A heterogeneous Rh/CPOL-BINAPa&PPh3 catalyst for hydroformylation of olefins: chemical and DFT insights into active species and the roles of BINAPa and PPh3

Porous organic polymers (CPOL-BINAPa&PPh3 and CPOL-BINAPa&PhPh3) were synthesized via copolymerization of a divinyl-functionalized phosphoramidite ligand (2vBINAPa) and various trivinyl-monomers (3vPPh(3) and 3vPhPh(3)). After metalation with Rh(acac)CO2, Rh/CPOL-BINAPa&PPh3 showed the better catalytic performance than Rh/CPOL-BINAPa&PhPh3 in the heterogeneous hydroformylation. A corresponding catalytic Rh-H species has been investigated by FT-IR and/or NMR spectroscopy. The results indicated that two kinds of Rh-H species were formed in the Rh/CPOL-BINAPa&PPh3 catalyst. The ee species containing the BINAPa ligand contributed to the high activity in hydroformylation. The three P coordinated Rh-H species consisting of BINAPa and PPh3 ligands resulted in the high regioselectivity owing to the steric hindrance. Furthermore, the DFT calculations and cycle test results of the catalysts indicated that the PPh3 moieties could improve the stability of the Rh-H species, prevent dissociation of Rh from the BINAPa moieties and reduce the loss of Rh in the catalytic process.

Automated summary

Porous organic polymers were synthesized and used as catalysts in hydroformylation reactions. One of the catalysts showed better performance than the others. Two kinds of Rh-H species were identified in the catalyst, with one contributing to high activity and the other to high regioselectivity. DFT calculations and cycle test results indicated that the presence of PPh3 moieties improved the stability of the Rh-H species.