CO₂ Cycloaddition to Plant Oil Based Epoxidized Monoester: Optimization and Catalyst Screening

Abstract

Migration of epoxidized monoester plasticizers based on bio‐oil can be reduced by adopting a green strategy of incorporating CO2 into the epoxy rings of the plasticizer. In the present work, three different approaches are evaluated to optimize reaction output and the time required to complete the cycloaddition of CO2 in epoxidized monoester of soybean oil with glycerol formal. In the first approach, deep eutectic solvent (DES) is utilized along with conventionally used tetrabutylammonium bromide (TBAB) catalyst to analyze the effect of DES on reaction, while in the second approach a co‐catalyst system along with onium halide is employed. In the third strategy, a simple catalyst system comprising potassium iodide (KI) and polyethylene glycol with a molecular weight of 400 (PEG 400) or 18‐crown ether as phase transfer catalysts is investigated. In all three approaches, experimental parameters such as temperature, pressure, stirring rate, time, catalyst type, and catalyst concentration are systematically evaluated. TBAB catalyst along with equimolar (DES) under 40 bars pressure demonstrated the best conversion of epoxy groups to five‐membered cyclic carbonated rings within 4 h. Fourier transform Infrared spectroscopic (FTIR) analyses are regularly performed to monitor reaction progress while nuclear magnetic resonance spectroscopic (NMR) analysis is performed to confirm purity of the final product.