Novel Ir-Complexes for Hydroformylation of Olefins with H2O as the Hydrogen Source

A series of novel Ir-complexes, namely Ir-L1, Ir-L2, Ir-L3 and Ir-L4, where L1 similar to L4 represent phosphine ligands having different electronic and steric effects, were synthesized in this work. Then the effect of the as-synthesized phosphine ligands on the performance of the Ir(I)-complexes catalysts was investigated for the hydrofonnylation reaction using H2O as the hydrogen source. It was found that the Ir-complex modified by the ionic bi-dentate phosphines IA with a strong pi-accepting ability ((1)J(np.77Se) =781 Hz) can effectively promote water gas shift reaction (WGSR) and hydrofonnylation of olefins at the same time. As a result, a I-hexene conversion of 93% was obtained, and the total yields of the target (linear and branched) aldehydes were up to 93% when using the Ir-L4 catalyst. Meanwhile, the yield of hexane from the hydrogenation of I -hexene was less than 1%, showing that the side reaction of olefin hydrogenation can be almost completely inhibited when using H2O as the hydrogen source. Moreover, by using the ionic liquid of [MePh3P]Br as the solvent, Ir-L4 catalyst can be efficiently recovered for at least 5 times.

Automated summary

A series of novel Ir-complexes with different phosphine ligands were synthesized, and their effects on the catalysts performance were investigated. The results showed that Ir-complex modified by ionic bi-dentate phosphines with strong pi-accepting ability can effectively promote water gas shift reaction and hydroformylation of olefins, achieving high reaction yields.