A Novel Strategy of Homogeneous Catalysis and Highly Efficient Recycling of Aqueous Catalyst for the Hydroformylation of Higher Olefins Based on a Simple Methanol/Water Mixed Solvent

Abstract

This paper describes the homogeneous catalysis and highly efficient recycling of aqueous catalyst for the hydroformylation of higher olefins in the methanol/water mixed solvent for the first time. When sufficient methanol is added into aqueous HRh(CO)(TPPTS)3/TPPTS solution and 1-hexene, the reaction mixture becomes a single phase at reaction temperature (TPPTS: Trisodium triphenylphosphine-3,3′,3″-trisulfonate), which makes the 1-hexene hydroformylation proceed homogeneously. The turnover number (TON) is 11880 during an hour, and TON is up to 10428 during half an hour at a substrate to catalyst ratio of 12000. After the reaction, the methanol with low boiling point can be readily recovered by distilling the product mixture at the reaction temperature. And then, what's left is the aqueous organic two-phase mixture. The aqueous catalyst solution can be separated from the products by a simple decantation. The recovered aqueous catalyst solution as well as methanol can be recycled for seven runs without significant loss of activity and selectivity for aldehydes. Moreover, the average rhodium leaching in products is less than 0.09 wt%.