Selective Preparation of Monoricinolein by the Glycerolysis of Castor Oil Using Imidazole-Based Ionic Liquid as a Homogeneous catalyst

Monoricinolein (MRO) is a renewable and biodegradable surfactant derived from castor oil (CO). In this work, a novel ionic liquid (IL)-catalyzed method for selective MRO preparation by the glycerolysis of CO was investigated. Six basic ILs ([Bmim]Im, [Bmim]OH, [Bmim]DCN, [Bmim]OAc, [Emim]OAc, [Emim]Im) were screened and evaluated as homogeneous catalysts. Among the tested ILs, [Bmim]Im showed the best catalysis performance. An evaluation of the effects of reaction variables on the IL-catalyzed glycerolysis was carried out (temperature, reaction time, IL load and substrate ratio). The maximum MRO yield (75.77 ± 1.20%) and triacylglyceride (TAG) conversion (96.67 ± 0.10%) were obtained under the following optimized conditions: CO/glycerol molar ratio 1:6, IL load 10%, 180 °C, 3 h, and no water added. The results showed that the selectivity of MRO was enhanced. The activation energies (Ea) for CO conversion and formation of the MRO were 44.07 kJ/mol and 54.99 kJ/mol, respectively. Graphical Abstract