摘要:

Abstract5‐Chloro‐2‐methylpent‐2‐ene decomposes at temperatures of 370–420°C with initial pressures from 61to 158 torr to yield hydrogen chloride and a mixture of methylpentadiene isomers. In a static system, with seasoned vessel and propene inhibitor, the reaction is homogeneous, unimolecular, and of the first order. The rate coefficient is expressed by the following Arrhenius equation: logk(sec−1) = (13.43 ± 0.30) − (215.0 ± 3.7) kJ/mol/2.303RT. The result ofthe present work additionally supports the participation of the neighboringaliphatic olefinic double bond in the rate of HCl elimination of alkenyl chlorides in the gas phase. Moreover, it also confirms the three‐membered conformation as the most favored structure for a

ISSN:0538-8066    

DOI:10.1002/kin.550130102

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe pyrolysis of gaseous neopentyl bromide to 2‐methyl‐2‐butene, 2‐methyl‐1‐butene, and hydrogen bromide was studied under conditions of maximal inhibition by cyclohexene over the temperature range of 389−444°C. This reaction was shown to beconsistent with a first‐order homogeneous molecular process, with Arrhenius parameters ofE= 247 ± 5 kJ/mol and logA(sec−1) = 14.2 ± 0.3. Examination of the uninhibited reaction showed it to be a radical process, simpler than that with neopentyl chloride, there being only one propagation step, thedissociation of the γ‐radical to 1,1‐dimethylcyclop

ISSN:0538-8066    

DOI:10.1002/kin.550130103

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe kinetics and mechanism of the free‐radical chain dechlorination of C2Cl6, C2Cl5H, andsym‐C2Cl4H2in Et3SiH wereinvestigated over a wide temperature range. The propagation step of the dechlorination of chloroethanes (C2ClxH6−x) proceeds by the following reactions:Analysis of the temperature dependence of product formation gave the Arrhenius expressions fork4/k3which in turn were utilized for the estimation of the absolute Arrhenius parameters for hydrogen abstraction from Et3SiH. Our results show that the values ofEabsare lower in Et3SiH than inc‐C6H12by about 2–3 kcal/mol, while theAfactors are almost equal. In competitive studiesk2was determined versus Br abstraction fromn‐C5H11Br. The relative Arrhenius parameters determined by this method show that variations in bothAfactors and activationenergies are responsible for the reactivity trends observed in the Cl transfer reactions of Et3

ISSN:0538-8066    

DOI:10.1002/kin.550130104

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractA small tubular reactor having an inner diameter of 1–2 mm andused as the source in a molecular beam apparatus is described in detail. This arrangement allows the study of fast reactions with reaction times smaller than 1 msec. The preexplosive reaction phase between F2and H2and CH4, respectively, is investigated to find out the initiation reactions. In the F2/H2reaction, initiation is brought about by heterogeneous generation of F atoms or some other surface reaction. Evidence is also obtained for chain branching reactions. In the F2/CH4case the dominant initiation reaction is the homogeneous reaction CH4+ F2→ CH3+ HF + F. The rate constant for the reaction between 300 and 400 K is 1012.3±0.3exp[−47 ± 8 kJ/mol/RT] cm3/mol sec. The analysis of the experimental data also yields the rate constant for the propagation reaction CH3+ F2→ CH3F + F, which is 1012.3±0.3exp[−4.6 ±2.1 kJ/mol/RT

ISSN:0538-8066    

DOI:10.1002/kin.550130105

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractA mixture of Br2+ HBr + C2F5I was photolyzed in the vapor phase. The reaction\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Br + C}_{\rm 2} {\rm F}_{\rm 5} {\rm I} \to {\rm IBr + C}_{\rm 2} {\rm F}_{\rm 5} $$\end{document}forms C2F5radicals which are removed byCompetitive studies over the range of 74–146°C gave ratios ofk10/k9, and these were combined with values obtained previously by different methods at higher temperatures upto 515°C to give\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm log(}k_{10} /k_9) = (- 0.47 \pm 0.03) - (12,500 \pm 300)/\theta $$\end{document}where θ = 2.303RTJ/mol. A value is assigned to the activation energyE10, and this, with other data, leads to\documentclass{article}\pagestyle{empty}\begin{document}$$ D{\rm (C}_{\rm 2} {\rm F}_{\rm 5} - {\rm H}) = 429.8 \pm 2.1{\rm KJ}/{\rm mol} $$\end{document}at 25°C. This result is in excellent agreement with two previous independent determina

ISSN:0538-8066    

DOI:10.1002/kin.550130106

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe reaction of O(3P) atoms with propanehas been studied at temperatures near 300 K by using a discharge flow system. Oxygen atoms were generated in the absence of molecular oxygen by the reaction N + NO → N2+ O, nitrogen atoms having been generated in a microwave discharge. Rate constants for the reaction were measured in two ways, either by measurement of O‐atom decay in the presence of excess propane or by measuring the change in propane concentration after an appropriate time in the presence of an excess of oxygen atoms. The two methods were in good agreement, and the mean rate constant at 306 K is given by\documentclass{article}\pagestyle{empty}\begin{document}$$ k_1 = (4.7 \pm 0.8) \times 10^6 {\rm dm}^3 /{\rm mol}\;\sec $$\end{document}A study of the products of the reaction under conditions corresponding to complete removal of oxygen atoms has shown that an important product of the reaction in the early stages is propene. This is difficult to explain interms of a mechanism involving alkoxy radicals similar to that which has been proposed for some other O(3P)–hydrocarbon reactions. An alternative mechanism is proposed in terms of successive hydrogen abstraction reac

ISSN:0538-8066    

DOI:10.1002/kin.550130107

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe kinetics of oxidation of dimethyl, dipropyl, and diphenyl sulfides by pyridinium chloro chromate in chlorobenzene–nitrobenzene mixtures are reported. The rate data show Michaelis–Menten behavior. The oxidation process is catalyzed by the organic acids like dichloro and trichloro acetic acids. The rate‐determining step appears to be a unimolecular decomposition of a complex of the reac

ISSN:0538-8066    

DOI:10.1002/kin.550130108

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

摘要:

AbstractStoichiometric and, in most cases, absolute rates of coupling of a series ofm‐ andp‐substituted benzenediazonium ions with 2,3‐dihydroxynaphthalene‐6‐sulfonate ion (1) have been determined (i) at pH 5.6 (when one OH group is partly monoionized) and (ii) at pH 9.9 (when one OH group is completely ionized and the second slightly so). The rates at both pH values correlate with the σ+parameter (except for the most reactive ArN 2+at pH 9.9) and the contributions of the two reactive forms of the coupler evaluated. Detailed pH dependences of the coupling rate of thep‐chlorobenzenediazonium ion with (1) reveal a strong interaction between (1) and the borate ion, which strongly influences the coupling rate. Coupling rates have also been measured for both diazonium ions and couplers of importance in the diazo reprog

ISSN:0538-8066    

DOI:10.1002/kin.550130109

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550130101

出版商:John Wiley&Sons, Inc.    

年代:1981

数据来源: WILEY