摘要:

AbstractThe pyrolysis ofn‐hexane has been investigated in the ranges 723–823 K and 10–100 Torr at up to 3% decomposition. The reaction is homogeneous and free from the self‐inhibition by olefin products observed for several other alkanes. The products of the reaction are hydrogen, methane, ethane, ethene, propene, but‐1‐ene, and pent‐1‐ene, with smaller amounts of propane. It is shown that the results are in quantitative agreement with a conventional Rice‐Herzfeld chain mechanism terminated by the combination and disproportionation of ethyl radicals, but with the mechanism extended so as to include the unimolecular isomerizations via a six‐membered cyclic transition state between 1‐hexyl and 2‐hexyl (1‐methylpentyl) radicals.The overall rate constant of initiation is estimated to be given by\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log(}k_1 /{\rm s}^{ - {\rm 1}}) = 17.77 - (83.8\,{\rm kcal\, mol}^{ - {\rm 1}})/(2.3{\rm }RT) $$\end{document}The rate constant for the reactionis given by\documentclass{article}\pagestyle{empty}\begin{document}$$ \log (k_9 /{\rm cm}^{\rm 3}\, {\rm mol}^{ - 1} {\rm s}^{ - 1}) = 13.30 - (17.9{\rm \, kcal\, mol}^{ - 1})/(2.3{\rm }\,RT) $$\end{document}which when combined with published data gives an Arrhenius plot curved upwards at low values of 1/Tas has been observed for several other hydrogen abstraction reactions of methyl and of ethyl. Estimates are made of rate constants and ratios of rate constants for several reactions of the free radicals involved in the reaction. It is suggested that the minor product propane arises mainly from a hydrogen abstraction by 1‐propyl from hexane with a contribution from a minor termination process

ISSN:0538-8066    

DOI:10.1002/kin.550190202

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractSolid solutions of Cu2O alone and Cu2O with ZnO or Cr2O3in ZnO · Cr2O3as well as solid solutions of ZnO in Cu2O · Cr2O3have activities and selectivities for methanol synthesis comparable to solid solutions of Cu2O in ZnO. Addition of a secondary phase to these solid solutions limits the grain growth and produces higher surface area

ISSN:0538-8066    

DOI:10.1002/kin.550190203

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractAcetylperoxy radicals were produced by the flash photolysis of chlorine in the presence of acetaldehyde and oxygen. By adding various concentrations of nitrogen dioxide, the rate constant for the reaction producing PANwas measured to bek4(153 Torr) = (2.29 ± 0.05) × 109L/mol s.The effect of pressure has been studied over the range 76–612 Torr and the data fitted to a fall‐off curve withk 4∘= 1.85 × 1013L2/mol2s. andk 4x= 3.67 × 109L/mol s. With a calculated value of the dissociation constant,k −4∘= 268 L/mol s and of the equilibrium constant,K4= 1.04 × 1012L/mol, the expected strong collision value fork 4∘is 2.79 × 1014L2/mol2s.The ultraviolet absorption spectrum of PAN has been characterize

ISSN:0538-8066    

DOI:10.1002/kin.550190204

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe gas phase chemical kinetics of SF4, SF5, and S2F10are reviewed with particular emphasis on relevance to the general problem of the dielectric breakdown of SF6. Specific reaction systems treated are SF4+ F2, SF5+ SF5, and the pyrolysis of S2F10. Computer modeling calculations were carried out to arrive at the best estimates of rate parameters. Based on the results of these calculations, sets of recommended rate parameters are provided. The major discrepancies and problems in establishing the kinetic data base are described. Thermochemical consequences of different model calculations are given.

ISSN:0538-8066    

DOI:10.1002/kin.550190205

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractThe aqueous cleavage ofN‐(2‐bromoethyl)phthalimide (NBEPH),N‐(3‐bromopropyl)phthalimide (NBPPH), andN‐carbethoxyphthalimide (NCPH) have been studied within the [ŌH] range of 5 × 10−4M to 2 × 10−3M, pH range of 8.82 to 10.62 and 8.06 to 8.66, respectively. The observed pseudo‐first‐order rate constants,kobs, reveal a linear relationship with [ŌH] with essentially zero intercept. The alkaline hydrolysis ofN‐(hydroxymethyl)phthalimide (NHMPH) has been studied within the [ŌH] range of 5.64 × 10−6M to 2.0 M. The [OH]‐rate profile reveals that both ionized and nonionized NHMPH are reactive toward ŌH. The second‐order rate constant,kOH, for the reaction of ŌH with non‐ionized NHMPH is ca. 104times larger than that with ionized NHMPH. The values ofkOHobtained for NBEPH, NBPPH, NCPH, and nonionized NHMPH show a reasonable linear relationship with Taft substituent constants, and the slope (ρ*) of the plot is 1.01 ± 0.10. The low value of ρ* of 1.01 is attributed to nucleophilic attack as the rate‐limiting. ThekOHvalue for ionized NHMPH reveals nearly 103‐fold ne

ISSN:0538-8066    

DOI:10.1002/kin.550190206

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractA kinetic reinvestigation of the title redox system in aqueous alkaline media at 35°C and an ionic strength of 0.5 mol dm−3shows that the reaction follows a pseudosecond‐order Fe(CN) 63−disappearance. While varying [phenol]0and [OH−] exhibit a linear influence on the pseudo‐second‐order rate constant, varying[Fe(CN) 63−]0and [Fe(CN) 64−]0, initially taken, have a complicated inhibitory effect on the same. The major phenoloxidation products isolated under a chosen condition are 2,2′‐ and 4,4′‐ dihydroxydiphenyl. Results are interpreted in terms of a probable mechanism which envisages a reversible formation, by the first one‐electron transfer, of a reactive phenoxy radical (PhO˙) which on the second one‐electron transfer forms a less reactive ion‐pair intermediate (stabilized by the Fe(CN) 64−produced) to decompose rate‐determiningly to phenoxonium cation (PhO+) and Fe(CN) 64−, the product‐formation steps b

ISSN:0538-8066    

DOI:10.1002/kin.550190207

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550190201

出版商:John Wiley&Sons, Inc.    

年代:1987

数据来源: WILEY