THE USE OF IR SPECTROSCOPY TO STUDY THE STRUCTURAL FEATURES OF PRODUCTS FROM THE LIQUID-PHASE CATALYTIC OXIDATION OF HIGHER FATTY ACIDS RELEASED FROM VARIOUS VEGETABLE OILS

Liquid-phase catalytic oxidation of a mixture of higher fatty acids released from various vegetable oils in the presence of transition metal naphthenates of manganese and chromium was studied. The oxidation process was carried out with atmospheric oxygen at 80 degrees C during 5 h. The amount of catalyst to the raw material was 0.5% mas. The primary components, as well as the products of the oxidation reaction were studied by IR spectroscopy on BRUKER ALPHA IR-Fourier spectrometer in the wave frequency range 4000-600 cm-1. As is evident from the spectra, change was determined in the optical densities of C=C, C=O (acid) and C=O (aldehyde) bonds of initial and resulted products. Analysis of the data revealed that both in the presence of manganese naphthenate and chromium naphthenate, the optical density of the C=C bond decreases and the optical density of the C=O bond of acids increases, as well as the formation of a new C=O bond (1740 cm-1), characteristic C=O bond of saturated aldehydes, which in turn indicates a partial opening of C=C bonds during oxidation with the formation of aldehyde acids and dibasic acids with a smaller number of carbon atoms than those of higher fatty acids