1-(1-Naphthyl)ethylamine adsorption on platinum surfaces: on the mechanism of chiral modification in catalysis.
J Am Chem Soc
; 130(44): 14597-604, 2008 Nov 05.
Article
en En
| MEDLINE
| ID: mdl-18847203
ABSTRACT
The adsorption of 1-(1-naphthyl)ethylamine (NEA) on platinum surfaces has been characterized by reflection-absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) both under ultrahigh vacuum and in situ from liquid solutions. The main focus of this study was to identify the mechanism by which single enantiomers of NEA bestow chirality on the platinum surface. Evidence was acquired for both of the prevailing explanations available in the literature for the NEA behavior formation of supramolecular chiral templates and complexation of individual modifiers with the reactant. Indeed, TPD titrations of NEA-modified Pt(111) using propylene oxide (PO) as a chiral probe point to a relative enhancement in the adsorption of one enantiomer over the other at intermediate NEA coverages, which is the behavior expected from the templating mechanism. However, a difference in adsorption energetics was also observed. Both the TPD and RAIRS data suggest possible interactions between the adsorbed NEA and adjacent PO that differ according to the relative chirality of the two compounds. The NEA uptake from solution displays additional enantioselectivity, in particular when the adsorption of enantiopure compounds is compared with that of racemic mixtures, and also points to possible adsorption changes induced by ethyl pyruvate, a common reactant in chiral hydrogenation processes.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Platino (Metal)
/
Etilaminas
/
Naftalenos
Idioma:
En
Revista:
J Am Chem Soc
Año:
2008
Tipo del documento:
Article
País de afiliación:
Estados Unidos