Iodine and Nitric Oxide Catalyzed Isomerization of Olefins. VII. The Stabilization Energy in the Pentadienyl Radical and the Kinetics of the Positional Isomerization of 1,4-Pentadiene¹

The kinetics and thermochemistry of the gas phase reaction of cyclopentadiene and iodine. Relevance to the heat of formation of cyclopentadienyl iodide and cyclopentadienyl radical

“…18 kcal/mole, a value which can be made compatible with earlier work of Egger and Benson [12] on the I atom-catalyzed positional isomerization of 174-pentadiene only by assuming that the activation energy for pentadienyl and HI to give 1,4-pentadiene and I atoms is ca. 4 kcal/mole.…”

“…The expression was used to compute rate constants from the various runs, and these are tabulated in Table II.3 (12) log (k4/M-l sec-l) = (8.46 f 0.19) -(10.67 f 0.43)/0 where 0 = 2.303RT.…”

Effect of thermal activation on the reaction of toluene with hydrogen atoms

“…This was inferred from trial calculations. For example, using this method, our calculated and their listed values of AH", for schemes (11) and (111) Since it is likely that Eatsbi1 (c6H.1) is in the range of 23-25 kcal/mole [20,22], this value of AZPf(C7H9) = 26.8 kcal/mole may be too low. In addition, the activation energy of H atom addition to toluene EH and that of CHa addition to benzene E C H~ are required to draw the potential energy diagram.…”

“…Taken from [22]. The internal consistency of the models was checked by comparing the entropy at 500°K from the group additivity method (89.5 eu) with that (89.2 or 91.1 eu) computed by summing up rotational (25.2), translational (40.4), CHs rotor (6.0), and vibrational (1 7.6 for normal and 19.5 for modified model) entropies.…”

Homopolar and Heteropolar Bond Dissociation Energies and Heats of Formation of Radicals and Ions in the Gas Phase II. The relationship between structure and bond dissociation in organic molecules

“…Using schematic valence-bond structures [33], this has been represented with 3-electron bond structures and a semiion pair type charge separation. The stabilization energies listed in table 6 appear to substantiate the concept of such an additional small inductive effect for alkyl substituents whereby the substitution of the first hydrogen atom by an alkyl group would have a much more pronounced effect compared to the introduction of further alkyl substituents.…”