Epoxidation of Canola and Sunflower Oils Using Dimethyldioxirane in Microemulsions

Abstract

Epoxidized vegetable oils (EVOs) are sustainable, bioderived epoxides potentially useful as green polymer precursors, offering low toxicity, biodegradability, and low environmental impact. This study investigates the epoxidation of canola and sunflower oils using in situ-generated dimethyldioxirane (DMDO) as an active oxidizing agent in a microemulsion, with a focus on optimizing reaction conditions and evaluating product yield and conversion. Effects of reaction time, Oxone/vegetable oil molar ratio, pH, cetyltrimethylammonium hydrogensulfate (CTAHS) surfactant concentration, stirring speed, and acetone concentration on epoxidation efficiency were systematically studied. 1H NMR, 13C NMR spectroscopy, and FTIR analyses confirmed efficient and selective transformation of double bonds in unsaturated fatty acid moieties into oxirane rings, with no significant formation of undesired byproducts. Optimal epoxidation was achieved at pH 7–8, an Oxone/oil ratio of 2:1, CTAHS concentration of 13.1–17.46 mM in the aqueous phase, and a 700 rpm stirring rate, yielding 100% conversion for sunflower and canola oil. Sunflower oil, which is rich in polyunsaturated linoleic acid, showed a higher epoxidation rate than monounsaturated canola oil under identical conditions. These results demonstrate the effectiveness of DMDO in the microemulsion process for green, selective epoxidation of vegetable oils.