| Issue |
J. Chim. Phys.
Volume 77, 1980
|
|
|---|---|---|
| Page(s) | 899 - 905 | |
| DOI | https://doi.org/10.1051/jcp/1980770899 | |
| Published online | 29 May 2017 | |
Evaluation quantitative des effets de substituants sur les premiers potentiels d'ionisation de composés monofonctionnels aliphatiques
1
Laboratoire de Physico-Chimie Instrumentale, Université Paris VII, 2, place Jussieu, 75221 Paris Cedex 05, France.
2
Laboratoire de Chimie Organique Physique, associé au CNRS, Université Paris VII, 1, rue Guy de la Brosse, 75005 Paris, France.
Il est possible d'établir d'excellentes corrélations homogènes entre les PI de composés identiquement substitués de diverses familes de composés monofonctionnels aliphatiques (alcynes, alcènes, aldéhydes-cétones, eau-alcools-éthers-oxydes, hydrogène sulfuréthiols-thioéthers). Ces corrélations permettent de séparer l'effet polaire propre des substituants des interactions intermoléculaires caractéristiques du site fonctionnel.
Pour ces composés, on peut ainsi proposer un modèle empirique de variation des potentiels d'ionisation en fonction d’une nouvelle échelle d'effets polaires qui donne des résultats d'une très bonne précision.
Abstract
The great number of ionization potentials measured by Photoelectron Spectroscopy (UPS) allows the determination of correlations between structures and ionization potentials. Several families of monofunctional organic compounds have now been studied. In view of an analytical application of UPS, we have developped a model which closely describes the additive effects of substituents on the first ionization potential.
The basic ideas are:
— To build a model able to describe the effects for several populations of organic compounds.
— To find an extension for polyfunctional compounds.
— To take account of steric effects and interactions between substituents.
The results obtained on the basis of a linear model are not very satisfactory and fail to account of the effects of large substituents.
The family of the alcynes was chosen to determine the parameters of substituents. In these compounds, there is no interaction between the substituents (the characterization of the effect is more effective) and the measure of the ionization potential is very accurate. A large number of substituents has been studied for this population.
The report shows the determination of the additive model and its predictive ability. The results are very promising and the analytical application for identification of compounds becomes very clear. The model has been successfully applied to different families (alkenes, aldehydes-ketones, water-alcohols-ethersoxydes, hydrogen sulfide-thiols-thioethers).
© Paris : Société de Chimie Physique, 1980