Synthesis of maleated-castor oil glycerides from biodiesel-derived crude glycerol

Castor oil glycerides were obtained from the glycerolysis of castor oil or its methyl esters with alkaline-crude glycerol. High monoglyceride yields were obtained between 20–30 min and 180–200 ̊C with both substrates. The glycerolysis of castor oil afforded highest yield of products at 180 ̊C and 30 min (50.4 of monoglycerides and 35% of diglycerides). However, the glycerolysis of methyl esters was more selective toward the formation of monoglycerides. Castor oil glycerides were further esterified with maleic anhydride without catalyst. Reaction was followed by acid value and 1H NMR. ca. 87% conversion of hydroxyl groups was obtained at 90 ̊C. The final product contained 2.6 maleate groups per glyceride molecule.