摘要:

AbstractThe pyrolysis ofn‐propyl allyl sulfide has been studied in static and stirred‐flow systems at temperatures between 270 and 400°C. Propene and 2,4,6‐triethyl‐1,3,5‐trithiane were the only reaction products. The order of the reaction was 0.99 ± 0.05 at 377°C. The first‐order rate coefficients followed the Arrhenius equation\documentclass{article}\pagestyle{empty}\begin{document}$$k{\rm (s}^{- 1} {\rm) = 10}^{{\rm 11}{\rm .52} \pm {\rm 0}{\rm .16}} {\rm exp[(- 157} \pm {\rm 2) kJ/mol/R}T]$$\end{document}The rate coefficients and the product distribution remained unchanged when cyclohexene was used as carrier gas. A molecular mechanism involving a six‐centered cyclic transition state is proposed to explain the present results. This mechanism is further supported by the pyrolysis of 4‐thia‐5‐dideutero‐1‐heptene at 377°C, where only 3‐deuteropropene is formed. The kinetic deuterium isotope effect had a value of 2.6 ± 0.3 at this temperature. The results are compared with those obtained in the pyrolysis ofn‐butyl a

ISSN:0538-8066    

DOI:10.1002/kin.550140602

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe thermal unimolecular decomposition of pent‐2‐yne has been studied over the temperature range of 988–1234 K using the technique of very low‐pressure pyrolysis (VLPP). The main reaction pathway is C4C5bond fission producing the resonance‐stabilized 3‐methylpropargyl radical. There is a concurrent process producing molecular hydrogen and penta‐1,2,4‐triene presumably via the intermediate formation ofcis‐penta‐1,3‐diene. The 1,4‐hydrogen elimination fromcis‐penta‐1,3‐diene is the rate‐determining step in the molecular pathway. This is supported by an independent VLPP study ofcis‐ andtrans‐penta‐1,3‐diene. RRKM calculations show that the experimental rate constants for CC bond fission are consistent with the following high‐pressure rate expression at 1100 K:\documentclass{article}\pagestyle{empty}\begin{document}$$\log k_1 = \left({s^{ - 1}} \right) = \left({16.0 \pm 0.3} \right) - \left({72.6 \pm 2.0} \right)/\theta $$\end{document}where θ = 2.303RTkcal/mol and theAfactor was assigned from the results of shock‐tube studies of related alkynes. The activation energy leads to ΔH f,3000[CH3CCĊH2] = 70.3 andDH 3000[CH3CCCH2H] = 87.4 kcal/mol. The resonance stabilization energy of the 3‐methylpropargyl radical is 10.6 ± 2.5 kcal/mol, which is consistent

ISSN:0538-8066    

DOI:10.1002/kin.550140603

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe thermal unimolecular reactions ofcis‐ andtrans‐penta‐1,3‐diene (c‐PTD andt‐PTD) have been studied over the temperature range of 1002–1235 K using the technique of very low‐pressure pyrolysis (VLPP).c‐PTD decomposes via 1,4‐hydrogen elimination analogous to that previously reported forcis‐but‐2‐ene. RRKM calculations incorporating a six‐center transition state show that the experimental rate constants are consistent with the following high‐pressure rate expression at 1100 K:\documentclass{article}\pagestyle{empty}\begin{document}$$\log k_\infty = \left({s^{ - 1}} \right) = \left({13.0 \pm 0.6} \right) - \left({64.5 \pm 2.0} \right)/\theta $$\end{document}where θ = 2.303RTkcal/mol, and theAfactor was assumed to be the same as that forcis‐but‐2‐ene. The activation energy is in excellent agreement with that obtained forcis‐but‐2‐ene.t‐PTD also undergoes decomposition by H2elimination presumably via the prior rapid isomerization toc‐PTD the resu

ISSN:0538-8066    

DOI:10.1002/kin.550140604

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe kinetics of Rh(III) catalyzed oxidative cleavage of styrene, stilbene, and phenylacetylene by periodate have been investigated in the presence of HClO4in aqueous acetic acid medium. The kinetic orders are completely dependent on the nature of unsaturation. In the cases of styrene and stilbene the reactions are first order in the oxidant and Rh(III), zero order with respect to the substrate, and independent of [H+], whereas in the case of phenyl acetylene the reaction is zero order with respect to the oxidant and first order with respect to the substrate and Rh(III). The reaction is independent of [H+] in the range of 0.01−0.05Mstudied. A mechanism involving higher Rh(V) species has been postulated in the case of styrene as well as stilbene, and metal ion catalyzed hydration has been postulated in case of phenylacetylene. The influence of the solvent has been investigated, and a comparative analysis of the kinetic orders of styrene and stilbene is made with those of phenylacetylen

ISSN:0538-8066    

DOI:10.1002/kin.550140605

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractAn iterative method has been devised for the simulation of chemiluminescence data during the oxidative decomposition of αα′ azobisisobutyronitrile in the presence of ethylbenzene. From this simulation the cross termination rate constant of the two types of peroxy radicals present has been estima

ISSN:0538-8066    

DOI:10.1002/kin.550140606

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe kinetics of the gas‐phase thermal reaction between CF2(OF)2and CO has been studied in a static system at temperatures ranging between 110 and 140°C. The only reaction products were CF2O and CO2, giving the following stoichiometry:\documentclass{article}\pagestyle{empty}\begin{document}$${\rm CF}_{\rm 2} {\rm (OF)}_{\rm 2} {\rm + 2CO = 2CF}_{\rm 2} {\rm O + CO}_{\rm 2} {\rm}\Delta n{\rm = 0}$$\end{document}The reaction is homogeneous. The rate is strictly second order in CF2(OF)2and CO, and is not affected by the total pressure or by the presence of reaction products. Oxygen promotes a sensitized oxidation of CO and inhibits the formation of CF2O.The experimental results in the absence of oxygen can be explained by a chain mechanism similar to that proposed for the reaction between F2O and CO with an overall rate constant of\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = 1.45 \times 10^9 {\rm exp}(- 20,900/RT)L/mol \cdot s$$\end{document}From the experimental data obtained on the oxygen‐inhibited reaction, the rate constant for the primary process can be calculated:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {({\rm I})} \quad {{\rm CF}_{\rm 2} ({\rm OF)}_{\rm 2} + {\rm CO} \to {\rm CF}_{\rm 2} (\mathop {\rm O}\limits^{\rm .}){\rm OF} + {\rm F}\mathop {\rm C}\limits^{\rm .} {\rm O}} \quad\quad {k_1 = 1.45 \times 10^9 {\rm exp}(- 20,900/RT)L/mol \cdot s} \\\end{array}$$\end{document}The chain lengthv= 2.5 is independent of the temperature. Taking for collision diameters σ CF 2 (OF) 2= 6 Å and σCO= 3.74 Å, a value α = 5.3 × 10−3for the steri

ISSN:0538-8066    

DOI:10.1002/kin.550140607

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe kinetics of gamma‐radiation‐induced free‐radical reactions in carbon tetrachloride solutions of ethanol andn‐pentanol were studied in the range of 0.05–0.80Mand 25–170°C. The rate constant for the reaction\documentclass{article}\pagestyle{empty}\begin{document}$${\rm CCl}_{\rm 3} + {\rm R} - CH_2 - {\rm OH}\mathop \to \limits^{k1} {\rm CHCl}_{\rm 3} + {\rm R} - {\rm CH} - {\rm OH}$$\end{document}was found as\documentclass{article}\pagestyle{empty}\begin{document}$$k1(M^{- 1} \cdot s^{- 1}) = 10^{8.6 \pm 0.4} \exp - (\frac{{9900 \pm 600{\rm cal}}}{{RT}})$$\end{document}The activation energy is larger by 0.8 kcal/mol than for secondary alcohols, while theA1factors are ab

ISSN:0538-8066    

DOI:10.1002/kin.550140608

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractThe title reaction has been investigated in the temperature range of 490‐573 K. Initial reactant pressures were varied in the range of 0.2‐5.2 torr (I2) and 2‐20 torr (C6H5SiH3). The rate of iodine consumption, monitored spectrophotometrically, was found to obey\documentclass{article}\pagestyle{empty}\begin{document}$$ - \frac{{d[{\rm I}_{\rm 2}]}}{{dt}} = \frac{{k_{3/2} [{\rm I}_{\rm 2}]^{{\raise0.7ex\hbox{$1$} \!\mathord{\left/ {\vphantom {1 2}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{$2$}}} [{\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm SiH}_{\rm 3}]}}{{1 + k'[HI]/[I_2]}}$$\end{document}both by initial rate and integrated equation fitting procedures. The effect of added initial HI conformed to this expression. The data are consistent with a conventional I‐atom propagated chain reaction, and for the step\documentclass{article}\pagestyle{empty}\begin{document}$${\rm I}^{\rm .} + {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm SiH}_{\rm 3} \to {\rm C}_{\rm 6} {\rm H}_{\rm 5} \mathop {\rm S}\limits^{\rm .} {\rm iH}_{\rm 2} + {\rm HI}$$\end{document}the rate constant is given by\documentclass{article}\pagestyle{empty}\begin{document}$${\rm log}k_1 (dm^3 /mol \cdot s) = (11.52 \pm 0.08) - (76.8 \pm 0.8{\rm kJ/mol})/RT{\rm ln}10$$\end{document}From this is derived the bond dissociation energy value C6H5SiH2H = 374 kJ/mol(88 kcal/mol). A comparison with other SiH dissociation energy values indicates that the “silabenzyl” stabilization energy is s

ISSN:0538-8066    

DOI:10.1002/kin.550140609

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractA nozzle‐beam‐skimmer sampling system is used to measure species concentration profiles for a lean one‐dimensional premixed COO2Ar flame, into which small amounts of sulfur dioxide are introduced. The net formation rate for sulfur trioxide is obtained from the flux fraction profile for this species. The kinetic schemeis then utilized, along with the measured temperature profiles, to evaluate the rate coefficientsk1andk2over the temperature range of 1435–1850 K. The most satisfactory agreement between the measured net formation rate for SO3and that calculated on the basis of reactions (1) and (2) is obtained with the rate coefficients\documentclass{article}\pagestyle{empty}\begin{document}$$k_1 = 4.4 \times 10^{14} \exp [3163/T]{\rm cm}^{\rm 6} {\rm /mol}^{\rm 2} \cdot {\rm s}$$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$k_2 = 1.32 \times 10^{12} \exp [- 3070/T]{\rm cm}^{\rm 3} {\rm /mol} \cdot {\rm s}$$\end{document}Reactions (1) and (2) are found to be nearly balanced in a substantial region of the flame. Here the data are more sensitive to the difference in activation energies, as opposed to a particular value for either. Implications of this observation on the uncertainty of the deduced temperature dependence for each reaction are discussed, as are some of the procedures used in the da

ISSN:0538-8066    

DOI:10.1002/kin.550140610

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY

摘要:

AbstractDiethylhydroxylamine, (C2H5)2NOH, was oxidized by NO2at 25°C in a long‐path‐length infrared gas cell. The measured products of the reaction were HONO and CH3CHO. The reaction scheme which explains the reaction iswas oxidized by NO2, and the reaction was found to be very rapid withk1>10−16cm3/s. The products of the reaction were verified by both infrared absorption (CH3CHO, C2H5NO) and gas chromatography (CH3CH

ISSN:0538-8066    

DOI:10.1002/kin.550140611

出版商:John Wiley&Sons, Inc.    

年代:1982

数据来源: WILEY