Green and sustainable solvents for biocatalytic oxidations

Abstract

The discovery that enzymes could function efficiently in organic solvents revolutionized their use in industry but represented a change from the natural “green” solvent, water, to a host of environmentally undesirable solvents. Considerable effort is being devoted to making such processes greener again. Bio-based solvents, derived from waste biomass, possess the desirable attributes of traditional organic solvents but are more conducive to a circular bio-based economy. Although biocatalytic oxidations have only been tested in bio-based ether solvents, there is considerable scope for expanding this to include bio-based ester solvents. Alternatively, both ionic liquids and deep eutectic solvents, with tunable properties, are proving very interesting solvents for biocatalytic oxidations. In particular, oxidative depolymerization of lignin, catalyzed by laccases, has been extensively investigated. Finally, designer amphiphiles can facilitate the formation of micelles that act as hydrophobic nanoreactors for performing biocatalytic oxidation processes while surrounded by aqueous buffer as solvent.