Tetronics/cyclodextrin-based hydrogels as catalyst-containing media for the hydroformylation of higher olefins

Abstract

The rhodium-catalyzed hydroformylation of alkenes has been investigated under biphasic conditions using combinations of α-cyclodextrin (α-CD) and poloxamines (Tetronics®). Thermo-responsive hydrogels containing the Rh-catalyst are formed under well-defined conditions of concentration. Hydrogels consisting of the reverse-sequential Tetronic® 90R4 prove to be more effective than those containing the conventional sequential Tetronic® 701. The presence of α-CD is crucial to provoke the decantation of the multiphasic system once the reaction is complete. Optimized conditions (CO/H₂ pressure, Rh-precursors, phosphanes, etc.) show that the catalytic system is especially applicable to the hydroformylation of terminal alkenes. The catalytic performance remains unchanged upon recycling as the hydrogel matrix prevents the oxidation of the phosphane.