Ionic Liquid-Aqueous Micellar Systems for Sustainable Catalysis

The growing interest in ionic liquids (ILs, salts melting below 100 C) as alternative solvents is mostly caused by the possibility to avoid large volumes of volatile solvents that are always associated with human risk, safety issues and poor environmental performance. However, the comparably high price of pure ILs, as well as their often high viscosity is still a major drawback for their application in synthesis or catalysis. Recently, there has been a tremendous increase of interest in the behavior of ILs in the presence of water. It has already been shown that certain ILs can form surfactant aggregates (micelles) in aqueous solution. In this proposal, we will investigate ionic liquid aggregates in IL-water biphasic systems as a novel and compared to conventional organic solvents safer but yet cost-efficient reaction media for organic and industrial synthesis with particular focus on palladium catalyzed reactions. Micellar catalysis in ionic liquid-water systems could not only dramatically improve conversion and efficiency of a chemical reaction, but might even lead to a new spectrum of reactivity.

The growing interest in ionic liquids (salts melting below 100 C) as alternative solvents is mostly caused by the possibility to avoid large volumes of volatile solvents that are always associated with human risk, safety issues and poor environmental performance. Furthermore, the particular properties of ionic liquids make them an interesting media for catalysis that can give rise to distinct chemistry of their own compared to traditional molecular solvents. However, the comparably high price of pure ionic liquids, as well as their often high viscosity is still a major drawback for their application in synthesis or catalysis. As a result, there has been a tremendous increase of interest in the behavior of ionic liquids in the presence of water. It has already been shown that certain ionic liquids can form surfactant aggregates (micelles) in aqueous solution. Within this project, we investigated the use of ionic liquid aggregates in water as a novel safer but yet cost-efficient reaction media for organic and industrial synthesis. Apart from the application in organic reactions, particular emphasis was dedicated to palladium catalyzed cross-coupling reactions or to oxidations. In parallel, surface-active ionic liquids in water were established as novel extraction media for the recovery of valuable fine chemicals and natural products such as piperin or oleanolic acid from agricultural waste. In several examples it was demonstrated that micellar catalysis in ionic liquid-water systems could not only dramatically improve conversion and efficiency of a chemical reaction, but resulted in a new spectrum of reactivity. Through the replacement of conventional and volatile organic solvents with emission-free reaction media, considerable progress was made in terms of green and sustainable chemistry,