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Supported Ionic Liquids. New Recyclable Materials for the L ‐Proline‐Catalyzed Aldol Reaction
Author(s) -
Gruttadauria Michelangelo,
Riela Serena,
Aprile Carmela,
Meo Paolo Lo,
D'Anna Francesca,
Noto Renato
Publication year - 2006
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200505227
Subject(s) - chemistry , aldol reaction , ionic liquid , proline , acetone , adsorption , monolayer , catalysis , ionic bonding , covalent bond , homogeneous , filtration (mathematics) , chemical engineering , organic chemistry , silica gel , chromatography , ion , amino acid , biochemistry , physics , statistics , mathematics , engineering , thermodynamics
New materials for L ‐proline recycling have been developed. These materials have been applied to the L ‐proline‐catalyzed aldol reaction between acetone and several aldehydes. The L ‐proline has been supported on the surface of modified silica gels with a monolayer of covalently attached ionic liquid with or without additional adsorbed ionic liquid. Good yields and ee values, comparable with those obtained under homogeneous conditions, have been obtained especially with imidazolinium‐modified and 4‐methylpyridinium‐modified silica gels. Moreover, these materials have been easily recovered by simple filtration and studies about their reuse have been carried out. These studies showed that these materials can be used at least up to seven times. Finally, in the case of imidazolinium‐modified silica gel, investigations showed that this support can be regenerated giving again a recyclable material with high isolated yields and reproducible ee values up to 13 cycles.