Rhodium complexes non-covalently bound to cyclodextrins: novel water-soluble supramolecular catalysts for the biphasic hydroformylation of higher olefins.
A new class of cationic alpha-cyclodextrins bearing 2-hydroxy-3-trimethylammoniopropyl groups has been synthesised. We investigated their efficiency as mass-transfer promoters in a biphasic hydroformylation reaction catalysed by a rhodium trisulfonated triphenylphosphine system. These cationic alpha-cyclodextrins greatly increased the reaction rate, the chemoselectivity, and, surprisingly, the linear-to-branched aldehyde ratio. We attributed this unexpected enhancement of the linear-to-branched aldehyde ratio to the in situ formation of new catalytic supramolecular species obtained by ion-exchange between the catalyst ligand and the cationic alpha-cyclodextrins.
Sueur
Benoît
B
Laboratoire de Physico-Chimie des Interfaces et Applications, FRE CNRS 2485, Université d'Artois, Faculté des Sciences Jean Perrin, Lens, France.
Leclercq
Loïc
L
Sauthier
Mathieu
M
Castanet
Yves
Y
Mortreux
André
A
Bricout
Hervé
H
Tilloy
Sébastien
S
Monflier
Eric
E