Supramolecularly controlled surface activity of an amphiphilic ligand. Application to biphasic hydroformylation of higher olefins

A biphasic catalytic system has been elaborated in which the amphiphilic species concentrations at the aqueous/organic interface could be thermocontrolled by the supramolecular interaction between b-cyclodextrins and the 1-(4-tert-butyl)benzyl-1-azonia-3,5-diaza-7-phosphaadamantyl ligand (1). The system proved efficient in Rh-catalyzed hydroformylations of higher olefins. An increase in the catalytic activity was observed without alteration in either the chemo- or the regio-selectivity. The main advantage of the cyclodextrin/1 couple lies in the rapid decantation of the biphasic system at the end of the reaction. This study represents the first example of thermoregulation of the surface activity of an amphiphilic phosphane by a cyclodextrin