Rhodium Pyrrolylphosphine Complexes as Highly Active and Selective Catalysts for Propene Hydroformylation: The Effect of Water and Aldehyde on the Reaction Regioselectivity

Abstract

The hydroformylation of propene catalyzed by Rh(acac)(CO)2 (acac=acetylacetonate) with a 13‐fold excess of N‐pyrrolylphosphine ligands PPyr3, PPh2Pyr, or PPh(Pyr)2 (Pyr=NC4H4) was investigated under a pressure of 15 bar (propene/H2/CO=5:5:5) at 80 °C. The N‐pyrrolylphosphine ligands facilitated an excellent regioselectivity towards n‐butanal aldehyde, significantly better than PPh3 and PCy3 under the same conditions. In the presence of the strongest π‐acceptor, PPyr3, the linear‐to‐branched aldehyde (l/b) ratio was 8.6, which increased to 27.1 if water was added to the system. The application of a pure aldehyde as a solvent instead of toluene caused a significant increase in the aldehyde yield but with a decreased l/b ratio (2.9–7.6). The regioselectivity parameter l/b increased to 19.3 after the introduction of water as a cosolvent.

The mechanism of MOF as a heterogeneous catalyst for propene hydroformylation: a DFT study

“…This result is consistent with previous theoretical studies involving homogeneous hydroformylation Rh-based catalysts. [69][70][71][72] The Reaction Chemistry & Engineering Paper energy profile of Fig. 10 shows that the CO coordination to the Rh-alkyl complex, (2a) and (2b), which is formed in the previous step, is energetically favored for the linear and branched pathways, with the adsorption energies of −1.59 eV and −1.78 eV, respectively.…”

Iridium–phosphine ligand complexes as an alternative to rhodium-based catalysts for the efficient hydroformylation of propene

“…According to previous reports, the Rh( i )- L1 complex has a very good catalytic reactivity for the hydroformylation of propene. 45 However, for the Ir-based catalysts, the reactivity of the Ir( i )- L1 complex is obviously weaker than those of Ir( i )- L5 , Ir( i )- L6 , and Ir( i )- L7 complexes. Furthermore, it is interesting that Rh( i )- L5 is not as active as Ir( i )- L5 .…”

“…9–34 Compared to the first-generation Co-based catalysts, which typically operate at reaction temperatures of up to 160 °C and under high reaction pressure of 10 MPa, 35,36 and Ru-based catalysts with low activity and poor selectivity for aldehydes, 37,38 Rh-based catalysts have incomparable advantages in olefin hydroformylation, such as mild reaction conditions (80–120 °C and below 3 MPa) and high selectivity for aldehydes (>98%). 19,39–45 Consequently, a significant number of research studies have been directed towards the modification of Rh catalysts. Nevertheless, the utilization of Rh catalysts is associated with a significant rise in production expenses due to their exorbitant cost.…”

A Highly Active Hydroformylation Catalyst Using a Self‐Assembling Bis‐N‐Pyrrolyl Phosphine Ligand

“…Such ligands facilitate the dissociation of CO from the catalytically active [HRh(L) x (CO) 2 ] species. Hydroformylation catalysts applying the P( N ‐pyrrolyl) 3 ligand showed increased linear selectivity and superior activity compared to catalysts based on PPh 3 [10b,d,k,l] . Recognizing this, van Leeuwen et al .…”