A General and Efficient Iridium‐Catalyzed Hydroformylation of Olefins

Abstract

Breaking with conventional wisdom: Hydroformylation catalysts are generally based on rhodium; earlier, cobalt was used. Iridium, which is less expensive than rhodium, was considered too unreactive. However, iridium/phosphine complexes have now been shown to form active catalysts for the hydroformylation of olefins under mild conditions (see scheme; R1, R2=H, alkyl, aryl; R3=H, alkyl). Competing hydrogenation side reactions can be suppressed.

Crucial role of additives in iridium-catalyzed hydroformylation

“…The experimental investigations of iridium-catalyzed hydroformylation of 1-octene described here generally achieved linear to branched aldehydes in a ratio of approximately 75:25. Experiments with different ligands or additives showed no significant effects on regioselectivity [19].…”

“…Based on the results and findings of Beller et al [19] and Haukka et al [22], this paper describes the development of an appropriate catalyst system that ensures high reaction rates and aldehyde yields under mild conditions (p, T). An investigation and optimization of iridium-catalyzed hydroformylation of 1-octene was undertaken using an Ir(cod)(acac)/PPh 3 catalyst with the addition of salts and other additives.…”

“…With the increasing demand for rhodium on the market, the prize for this rare metal has increased significantly over time. Therefore, it has become necessary to look for alternative metals for hydroformylation reactions, such as iridium, platinum, ruthenium or iron [4,[15][16][17][18] Recent Beller research by Piras et al [19] has shown that the old assumption concerning the activity of unmodified metals must be reexamined and corrected. Using iridium as an alternative metal, good results with homogeneous catalyzed hydroformylation are possible.…”

“…Using iridium as an alternative metal, good results with homogeneous catalyzed hydroformylation are possible. Iridium complexes based on the precursor Ir(cod)(acac) and the ligand PPh 3 show good activity and high yields of aldehydes using a variety of substrates [16,[19][20][21].…”

First efficient catalyst recycling for the iridium-catalysed hydroformylation of 1-octene

“…3,4,8,9 The use of noble metals such as rhodium or iridium in homogeneous catalysis raises the question as to how the catalyst can be recycled most effectively. 3,4,8,9 The use of noble metals such as rhodium or iridium in homogeneous catalysis raises the question as to how the catalyst can be recycled most effectively.…”