Energy transfer in thermal methyl isocyanide isomerization. Incremental and relative cross sections of hydrocarbons

Lin, Yueh Neu; Chan, Siu C.; Rabinovitch, B. S.

doi:10.1021/j100852a013

Cited by 19 publications

(4 citation statements)

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“…Figure 9 shows plots of Rnl vs. / for alkanes, alkenes, and alkynes measured at infinite dilution of the substrate in the CH3NC isomerization system at 280 °C. 112 The expected relation was found; ncriticai is 4 for alkanes and alkenes and is 5 for alkynes. Similar behavior was found113 for perfluoroalkanes for which ncrit is 3.…”

Section: Master Equation and Solutionmentioning

confidence: 81%

Intermolecular vibrational energy transfer in thermal unimolecular systems

Tardy¹,

Rabinovitch²

1977

Chem. Rev.

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475

234

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Section: Master Equation and Solutionmentioning

confidence: 81%

Intermolecular vibrational energy transfer in thermal unimolecular systems

Tardy¹,

Rabinovitch²

1977

Chem. Rev.

Self Cite

475

234

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“…Troe’s formulation of limiting low-pressure rate constants , also employed Z LJ as a reference collision frequency. One rationalization of this practice is that the measurements of relative collision efficiency − indicated that Z ( E ′) is at least proportional to Z LJ for sufficiently large bath gases. Although any inadequacies of this reference can be compensated for via the total cross-section factor , of the collision efficiency β c , this factor has been implicitly or explicitly assumed to be unity in many applications.…”

Section: Introductionmentioning

confidence: 99%

Collision Frequency for Energy Transfer in Unimolecular Reactions

Matsugi

2018

J. Phys. Chem. A

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Pressure dependence of unimolecular reaction rates is governed by the energy transfer in collisions of reactants with bath gas molecules. Pressure-dependent rate constants can be theoretically determined by solving master equations for unimolecular reactions. In general, master equation formulations describe energy transfer processes using a collision frequency and a probability distribution model of the energy transferred per collision. The present study proposes a novel method for determining the collision frequency from the results of classical trajectory calculations. Classical trajectories for collisions of several polyatomic molecules (ethane, methane, tetrafluoromethane, and cyclohexane) with monatomic colliders (Ar, Kr, and Xe) were calculated on potential energy surfaces described by the third-order density-functional tight-binding method in combination with simple pairwise interaction potentials. Low-order (including non-integer-order) moments of the energy transferred in deactivating collisions were extracted from the trajectories and compared with those derived using some probability distribution models. The comparison demonstrates the inadequacy of the conventional Lennard-Jones collision model for representing the collision frequency and suggests a robust method for evaluating the collision frequency that is consistent with a given probability distribution model, such as the exponential-down model. The resulting collision frequencies for the exponential-down model are substantially higher than the Lennard-Jones collision frequencies and are close to the (hypothetical) capture rate constants for dispersion interactions. The practical adequacy of the exponential-down model is also briefly discussed.

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“…Another version of this reaction may be the cis-trans isomerization involving III and V (Figures 1 and 2). Without the involvement of a relatively stable intermediate, one would not expect the chemically activated radicals in this system to be able to undergo cis-trans isomerizations, as normally such reactions require about 60 kcal/mol,17 and the radicals here have only [40][41][42][43][44][45][46][47][48][49][50] kcal/mol. However, if a cyclopropyl form is a long lived enough intermediate in the homoallylic rearrangement, as calculations imply,14 it would be reasonable to expect the cis-trans isomerization of homoallylic radicals such as III and V to occur with the same sort of extreme rapidity.…”

Section: Introductionmentioning

confidence: 99%

Reactions of chemically activated pentenyl radicals. Kinetic parameters of 1,4 hydrogen shifts and the cis-trans isomerization of homoallylic radicals

Carter¹,

Tardy²

1974

J. Phys. Chem.

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The reactions resulting from adding H atoms to 2-pentyne in the gas phase have been studied using several deactivating gases. Measured decomposition products are propyne, 1-butyne, and 1,2-butadiene, resulting from decompositions of initially formed radicals at rates consistent with thermal results. 1,3-Butadiene, resulting from isomerization of initially formed 2-penten-2-yl first via a 1,4 H shift and then via a cis-trans isomerization of homoallylic 2-penten-5-yl, was also formed. Information about the rates of these isomerizations was obtained. 1,4 H shift activated complex models could be tested using this work and literature results, and the use of looser activated complex models is supported. Using loose 1,4 H shift activated complex frequencies and a 0°K primary vinylic C-H bond dissociation energy of 110.2 kcal/mol, a 1,4 H shift critical energy of 18.9 kcal/mol, and a cis-trans homoallylic isomerization critical energy of 23.4 kcal/mol are obtained. In addition, there is evidence of a possible 1,3 H shift of 2-penten-3-yl occurring with a critical energy of about 30 kcal/mol.

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Energy transfer in thermal methyl isocyanide isomerization. Incremental and relative cross sections of hydrocarbons

Cited by 19 publications

References 0 publications

Intermolecular vibrational energy transfer in thermal unimolecular systems

Intermolecular vibrational energy transfer in thermal unimolecular systems

Collision Frequency for Energy Transfer in Unimolecular Reactions

Reactions of chemically activated pentenyl radicals. Kinetic parameters of 1,4 hydrogen shifts and the cis-trans isomerization of homoallylic radicals

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