TheStudiesonHydroformylationofLong-Chain Olefins Catalyzed By Rhodium-Phosphine Complexes In Ionic Liquid/Organic Biphasic System And Selective Hydrogenation Of Cinnamaldehyde Catalyzed By Ruthenium Phosphine Complex In Aqueous/Organic Biphasic Syste

The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF₄) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆) were synthesized and used as solvent in long-chain olefins hydroformylation. The results suggest the activity of the catalyst in [bmim]BF4 was much higher than that in [bmim]PF6. The reason may be ascribe to that solubility of TPPTS (P(m-C₆H4SO₃Na)₃) and Rh-TPPTS complexes in the [bmim]BF₄ was much higher than that in [bmim]PF₆. The rhodium complex with TPPTS ligand was immobilized in ionic liquid, so the catalyst was easy separated by decantation and reused in next run. The activity and selectivity almost kept unchanged in catalytic cycle experiment, if the concentration of the phosphine was high. The ratio of linear to branched (L/B) of the aldehyde is not significant influenced by the phosphine concentration. The comparison of the different catalyst activities showed that the catalyst RhCl(CO)(TPPTS)₂ and [Rh(COD)Cl]₂ containing the halogen ions were very inactivity, however, the catalyst HRh(CO)(TPPTS)3 and Rh(CO)2(acac) which didn't contain halide showed very high activity in the reaction. The phenomena encouraged us to investigate the influence of halide on the reaction. The experimental results indicated the activity of the catalyst dropped quickly, if some compounds that contain halide were added into the reaction system. The reason may be that complex formed by rhodium and halide was difficult to produce the catalytic active species. Therefore halide ion was the poison for the rhodium catalyst in hydroformylation of olefins in ionic liquid. The effect of double long chain cationic surfactant (DCMAB, dicetyl dimethylammonium bromide) on selective hydrogenation of cinnmaldehyde catalyzed with RuCl3·x H2O/TPPTS was studied. The results showed that the promotion effect of double long chain cationic surfactant was stronger than that of the mono cationic surfactant (CTAB, cetyl trimethylammonium bromide). The CMC (critical micelle concentration) of the DMAMB is lower than the CTAB, and the solubility of the substrate in DMAMB solution is higher than that in CTAB solution. The lower CMC and surface tension of DMAMB are favorable for increasing the interfacial area of two phases, breaking phase barrier and promoting the substrate transfer to interface of two phases where the substrates coordinate with the active species of rhodium complex anion, thereby, the reaction is accelerated.