Ion speciation driving chirality transfer in imidazolium-based camphorsulfonate ionic liquid solutions
Huang MM, Schneiders K, Schulz P, Wasserscheid P, Weingaertner H (2011)
Publication Type: Journal article
Publication year: 2011
Journal
Publisher: Royal Society of Chemistry
Book Volume: 13
Pages Range: 4126--4131
Volume: 13
Issue: 9
Journal Issue: 9
DOI: 10.1039/C0CP01120G
Abstract
The underlying principle of the chirality transfer in imidazolium-based camphorsulfonate ionic liquids is rationalized by linking catalytic results from the hydrogenation of [N-(3$\prime$-oxobutyl)-N-methylimidazolium] [(+)-camphorsulfonate] to [N-(3$\prime$-hydroxybutyl)-N-methylimidazolium] [(+)-camphorsulfonate] in tetrahydrofuran with electrolyte theory by the help of dielectric relaxation spectroscopy. Using this approach we are able to explain why the maximum of the enantiomeric excess of the hydrogenation reaction in tetrahydrofuran is found at a medium concentration of 0.15 mol L$-$1, whereas it declines at both, lower and higher concentrations. Dielectric spectra in the concentration range between 0.05 and 1.0 mol L$-$1 reveal a solute mode due to dipolar ion pairs and larger dipolar ion clusters. They verify that at very low concentrations the ionic liquid ions are fully solvated with an increasing tendency to form neutral ion pairs with increasing concentration. Already at 0.025 mol L$-$1 the degree of dissociation reaches a minimum reflecting a maximum of neutral ion pair formation. With increasing ionic liquid concentration ordered ion clusters are formed by two and more ion pairs. At high concentrations these clusters collapse by dilution in the excess ionic liquid and the defined ion contact necessary for the chirality transfer is lost to a great extent.
Authors with CRIS profile
Karola Schneiders
Lehrstuhl für Chemische Reaktionstechnik
Peter Schulz
Lehrstuhl für Chemische Reaktionstechnik
Peter Wasserscheid
Lehrstuhl für Chemische Reaktionstechnik
Additional Organisation(s)
Involved external institutions
Germany (DE)How to cite
APA:
Huang, M.-M., Schneiders, K., Schulz, P., Wasserscheid, P., & Weingaertner, H. (2011). Ion speciation driving chirality transfer in imidazolium-based camphorsulfonate ionic liquid solutions. Physical Chemistry Chemical Physics, 13(9), 4126--4131. https://doi.org/10.1039/C0CP01120G
MLA:
Huang, Mian-Mian, et al. "Ion speciation driving chirality transfer in imidazolium-based camphorsulfonate ionic liquid solutions." Physical Chemistry Chemical Physics 13.9 (2011): 4126--4131.
BibTeX: Download