Features of the Fatty Acid Methyl Esters' Hydroperoxides Formation and Decomposition Processes

The present work is devoted to studying the regularities of synthesis and decomposition of hydroperoxides of methyl esters of fatty acids. Fatty acid methyl esters of sunflower oil were used as raw material. In the case of non-catalytic oxidation at 70°C, the maximum concentration of hydroperoxides is observed (~45 wt.%), but 14 h of synthesis are required to achieve it. The use of N-hydroxyphthalimide as a catalyst makes it possible to reduce the reaction time to 8 h without affecting the yield of hydroperoxides. In turn, the results of studying the decomposition of hydroperoxides in the temperature range of 90°C–170°C demonstrate the presence of an unusual temperature dependence of the process activation energy. Upon passing to elevated temperatures, from approximately 120°C, a decrease in the activation energy of the process is observed from 83.6 to 35.8 kJ/mol, which means the transition of the process to the region of entropy control, in which the decomposition of hydroperoxides is preceded by the formation of hydrogen bonds of hydroperoxide molecules with each other and/or with other components of the reaction mixture.