An Immobilized Rh-Based Solid Molecular Catalyst for the Reductive Hydroformylation of 1-Octene.

The reductive hydroformylation of olefins is an important process in the chemical industry to produce alcohols directly without isolating the aldehydes as intermediates. As the hydroformylation is a homogeneously catalyzed reaction, the catalyst recycling and down-stream processing is often complex and energy intensive. A heterogeneous reductive hydroformylation catalyst was developed in this work by immobilizing Rh on polymeric amine macroligands to form solid molecular catalysts (SMCs). An iterative macroligand improvement was carried out by increasing the basicity and number of amine groups at the immobilization sites. With the best performing SMC, olefins were fully converted to >99% alcohols without a hydrogenation of the substrate in a solvent free environment, thus requiring only a separation of the heterogeneous catalyst to yield the pure product. The catalyst was successfully recycled over 12 runs with a perpetual Rh leaching as low as 1.2%, and the metal to macroligand ratio was identified as most important parameter in reducing metal loss.