diphenyl-4R-phenoxyl radicals, where R==OCH3 (I), Ph (II), OC2H5 (III), O-n-C18H37 (IV), and 2,6-dicyclohexyl-4-phenylphenoxyl radical (V), in various solvents are obtained. The k1 values of radicals I to V are within (5.5 ± 1.0) × 107-(1.4 ± 0.3) × 109M-1·sec-1 in propanol. The solvent effect on k1 for radicals I and II was studied. The dimerization of radical I is diffusion-controlled in all solvent studies. The dimerization of radical II is viscosity-dependent but not diffusion-controlled. Plots of k1 against ET have a V shape. Specific solvent-solute interactions are seeming to be responsible for numerical k1 values of radicals I and II. The solvent effect is more pronounced for “slow” dimerization of radicals II than for “fast” dimerization of radicals I. The minimum k1 values correspond to pyridine and chloroform. The reaction (1) rate strongly depends upon the composition of a chloroform (S)-cosolvent binary mixture. Besides reaction (1) the following reactions proceed in binary mixture: \documentclass{article}\pagestyle{empty}\begin{document}$$ K_{14} = 0.18 \pm 0.05M^{ - 1},k_{15} = (2.0 \pm 1.0) \times 10^8 M^{ - 1} \cdot \sec ^{ - 1} $$\end{document} (radical I, S-CCL4 mixture) \documentclass{article}\pagestyle{empty}\begin{document}$$ K_{14} = 0.9 \pm 0.2M^{ - 1},k_{15} = (1.2 \pm 0.5) \times 10^7 M^{ - 1} \cdot \sec ^{ - 1} $$\end{document}(radical II, S-C6H14 mixture) \documentclass{article}\pagestyle{empty}\begin{document}$$ K_{14} = 0.45 \pm 0.10M^{ - 1},k_{15} = (9.0 \pm 2.0) \times 10^6 M^{ - 1} \cdot \sec ^{ - 1} $$\end{document}(radical II, S-CCL4 mixture)In all cases k16 ≪ k15. Factors influencing dimerization rates in strongly nonideal mixtures CH3OH-CCL4 and CH3OH-CHCl3 are discussed.
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    International Journal of Chemical Kinetics 11 (1979), S. 415-425 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the redox reaction between mandelic acid (MA) and ceric sulfate have been studied in aqueous sulfuric acid solutions and in H2SO4—MClO4 (M+ = H+, Li+, Na+) and H2SO4—MHSO4 (M+ = Li+, Na+, K+) mixtures under various experimental conditions of total electrolyte concentration (that is, ionic strength) and temperature. The oxidation reaction has been found to occur via two paths according to the following rate law: rate = k[MA] [Ce(IV)], where k = k1 + k2/(1 + a)2[HSO4-]2 = k1 + k2/(1 + 1/a)2[SO42-]2, a being a constant. The cations considered exhibit negative specific effects upon the overall oxidation rate following the order H+ ≤ Li+ 〈 Na+ 〈 K+. The observed negative cation effects on the rate constant k1 are in the order Na+ 〈 Li+ 〈 H+, whereas the order is in reverse for k2, namely, H+ ≤ Li+ 〈 Na+. Lithium and hydrogen ions exhibit similar medium effects only when relatively small amounts of electrolytes are replaced. The type of the cation used does not affect significantly the activation parameters.
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    International Journal of Chemical Kinetics 11 (1979), S. 445-449 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Formic acid molecules highly diluted in argon were passed through a clean platinum screen at 420-730 K and condensed onto an 8-K CsI window. The well-known decomposition products, CO2, CO, and H2O, were observed in the infrared spectra of the resulting matrices. In addition, new absorptions which are attributed to the OCOH free radical were also observed. Experiments with partially deuterated formic acids confirmed that the carbon-hydrogen bond of the formic acid was lost in the formation of the new intermediate species. The activation energy for CO2 production, Ea = 3.5 ± 0.2 kcal/mol, was determined by monitoring its appearance rate at several different catalyst temperatures.
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    International Journal of Chemical Kinetics 11 (1979) 
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    Keywords: Chemistry ; Physical Chemistry
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  • 64
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    International Journal of Chemical Kinetics 11 (1979), S. 345-355 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the radiolysis of water vapor containing small concentrations of cyclohexane, the principal products which account for about 98% of all end products are found to be hydrogen, cyclohexene, and bicyclohexyl. Cyclohexene and bicyclohexyl yields were determined over a range of temperatures (70-200°C), total pressures (50-2400 torr), and total doses (0.15-2.0 Mrad). The disproportionation-combination ratio kdH/kcH for c-C6H11 radicals could be determined as 0.56 ± 0.01 from the ratio of cyclohexene to bicyclohexyl yield. By using c-C6D12, the ratio kdD/kcD for c-C6D11 radicals is found to be 0.38 ± 0.01. Comparison of the reactivity pattern of C6H11 and C6D11 radicals leads to (kdH)/(kcH)/(kdD/kcD) = 1.47 ± 0.02. The corresponding values for the reactions of c-C6H11 with c-C6D11 were also determined.
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    International Journal of Chemical Kinetics 11 (1979), S. 411-413 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quartz surface has been prepared for which γ, the mean collisional efficiency for removal of hydrogen atoms, is given by \documentclass{article}\pagestyle{empty}\begin{document}$$ 10^4 \gamma = 0.78 \pm 0.30 $$\end{document} over the temperature range from 315 to 818 K. The preparation “cleans” the surface by contact with 10M aqueous NaOH for ˜ 15 hr and then deactivates it by contact with 10M aqueous HNO3 for ˜15 hr. The surface is stable and long-lived even after prolonged contact with air. Preliminary results show that a similar result can be obtained using Pyrex glass surfaces.
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    International Journal of Chemical Kinetics 11 (1979), S. 427-444 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An algorithm for the automatic sensitivity analysis of kinetic mechanisms based on the Fourier amplitude sensitivity test (FAST) method of Shuler and co-workers is reported. The algorithm computes a measure of the relative sensitivity of each concentration to each parameter of interest, such as rate constants, Arrhenius parameters, stoichiometric coefficients, and initial concentrations. Arbitrary variations in the magnitude of the parameters are allowable. The algorithm is illustrated for the simple example of computing the sensitivity of the concentration of species A to variation of the two Arrhenius parameters for the hypothetical reaction A + A →.
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    International Journal of Chemical Kinetics 11 (1979), S. 317-331 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Unimolecular rate data from systems such as very-low-pressure pyrolysis (steady-state flow) and static experiments where gas-gas collisions compete with gas-wall collisions must be interpreted in terms of reactant inhomogeneity arising from finite diffusion rates, rather than using the usual assumption of a well-stirred reactor. An integrodifferential equation describing this process is derived, and a numerical variational solution applicable to weak gas-gas collisions is presented. This gives a powerful method for obtaining collisional energy transfer probabilities from such experiments. Previously reported data (on cyclobutane and cycloheptatriene reactions) are reinterpreted to give conventional values for average energy transfer, replacing the anomalously low collisional efficiencies proposed previously.
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    International Journal of Chemical Kinetics 11 (1979), S. 399-410 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mechanism for ozone-olefin reactions is developed that is consistent with the recent findings of several investigations. These findings suggest a reaction sequence leading to the production of fewer free radical species than has been assumed in the past. Computer simulations using the new mechanism reproduce experimental results obtained from the ozonolysis of propylene in air.
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  • 69
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    Topics: Chemistry and Pharmacology
    Notes: N-Methyl-N-β-hydroxyethyl picramide (PH) forms a 1:1 (PHS2-) and a 1:2 (PHS24-) anionic σ-complex with sulfite ion. In alkaline solution PH is present mainly in the form of its spiro Meisenheimer complex (M-) which also adds sulfite ion to form a complex MS3-. Rate and equilibrium constants for the various reactions which interrelate the five species PH, PHS2-, PHS24-, M-, and MS3- (scheme I) were determined. PHS24- and MS3- can, in principle, exist in the form of two geometric isomers. Despite a careful search by nuclear magnetic resonance and kinetic techniques, no experimental manifestation of this isomerism could be found. Various limiting situations are discussed under which the absence of experimental evidence does or does not exclude the presence of two isomers. Our preferred but unproven interpretation is that in the case of PHS24- one isomer (trans?) is thermodynamically strongly favored over the other, whereas in the case of MS3- both isomers are of similar thermodynamic stability and have also similar rates. This latter feature would make the isomerism kinetically undetectable. Several other features of scheme I make it an instructive example in complex chemical kinetics.
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    International Journal of Chemical Kinetics 11 (1979), S. 705-713 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate constant for the bimolecular combination of benzyl radicals in cyclohexane and toluene is determined as a function of temperature. Further, it is studied in cyclohexane-toluene mixtures of different compositions. In the entire range covered, 9.8 × 108 ≤ 2kt ≤ 9.0 × 109M-1·sec-1, the data are very well described by the Smoluchowski equation for a diffusion-controlled reaction to ground-state products using a spin statistical factor of 1/4, a temperature- and solvent-independent reaction distance, and the known diffusion coefficient of toluene.
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    International Journal of Chemical Kinetics 11 (1979), S. 757-774 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Initial rates of formation of primary products have been measured in the pyrolysis of ethylene at 500°C, and a mechanism for the reaction is proposed based on the isomerization of the n-hexyl radical. Additions of oxygen in amounts less than 0.1% markedly increased the rate of formation of all products, but oxygen was not completely consumed in the reaction. It is shown that secondary initiation processes are important at very low conversions, and butene-1 is the most reactive product. Bimolecular reactions between olefins and with oxygen are important steps in the mechanism.
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    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.
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    International Journal of Chemical Kinetics 11 (1979), S. 907-914 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of Cl2, CH4, and O2 were flash photolyzed at room temperature and pressures of ∽60-760 Torr to produce CH3O2. The CH3O2 radicals decay by the second-order process with k6 = (3.7 ± 0.3) × 10-13 cm3/sec in good agreement with other studies. This value ignores any removal by secondary radicals produced as a result of reaction (6), and therefore the true value might be as much as 30% lower. The value is independent of total pressure or the presence of H2O vapor. With SO2 also present, the CH3O2 decay becomes pseudo first order at sufficiently high SO2 pressure which indicates the reaction The value of (8.2 ± 0.5) × 10-15 cm3/sec at about 1 atm total pressure (mostly CH4) was found for CH3O2 removal by SO2, in good agreement with another recent measurement. This value can be equated with k1, unless the products rapidly remove another CH3O2 radical, in which case k1 would be a factor of 2 smaller.
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    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.
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    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.
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    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.
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    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.
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  • 80
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    International Journal of Chemical Kinetics 11 (1979), S. 693-703 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Since 1926 investigations of the Dushman reaction have relied mainly upon “constant-rate” measurements, usually by instrumental methods. Since about that time, the confusion surrounding this venerable reaction has been growing. In part, the confusion arises because the reaction involves reactive intermediate species that have not been studied directly - and may never be. Alternative detailed mechanisms have been assumed with little restraint. One of these, which is built around H2I2O3, has been explored by computer with promising results. The mechanism seems capable of reducing the confusion now attending the Dushman reaction and others related to it.
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  • 81
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    International Journal of Chemical Kinetics 11 (1979), S. 715-730 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal unimolecular decomposition of three vinylethers has been studied in a VLPP apparatus. The high-pressure rate constant for the retro-ene reaction of ethylvinylether was fit by log k (sec-1) = (11.47 + 0.25) - (43.4 ± 1.0)/2.303 RT at 〈T〉 = 900 K and that of t - butylvinylether by log k (sec-1) = (12.00 ± 0.27) - (38.4 ± 1.0)/2.303 RT at 〈T〉 = 800 K. No evidence for the competition of the higher energy homolytic bond-fission process could be obtained from the experimental data. The rate constant compatible with the C—O bond scission reaction in the case of benzylvinylether was log k (sec-1) = (16.63 ± 0.30) - (53.74 ± 1.0)/2.303 RT at 〈T〉 = 750 K. Together with ΔHf,3000(benzyl·) = 47.0 kcal/mol, the activation energy for this reaction results in ΔHf,3000(CH2CHO) = +3.0 ± 2.0 kcal/mol and a corresponding resonance stabilization energy of 3.2 ± 2.0 kcal/mol for 2-ethanalyl radical.
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  • 82
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    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.
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  • 83
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    International Journal of Chemical Kinetics 11 (1979), S. 789-798 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of diethylether has been studied at 500°C and 50 Torr initial pressure in packed vessels (surface-to-volume ratio 11 cm-1). In untreated vessels the reaction appears to be essentially homogeneous as reported before. On the contrary, it is very sensitive to the walls of PbO-coated or NaOH-treated vessels. Thus most of the initial rates of product formation are increased in the PbO-coated vessel and decreased in the NaOH-treated vessel. The efficiency of the walls has been monitored for several weeks and was shown to decrease slowly with the vessel aging time. These phenomena are interpreted in terms of a free-radical chain mechanism in which a part of the initiation or termination steps occurs at the walls, the propagating steps being homogeneous. The present work clearly proves the existence of hetero-homogeneous chain reactions at 500°C. This new class of reaction could be of practical interest in the design of industrial reactors.
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  • 84
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    International Journal of Chemical Kinetics 11 (1979), S. 843-851 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between NO(g) at concentrations between 0.1 and 1.0 Torr in 1-atm N2 and aqueous solutions of NaClO has been studied over the pH range of 6-12 and hypochlorite concentrations between 0.01 and 1.0M. A very rapid and efficient reaction occurs leading to the production of about 30%-40% of the NO as NO2 and with conversions of NO up to 98% at about 1-sec contact time. It is shown that a fast chain reaction initiated by the endothermic step can account for the data. The very exothermic reaction NO + ClO- → NO2 + Cl- is shown to be at least 30-fold slower than i. The overall reaction seems very promising as a method of reducing NO and NO2 emissions from the exhausts of industrial plants.
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  • 85
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    International Journal of Chemical Kinetics 11 (1979), S. 867-882 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hexamethylethane has been decomposed in a flow system in the temperature range of 700-900 K. The mechanism involves carbon-carbon bond cleavage at the most highly substituted position and rapid formation of isobutene from the t-butyl radical. The rate expression is \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{k({\rm (tC}_{\rm 4} {\rm H}_{\rm 9})_2 \to 2t{\rm C}_{\rm 4} {\rm H}_{\rm 9}.) = 10^{17.4} {\rm exp(} - 36,000/{\rm T)}} & {{\rm sec}^{ - 1}}\\\end{array} $$\end{document} and is completely consistent with deductions from radical buffer, shock-tube, and direct recombination studies. Of special importance is experimental evidence for large decreases of the A factor with increasing temperature and a high heat of formation for the t-butyl radical, ΔHf(tC4H9·)300 = 52.7 ± 6 kJ.
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  • 86
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    International Journal of Chemical Kinetics 11 (1979), S. 921-933 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methylperoxy radicals were generated by the flash photolysis of azomethane-oxygen mixtures. The observed broadband spectrum of the CH3O2 radical is similar, but not identical to those reported previously. The CH3O2 decay followed second-order kinetics at high CH3O2 concentrations with k4' = (2.5 ± 0.3) × 108 liter/mol·sec (23 ± 2°C); 2CH3O2 → products (4). Because of the potential loss of CH3O2 through the reactions with HO2 and CH3O radicals subsequently formed in this system, simulations suggest that the true k4 is in the range: 2.5 × 108 ≥ k4 ≥ 2.3 × 108 liter/mol·sec. Deviations from linearity of the plot of the reciprocal of the CH3O2 absorbance versus time were seen at long times and were attributed to the reaction (5) with an apparent rate constant k5' ⋍ (1.6 ± 0.4) × 105 liter/mol·sec; CH3O2 + Me2N2 → product (5). The CH3O2-SO2 reaction, CH3O2 + SO2 → products (16), was studied by observing CH3O2 decay in flashed mixtures of Me2N2, O2, and SO2. The results gave the apparent second-order rate constant k16' ⋍ (6.4 ± 1.4) × 106 liter/mol·sec. It appears likely that each occurrence of reaction (5) and (16) is followed by the loss of an additional CH3O2 radical and that k5 ⋍ k5'/2 and k16 ⋍ k16'/2. Our findings suggest that a significant fraction of the SO2 oxidation in a sunlight-irradiated NOx-RH-polluted atmosphere, may occur by reaction with CH3O2 as well as from the HO and HO2 reactions.
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  • 87
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    International Journal of Chemical Kinetics 11 (1979), S. 969-976 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Arrhenius parameters for the title reaction have been measured in a very-low-pressure pyrolysis apparatus in the temperature range 644-722 K and are given by log k2 (M-1 · sec-1) = 9.68 - 2.12/θ, where θ = 2.303RT in kcal/mol. Together with the published Arrhenius parameters for the reverse reaction from iodination studies, they result in a standard heat of formation of the t-butyl radical of 8.4 kcal/mol, accepting S0(C4H9·) = 72.2 e.u. at 300 K from other kinetic data, and thus confirm the accepted value for ΔHf0(t-C4H9·), at variance with recent investigations which yielded significantly higher values. This value for ΔHf0(t-C4H9·) results in a bond-dissociation energy (BDE) for isobutane of 92.7 kcal/mol.
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  • 88
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    International Journal of Chemical Kinetics 11 (1979), S. 1279-1286 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 4-Chloro-1-butene, 5-chloro-1-pentene, and 6-chloro-1-hexene have been shown to decompose, in a static system, mainly to hydrogen chloride and the corresponding alkadienes. In packed and unpacked clean Pyrex vessels the reactions were significantly heterogeneous. However, in a vessel seasoned with allyl bromide these reactions were homogeneous, unimolecular, and follow a first-order law. The working temperature range was 389.6-480.0°C and with a pressure range of 53-221 Torr. The rate constants for the homogeneous reactions were expressed by the following Arrhenius equations: 4-chloro-1-butene: logk(sec-1) = (13.79 ± 0.17) - (223.8 ± 2.1)kJ/mole/2.303RT; 5-chloro-1-pentene: logk(sec-1) = (14.25 ± 1.20) - (238.4 ± 12.7)kJ/mole/2.303RT; and 6-chloro-1-hexene: logk(sec-1) = (12.38 ± 0.22) - (209.6 ± 2.9)kJ/mole/2.303RT. The olefinic double bond has been found to participate in the rate of dehydrohalogenation of 4-chloro-1-butene. The insulation of the CH2=CH in chlorobutene by one or two methylene chains to the reaction center does not indicate neighboring group participation. The three-membered conformation is the most favored structure for anchimeric assistance of the double bond in gas phase pyrolysis of alkenyl chlorides. The heterolytic nature of these eliminations is also supported by the present work.
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  • 89
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    International Journal of Chemical Kinetics 7 (1975), S. 23-31 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The high-temperature oxidation of formaldehyde in the presence of carbon monoxide was investigated to determine the rate constant of the reaction HO2 + CO = CO2 + OH (10). In the temperature range of 878-952°K from the initial parts of the kinetic curves of the HO2 radicals and CO2 accumulation at small extents of the reaction, when the quantity of the reacted formaldehyde does not exceed 10%, it was determined that the rate constant k10 is \documentclass{article}\pagestyle{empty}\begin{document}$$ k_{10} = (1.7 \pm 0.5) \times 10^{ - 10} \exp [ - (23,000 \pm 3000/RT)]\,{\rm cm}^{\rm 3} /{\rm molec}{\rm.sec} $$\end{document} A computer program was used to solve the system of differential equations which correspond to the high-temperature oxidation of formaldehyde in the presence of carbon monoxide. The computation confirmed the experimental results. Also discussed are existing experimental data related to the reaction of HO2 with CO.
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  • 90
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    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modified nuclear recoil techniques have been used to obtain accurate relative bimolecular rate coefficients for thermally induced hydrogen abstraction reactions by atomic fluorine. New results are reported for 12 hydrocarbons and partially fluorinated hydrocarbons studied at 303°K.
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  • 91
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    International Journal of Chemical Kinetics 7 (1975), S. 45-62 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of the electronically excited sulfur-dioxide sensitized isomerization of cis-2-butene has been studied through the measurement of the initial quantum yields of trans-2-butene formation in 3130-A irradiated gaseous binary mixtures of SO2 and cis-2-butene and ternary mixtures of SO2, cis-2-butene, and CO2. The kinetic treatment of the present data from the SO2—C4H8 mixtures and those of recent similar studies of Penzhorn and Güsten [3] and Cox [4] are all consistent with the involvement of only the long-lived fluorescent 1B1 and phosphorescent 3B1 states of SO2 in the isomerization mechanism. The data give (k2a + k2b)=0.21±0.04; SO2(1B1) + SO2 → SO2(3B1) + SO2(2a); SO2(1B1) + SO2 → (2SO2) (2b). The analogous intersystem crossing ratio for the SO2(1B1)-cis-2-butene quenching collisions is the largest observed among the many quencher molecules studied; the value lies in the range of 0.85 to 0.37, with the extremes representing different choices of alternative data and possible mechanisms. From the present data the ratio of the SO2(3B1) quenching rate constant with SO2 to that with cis-2-butene as quencher is estimated to be (2.7±1.2) × 10-3, in good agreement with our directly measured ratio from lifetime studies (2.91±0.23) × 10-3 [30-32], and the value found in isomerization studies by Cox (2.40±0.09) × 10-3 [4]. The simple two-excited state mechanism, which is seemingly applicable to the relatively low-pressure binary SO2-butene mixture results, is not adequate to explain the data obtained in experiments with large quantities of added CO2 gas. Here an “excess” quantum yield of isomerization is observed. Several alternative mechanisms can be used to rationalize these results, but all alternatives must incorporate some other excited SO2 species (X) as well as SO2(3B1) and SO2(1B1). The kinetics suggest that the ill-defined state is unreactive toward the olefin and decays nonradiatively to SO2 largely in experiments at the lower pressures, X → SO2 (11); it may generate SO2(3B1) in a collisionally induced process at high added inert gas (CO2) pressures, X + CO2 → SO2(3B1) + CO2 (10a) and X + CO2 → SO2 + CO2 (10b). The data give k11/(k10a + k10b)=0.026 mole/l.
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  • 92
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    International Journal of Chemical Kinetics 7 (1975), S. 143-157 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the reactions of O(3P) and D atoms with cyclohexane have been investigated using fast-flow techniques. The rates of reaction were computed by monitoring changes in both atom and cyclohexane concentrations using electron spin resonance and mass spectrometric methods, respectively. The O(3P) + C6H12 reaction was studied over a temperature range of 344 to 513°K and we obtain a specific rate constant of (3.2±0.6) × 1014 exp (-4400±400/RT) cm3/mole·sec for this reaction. The only reaction product detectable mass spectrometrically under flow conditions of excess oxygen atoms is formaldehyde.The D + C6H12 reaction was studied over a temperature range of 297 to 596°K. A specific rate constant of (4.1±1.0) × 1013 exp (-4000±300/RT) cm3/mole·sec was obtained for this reaction. On the basis of the results obtained in these studies, the important primary process in both the O(3P) and D atom reactions is concluded to be abstraction of a hydrogen atom from the cyclohexane molecule.
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  • 93
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    International Journal of Chemical Kinetics 7 (1975), S. 161-182 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quantum yields of SO3 formation have been determined in pure SO2 and in SO2 mixtures with NO, CO2, and O2 using both flow and static systems. In separate series of experiments excitation of SO2 was effected within the forbidden band, SO2(3B1) ← \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm SO}_2 (\tilde X,^1 A_1 ) $$\end{document}, and within the first allowed singlet band at 3130 Å. The values of ΦSO3 were found to be sensitive to the flow rate of the reactants. These results and the apparently divergent quantum yield results of Cox [10], Allen and coworkers [24, 26, 29], and Okuda and coworkers [11] were rationalized quantitatively in terms of the significant occurrence of the reactions SO + SO3 → 2SO2 (2), and 2SO → SO2 + S [or (SO)2] (3), in experiments of long residence time. From the present rate data, values of the rate constants were estimated, k2=(1.2±0.7) × 106; k3=(5±4) × 105 l·/mole · sec. ΦSO3 values from triplet excitation experiments at high flow rates of NO—SO2 and CO2—SO2 mixtures showed the sole reactant with SO2 leading to SO3 formation in this system to be SO2(3B1); SO2(3B1) + SO2 → SO3 + SO(3Σ-) (la); k1a=(4.2±0.4) × 107 l./mole · sec. With excitation of SO2 at 3130 Å both singlet and triplet excited states play a role in SO3 formation. If the reactive singlet state is 1B1, the long-lived fluorescent state, SO2(1B1) + SO2 → SO3 + SO (1 Δ or 3Σ-) (lb), then k1b=(2.2±0.5) × 109 l./mole · sec. From the observed inhibition of SO3- formation by added nitric oxide, it was found that the SO3-forming triplet state, generated in this singlet excited SO2 system, had a relative reactivity toward SO2 and NO which was equal within the experimental error to that observed here for the SO2(3B1) species. Either SO2(3B1) molecules were created with an unexpectedly high efficiency in 3130 Å excited SO2(1B1) quenching collisions, or another reactive triplet (presumably 3A2 or 3B2) of almost identical reactivity to SO2(3B1) was important here.
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  • 94
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    International Journal of Chemical Kinetics 7 (1975), S. 273-285 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the thermal bromination reaction \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Br + CF}_{\rm 3} {\rm I} \to {\rm IBr + CF}_{\rm 3} {\rm Br} $$\end{document} have been studied in the range of 173-321°C. For the step we obtain \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log}\,k_{11} \,({\rm cm}^{\rm 3} /{\rm mole} \cdot {\rm sec) = (13}{\rm .19) - (10840} \pm {\rm 460)/}\theta $$\end{document} where θ=2.303RT cal/mole. From the activation energy for reaction (11), we calculate that \documentclass{article}\pagestyle{empty}\begin{document}$$ D({\rm CF}_{{\rm 3}^{\rm - } } {\rm I) = 52}{\rm .6} \pm {\rm 1}{\rm .1}\,{\rm kcal/mole}\,{\rm at 25}{}^{\rm 0}{\rm C} $$\end{document} This is compared with previously published values of D(CF3-I). The relevance of the result to published work on kc for a combination of CF3 radicals is discussed.
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  • 95
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    International Journal of Chemical Kinetics 7 (1975), S. 331-339 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rate of the inhibited pyrolysis of pentachloroethane was studiedover the temperature range of 820 to 865°K using the toluene-carrier technique in a stirred-flow reactor. The pyrolysis rate was found to be first order in reactant, and the rate constant is described by k=1011.6±0.7 exp [(-48,200±2600)/RT] sec-1. An increase by a factor of 6.6 in the surface/volume of the reactor had a negligible effect on the rate. This observation, in addition to a reevaluation of earlier kinetic data for the pyrolysis of pentachloroethane, lead to the following conclusions concerning the pyrolysis mechanism. The initiation and termination as well as the propagation reactions were homogeneous, the termination involved both Cl and C2Cl5 radicals (crosstermination), and autocatalysis was caused by interaction between chlorine and pentachloroethane rather than by dissociation of molecular chlorine.
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  • 96
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    International Journal of Chemical Kinetics 7 (1975), S. 399-415 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The oxidation of CFClCFCl and CF2CCl2 were studied at room temperature by chlorine- and oxygen-atom initiation. The chlorine-atom initiated oxidation of CFClCFCl yields CCl2FCF(O) as the exclusive product. Its quantum yield is ∼420, which gives k3a/k3b=210 where reactions (3a) and (3b) are The O(3P)—CFClCFCl reaction gives CClFO with a quantum yield of 0.80, polymer, and small amounts of an unidentified product which is probably cyclo-(CFCl)3. Thereaction paths are with k9a/k9=0.80. The overall reaction of O(3P) with CFClCFCl proceed one fifth as fast as the O(3P)-C2F4 reaction. When O2 is also present, the same free-radical chain oxidation occurs by O(3P)initiation as by chlorine-atom initiation.The chlorine-atom initiated oxidation of CF2CCl2 gives CF2ClCCl(O) as the major product, with quantum yields ranging from 42 to 85. Smaller amounts of CF2O and CCl2O are produced in equal amounts with quantum yields of ∼3.5. The reactions responsible for the products are The O(3P)-CF2CCl2interaction yields CF2O and with quantum yields of 1.0 and ∼0.85, respectively. In thepresence of O2 the radical chain products are observed, but the mechanism is different than that for other chloroolefins.
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  • 97
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    International Journal of Chemical Kinetics 7 (1975), S. 639-648 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rate constants for the combination of methyl radicals with NO and O2 have been measured by flash photolysis of azomethane coupled with product analysis by gas chromatography. Values of the rate constants have been obtained over the pressure region from 50 to 700 torr with He, N2, and Ar as quenching molecules.The high-pressure limits were obtained through an RRKM model calculation and were found to be \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm CH}_{\rm 3} + {\rm NO} + {\rm M} \to {\rm CH}_{\rm 3} {\rm NO} + {\rm M}} \hfill & {k_\infty = 3.2 \times 10^{ - 11} {{{\rm cm}^{\rm 3} } \mathord{\left/ {\vphantom {{{\rm cm}^{\rm 3} } {{\rm molec} \cdot {\rm sec}}}} \right. \kern-\nulldelimiterspace} {{\rm molec} \cdot {\rm sec}}}} \hfill \\ {{\rm CH}_{\rm 3} + {\rm O}_{\rm 2} + {\rm M} \to {\rm CH}_{\rm 3} {\rm O}_{\rm 2} + {\rm M}} \hfill & {k_\infty = 1.7 \times 10^{ - 12} {{{\rm cm}^{\rm 3} } \mathord{\left/ {\vphantom {{{\rm cm}^{\rm 3} } {{\rm molec} \cdot {\rm sec}}}} \right. \kern-\nulldelimiterspace} {{\rm molec} \cdot {\rm sec}}}} \hfill \\ \end{array} $$\end{document} The rate constants were measured relative to the methyl combination reaction k1 with k1 = 9.5 × 10-11 cm3/molec · sec. The RRKM model suggests D0(CH3—O2) = 32 ± 3 kcal/mole.
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    International Journal of Chemical Kinetics 7 (1975), S. 907-917 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism and kinetics of the reaction of O(3P) atoms with propane were investigated using molecular modulation spectroscopy, with the O(3P) atoms being generated by the Hg photosensitized decomposition of N2O. The absorption spectrum of the X2II3/2 state of OH was observed in the ultraviolet between 307 and 309 nm, and it was confirmed that OH was the product of the O(3P) reaction with propane. The rate constants for the reactions of O(3P) and OH with propane were determined to be 3.9±0.7±1010 and 1.19±0.05±1012 cm3/mole·sec, respectively, at T=56±5°C.
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    International Journal of Chemical Kinetics 7 (1975), S. 919-926 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Kinetics of protonation of Li+, Na+, K+, and Cs+ salts of anthracene radical anions (A-·,Cat+) and dianions (A2-, 2Cat+) by MeOH and MeOD in tetrahydrofuran (THF) and dimethoxyethane (DME) led to the determination of the isotope effect (kH/kD) in the following reactions: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm MeOH(MeOD) + A}\bar \cdot {\rm,Cat}^{\rm + } \to MeO^ - {\rm,Cat}^{\rm + } {\rm + AH} \cdot {\rm (D)} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm (MeOH)}_{\rm 2} {\rm or (MeOD)}_{\rm 2} {\rm + A}\bar \cdot {\rm,Cat}^{\rm + } \to {\rm MeOH,MeO}^ - {\rm,Cat}^{\rm + } {\rm + AH} \cdot {\rm (D)} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm MeOH (MeOD) + A}^{{\rm 2 - }} {\rm,2Cat}^{\rm + } \to {\rm MeO}^ - {\rm,Cat}^{\rm + } {\rm + AH(D)}^{{\rm - 1}},{\rm Cat}^{\rm +} $$\end{document} \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm MeOH (MeOD) + (A,Cat}^{\rm + } {\rm,A}^{{\rm 2 - }} {\rm,Cat}^{\rm + }) \to {\rm MeO}^ - {\rm,Cat}^{\rm + } {\rm + A + AH(D)}^{\rm - },{\rm Cat}^{\rm +} $$\end{document}Studies of cation and solvent influence on the rate constants of these reactions and on the magnitude of the isotope effect permitted us to draw some conclusions about the structure of the pertinent transition states. It seems that only the tight A-·,Na+ pairs participate in the protonation, and on this basis the fraction of tight ion paris of A-·,Na+ in DME was estimated. Our results have been compared with data reported in the literature.
    Additional Material: 2 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 187-197 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The flash photolysis resonance fluorescence technique has been utilized to determine the rate constants for three reactions involving the hydroxyl radical [OH(2≅)] and three halogenated C2 alkanes. The nominal temperature range covered was 250-375 K. The compounds studied and the resulting Arrhenius expressions in units of cm3/molec·sec are The error limits in these expressions are such that they include any possible systematic errors due to the presence of impurities in the halocarbon samples. Tropospheric lifetimes have been calculated for the above species by combining the above rate constant data with global seasonally and diurnally averaged hydroxyl radical concentrations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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