Continuous synthesis of castor oil ethyl esters under supercritical ethanol

▶ High conversions of castor oil to ethyl esters by supercritical ethanolysis were achieved at lower temperatures than with conventional oils. ▶ Due to the high content of a hydroxy-fatty acid, castor oil could suffer several side reactions during the process. ▶ A maximum ester content of 75%, accompanied by 10 wt% degradation, was achieved at 573 K and 20 MPa. ▶ Water favorably affected the efficiency of the process, unlike on conventional alkali-catalyzed process.