Solvent engineering applied to lipase‐catalyzed glycerolysis of triolein

Abstract

AbstractSolvent engineering was applied to lipase‐catalyzed glycerolysis of triolein for the selective synthesis of monoolein and diolein. The effect of different binary mixtures of n‐hexane and 2‐methyl‐2‐butanol (2M2B) on the selective production of mono‐ or diacylglyceride was established. Conditions for high selectivity toward monoolein synthesis were enhanced from 10.6 mol% in pure n‐hexane to 64 mol% in 2M2B. On the contrary, the highest production of diolein, corresponding to 62 mol%, was achieved in n‐hexane. Concerning triolein conversion, the best results were obtained in 100% 2M2B, with a conversion of 75%. The effect of the n‐hexane/2M2B ratio on diolein regioisomer production during triolein glycerolysis was also evaluated. Two different profiles of diolein regioisomers were observed as a function of solvent composition: Although the production of the 1,2‐diolein isomer was favored as the proportion of 2M2B in n‐hexane was increased, the 1,3‐isomer was preferentially synthesized in reactions where n‐hexane was the predominant solvent. When 100% n‐hexane was used as a solvent, 1,3‐diolein comprised 72 mol% of the total diolein population (58 mM). On the contrary, when the reaction was carried out in 100% 2M2B, the total concentration of diolein was lower (21 mM) but the 1,2‐diolein regioisomer was preferentially formed (89%). These results were explained as a consequence of the different extents of hydrolysis‐synthesis reactions involved in the glycerolysis process, which are strongly dependent on solvent mixtures and water concentration. Finally, some advantages of the use of binary mixtures of solvents compared with other strategies applied to glycerolysis reactions are discussed.