Correlation between Chiral Modifier Adsorption and Enantioselectivity in Hydrogenation Catalysis
Yufei Ni1, Alexander D Gordon1, Florisa Tanicala1
1Department of Chemistry and UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA.
Angewandte Chemie (International Ed. in English)
|May 16, 2017
Summary
Chiral modifiers like 1-(1-naphthyl)-ethylamine adsorb onto platinum catalysts via their amine group, not the aromatic ring. This adsorption is crucial for enantioselective hydrogenation of alpha-keto esters.
Area of Science:
- Heterogeneous catalysis
- Surface chemistry
- Organic synthesis
Background:
- Chiral modifiers are essential for enantioselective hydrogenation.
- The adsorption mechanism of 1-(1-naphthyl)-ethylamine on platinum catalysts was previously unclear.
- It was widely believed that adsorption occurred through the aromatic ring.
Purpose of the Study:
- To elucidate the adsorption mechanism of 1-(1-naphthyl)-ethylamine on platinum-supported catalysts.
- To identify the specific functional group responsible for adsorption.
- To correlate adsorption behavior with catalytic performance.
Main Methods:
- In situ infrared absorption spectroscopy at the solid-liquid interface.
- Comparative studies using modified naphthalene derivatives with targeted substitutions.
Main Results:
- Adsorption of 1-(1-naphthyl)-ethylamine occurs through the amine group, not the aromatic ring.
- Naphthalene derivatives lacking amine groups or possessing tertiary amines showed negligible adsorption.
- A direct correlation exists between amine adsorption strength and enantioselectivity in hydrogenation.
Conclusions:
- The amine group is the key moiety for adsorption of 1-(1-naphthyl)-ethylamine on platinum catalysts.
- Adsorption via the amine group is critical for achieving enantioselectivity in hydrogenation reactions.
- Understanding adsorption mechanisms can guide the design of improved chiral modifiers.
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