Application du dosage quantitatif dans 1'infra-rouge de groupements fonctionnels et radicaux spécifiques à la résolution de problèmes chimiques: Spectres d'absorption infra-rouges des depsides—note n [1

Abstract

The possibility of applying the KBr-disc technique in the quantitative infra-red analysis of specific structural groups was studied. In particular the method was applied to establish the formula of complex ethers derived from aromatic acids, such as caffeic, and alicyclic polyhydroxy-acids such as quinic acid. It was found that the spectra of the more complex compounds show a perfect additivity of the spectra of the simple starting materials, both qualitatively and quantitatively. When assigning particular bands to specific oscillators (C=O, C=C) or to entire caffeic and quinic radicals and allowing for the relative molecular concentration, empirical absorption coefficients can be calculated for every oscillator or radical. It is then also possible to calculate beforehand the amount of absorbance expected for specific bands in similar compounds. The agreement between calculated and experimental values is very satisfactory and allows the solution of structural problems which are difficult to solve by chemical methods.