Chirality transfer in ionic liquids via ion pairing effects

• Applicant: Professor Dr. Peter Wasserscheid
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation ; Technical Chemistry
• Term: from 2006 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 29262616

Despite of a number of publications on the synthesis of chiral ionic liquids, successful examples to apply those for chiral induction in organic synthesis are rare so far. As one of the pioneering research groups in the field of chiral ionic liquids we have concluded from our experimental results in the past that a chiral ion of an ionic liquid does not easily transfer its chiral information to the transition state of a reaction due to the usually much stronger interaction with its own counter-ion. To verify this hypothesis we intend in this project to investigate systematically reactions of prochiral ions in the presence of their chiral and enantiomeric-pure counter-ions as a probe for the intimacy of ion pairing in ionic liquids. Indeed, our preparative studies for this project have shown that it is e.g. possible to hydrogenate [N-(butyl-3´-one)-N-methylimidazolium] [(S)-camphorsulphonate] to the corresponding chiral [N-(3´-hydroxybutyl)-N-methylimidazolium] [(S)-camphorsulphonate] with significant enantiomeric excess in the cation, using an achiral, heterogeneous Ru catalyst. Important parameters that we like to investigate and understand in detail in the project concern the influence of different ion structures, catalysts (chiral and achiral, homogeneous and heterogeneous), reaction parameters (e.g. hydrogen pressure) as well as the role of additional solvents. Here we expect ¿ion-pair separation effects¿ using polar solvents and ¿compression effects¿ using unpolar solvents. The study will also give access to a number of new, functionalized and chiral ionic liquids.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1191: Ionic Liquids