Ion speciation driving chirality transfer in imidazolium-based camphorsulfonate ionic liquid solutions

Beitrag in einer Fachzeitschrift


Details zur Publikation

Autor(en): Huang MM, Schneiders K, Schulz P, Wasserscheid P, Weingaertner H
Zeitschrift: Physical Chemistry Chemical Physics
Verlag: Royal Society of Chemistry
Jahr der Veröffentlichung: 2011
Band: 13
Heftnummer: 9
Seitenbereich: 4126--4131
ISSN: 1463-9076
eISSN: 1463-9084


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.



FAU-Autoren / FAU-Herausgeber

Schneiders, Karola
Lehrstuhl für Chemische Reaktionstechnik
Schulz, Peter Dr.
Lehrstuhl für Chemische Reaktionstechnik
Wasserscheid, Peter Prof. Dr.
Lehrstuhl für Chemische Reaktionstechnik


Zusätzliche Organisationseinheit(en)
Exzellenz-Cluster Engineering of Advanced Materials


Autor(en) der externen Einrichtung(en)
Ruhr-Universität Bochum (RUB)


Zitierweisen

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://dx.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.

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Zuletzt aktualisiert 2018-11-08 um 02:31