Autocatalytic epoxidation of hybrid neem oil and oleic acid using lactic acid as oxygen carrier

Abstract

The autocatalytic epoxidation of a hybrid neem oil–oleic acid system using lactic acid as an oxygen carrier was investigated as a greener alternative to conventional mineral-acid epoxidation routes. A feasibility study demonstrated rapid oxirane formation during the early reaction stage, achieving a maximum relative conversion of approximately 28 % within 20–30 min before gradual decline due to ring-opening side reactions. Process optimisation using the Taguchi L16 design identified temperature as the dominant factor influencing epoxidation efficiency, with the optimal condition achieved at 55 °C, a low oxidant ratio and moderate agitation. FTIR analysis confirmed successful epoxidation by the appearance of characteristic oxirane bands and the simultaneous reduction in C=C absorbance. Kinetic modelling using MATLAB produced an excellent fit between simulated and experimental data, reflected by a high R ² value of 0.9982, validating the proposed reaction mechanism. The results highlight the feasibility of lactic-acid-mediated epoxidation and demonstrate that hybrid feedstocks can enhance double-bond availability while maintaining reaction controllability. This study offers a promising pathway to produce bio-epoxides under milder and more environmentally acceptable conditions, supporting future development of renewable polymer precursors.