Supported aqueous-phase catalysts

This work describes a novel family of catalysts denoted supported aqueous-phase catalysts. These catalysts consist of a water-soluble organometallic complex supported in a thin film of water residing on a high-surface-area hydrophilic solid. The catalytic reaction takes place at the water-organic interface where the organic phase contains the reactants and products. Supported aqueous-phase catalysis is demonstrated by liquid-phase hydroformylation. The solid support used here was either CPG-240 or CPG-350; both are porous glasses with narrow pore volume distributions. The catalytic species, HRh(CO)[m-P(PhS03Na)3]3 was synthesized from Rh(CO)2(acac) by a new synthetic route and impregnated onto CPG-240. Solution and solid-state 31P NMR data are consistent with a mobile rhodium species in the aqueous phase in hydrated forms of the catalyst. The hydroformylation of oleyl alcohol (OLOH) was accomplished at 100°C and 5.1 MPa of H2/CO (1/1) using 0.002 g Rh/g OLOH. For example, conversions of up to 96.6% could be achieved in 5.5 h. It is postulated that no significant leaching of Rh occurs, since after filtration to remove the solid catalyst the remaining solution showed no activity for either the hydroformylation of additional OLOH or the hydrogenation of added 1-hexene. The observations that (1) OLOH and its hydroformylation products are not water soluble, (2) the double bond of OLOH is internal, and (3) the Rh does not leach into the organic phase demonstrate the concept of SAP catalysis; the immobilized homogeneous catalyst is active at the interface of two immiscible phases.