摘要:

AbstractThe abstraction of hydrogen/deuterium from CH3CH2Cl, CH3CHDCl, and CH3CD2Cl by photochemically generated ground‐state chlorine atoms has been investigated over the temperature range of 8–94°C using methane as a competitor. Rate constant data for the following reactions have been obtained:The temperature dependence of the relative rate constantski/kjwas found to conform to the Arrhenius rate law, where the stated error limits are one standard deviation:\documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 /k_2 = (1.099 \pm 0.015)\exp [(429 \pm 2)/T] $$ $$ k_1 /k_r = (1.422 \pm 0.026)\exp [(1113 \pm 3)/T] $$ $$ k_2 /k_r = (1.295 \pm 0.029)\exp [(684 \pm 3)/T] $$ $$ k_3 /k_r = (1.177 \pm 0.025)\exp [(717 \pm 4)/T] $$ $$ k_4 /k_r = (1.115 \pm 0.023)\exp [(732 \pm 2)/T] $$ $$ k_5 /k_r = (0.978 \pm 0.020)\exp [(985 \pm 2)/T] $$\end{document}andkris the rate constant for the reference reaction (CH4+ Cl → CH3+ HCl). The β secondary kinetic isotope effects (k2/k3/k4) are close to unity and show a slight inverse temperature dependence. Both preexponential factors and activation energies decrease as a result of deuterium substitution in the adjacent chloromethyl group. The trends are well outside the limits of experimenta

ISSN:0538-8066    

DOI:10.1002/kin.550160602

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractWe report laser absorption measurements of NH3decay within the flame front region of rich, atmospheric pressure ammonia flames. These data are combined with earlier OH, NH, and NH2measurements to obtain new estimates for the oscillator strength of NH2. This value,fi= 6.4 × 10−5for thePQ1,7line in the (0,9,0) ← (0,0.0) vibrational band of theA2A1←X2B1transition, suggests ΔH °f(NH) ≅ 87 kcal/mol. The ammonia profiles were also combined with previous data on NO, NH, NH2, and OH to provide an extensive database at fuel equivalence ratios (ø) of 1.28, 1.50, and 1.81 for comparison to our kinetic model predictions. This modeling used a one‐dimensional flame code which explicitly accounts for the diffusional component in our flame experiments. Modeling results using a conventional mechanism predicted concentration profiles which deviated markedly from our observations. It was possible to obtain much more satisfactory fits by postulating reactions between various NHi(i= 1, 2) species to form N—N bonds. The N2Hj(j= 1–3) species could then lose H atoms via dissociation to ultimately form N2. Inclusion of these reactions in the mechanism allowed us to predict concentration—distance profiles for five different species at three different equivalence ratios that are in good agreement with experiment. The most important component of this mechanism is the recognition that the NHi+ NHireactions dominate the kinetics in rich flames. A most satisfying aspect of these calculations is that the key rate constants in the NHi+ NHisequence were estimated us

ISSN:0538-8066    

DOI:10.1002/kin.550160603

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effect of particle size, type of crucible, and heating rate on the thermal curves obtained simultaneously for CuSO4· 5H2O were discussed. The dissociation steps were confirmed. Thermogravimetric techniques for determining the rate‐controlling processes and kinetic parameters were applied for the dehydration steps and the calcination of CuSO4and CuSO4· CuO. For the dehydration of the monohydrate one mechanism operates but the activation energy and preexponential factor vary over wide ranges. Differentiating between various mechanisms using the same technique was sometimes difficult giving completely different values for the kinetic parameters. In view of such difficulties the various methods were assessed, the best techniques to treat similar results were recommended and the operating mechanisms and kinetic parameters for the various steps were thus establis

ISSN:0538-8066    

DOI:10.1002/kin.550160604

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe technique of laser photolysis of alkyl and perfluoroalkyl iodides at 266 nm followed by time‐resolved detection of the 1.3‐μm emission from I*(2P1/2) has been used to measure the rate constants for deactivation of I*by CH3I, C2H5I, CF3I, and CH4. The recommended values are (2.76± 0.22) × 10−13, (2.85 ± 0.40) × 10−13, (3.5 ± 0.5) × 10−17, and (7.52 ± 0.12) × 10−14, respectively, in units

ISSN:0538-8066    

DOI:10.1002/kin.550160605

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe pyrolysis of 1 and 2% ethane in krypton has been studied in shock waves by the laser‐schlieren technique over 1700–4800 K. For 2400–2800 K an effective zero density gradient is seen following the rapid dissociation of the ethane. Through simulation with various mechanisms it is evident that the high rates for the dissociative recombination reactions of methyl radicals\documentclass{article}\pagestyle{empty}\begin{document}$$ 2{\rm CH}_3 \to {\rm C}_2 {\rm H}_4 + {\rm H}_2 $$ $$ 2{\rm CH}_3 \to {\rm C}_2 {\rm H}_5 + {\rm H} $$\end{document}obtained in recent shock‐tube studies, are incompatible with this observation; these rates must be reduced at least an order of magnitude. On the basis of theory and previous low‐temperature (T) measurements,k= 7.8 × 1011(‐6562/T) (cm3/mol s) is recommended for the second of the

ISSN:0538-8066    

DOI:10.1002/kin.550160606

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe kinetics of the gas phase reactions of NO2with a series of organics have been studied at 295 ± 2 K. It was observed that only 2,3‐dimethyl‐2‐butene and the conjugated dialkenes studied reacted at observable rates, with rate constants which ranged from 1.5 × 10−20cm3molecule−1s−1for 2,3‐dimethyl‐2‐butene to 1.3 × 10−17cm3molecule−1s−1for α‐phellandrene. These rate constants are compared with the available literature data and the mechanisms of

ISSN:0538-8066    

DOI:10.1002/kin.550160607

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe reactions of labeled N15NO+with CO, NO, O2,18O2, N2, NO2, and N2O have been investigated using a tandem ICR instrument. In each case the total rate coefficient, product distribution, and kinetic energy dependence were measured. The results indicate that very specific reaction mechanisms govern these reactions. This conclusion is suggested by the lack of isotopic scrambling in many cases and by the complete absence of energetically allowed products in almost all of the systems. The kinetic energy studies indicate that most of the reaction channels proceed through an intermediate complex at low energies and via a direct mechanism at higher kinetic energies. Such direct mechanisms include long range charge transfer and atom or ion transfer.

ISSN:0538-8066    

DOI:10.1002/kin.550160608

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractMixtures of NH3and N2O dilute in Ar were heated behind incident shock waves in the temperature range 1750–2060 K. A cw ring dye laser, tuned to the center of an OH absorption line in the ultraviolet, was used to monitor OH concentration profiles by absorption spectroscopy. Infrared emission was used to follow N2O (at 4.5 μm) and NH3(at 10.5 μm) concentration—time histories. The early‐time NH3and OH concentration profiles were sensitive to the rate constants of the reactionsleading to the following best‐fit expressions fork2andk3:k2= 1013.34±0.3exp(−4470/T) andk3= 1013.91±0.2exp(‐4230/T) cm3mol−1s−1. The results of this study combined with previous low‐temperature data suggest a significant non‐Arrhenius b

ISSN:0538-8066    

DOI:10.1002/kin.550160609

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe reactions of hydrogen atoms produced by the mercury‐photosensitized decomposition of H2with bis(trifluoromethyl)disulfide has been studied. The rate coefficient for the primary reaction, H + CF3SSCF3→ CF3SH + CF3S, was determined in competition with the reaction H + C2H4S → SH + C2H4to have the valuek= (3.0 ± 0.18) × 1014exp[‐(4560 ± 140)/RT] cm3mol−1S−1. The highAfactor can be partially accounted for by assuming free rotation for the two CF3groups and the SCF3groups about the S—S bond in the transition state. The relatively high activation energy is attributed to inductive and orbital overlap effects. CH3SH, H2S, and CF3SH all react with CF3SSCF3to yield solid complexes which were not

ISSN:0538-8066    

DOI:10.1002/kin.550160610

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of azoethane (AE) was studied by detailed product analysis in the temperature and pressure intervals 508–598 K and 2.7–13.3 kPa. Besides the hydrocarbon products, three characteristic and quantitatively important nitrogen‐containing compounds were also determined: ethyl‐2‐butyldiimide, ethanal‐diethylhydrazone, and tetraethyl‐hydrazine. Apart from the predominant termination reactions of the ethyl radical with itself and with the μ2radical, the decomposition is characterized by a very short chain reaction. The measurements led to determination of the following rate constants and rate constant ratios:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{rcl} {\rm log}(k_1 /S^{ - 1} ) &=& (16.0 \pm 0.2) - (207.6 \pm 2.0){\rm kJ mol}^{ - 1} /2.3RT\\ log(k_4 /k_3^{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} {\rm dm}^{{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} {\rm mol}^{{{ - 1} \mathord{\left/ {\vphantom {{ - 1} 2}} \right. \kern-\nulldelimiterspace} 2}} s^{{{ - 1} \mathord{\left/ {\vphantom {{ - 1} 2}} \right. \kern-\nulldelimiterspace} 2}} ) &=& (3.3 \pm 0.1) - (54.3 \pm 1.3){\rm kJ mol}^{ - 1} /2.3RT \\ \log (k_5 /k_3^{1/2} {\rm dm}^{{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} {\rm mol}^{{{ - 1} \mathord{\left/ {\vphantom {{ - 1} 2}} \right. \kern-\nulldelimiterspace} 2}} {\rm s}^{{{ - 1} \mathord{\left/ {\vphantom {{ - 1} 2}} \right. \kern-\nulldelimiterspace} 2}} ) &=& (3.0 \pm 0.1) - (33.7 \pm 1.4){\rm kJ mol}^{ - 1} /2.3RT \\ k_{11} /k_{12} &=& 1.3 \pm 0.1 \end{array} $$\end{document}for the follo

ISSN:0538-8066    

DOI:10.1002/kin.550160611

出版商:John Wiley&Sons, Inc.    

年代:1984

数据来源: WILEY