NIESEL – Niedrig schmelzende eutektische Solventien als Lösungsmittel für die Biokatalyse

The biocatalytic transformation of substrates that are sparingly soluble in aqueous media is challenging in terms of reaction and process design. On the one hand, suitable solvents are necessary to deliver water-insoluble substrates to the respective target enzyme. On the other hand, solvent-resistant enzymes or microorganisms are required exhibiting good activity in organic solvents. The existing concepts to overcome such limitations comprise two-phase systems, supercritical fluids or the application of ionic liquids. However, from an ecological as well as from an economical perspective some of these solutions are sometimes inacceptable.

In this project the application of deep eutectic solvents (DES; also called NADES in the case of natural deep eutectic solvents) is investigated in terms of dissolution or extraction of sparingly water-soluble substrates. DESs are a novel class of solvents generated by mixing two solids, upon which a depression of the freezing point is caused by the interaction of the initial compounds on the molecular level (hydrogen bond). In contrast to classical ionic liquids, DESs are associated with less toxicity, better storability and higher biodegradability. Moreover, DESs are non-volatile and might be an interesting alternative to conventional solvents when hardly soluble substrates are present in a biocatalytic reaction.

Within the framework of this project different DESs will be synthesized, characterized by different methods and eventually applied in various biotransformations. The results obtained with DES-based biotransformations will be compared to already established systems such as organic solvent or ionic liquids.