A new non-cinchona chiral modifier immobilized on Pt/SiO 2 catalysts for enantioselective heterogeneous hydrogenation
| Autor: | Cecilia C. Torres, Patricio Reyes, Doris Ruiz, Cristian H. Campos, Paula Osorio-Vargas, Julio Belmar, Claudio Mella, José Luis García Fierro, Ariel Leyton |
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| Přispěvatelé: | Comisión Nacional de Investigación Científica y Tecnológica (Chile) |
| Rok vydání: | 2015 |
| Předmět: |
inorganic chemicals
Enantioselective hydrogenation biology Chemistry Hydrogen bond Process Chemistry and Technology Enantioselective synthesis Cinchona Chiral Pt catalysts biology.organism_classification Heterogeneous catalysis Catalysis Covalent immobilization Solvent Non-chincona modifiers Adsorption Moiety Organic chemistry |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 0926-860X |
| DOI: | 10.1016/j.apcata.2015.01.048 |
| Popis: | Pt heterogeneous catalysts were prepared by the covalent immobilization of (4′R,5′S)-4′,5′-dihydro-4′,5′-diphenyl-2-(6-cyanopyridyl)imidazoline (PyIm) as the asymmetric modifier. These novel series of catalysts were studied in the 1-phenyl-1,2-propanodione (PPD) hydrogenation. The effects of the PyIm surface concentration, hydrogen pressure, solvent nature and recycles on the reaction were studied. These modified catalysts represent the first effective immobilized chiral non-Cinchona-type modifier of Pt for the enantioselective hydrogenation. The enantio-differentiation was attributed to the substrate–modifier interactions involving hydrogen bonding between the keto-carbonyl O atom and the NH moiety PyIm. The results confirmed that the variations in the H2 pressure and the solvent affect the activity and the enantioselectivity due to the substrate adsorption on the active sites of the metal. Additionally, this heterogeneous catalyst can be conveniently reused at least five times without loss of its catalytic efficiency, but the enantioselectivity decreased, which may be due to the leaching of the modifier. The authors would like to thank CONICYT for their financial support (FONDECYT GRANT 1061001, FONDECYT Initiation GRANT 11121631, FONDECYT postdoctoral 3140130 and 3140157) and the REDOC.CTA doctoral network. |
| Databáze: | OpenAIRE |
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