摘要:

AbstractA 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 concentratio

ISSN:0538-8066    

DOI:10.1002/kin.550110802

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractDuring 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 HO2radicals. 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 sys

ISSN:0538-8066    

DOI:10.1002/kin.550110803

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe reaction between NO(g) at concentrations between 0.1 and 1.0 Torr in 1‐atm N2and 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 NO2and 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 stepcan account for the data. The very exothermic reaction NO + ClO−→ NO2+ Cl−is shown to be at least 30‐fold slower thani. The overall reaction seems very promising as a method of reducing NO and NO2emissions from the exhausts of in

ISSN:0538-8066    

DOI:10.1002/kin.550110804

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractA 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 energiesU±and heat effectsQ. Taking into account the shift of a TS position, the following relation between these quantities is obtained:U±−;U 0±=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

ISSN:0538-8066    

DOI:10.1002/kin.550110805

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractHexamethylethane 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 thet‐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 theAfactor with increasing temperature and a high heat of formation for thet‐butyl radical, ΔHf(tC4H9·)300=

ISSN:0538-8066    

DOI:10.1002/kin.550110806

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe oxidation of fluorene by vanadium(V) in aqueous acetic acid containing sulfuric acid (1.0M) at 50°C produces fluorenone and 2‐hydroxy diphenyl 2′‐carboxaldehyde. The order with respect to each reactant is found to be 1. The order dependence on sulfuric acid concentration is 4, indicating that V(OH)23+could be the active species. An increase in the acetic acid percentage in the solvent medium increases the rate of the reaction. The effect of solvent variation has been discussed in the light of the acidity function and the polarity of the medium. The effect of substituents on the rate has been studied for seven substituted fluorenes, and a linear relationship exists between logkversus σ values with the slope ρ = ‐3.2. A small isotope effect is observed for the oxidation of the parent compound (kH/kD= 1.2). The effect of temperature on the rate of the reaction has been studied, and the activation parameters are discussed. A mechanism involving the rate‐limiting formation of a cation‐radical intermedia

ISSN:0538-8066    

DOI:10.1002/kin.550110807

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe 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 energi

ISSN:0538-8066    

DOI:10.1002/kin.550110808

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractMixtures of Cl2, CH4, and O2were flash photolyzed at room temperature and pressures of ∽60–760 Torr to produce CH3O2. The CH3O2radicals decay by the second‐order processwithk6= (3.7 ± 0.3) × 10−13cm3/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 SO2also present, the CH3O2decay becomes pseudo first order at sufficiently high SO2pressure which indicates the reactionThe value of (8.2 ± 0.5) × 10−15cm3/sec at about 1 atm total pressure (mostly CH4) was found for CH3O2removal by SO2, in good agreement with another recent measurement. This value can be equated withk1, unless the products rapidly remove another CH3O2radical, in which casek1would be a factor

ISSN:0538-8066    

DOI:10.1002/kin.550110809

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractCyclopropane in argon mixtures was heated in a single‐pulse shock tube, and syringes were used to withdraw samples from both the central gas slug and the gas adjacent to the tube walls. Differences were observed in the measured conversion, with larger conversion found in the center location. The discrepancy increased with increasing conversion, and the results indicate that boundary‐layer effects can seriously affect the results of absolute single‐pulse shock‐tube studies when percent conversion i

ISSN:0538-8066    

DOI:10.1002/kin.550110810

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractMethylperoxy radicals were generated by the flash photolysis of azomethane–oxygen mixtures. The observed broadband spectrum of the CH3O2radical is similar, but not identical to those reported previously. The CH3O2decay followed second‐order kinetics at high CH3O2concentrations withk4' = (2.5 ± 0.3) × 108liter/mol·sec (23 ± 2°C); 2CH3O2→ products (4). Because of the potential loss of CH3O2through the reactions with HO2and CH3O radicals subsequently formed in this system, simulations suggest that the truek4is in the range: 2.5 × 108≥k4≥ 2.3 × 108liter/mol·sec. Deviations from linearity of the plot of the reciprocal of the CH3O2absorbance versus time were seen at long times and were attributed to the reaction (5) with an apparent rate constantk5' ⋍ (1.6 ± 0.4) × 105liter/mol·sec; CH3O2+ Me2N2→ product (5). The CH3O2–SO2reaction, CH3O2+ SO2→ products (16), was studied by observing CH3O2decay in flashed mixtures of Me2N2, O2, and SO2. The results gave the apparent second‐order rate constantk16' ⋍ (6.4 ± 1.4) × 106liter/mol·sec. It appears likely that each occurrence of reaction (5) and (16) is followed by the loss of an additional CH3O2radical and thatk5⋍k5'/2 andk16⋍k16'/2. Our findings suggest that a significant fraction of the SO2oxidation in a sunlight‐irradiated NOx−RH‐polluted atmosphere, may occur by reaction with

ISSN:0538-8066    

DOI:10.1002/kin.550110811

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY