Lipase‐catalyzed methanolysis of triricinolein in organic solvent to produce 1,2(2,3)‐diricinolein

The objective of this study was to find the optimal parameters for lipase‐catalyzed methanolysis of triricinolein to produce 1,2(2,3)‐diricinolein. Four different immobilized lipases were tested, Candida antarctica type B (CALB), Rhizomucor miehei (RML), Pseudomonas cepacia (PCL), and Penicillium roquefortii (PRL). n‐Hexane and diisopropyl ether (DIPE) were examined as reaction media at three different water activities (aw), 0.11, 0.53, and 0.97. The consumption of triricinolein and the formation of 1,2(2,3)‐diricinolein, methyl ricinoleate, and ricinoleic acid were followed for up to 48 h. PRL gave the highest yield of 1,2(2,3)‐diricinolein. Moreover, this lipase showed the highest specificity for the studied reaction, i.e., high selectivity for the reaction with triricinolein but low for 1,2(2,3)‐diricinolein. Recoveries of 93 and 88% DAG were obtained using PRL in DIPE at aw of 0.11 and 0.53, respectively. Further, NMR studies showed that a higher purity of the 1,2(2,3)‐isomer vs. the 1,3‐isomer was achieved at higher aw (88% at aw=0.53), compared to lower aw (71% at aw=0.11). The DAG obtained was acylated by the DAG acyltransferase from Arabidopsis thaliana. Therefore, this enzymatic product is a useful enzyme substrate for lipid biosynthesis. Accordingly, the use of PRL in DIPE at aw 0.53 is considered optimal for the synthesis of 1,2(2,3)‐diricinolein from triricinolein.