摘要:

AbstractReinvestigation of the gas phase thermal reaction of 1,1,2,2‐tetramethylcyclopropane (699‐759°K) gave for the unimolecular disappearance of reactant,k(TMC)= 1015.27–63.93/θsec−1, in good agreement with the original results of Frey and Marshall. However, evidence for a high activation energy (E= 79 ± 5 kcal/mole), competitive unimolecular decomposition to 2,3‐dimethyl‐1 and ‐2‐butenes was also obtained. It is proposed that the serious discrepancy noted [1] between the experimentally observed Arrhenius parameters for the overall reaction kinetics, and those predicted by transition state calculations assuming a biradical mechanism for the isomerization reactions (previously believed to be the only primary reaction mode) can be explained in terms of the increasing importance of the decomposition reactions at higher rea

ISSN:0538-8066    

DOI:10.1002/kin.550020102

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThe kinetics of the gas‐phase reaction CH3COCH3+ I2⇄ CH3COCH2I + HI have been measured spectrophotometrically in a static system over the temperature range 340–430°. The pressure of CH3COCH3was varied from 15 to 330 torr and of I2from 4 to 48 torr, and the initial rate of the reaction was found to be consistent with\documentclass{article}\pagestyle{empty}\begin{document}$ {\rm CH}_3 {\rm COCH}_3 + {\rm I}^{\rm .} \stackrel{1}{\rightarrow}{\rm CH}_{\rm 3} {\rm COCH} + {\rm HI} $\end{document}as the rate‐determining step. An Arrhenius plot of the variation ofk1with temperature showed considerable scatter of the points, depending on the conditioning of the reaction vessel. After allowance for surface catalysis, the best line drawn by inspection yielded the Arrhenius equation, log [k1/(M−1sec−1)] = (11.2 ± 0.8) – (27.7 θ 2.3)/θ, where θ = 2.303RTin kcal/mole. This activation energy yields an acetone CH bond strength of 98 kcal/mole and δH f0(CH3COĊH2) radical = −5.7 ± 2.6 kcal/mole. As the acetone bond strength is the same as the primary CH bond strength in isopropyl alcohol, there is no resonance stabilization of the acetonyl radical due to delocalization of the radical site. By contrast, the isoelectronic allyl resonance energy is 10 kcal/mole, and reasons for the difference are discussed in terms of the π‐bond

ISSN:0538-8066    

DOI:10.1002/kin.550020103

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractDilute mixtures of 4‐methyl‐l‐pentyne have been pyrolyzed in a single‐pulse shock tube. The decomposition process involves bond breaking:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm HC} \equiv {\rm C} - {\rm CH}_2 ({\rm i - C}_{\rm 3} {\rm H}_{\rm 7} )\stackrel{k_B}{\longrightarrow}{\rm HC} \equiv {\rm C} - {\rm CH}_2 \cdot ({\rm propynyl}) + {\rm i - C}_{\rm 3} {\rm H}_{\rm 7} \cdot $$\end{document}as well as a molecular reaction:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm HC}\equiv {\rm C} - {\rm CH}_{\rm 2} ({\rm \rm i - C}_{\rm 3} {\rm H}_{\rm 7} )\stackrel{k_M}{\rightarrow}{\rm C}_{\rm 3} {\rm H}_4 ({\rm allene}) + {\rm C}_3 {\rm H}_6 . $$\end{document}The rate parameters are:\documentclass{article}\pagestyle{empty}\begin{document}$$k_{\bf B} = 10^{15.56} \exp {\rm (} - 34,940/T){\rm (sec}^{ - {\rm 1}}) $$ $$\begin{array}{*{20}c} k_{\rm M} = 10^{13.1} \exp {\rm (} - {\rm 29,670/}T){\rm (sec}^{ - {\rm 1}})&{\rm 1100}^ \circ {\rm K, 1}{\rm .5} - 5{\rm atm}\end{array}$$\end{document}The heat of formation of propynyl radical is thus ΔHf300= 338 kJ mol−1(80.7 kcal mol−1)˙ This leads to a propynyl resonance energy of 40 kJ mol−1(

ISSN:0538-8066    

DOI:10.1002/kin.550020104

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

摘要:

AbstractThe kinetics of the ethane pyrolysis have been studied at temperatures from 550 to 596°C and with 0 to 62% of added nitric oxide. The rates of production of various products were studied by gas chromatography; ethylene, hydrogen, methane, nitrogen, water, nitrous oxide and acetonitrile were found as primary products, with hydrogen cyanide, carbon monoxide, acetaldehyde,n‐butane, 1‐butene,cis‐ andtrans‐2‐butene and 1,3‐butadiene as secondary products. For all the primary products the orders with respect to C2H6and NO were determined, as were the activation energies at two different percentages of NO (15.7 and 45.5%).Nitric oxide was found to be rapidly consumed with a finite initial rate, and the rate of production of H2O was close to that of C2H4at higher nitric oxide pressures.A mechanism is proposed which gives good agreement with all of the observed results. Its main features are: (1) Initiation takes place mainly by the unimolecular dissociation of ethane; there is no evidence for or against the process NO + C2H6→ HNO + C2H5; (2) NO scavenges ethyl radicals to form acetaldoxime which decomposes, and in this way the breakdown of C2H5is hastened; (3) termination takes place mainly by the unimolecular decomposition of acetaldoxime to give inactive products. Some of the relevant rate parameters are evaluated. Reactions are proposed to account for the formation of the secondary pro

ISSN:0538-8066    

DOI:10.1002/kin.550020105

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550020106

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550020107

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550020108

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550020109

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550020110

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY

ISSN:0538-8066    

DOI:10.1002/kin.550020111

出版商:John Wiley&Sons, Inc.    

年代:1970

数据来源: WILEY