摘要:

AbstractThe thermal cyclodimerization of hexafluoropropene and its cycloaddition to chlorotrifluoroethene have been studied at 570–700 K and 8–62 kPa. Both reactions give 1,2‐substituted hexafluorocyclobutanes. For the intercombination product 1‐chloro‐2‐trifluoromethyl‐hexafluorocyclobutane infrared, nuclear magnetic resonance and mass spectra as well as vapor pressure are reported. The rates of reaction can be expressed by the following equations:\documentclass{article}\pagestyle{empty}\begin{document}$$ 2{\rm CF}_{\rm 2} {\rm = CFCF}_{\rm 3}\to{\rm C}_{\rm 4}{\rm F}_{\rm 6}{\rm(CF}_{\rm 3}{\rm )}_{\rm 2}{\rm, k = 8}{\rm .2}\times {10}^{3}{exp( - 143,700 J/mol}RT){\rm m}^3 /{\rm mol} \cdot {\rm sec} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm CF}_{\rm 2} {\rm = CFCF}_{\rm 3}+{ }{\rm CF}_{\rm 2}{\rm = CFCl} \to {\rm C}_{\rm 4}{\rm F}_{\rm 6}{\rm ClCF}_{\rm 3}{\rm, k = 7}{\rm .25}\times { 10}^{3} { exp( - 118,400 J/mol }RT){\rm m}^3 /{\rm mol} \cdot {\rm sec} $$\end{document}The reactions probably proceed by a biradi

ISSN:0538-8066    

DOI:10.1002/kin.550111002

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractUsing 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 ofk4is 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 105.6M−1·sec−1at 298 K. Extrapolation to temperatures where the combustion of organic compounds has been studied (813 K) produces a value of 107.7M−1·sec−1fork4. Under these conditions, reaction (4) competes with hydrogen abstraction or disproportionation reactions of the methoxy radical and its decomposition (3):In particulark3is 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 cy

ISSN:0538-8066    

DOI:10.1002/kin.550111003

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

Abstract1‐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 ofn‐propyl,i‐propyl, andt‐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

ISSN:0538-8066    

DOI:10.1002/kin.550111004

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe thermal unimolecular decomposition of hex‐1‐ene has been investigated over the temperature range of 915–1153 K using the technique of very low‐pressure pyrolysis (VLPP). The reaction proceeds via the competitive pathways of C3−C4fission and retro‐ene elimination, with the latter dominant at low temperatures and the former at high temperatures. This behavior results in an isokinetic temperature of 1035 K under VLPP conditions (both reactions in the unimolecular falloff regime). RRKM calculations, generalized to take into account two competing pathways, show that the experimental unimolecular rate constants are consistent with the high‐pressure Arrhenius parameters given by logk1(sec−1) = (12.6 ± 0.2) ‐(57.7 ± 1.5)/θ for retro‐ene reaction, and logk2(sec−1) = (15.9 ± 0.2) ‐ (70.8 ± 1.0)/θ for C‐C fission, where θ = 2.303RTkcal/mol. TheAfactors were assigned from the results of a recent shock‐tube study of the decomposition in the high‐pressure regime, and the activation energies were found by matching the RRKM calculations to the VLPP data. The parameters for C‐C fission are consistent with the known thermochemistry ofn‐propyl and allyl radicals. A clear measure of the importance of the molecular pathway in the decompos

ISSN:0538-8066    

DOI:10.1002/kin.550111005

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe kinetics of the reaction between benzene‐1,2‐diol(catechol) and hexachloroiridate (IV) have been measured in aqueous acidic perchlorate solutions by the stopped‐flow method. The reaction is second order overall, and first order in each reactant. A reverse reaction also occurs, but it is much slower than the forward process. Observed rate constants are dependent on acidity, but the variation can be attributed to activity rather than mechanistic effects. The reaction appears to proceed predominantly by an outer sphere electron transfer mechanism, yieldingo‐benzoquinone and hexachloroiridate (III), although monoaquopentachloroiridate (III) is formed also at the higher [catechol]/[IrCl62

ISSN:0538-8066    

DOI:10.1002/kin.550111006

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of SF5O3SF5in the presence of CO has been investigated between ‐9.8°C and + 9.9°C. Besides traces of S2F10, equimolecular amounts of SF5O2SF5and CO2are formed.\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm SF}_{\rm 5} {\rm O}_{\rm 3} {\rm SF}_{\rm 5} {\rm + CO } \to {\rm SF}_{\rm 5} {\rm O}_{\rm 2} {\rm SF}_{\rm 5} {\rm + CO}_{\rm 2}{\rm,}\Delta _n {\rm = 0} $$\end{document}The reaction is homogeneous. Its rate is proportional to the pressure of the trioxide and in dependent of the total pressure, the pressure of inert gases and of carbon monoxide:\documentclass{article}\pagestyle{empty}\begin{document}$$ - {\rm }\frac{{d[{\rm SF}_5 {\rm O}_{\rm 3} {\rm SF}_5 ]}}{{dt}}{\rm = +}\frac{{d[{\rm SF}_5{\rm O}_{\rm 2} {\rm SF}_5 }}{{dt}} = {\rm}k[{\rm SF}_5 {\rm O}_{\rm 3}{\rm SF}_5 ] $$\end{document}wherek=k1∞= 1016.32±0.40exp(−25,300 ± 500 cal)/RTsec−1. Consequently,\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm D}_{{\rm SF}_{\rm 5} {\rm O - O}_{\rm 2} {\rm SF}_{\rm 5}} {\rm =}25.3{\rm}\pm {\rm 0}{\rm .5 kcal} $$\end{document}In the presence of oxygen a sensitized CO2formation is observed. A mechanism is given which explains the experimen

ISSN:0538-8066    

DOI:10.1002/kin.550111007

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractA 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.

ISSN:0538-8066    

DOI:10.1002/kin.550111008

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractPyrolytic 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 CSe2at 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 × 10−5mol/cm3dilute (1.0–9.0 × 10−9mol/cm3) CSe2pyrolyzed with measured first‐order decay rates in the range of log10k1(sec−1) = 3.0−5.7; at midrange (2100°K and 4.3 × 10−5mol/cm3in Ar)k1≈ 3 × 104sec−1. The decay probably occurs via a unimolecular low‐pressure process, first order in both CSe2and Ar, for whichk2± 109cm3/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 CSe2with other molecules which are isoelectronic in their valence

ISSN:0538-8066    

DOI:10.1002/kin.550111009

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550111010

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550111011

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY