Synergistic effect between monophosphine species for regioselective hydroformylation of olefin with CO2

Abstract

CO2 as a substitute for CO in hydroformylation is promising for alleviating greenhouse effect. Phosphine ligand has a significant impact on the regioselectivity of olefin hydroformylation with CO2. Compared with complex and expensive bisphosphine ligands, easily available and inexpensive monophosphine ligands are potential for widespread application especially in industrial hydroformylation. However, the regioselectivity of monophosphine ligand catalysts is still unsatisfactory. Herein, we proposed synergistic effect existing in two types of monophosphine species, which was copolymerized in a concise manner. The single-atom catalysts (Rh-POL-PPO&PPh3) obtained through such a strategy, are efficient for olefins/CO2 hydroformylation with high regioselectivity (l/b = 18.4) and conversion (94.9 %), which is comparable to diphosphine ligand. The characterization and DFT calculations reveal that high hydroformylation regioselectivity is attributed to the synergistic effect between two monophosphine species, which endows the catalyst with better configuration of active sites, and can promote the association of Rh with the terminal carbon of olefin.