Enzyme-mediated epoxidation of methyl oleate supported by imidazolium-based ionic liquids

In the present manuscript we describe and discuss the use of hydrophobic and hydrophilic ionic liquids (ILs) as efficient supports to the enzyme-catalyzed epoxidation of biodiesel. The use of nine different lipases in three different ILs (BMI.PF6, BMI.NTf2 and BMI.BF4) gave high biodiesel conversion rates in short reaction times using hydrogen peroxide (30%, v/v) as the epoxidation agent. A drastic behavior change is observed by altering the media from a hydrophobic IL to a hydrophilic IL. For instance, the use of Amano A. lipase (from Aspergillus niger) in hydrophilic BMI.BF4 yielded the epoxidized compound in 89% in the first reaction hour, and in the mean time, hydrophobic BMI.PF6 yielded the same product in 67%. The use of other lipases resulted in the desired epoxidized derivative and also in the 1,2-diol as a result of a reversible epoxy ring-opening promoted in the reaction media. Conversions and selectivities depended on the nature of the IL, on reaction time and on the selection of the lipase enzyme.