Applications of ionic liquids in biocatalysis

Ionic liquids (ILs), a class of organic salts with melting points below 100 °C, have attracted a great deal of attention as possible replacement for conventional molecular solvents in catalysis. Indeed, the choice of reaction medium is considered as important in the set-up of a reaction as the catalyst itself. ILs have initially been proposed as neoteric solvents for sustainable chemistry due to their peculiar properties, such as negligible vapour pressure (thus eliminating VOC release in the environment), non-flammability, high dissolving power, the possibility of modulating physico-chemical properties (e.g., hydrophilicity/hydrophobicity balance) and, in some cases, their relatively low toxicity. Although these factors do not represent per se sufficient conditions for intrinsically green processes, they are considered advantageous starting points for the design of environmentally friendly chemical transformations. Along with their benign characteristics as solvents, ILs offer the chemist new and promising media for synthesis and catalysis on both a laboratory and an industrial scale. Over the past decade, the use of ILs in biocatalysis has been extensively studied [1]. In this work, we will illustrate the use of ILs as solvents in two different biocatalytic processes involved in the conversion of natural biomolecules: the enzymatic one-pot depolymerization of cellulose [2] and the enzymatic transformation of natural phosphatidylcholine in high value phospholipids [3]. Both processes are characterized by a high potential commercial interest, in the framework of environmentally friendly chemistry.