Determination of the Number of Epoxides Groups by FTIR-HATR and Its Correlation with 1H NMR, in Epoxidized Linseed Oil

Abstract

By varying the conditions of the epoxidation reaction, samples of epoxidized linseed oil with different epoxidation degrees were obtained. The epoxidation of linseed oil was carried out by the formation of peracetic acid in situ using acetic acid, hydrogen peroxide solution, Amberlite IR-120H as the catalyst, and toluene as solvent. The quantification of the number of epoxides was carried out by 1H-NMR and the values obtained were correlated with the absorbance of the epoxy group signal in the FTIR-HATR spectrum. The method used to quantify the absorbance of the epoxy group signal by FTIR-HATR is based on the analysis of two regions: the area between 765-854 cm-1, and the net absorbance at 821 cm-1. Both signals analysis showed high linear correlation coefficients corroborating that this methodology represents an easy, fast, and reliable technique in the quantification of epoxides in natural oils.