摘要:

AbstractThe kinetics of the reaction\documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_{\rm 3} + {\rm O}_{\rm 2} (+ {\rm M}) \to {\rm CH}_{\rm 3} {\rm O}_{\rm 2} {\rm (+ M)}$$\end{document}have been studied, using the technique of flash photolysis and kinetic spectroscopy to follow the methyl radical concentration. The order of the reaction lies between 2 and 3 throughout the range of pressure from 25 to 380 torr at 22°C, and the results are consistent with a single reaction sequence:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} {\rm CH}_{\rm 3} + {\rm O}_{\rm 2} \mathop {{\rm \rightleftharpoons}}\limits_{\rm b}^{\rm a} {\rm CH}_{\rm 3} {\rm O}_{\rm 2} ^* \\ {\rm CH}_{\rm 3} {\rm O}_{\rm 2} ^* {\rm } + {\rm M}\mathop {{\rm \rightarrow}}\limits^{\rm c} {\rm CH}_{\rm 3} {\rm O}_{\rm 2} {\rm + M} \\ \\\end{array}$$\end{document}The limiting values of the third‐order rate coefficients at low pressures are (3.6±0.3) × 10111.2mole−2sec−1when M is neopentane, and (0.94 ± 0.03) × 10111.2mole−2sec−1when M is nitrogen. The limiting value of the second‐order rate coefficient at high pressures is (3.1 ± 0.3) × 1081. mole−1sec−1. The rate constant for the independent second‐order reaction\documentclass{article}\pagestyle{empty}\begin{document}$${\rm CH}_{\rm 3} + {\rm O}_{\rm 2} \to {\rm CH}_{\rm 2} {\rm O} \to {\rm OH}$$\end{document}is shown to be not much greater than 2 × 1051. mole−1sec−1, so that this reaction does not complete significantly with the combination reaction.This new interpretation is contrar

ISSN:0538-8066    

DOI:10.1002/kin.550040202

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractProducts of radical combination from the free‐radical buffer system\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$${{\rm R}^{\rm .} + {\rm R}^{\rm '} {\rm I}\mathop {\leftrightharpoons}\limits^{{\rm K}_{{\rm RR}}}{\rm RI} + {\rm R}^{'}}$$\end{document}. have been analyzed for the two cases, R = Me, R′ = iPr and R = Et, R′ = iPr. Results are consistent with the previously examined system where R = Me, R′ = Et, and give a value ofkPfor iPr· combination of 108.6±1.

ISSN:0538-8066    

DOI:10.1002/kin.550040203

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe kinetics of the gas phase isomerization of 1‐chloro‐4‐bromobicyclo[2.2.0]hexane to 2‐chloro‐5‐bromohexa‐1,5‐diene have been measured in a static system over the temperature range of 135–215°C, with a variation in the total pressure from 0.6 to 400 torr. For these conditions the rate constants are well represented by the Arrhenius equation:\documentclass{article}\pagestyle{empty}\begin{document}$${\rm log (}k{\rm /sec}^{ - {\rm 1}} {\rm)} = {\rm (13}{\rm .2} \pm {\rm 0}{\rm .2)} - (34.5 \pm 0.4)/\theta$$\end{document}where θ = 2.303RTkcal/mole. Transition state estimates for the biradical mechanism for the isomerization of bicyclo[2.2.0]hexanes are shown to be in good agreement with these Arrhenius parameters. By comparison of the activation energy with that for the isomerization of bicyclo[2.2.0]hexane and 1,4‐dichlorobicyclo[2.2.0]hexane, the radical stabilization energy of an α‐bromine atom is shown to be 1.0 ± 1.8 kcal/mole. Rates are also reported in the liquid phase at temperatures of 155°C and 175°C with diphenyl ether, nitrobenzene, and dimethylsulfoxide as solvents. The observed rate constants are all faster (by a factor of 1.1–1.7) than those measured in the gas phase and display no correlation betw

ISSN:0538-8066    

DOI:10.1002/kin.550040204

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe gas‐phase thermal isomerization of N‐propylidenecyclopropylamine has been studied in the temerature range of 573° to 635°K. The reaction is homogeneous and kinetically first order and yields 5‐ethyl‐1‐pyrroline as the sole product. The rate constants are independent of pressure in the range of 2.5 to 55 torr and fit the Arrhenius relationship logk(sec−1) = (14.05 ± 0.06) ‐ (47.77 ± 0.16)/θ where θ = 2.303 RT in units of kcal/mole, or logk(sec−1) = (14.05 ± 0.06) ‐ (199.9 ± 0.7)/θ, where θ = 2.303RTin kJ/mole. From considerations of a biradical pathway it is concluded that the resonance stabilization energy of the substituted 2‐aza‐allyl radical is very similar t

ISSN:0538-8066    

DOI:10.1002/kin.550040205

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractQuantum yields of the triplet sulfur dioxide (3SO2)‐sensitized phosphoresence (Φsens) in biacetyl (Ac2) have been determined in experiments over a wide range of pressures of SO2and Ac2. Excited singlet sulfur dioxide (1SO2) was generated using 2650‐Å and 28757hyphen;Å light. The values of Φsenswere dependent on the [SO2]/[Ac2] ratio, as anticpated theoretically. However, in runs at a fixed [SO2]/[Ac2] ratio, the measured Φsensvalues were dependent on the total pressure. This theoretically unexpected effect is probably largely the result of biacetyl triplet diffusion with deactivation at the cell wall. Treatment of the quantum yield data in terms of the complete mechanism gave new estimates of the following rate functions:1SO2+ SO2→ (2SO2) (1),1SO2+ SO2→3SO2+ SO2(2),k2/(k1+k2) = 0.082 ± 0.003 (2650 Å), 0.095 ± 0.005 (2875 Å)3SO2+ Ac2→ SO2+3Ac2(9a),3SO2+ Ac2→ SO2+ Ac2(9b),k9a+k9b= (8.4 ± 2.1) × 1010(2650 Å), (8.1 ± 3.0) × 1010l./mole‐sec (2875 Å)3SO2→ SO2+hvp

ISSN:0538-8066    

DOI:10.1002/kin.550040206

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe quantum yields of the sulfur dioxide triplet (3SO2)‐sensitized phosphorescence of biacetyl (Φsens) were determined in experiments with N2–SO2–Ac2andc‐C6H12–SO2–Ac2mixtures excited at 2875 Å at 27°C. The fraction of the biacetyl triplets which reacts homogeneously by radiative or nonradiative decay reactions was determined in a series of runs at constant [SO2]/[M]and [SO2]/[Ac2] ratios but at varied total pressure. A kinetic treatment of the Φsensresults and singlet sulfur dioxide (1SO2) quenching rate constant data gave the following new kinetic estimates:1SO2+ M → (SO2–M) (1b)1SO2+ M →3SO2+ M (2b); for1SO2–N2collisions,k2b/(k1b+k2b) = 0.033 ± 0.008; for1SO2–c‐C6H12collisions,k2b/(k1b±k2b) = 0.073 ± 0.024; previous studies have shown this ratio to be 0.095 ± 0.005 for1SO2–SO2collisions. It was concluded that the inter‐system crossing ratio in1SO2induced by collision is relatively insensitive to the nature of the collision partner M. However, the individual rate constants for the collision‐induced spin inversion of1SO2(k2b) and the total1SO2‐quenching constants (k1b+k2b) are quite sensitive to the nature of M:k2b/k2avaries from 0.10 ± 0.03 for M = N2to 1.11 ± 0.37 for M =c‐C6H12, and (k1b+k2b)/(k1a+k2a) varies from 0.29 for M = N2to 1.44 for M =c‐C6H12;k1aandk1bare the rate constants for the reactions1SO2‐ SO2→ (2S

ISSN:0538-8066    

DOI:10.1002/kin.550040207

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe quantum yields of phosphorescence (Φp) of biacetyl have been determined in pure biacetyl, biacetyl‐SO2, and biacetyl‐c‐C6H12mixtures in experiments using bands of radiation centered at 3450, 3650, 3880, and 4348 Å. It has been shown that the unexpected effect of gas concentration on the quantum yields of the sulfur dioxide triplet‐sensitized phosphorescence of biacetyl resulted largely from the significant destruction of biacetyl triplets at the wall of the cell. The kinetics of the variation of Φpwith [Ac2], wavelength of the absorbed light, and added gases provide new estimates of the energy relations and the rate constants for the decomposition reaction of vibrationally rich biacetyl molecules in the first excited singlet state (1Ac2‡):1Ac2‡ → products (1),1Ac2‡ + Ac2→1Ac2+ Ac2(2); the minimum energy necessary in1Ac2‡ for reaction (1) to occur is estimated to be about 72.8 kcal/mole above the ground state of biacetyl:k1/k2= (4.3 ± 0.1) × 10−3Mat 3450 Å, (4.07 ± 0.04) × 10−4Mat 3650 Å, and (5.6 ± 0.4) × 10−5Mat about 3800 Å. The variation of the rate constant ratio is shown to be consistent with the expectations of the simple theory of excited molecule decomposition. Biacetyl triplet (3Ac2) rate constants were determined by measurements of Φpin O2and NO‐containing mixtures:3Ac2+ S → (Ac2–S, products) (8); for O2= S,k8= (5.76 ± 0.40) × 108(3650 Å experiments), (5.76 ± 0.27) × 108(4358 Å); for NO = S,k8= (3.34 ± 0.20) × 109(3650 Å), (3.33 ± 0.18) × 1091./mole‐sec (4358 Å). A comparison between these and previous findings of the SO2triplet (3SO2)‐sensitized excitation of biacetyl [5,6] show that the decomposition of the initial3Ac2product of the exotherm

ISSN:0538-8066    

DOI:10.1002/kin.550040208

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of 3‐chloro‐3‐trichloromethyldizairine in carbon tetrachloride and iso‐octane has been investigated over the temperature range 75–115°C. The products, tetrachloroethylene and nitrogen, are formed quantitatively by a first‐order reaction which is probably unimolecular:The results yielded the following Arrhenius equations:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} k({\rm CCl}_{\rm 4} {\rm)} = {\rm 10}^{{\rm 13}{\rm .8} \pm {\rm 0}{\rm .2}} \exp (- 29,200 \pm 200/RT)\sec ^{ - 1} \\ k(iso - {\rm octane)} = {\rm 10}^{{\rm 13}{\rm .8} \pm {\rm 0}{\rm .2}} \exp (- 29,000 \pm 150/RT)\sec ^{ - 1} \\ \end{array}$$\e

ISSN:0538-8066    

DOI:10.1002/kin.550040209

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

摘要:

AbstractA comparative study of the kinetics of the N‐nitrosation of sulfanilamide by cyclohexyl nitrite and by nitrous acid has been made, using an automated technique. The results indicate that a common nitrosating species is effective in analogous reactions involving cyclohexyl nitrite or nitrous acid. The N‐nitrosation reaction has been followed spectrophotometrically by coupling the diazotized product with 1‐naphthol. Under certain conditions a competitive reaction takes place in which coupling occurs with unreacted sulfanil

ISSN:0538-8066    

DOI:10.1002/kin.550040210

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550040211

出版商:John Wiley&Sons, Inc.    

年代:1972

数据来源: WILEY