Homopolar‐ and Heteropolar Bond Dissociation Energies and Heats of Formation of Radicals and Ions in the Gas Phase. I. Data on organic molecules

Abstract

Prepared froni 4-(2,6,6-trimcthylcyclohex-l-cnyl) -but-3-yn-2-01 acetate by epoxidation followed by lithium aluminium hydridc reduction: NMR. (CDCI,) : 1.04(3H, s). 1.20(3H, s ) , 1.27(311, d, J = ~H z ) , 1.34(3H, s), 4,36(1H, q, ,I = 7 Hz), 5,46(1H, d x d , J = 7HZ, J' -5112) ppni; IR. (liq.): 3350, 1955 cm-l.Summary. The literature data on hcteropolar and homopolar 2-center bond dissociation energies in organic molecules in the gas phase and the corrcsponding heats of formation of radicals and ions havc been critically evaluated. Data for more than 500 bonds are represented in tabular form together with the pertinent literature references.Selected electron affinitics and n-bond dissociation energies have also bccn incorporated. The follow-up paper will discuss some cmpirical general aspects of these data particularly regarding the effect of structure on the bond dissociation energies.

Influence of the substituent on the major decomposition channels of the NO2 group inpara-substituted nitrobenzenes: a tandem mass spectrometric study

“…A comparison of the rate constants for the loss of NO 2 (fast) and NO (slower) 7,17 suggests, however, that formation of NO 2 by process (2) is unlikely. The reasoning is that since the dissociation energies of the C-N and C-O bonds of C 6 H 5 NO 2 and C 6 H 5 ONO, respectively, are similar (ca 70 kcal mol À1 ), 4,20 but the O-NO bond of C 6 H 5 NO is weak (17-24 kcal mol À1 ), 20,34 the rates of loss of NO 2 and NO would be expected to be similar if NO 2 came from the C 6 H 5 ONO isomer. As just noted, they have been found to be different.…”

Steric and electronic substituent effects on the carbon-carbon bond

“…Heats of formation (± 0.5 kcal • mol 1 ) were obtained by the experimental determination of heats of combustion 25 -27 ) using either a stirred liquid calorimeter 25 ) or an aneroid microcalorimeter 26 ); heats of fusion and heat capacities were measured by differential scanning calorimetry (DSC), heats of vaporization 21. 25.…”

“…2 or 3 or in Eq. (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) in general. Ali is equal to or slightly than the corresponding bond dissociation energy (BDE) 6 "' 81 ) as pointed out earlier.…”

Dissociative attachment in hot CH3Cl: Experiment and theory

“…Accurate values of many parameters are required, such as the experimental electron affinity 27 ͑EA͒ of Cl and the experimental dissociation energy, 28 D 0 ͑C-Cl͒, in methyl chloride. The calculated DA cross section is also sensitive to the precise values of the vibrational energies of the neutral molecule.…”