Three-Phase Microemulsion/Sol-Gel System for Aqueous Catalytic Hydroformylation of Hydrophobic Alkenes†
We extended the three-phase transport methodology to the catalytic hydroformylation of alkenes. The method enables to carry out an all-hydrophobic reaction – substrate, product and catalyst – in water. The alkene is microemulsified in the aqueous medium and the solubilized substrate is assumed to be carried to an organometallic rhodium catalyst entrapped within a partially hydrophobicized silica sol-gel matrix. The substrate is then spilled into the porous heterogenized catalyst in which the hydroformylation takes place. The products formed are desorbed from the ceramic material and microemulsified by the same surfactant. Upon breaking of the microemulsion the products are separated. The heterogenized catalyst can be easily separated from the reaction mixture by filtration and be recycled. The hydroformylation process was carried out on various alkenes with reaction yields from ca. 62 to 99 %. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)