A new non-cinchona chiral modifier immobilized on Pt/SiO2 catalysts for enantioselective heterogeneous hydrogenation

Cristian H. Campos, Cecilia C. Torres, Ariel Leyton, Julio Belmar, Claudio Mella, Paula Osorio-Vargas, Doris Ruiz, José L.G. Fierro, Patricio Reyes

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)76-87
Number of pages12
JournalApplied Catalysis A: General
Volume498
DOIs
Publication statusPublished - 5 Jun 2015

Keywords

  • Chiral Pt catalysts
  • Covalent immobilization
  • Enantioselective hydrogenation
  • Non-chincona modifiers

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

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