en
Scientific article
English

An in situ attenuated total reflection infrared study of a chiral catalytic solid-liquid interface: Cinchonidine adsorption on Pt

Published inJournal of the American Chemical Society, vol. 123, no. 48, p. 12074-12084
Publication date2001
Abstract

An in situ attenuated total reflection study of the chiral solid−liquid interface created by cinchonidine adsorption on a Pt/Al2O3 model catalyst is presented. Experiments were performed in the presence of dissolved hydrogen, that is under conditions used for the heterogeneous enantioselective hydrogenation of α-functionalized ketones. Cinchonidine adsorbs via the quinoline moiety. The adsorption mode is coverage dependent and several species coexist on the surface. At low concentration (10-6M) a predominantly flat adsorption mode prevails. At increasing coverage two different tilted species, α-H abstracted and N lone pair bonded cinchonidine, are observed. The latter is only weakly bound and in a fast dynamic equilibrium with dissolved cinchonidine. At high concentration (10-4−10-3 M) all three species coexist on the Pt surface. A slow transition from an adsorbate layer with a high fraction of α-H abstracted cinchonidine to one with a high fraction of N lone pair bonded cinchonidine is observed with the cinchonidine concentration being the driving force for the process. The reverse transition in the absence of dissolved cinchonidine is fast. Cinchonidine competes with solvent decomposition products for adsorption sites on the Pt, which may contribute to the observed solvent dependence of the heterogeneous enantioselective hydrogenation of ketones by cinchonidine-modified Pt.

Citation (ISO format)
FERRI, Davide, BUERGI, Thomas. An in situ attenuated total reflection infrared study of a chiral catalytic solid-liquid interface: Cinchonidine adsorption on Pt. In: Journal of the American Chemical Society, 2001, vol. 123, n° 48, p. 12074–12084. doi: 10.1021/ja011769u
Main files (1)
Article
accessLevelRestricted
Identifiers
ISSN of the journal0002-7863
567views
1downloads

Technical informations

Creation03/18/2011 1:57:02 PM
First validation03/18/2011 1:57:02 PM
Update time03/14/2023 4:13:52 PM
Status update03/14/2023 4:13:52 PM
Last indexation02/12/2024 7:35:25 PM
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack