Estimation of Molecular Parameters of C/H Fragments
- 1 April 1962
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 36 (7) , 1743-1753
- https://doi.org/10.1063/1.1701261
Abstract
In this paper, we have assembled the molecular constants needed for the computation of the thermodynamic functions and the standard heats of formation for most of the low molecular‐weight CmHn species which may be present in equilibrium at very high temperatures under a variety of external conditions. In the literature, the essential data are recorded for only 34 of the 73 species considered, and for those which are listed thermodynamic functions are given for the lower third of the temperature range included in our computations. In order to arrive at an estimate for each of the 39 molecular fragments the following steps were used: (a) assign to each fragment a formal electronic configuration (this establishes the framework for the analogies to be sought and fixes its ground‐state electronic degeneracy); (b) select several paths for dissociation which, when followed, generate the species under consideration in going from one molecule of known structure to another; and (c) estimate the bond dissociation energies from known simple dissociations, corrected for nonlocalized electron interactions. These corrections are relatively small and have been obtained by comparing similar reactions for known species. The success of this procedure is demonstrated by the good agreement found between a few predicted and experimental heats of formation. The self‐consistency of the method is proven by the close check between estimates made for the heats of formation for many species following independent paths.Keywords
This publication has 24 references indexed in Scilit:
- Bond Dissociation Energies in Small Hydrocarbon Molecules.Chemical Reviews, 1961
- Quantum Variational Calculations for a Range of CConfigurationsReviews of Modern Physics, 1960
- Free Radicals by Mass Spectrometry. XVII. Ionization Potential and Heat of Formation of Vinyl RadicalJournal of the American Chemical Society, 1960
- Spectrum and Structure of the Free Methylene RadicalNature, 1959
- Heats of hydrogenation. Part 3Transactions of the Faraday Society, 1959
- Heats of hydrogenation. Part 2.—Acetylene derivativesTransactions of the Faraday Society, 1958
- Ionization and Dissociation of Allene, Propyne, 1-Butyne, and 1,2- and 1,3-Butadienes by Electron Impact; the C3H3+ IonJournal of the American Chemical Society, 1957
- Ionization and dissociation by electronic impact. The ionization potentials and energies of formation of sec.-propyl and tert.-butyl radicals. Some limitations on the methodDiscussions of the Faraday Society, 1951
- Ionization and Dissociation by Electron Impact: The Methyl and Ethyl RadicalsPhysical Review B, 1943
- On the Strength of Carbon-Hydrogen and Carbon-Carbon BondsThe Journal of Chemical Physics, 1942