摘要:

AbstractThe flash photolysis–resonance fluorescence technique has been used to measure the reaction of ground‐state sulfur atoms with molecular oxygen as a function of both temperature and total pressure. The most suitable source of S(3P) for this study was found to be COS in the presence of CO2, as a diluent gas and with the photolysis flash filtered so as to remove all radiation of wavelengths below 1650 Å. Under these conditions, it was found that over the temperature range of 252–423°K the rate data could be fit to a simple Arrhenius‐type equation of the form\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = (2.24 \pm 0.27) \times 10^{ - 12} {\rm exp}\left({\frac{{{\rm - 0}{\rm .00} \pm {\rm 0}{\rm .10 kcal/mole}}}{{RT}}} \right)$$\end{document}Units are cm3molec−1s−1. The smallA‐factor for this reaction, the lack of any pressure dependence, and the direct observation of the production of O(3P) with increasing reaction time suggest that the S(3P) atom attacks the O2(3Σ) molecule end‐on forming SOO which rapidly falls apart to form

ISSN:0538-8066    

DOI:10.1002/kin.550040402

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractAbsolute rate constants for the reaction of S(3P) with ethylene were measured over an ethylene concentration range of 7, a total pressure of 50 to 400 torr, and a flash intensity range of 10. At 298°K, the bimolecular rate constant was found to be invariant over this range of variables and had a measured value of 4.96 × 10−13cm3molec−1s−1. Over the temperature range of 218° to 442°K, the rate data could be fit to a simple Arrhenius equation of the form\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = (7.13 \pm 0.74) \times 10^{ - 12} {\rm exp}\left({\frac{{{\rm - 1}{\rm .58} \pm {\rm 0}{\rm .08 kcal/mole}}}{{RT}}} \right)$$\end{document}Units are cm3molec−1s−1. The dependence of the measured value ofk1on the concentration of the reaction product ethylene episulfide

ISSN:0538-8066    

DOI:10.1002/kin.550040403

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe reaction of C2F5radicals with H2S\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {(2)} & {{\rm C}_{\rm 2} {\rm H}_{\rm 5} + {\rm H}_{\rm 2} {\rm S} \to {\rm C}_{\rm 2} {\rm F}_{\rm 5} {\rm H} + {\rm HS}} & {k_H } \\ \end{array}$$\end{document}was studied over the range 1°−123°C using C2F5radicals generated by photolysis of perfluoropropionic anhydride. The rate constantkHfor reaction (2) is given by\documentclass{article}\pagestyle{empty}\begin{document}$$\log {\rm }k_H ({\rm cm}^{\rm 3} {\rm mole}^{ - 1} \sec ^{ - 1}) = (11.70 \pm 0.19) - (4260 \pm 290)/\theta$$\end{document}where θ = 2.303RT/cal mole−1. The relevance of this result to conflicting published data on the analogous reaction between CF3radicals and H2S is discussed. It is concluded that there is little difference in the Arrhenius parameters for reaction of CF3and C2F5radicals wi

ISSN:0538-8066    

DOI:10.1002/kin.550040404

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractA metathetical reaction between carbon tetrachloride and toluene to give benzyl chloride and chloroform occurs at temperatures above 200°C(k= 4.8 × 1010e−32,900/RTcc mole−1sec−1). The reaction does not involve free radicals, as is shown by the kinetic behavior of the system, by the lack of effect of added free‐radical chain inhibitors, and by the absence of the expected chain termination product, hexachloroethane. The reaction is one of a general type between carbon tetrachloride and alkanes or alkylaromatics, but at the temperatures required it is often obscured by dehydrohalogenation of the product to the highly reactive olefin. At high temperatures, benzyl chloride reacts with toluene to give bibenzyl and hydrogen chloride, apparently also by a metathetical reaction. The transition state is postulated to be four‐center, in which the carbon‐chlorine and carbon–hydrogen bonds are broken and reformed: The experimental preexponential factor is in good agreement with that calculated from transiti

ISSN:0538-8066    

DOI:10.1002/kin.550040405

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe room‐temperature photolysis of N2O (10–100 torr) at 2139 Å to produce O(1D) has been studied in the presence of CH4(10–891 torr). The reactions of O(1D) with CH4were found to be\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {(4)} & {{\rm O(}^{\rm 1} D{\rm)} + {\rm CH}_{\rm 4} } & \to & {{\rm HO + CH}_{\rm 3} } & {0.95 \pm 0.05} \\ {(8)} & {} & \to & {{\rm O(}^{\rm 3} P{\rm)} + {\rm CH}_{\rm 4} } & {{\rm 0}{\rm .05} \pm {\rm 0}{\rm .05}} \\ {} & {} & \to & {{\rm CH}_{\rm 2} + {\rm H}_{\rm 2} {\rm O}} & {{\rm < 0}{\rm .03}} \\ {} & {} & \to & {{\rm CH}_{\rm 3} {\rm OH}} & {{\rm < 0}{\rm .01}} \\ {} & {} & \to & {{\rm CH}_{\rm 2} {\rm O + H}_{\rm 2}} & {{\rm < 0}{\rm .002}} \\\end{array}$$\end{document}The method of chemical difference was used to measure the rate constant ratiok4/(k2+k3), where reactions (2) and (3) are\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {(2)} & {{\rm O(}^{\rm 1} D{\rm)} + {\rm N}_{\rm 2} {\rm O}} & { \to {\rm N}_{\rm 2} + {\rm O}_{\rm 2} } \\ {(3)} & {} & { \to 2{\rm NO}} \\\end{array}$$\end{document}The CH3radicals produced in reaction (4) react with the O2and NO produced in reactions (2) and (3). Thus, near the endpoint of the internal titration, ϕ{C2H6} gives an accurate measure ofk4/(k2+k3). For the translationally energetic O(1D) atoms produced in the photolysis,k4/(k2+k3) = 2.28 ± 0.20. However, if He is added to remove the excess translational energy, thenk4/(k2+k3) drops to 1.

ISSN:0538-8066    

DOI:10.1002/kin.550040406

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe rate constants (kuni) for the first‐order disappearance of the title molecules have been determined under VLPP conditions. Thekuniare not the rate constants of ultimate interest since they reflect the fact that energy transfer competes with the chemical decomposition. Use of the Rice‐Ramsperger‐Kassel‐(Marcus) [RRK(M)] theory allows the determination of the high‐pressure rate constants (kα), if the mode of decomposition is known. The heats of formation of the radicals NH2, CH3NH, and (CH3)2N are known. These values should be usable for prediction of the activation energy for NN bond homolysis in the hydrazines. Measured rate constants for UDMH and TMH bear this out, but the rate constant for MMH does not. This and other evidence lead to the conclusion that MMH decomposes via molecular concerted elimination of NH3and H2not and by NN bond scission. The following values are preferred from this work (θ = 2.303RTin kcal/mole). Mode of decomposition is N—N bond scission unless noted otherwise in parenthesis:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{ll} \underline{{{{\rm Molecule}}}}& \underline{{{{\rm log }k_\infty /\sec ^{ - 1} (298^\circ {\rm K})}}}\\ {{{{\rm MMH}}}}&{{{13.2{\rm - }54/\theta (- {\rm NH}_{\rm 3});}}}\\ {} & {13.5{\rm - }57/\theta (- {\rm H}_{\rm 2})} \\ {{\rm UDMH}} & {17.0{\rm - }63/\theta } \\ {{\rm SDMH}} & {{\rm 13}{\rm .5 - 57/}\theta {\rm (} - {\rm H}_{\rm 2} {\rm)}} \\ {{\rm TMH}} & {{\rm 17}{\rm .4 - 54/}\theta } \\\end{array

ISSN:0538-8066    

DOI:10.1002/kin.550040407

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe kinetics of the “a” and “b” band emissions arising from the1Σ g+←3Ouand1Σ g+←3lutransitions of the diatomic mercury molecule at λmax∼ 4850 Å and 3350 Å, respectively, have been studied at low concentrations of mercury in the presence of N2, C2H6, C3H8, and N2O. Rate constant values have been obtained for the following reactions of the excimer molecule: Hg2(3lu) + N2→ Hg2(3Ou) + N2and Hg2(3Ou) + RH → Hg2(1Σ g+) + RH, where RH = C2H6or C3H8. From a consideration of the detailed kinetics of band emissions, it was also possible to derive rate constants for the quenching reactions of Hg(3P0) atoms. These values are in reasonable agreement with those obtained previously from monitoring atom concentrations dir

ISSN:0538-8066    

DOI:10.1002/kin.550040408

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe self‐radiolysis of CO2in excess tritium (3H2) has been studied at pressures of 0.1 to 1.0 atm, temperatures of −80° to +100°C, and in the presence of added H2O, He, or Ar. The primary products of decomposition are CO and3H2O. Secondary products are C3H4, C23H4, and a white polymer. The rates of disappearance of CO2and formation of products andG‐;values were measured. The disappearance of CO2initially obeys first‐order kinetics, then slows down with time at a rate depending upon the initial pressure of3H2. The initial rates are proportional to pressures of CO2and3H2. They are independent of temperature, decreased by addition of H2O vapor, and increased by addition of He or Ar. The proposed mechanism of decomposition of CO2and formation of products involves ionization of CO2followed by dissociative recombination forming CO and O. Then the O reacts with a hydrogen‐containing species forming OH and H2O, and a back reaction forms CO2fro

ISSN:0538-8066    

DOI:10.1002/kin.550040409

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550040401

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY