Cyclodextrin/Amphiphilic Phosphane Mixed Systems and their Applications in Aqueous Organometallic Catalysis

When mixed with a water-soluble phos- phane capable of self-assembling into micelles, native or modified b-cyclodextrins (b-CDs) show very contrasting behavior depending on their neutral or ionic nature. In the post-micellar region, neutral b-CDs led to a micelle destructuring. Conversely, mi- celles remained stable over a well-defined range of ionic b-CD concentrations. In that case, the micelle destruction was only observed when using a large excess of ionic b-CDs. The catalytic performances of these micellar systems have been evaluated in a rho- dium-catalyzed hydroformylation reaction of 1- decene. We showed that, using ionic b-CDs, the cata- lytic activity could be improved without a detrimental impact upon the regioselectivity. A linear/branched aldehyde ratio as high as 8.6 could be achieved. The best results were obtained with stoichiometric quan- tities of ionic randomly methylated b-CDs with re- spect to the phosphane with a beneficial effect on the decantation at the end of the reaction.