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Effect of the nature of the support on the enantioselective hydrogenation of 1-phenyl-1,2-propanedione over supported iridium catalysts

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dc.creator Marzialetti, Teresita
dc.creator Reyes, P.
dc.creator García Fierro, José Luis
dc.date 2007-11-16T09:02:42Z
dc.date 2007-11-16T09:02:42Z
dc.date 2005
dc.date.accessioned 2017-01-31T00:58:42Z
dc.date.available 2017-01-31T00:58:42Z
dc.identifier J. Chil. Chem. Soc., 50, N 1 (2005)
dc.identifier 0717-9707
dc.identifier http://hdl.handle.net/10261/2179
dc.identifier.uri http://dspace.mediu.edu.my:8181/xmlui/handle/10261/2179
dc.description The enantioselective hydrogenation of 1-phenyl-1,2-propanedione at 298 K and 40 bar over modified supported iridium catalysts has been studied. Cinchonidine has been used as chiral inducer. The catalysts were obtained by impregnation of Ir(acac)3 on three different supports: SiO2, TiO2 and MoO3, followed by calcination in air and reduction under hydrogen at 773 K. All the solids were characterized by nitrogen adsorption-desorption isotherms at 77 K, H2 chemisorption, XRD, TEM, TPR and XPS. It was found that Ir/SiO2 and Ir/TiO2 catalysts reduced at high temperatures, 773 K, possess similar metal particle size, close to 2.0 nm, eventhough the H/Ir ratio obtained from H2 chemisorption showed larger differences, with the H/Ir ratio being lower for titania- and molybdenum-supported iridium catalysts. In these samples, migration of the partially reduced supports, TiOx and MoOx moieties, on the metal crystals induce the creation of Ird+ species. TPR and XPS results confirmed that the metal component was not completely reduced. The activity was influenced by the nature of the support, being more active those in the SMSI state such as Ir/TiO2 and Ir/MoO3 being more active. This has been attributed to the presence of electron deficient metal species, Ird+, which are responsible for the polarization of the carbonyl bond of the substrates, thus favoring the activity and enantioselectivity of the reaction. The effect of different solvents on the activity and the enantioselectivity of the reaction was also studied. The highest enantiomeric excess (ee) of (R)-1-phenyl-1-hydroxy-2-propanone (20%) was obtained with the Ir/TiO2 catalyst using acetic acid as solvent.
dc.description The authors thank the support of Núcleo Científico Milenio ICM P99-92, and FONDECYT Grant 1030670.
dc.description Peer reviewed
dc.language eng
dc.publisher Sociedad Chilena de Química
dc.rights openAccess
dc.subject Ir
dc.subject 1-phenyl-1,2-propanedione
dc.subject Cinchonidine
dc.subject Hydrogenation
dc.subject Enantioselectivity
dc.title Effect of the nature of the support on the enantioselective hydrogenation of 1-phenyl-1,2-propanedione over supported iridium catalysts
dc.type Artículo


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