摘要:

AbstractThe oxygen‐hydrogen system, including the reactive species H, O, H2, O2, O3, OH, and HO2, is very complex, and contains numerous reactions whose kinetics and branches have been insufficiently explored. In the present study we use computer modeling to simulate observations made in a 300‐K ozone‐hydrogen mixture, in which a critical H2pressure leads to rapid ozone decomposition, and generation of high concentrations of atomic oxygen. Initiation of the reaction chain involves heterogeneous O and/or H atom production, and the chain branching step is the reaction OH(v) + O3→ OH + O + O2, which is shown to be the predominant pathway for these reactants. The critical H2pressure (ca. 3 torr) sets important constraints upon the system k

ISSN:0538-8066    

DOI:10.1002/kin.550170702

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractProducts of the reaction of OH radicals with 1‐butene have been investigated in the presence of NO in one atmosphere of air at room temperature using gas chromatography andin situlong pathlength Fourier transform infrared absorption spectroscopy. The major product observed was propionaldehyde, with a formation yield (after allowing for its subsequent loss processes) of 0.94 ± 0.12. Minor yields of organic nitrates (RONO2) and of peroxypropionyl nitrate, a secondary product arising from propionaldehyde, were also observed. However, none of the products expected from the reactions subsequent to H‐atom abstraction from 1‐butene by OH radicals were observed, allowing an upper limit of 10% for this process to be derived. These data are compared with the available literature results and the implications are dis

ISSN:0538-8066    

DOI:10.1002/kin.550170703

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe kinetics of the reversible recombination of the 2‐phenyl‐ (I), 2‐p‐methoxyphenyl‐(II), and 2‐p‐nitrophenyl‐3‐oxo‐2,3‐dihydrobenzothiophene‐2‐yl (III) radicalshave been investigated. Recombination rate constants of R(I–III) have been determined in different solvents (2k1∼ 109M−1s−1). The rate of reaction (I) with R(I–III) decreases with increasing solvent viscosity η. In the toluene‐vaseline oil mixture (2 ≲ η ≲ 120 cP) the recombination of R(I–III) is molecular mobility limited. The thermodynamic parameters of reaction (I) have been determined: ΔH0= 20–30 kcal/mol. Activation volumes ΔV 1≠for recombination of R(II) have been measured. Inn‐propanol ΔV 1≠is equal to the viscous flow activation volume of the solvent ΔV d≠. In toluene and chloroform ΔV 1≠<ΔV d≠. For the last two solvents the activation volumes of the cage reaction have been estimated ΔV 1≠(r)= −(2–3) cm3/mol. Visible‐range absorption spectra and ESR spectra have been recorded for R(I–III). The role of cage effect in the reactivity anisotropy averaging of R(I–III) is discussed. The potential of the high‐pressure tests fo

ISSN:0538-8066    

DOI:10.1002/kin.550170704

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe kinetics of the gas phase pyrolysis of dimethyl sulfide (DMS) was studied in a static system at 681–723 K by monitoring total pressure‐time behavior. Analysis showed the pressure increase to follow DMS loss. The reaction follows two concurrent paths:with a slow, minor, secondary reaction:In a seasoned reactor the reaction follows a 3/2 order rate law with rate coefficient given by\documentclass{article}\pagestyle{empty}\begin{document}$$ \log [k({\rm L}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} /{\rm mol}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} {\rm s})] = 13.84 \pm 0.21 - (51.4 \pm 0.7)/\theta $$\end{document}with θ = 2.303RTin kcal/mol. A free radical mechanism is proposed to account for the data and a theoretical rate coefficient is derived from independent data:\documentclass{article}\pagestyle{empty}\begin{document}$$\log [k({\rm L}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} /{\rm mol}^{{\raise0.7ex\hbox{${\rm 1}$} \!\mathord{\left/ {\vphantom {{\rm 1} {\rm 2}}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{${\rm 2}$}}} {\rm s})] = 12.8 \pm 0.3 - (47 \pm 1.5)/\theta $$\end{document}which agrees well with the experimental one over the range studied. The reaction is initiated by Me2S → Me + MeS⋅ and propagated by metathetical radical attack on Me2S. C2H4is formed by an isomerization reaction which may in part be due to a hot radical:Thermochemical data are listed, many from estimations, for both molecular and radical species of interest in the presen

ISSN:0538-8066    

DOI:10.1002/kin.550170705

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractThe kinetics and products of the decompositon of 9‐diazofluorene by copper(II) tetrafluoroborate in acetonitrile solvent have been investigated. The reaction is first order with respect to both 9‐diazofluorene and copper(II) tetrafluoroborate. A reaction mechanism has also been propo

ISSN:0538-8066    

DOI:10.1002/kin.550170706

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

摘要:

AbstractKinetic studies of oxidation ofL(−) arginine,L(+) ornithine,L(−) histidine,L(−) tryptophan,L(−) threonine have been carried out in alkaline medium. The reaction showed an inverse fractional order in OH−and first‐order dependence on both amino acid and chloroamine‐Tconcentration. The effect of varying ionic strength (KCl) on the rate of oxidation is negligible. A general mechanism for the oxidation has been suggested by considering interaction between anionic species of amino acid andp‐toluene‐sulphochloramide. The effect of solvent and temperature have been also discussed. The fractional order obtained in OH−is due to the fact that a fraction of overall reaction proceeds via an alternative OH−independent path. The combined rate law in accordance to observed kinetics is derived as\documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm CAT}]}}{{dt}} = \frac{{2k_1 K_1 [{\rm AA}]_T [{\rm CAT}]_T }}{{[{\rm OH}^ - ]}} + 2k_3 K_1 K_3 [{\rm AA}]_T [{\rm CAT}]_T $$\end{document}The rate constants predicted by the derived rate law as the concentration of OH−ions change, are in excellent agreement with the observed rate constants, thus further justifying these rate laws and hence the propo

ISSN:0538-8066    

DOI:10.1002/kin.550170707

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550170701

出版商:John Wiley&Sons, Inc.    

年代:1985

数据来源: WILEY