High pressure infrared and nuclear magnetic resonance studies of the rhodium-sulfoxantphos catalysed hydroformylation of 1-octene in ionic liquids

The rhodium-sulfoxantphos catalysed hydroformylation of 1-octene in 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMI.PF6) as a room temperature ionic liquid was monitored in situ by high pressure IR (HP-IR) and NMR (HP-NMR). Similar ee (bis-equatorial) and ea (equatorial-apical) (diphosphine)Rh(CO)(2)H catalytic species, as observed in organic solvents, are formed in the BMI.PF6 ionic liquid. The ratio of the ee and ea isomers is influenced by both the temperature and syngas pressure. An increase in hydrogen partial pressure has no effect on the activity of the system during the reaction performed in BMI.PF6, while some hydroformylation systems using xanthene backbone ligands in conventional organic solvents can be sensitive to hydrogen partial pressure.