Highly regioselective hydroformylation of higher olefins catalysed by rhodium-phosphine complexes in ionic liquid medium

Hydroformylation of higher olefins was performed efficiently in ionic liquids 1-n-alkyl-3-methylimidazolium p-toluenesulfonate ([Rmim1[p-CH3C6H4SO3], R = n-butyl, n-octyl, n-dodecyl, n-cetyl) with the rhodium-phosphine complex Rh-BISBIS (Rh = rhodium complex catalyst precursor; BISBIS = sodium salt of sulfonated 2,2'-bis (diphenylphosphinomethyl)-1,1'-biphenyl) as catalyst. The catalytic system offers excellent regioselectivity towards the linear alclehyde with high activity and chemoselectivity for aldehyde. Furthermore, the ionic liquid containing catalyst can be facilely separated and reused three times without a significant decrease in the activity and selectivity. The ionic liquids [Rmim1[p-CH3C6H4SO3] used as the reaction media bring some definitive advantages over the halogen-containing analogues [bmim]BF4 and [bmim]PF6.