A sustainable non-edible plant oil derived from Simarouba glauca (Lakshmi Taru) seed oil and its Prilezhaev epoxidation: an experimental and computational study

Simarouba glauca seed oil (SGO), non-edible vegetable oil, is one of the high content seed oil having oleic acid as a rich source of fatty acid with palmitic and stearic acid in triglyceride molecule extracted using traditional method (solvent extraction). Epoxidation of SGO was carried out by Prilezhaev reaction for the formation of its epoxidized product (ESGO). These structures were verified using spectroscopic techniques including FTIR, ¹H-NMR, and ¹³C-NMR spectra. Their physico-chemical properties were carried out, and acid value, iodine value of pure oil, and its epoxidized form found to be 7.92, 6.92 mg KOH/g of oil, 52.62 and 0.96 g I₂/100 g of oil. Oxirane oxygen content and epoxy equivalent weight of ESGO were found to be 2.20% and 726.31 g/eq. Thermal stability of SGO and ESGO was observed by TGA-DTG with four different heating rates. Thermo-kinetic analysis study was carried out by four methods: Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Starink, and Friedman. From thermo-kinetic property, the activation energy of ESGO was found to be 196.73 kJ mol⁻¹, i.e., more than the simple oil SGO having 189.96 kJ mol⁻¹ from Friedman method. Warming and cooling modes with triplicate scan were done to study melting point, cloud point, and pour point with change in enthalpy (ΔH) in both endothermic and exothermic reactions of pure oil and its epoxidized product using differential scanning calorimeter (DSC). The study of the reactivity and stability of pure oil, epoxidized form, and methyl ester fatty acids and their epoxidized form was conducted using computational methods along with vibrational frequency. Energy gap obtained from Frontier molecular orbital theory of ESGO was 6.974 eV and was observed that greater than SGO, i.e., 6.353 eV indicating ESGO exhibits hard molecule property. Molecular electrostatic potential (MEP) surface study illustrates the non-covalent bonding present in the molecule having nucleophilic and electrophilic attacking sites available in the triglyceride. ESGO resulted in an electrostatic potential of 127.704 kJ mol⁻¹, which is higher than its simple SGO consist of electrostatic potential of 122.506 kJ mol⁻¹. The simple oil and its epoxidized product can be the precursor for many applications in industrial scale like paints, coatings, plasticizers, flame retardants, and polyurethane foams.