Quantitative ligand effect and mechanism insight of Rh-biphosphine complexes in hydroformylation of formaldehyde

Abstract

Hydroformylation is one of the most important homogenous reactions with more than 10 million tons of aldehydes production each year. Due to monodentate ligands instable coordination under hydroformylation of formaldehyde, here, we introduced a range of chelating biphosphine ligands onto rhodium catalysts. Ligands, such as BINAP (TOFGA = 106.4 h−1), present higher activity relative to common monodentate ligand PPh3 (TOFGA = 73.4 h−1) with lower ligand to metal ratio. Density functional theory calculation revealed that Rh-biphosphine complexes follow the anion mechanism, with H2 oxidation addition being the rate-determining step. Activation strain analysis further demonstrated that lower H2 distortion energy resulting higher TOF of glycolaldehyde formation. Besides, the predictable quantitative structure–activity relationship model was established and suggested that both electronic and steric properties synergistically controlled formaldehyde hydroformylation activity. This combination of mathematical modeling and theoretical calculation will provide a reliable approach to activity prediction and catalyst design for important industrial hydroformylation reaction.