Immobilization of a rhodium catalyst using a diphosphine-functionalized ionic liquid in RTIL for the efficient and recyclable biphasic hydroformylation of 1-octene.

A highly efficient and stable Rh-P catalytic system in the RTIL of [PEmim]BF4 was developed for the biphasic hydroformylation of 1-octene by using the diphosphine-functionalized ionic liquid (FIL) of 2. While 2-Rh(acac)(CO)2 was immobilized in [PEmim]BF4 (solvent), a typical biphasic catalysis was fulfilled with advantages of facile separation and recycling ability - 9 runs without any loss of activity. It was found that not only the acquired π-acceptor character of 2, but also the synergetic role of the piperidyl group in [PEmim]BF4 as an N-containing donor, cooperatively contributed to the efficient hydroformylation due to the facilitated formation and stability of the Rh-H active species (ν 2045 cm(-1)). This was supported by the in situ high-pressure FT-IR spectral analysis.