Thermal Stability of Oleic Acid and Ethyl Linoleate

Oil-derived products can be subjected to conditions that promote oxidation of their unsaturated components during storage and use. The materials arising during oxidation and subsequent degradation can seriously impair the quality and performance of such products [1, 2]. Thus, oxidative stability is an important issue to face before studying their catalytic reactivity. The fatty acid alkyl chain is susceptible to oxidation both at double bonds and adjacent allylic carbons. Free-radical and photooxidation at allylic carbons are responsible for deterioration of unsaturated oils and fats [2-6]. Both autoxidation and photooxidation produce hydroperoxides in allylic bonds. During this process, the position and geometry of the double bond may change. The hydroperoxide mixtures produced by autoxidation and photooxidation are not identical, indicating that different mechanisms are involved [4-6]. The autoxidation reaction occurs in the presence of oxygen. Autoxidation is a free-radical chain reaction, which involves the series of reactions that initiate, propagate and terminate the chain [3].