Thermal safety assessment through the concept of structure–reactivity: application to vegetable oil valorization

The concept of linear free-energy relationships, and more particularly the Taft equation, was extended to a multiphase system with several reactions and reaction centers: the epoxidation of vegetable oils and free fatty acids. The epoxidation of vegetable oils and free fatty acids by different percarboxylic acids produced in situ is an exothermic reaction system which can lead to a thermal runaway. The safety criterion time-to-maximum-rate under adiabatic conditions (TMRad), linked to the kinetics of the system, was determined with the advanced reactive system screening tool (ARSST). We have demonstrated that TMRad values for the epoxidation of vegetable oils and free fatty acids by using different carboxylic acids follow the Taft equation. The epoxidation reaction series by different carboxylic acids was found to be more sensitive to the polar effect than steric effect. It was demonstrated that, by knowing the carboxylic acid used for the epoxidation, it is possible to predict the values of TMRad.