Heterogeneous Asymmetric Hydrogenation of Prochiral Alkenoic Acid: Origin of Rate and Enantioselectivity Enhancement by Amine Addition

The origin of rate and enantioselectivity enhancement by achiral amine addition in the asymmetric hydrogenation of alkenoic acid on chirally modified Pd has been a long-debated subject. We show by means of in situ attenuated total reflection infrared spectroscopy combined with modulation excitation...

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Bibliographic Details
Published inACS catalysis Vol. 2; no. 3; pp. 464 - 467
Main Authors Meemken, Fabian, Maeda, Nobutaka, Hungerbühler, Konrad, Baiker, Alfons
Format Journal Article
LanguageEnglish
Published American Chemical Society 02.03.2012
Subjects
chiral modifier
heterogeneous catalysis
in situ IR spectroscopy
modulation excitation spectroscopy
asymmetric hydrogenation
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Summary:The origin of rate and enantioselectivity enhancement by achiral amine addition in the asymmetric hydrogenation of alkenoic acid on chirally modified Pd has been a long-debated subject. We show by means of in situ attenuated total reflection infrared spectroscopy combined with modulation excitation spectroscopy that the rate enhancement in the presence of an amine originates from restructuring of surface acid–base type adducts dynamically involving the substrate, product, chiral modifier, and amine. Phase-sensitive detection provides insight into the surface dynamics at the solid–liquid chiral interface: the addition of the achiral amine changes the adsorption configuration of the chiral modifier on the Pd surface, leading to a better stereochemically controlled surface.
ISSN:2155-5435
2155-5435
DOI:10.1021/cs2006923