1H-NMR Spectroscopy Study of Oleic Acid and Methyl Oleate Ozonation in different reaction conditions

Abstract

Reactions of ozone with oleic acid or methyl oleate were carried out in presence of hexane, carbon tetrachloride, ethanol or water.
All the reaction mixtures were studied by 'H - Nuclear Magnetic Resonance Spectroscopy ('H-NMR) . Differences in the composition of the reaction mixture of the samples by IH-NMR analysis were found. During the ozonation of oleic acid, the acyl-oxy-alquil hydroperoxides were formed as major products in all the studied conditions, Nevertheless, during ozonation of methyl oleate, a striking dependence of reaction products with the solvent or additive used was found. In hexane, the corresponding ozonides/oligomers were obtained, whereas when ethanol is present, the ethoxy-hydroperoxides were the major products . The analysis in the presence of water only reveals the aldehyde and ozonides/oligomers signals. These results are discussed taking into account the Criegee mechanism, the characteristic of the bubbling reactor employed, and some properties of the solvents or additives used.