Hydroformylation of higher olefin in halogen-free ionic liquids catalyzed by water-soluble rhodium–phosphine complexes

The biphasic hydroformylation of higher olefins was performed efficiently in the halogen-free ionic liquids 1-n-alkyl-3-methylimidazolium p-toluenesulfonate ([Rmim][p-CH3C6H4SO3]) using Rh-TPPTS [TPPTS: trisodium salt of tri(m-sulphonylphenyl)phosphine] complexes as catalyst. The catalytic system offers high activity and chemoselectivity for aldehyde with a good retention of the catalyst in ionic liquid phase. The ionic liquid containing catalyst can be easily separated and reused several times without a significant decrease in the activity and selectivity. The results indicated that the cation and anion of ionic liquids strongly influenced the reaction rate. Furthermore, the reaction rate was markedly accelerated when the chain-length of alkyl in ionic liquids was comparable with that of olefin. A “matching effect” between the chain-length of alkyl in ionic liquids and that of olefins was firstly reported.

The biphasic hydroformylation of higher olefins catalyzed by water-soluble rhodium complexes has been efficiently performed in halogen-free ionic liquids [Rmim][p-CH3C6H4SO3]. The catalytic system shows high activity and chemoselectivity for aldehyde and the ionic liquid containing catalyst can be reused several times without a significant decrease in the activity and selectivity. The reaction rate is strongly dependent on the cation and anion of ionic liquids used.Figure optionsDownload as PowerPoint slide