Étude par Spectrométrie Infrarouge de la Complexation de Phénols Substitués par la Triéthylamine

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Abstract
By infrared spectrometric measurements, we have determined the complexation constants (K12) of several complexes formed by substituted phenols with triethylamine in carbontetrachloride solution, at 27°C.Plot of log K12 in function of the a substitution constant of Hammett show two straigth lines with different slopes. The first line, containing the substituents of group I (3–4 di‐CH3, p.CH3, p.I, p.Br, p.F), obeys the relation magnified image .The second line, containing the substituents of group II (3–5 di‐Cl, p.CN, p.NO2) follows the relation magnified image .For the complexes of group I, one may admit the predominance of normal hydrogen bonded complexes of the type magnified image .Compared with the values of ρ obtained previously for complexes formed by phenols with aniline or pyridine, the value of ρ found in this work is greater owing to the greater enthalpy of complexation.For the complexes of type II; our results suggest the predominance of an ion‐pair complexe of the type magnified image .This view is supported by experimental facts such as the variation of colour of the solutions, the diminution of solubility of the complexes and the apparition, in the infrared spectra, of a large band lying between 2900 and 2200 cm−1. This result agrees also with our earlier infrared spectrometric determinations.