Recherches sur les composés éthyléniques. V. Liens entre la structure des akènes et leur fréquence de vibration νC = C influence des effets structuraux et établissement d'une relation de topo-information

Abstract

An examination of spectroscopic data for 43 alkenes reveals the influence of increasing substitution at the carbon atoms α or β to the ethylenic bond. The presence of a particularly large steric constraint requires that there be a single preferred molecular conformation: in such a case the frequency of the νC = C vibrator is strongly decreased (10 cm−1).A quantitative analysis of the phenomenon can be achieved using the "topological-chemical method D.A.R.C.". Topologic-information relationships could be developed for the two series 2-alkylethylenes and 2,2-dialkylethylenes. These permit the calculation of the contribution of each topological site to the frequency νC = C. For the first series, the relationship, based on 9 compounds, permits predictions about 30 others. For the second series, deductions are made concerning 159 compounds from a relationship established on a base of 13 compounds. [Journal translation]