Studies On Acceleration Effect And Mechanism Of New Type Of Cationic Surfactants And Surface-Active Phosphines On Long-Chain Olefin Hydroformylation

The co-catalysis effect of a series of cationic surfactants including C16H33N(CH3)2CmH2m+1Br(m = 1, 2, 4, 8, 12, 16 ) and C22H45N(CH3)2CnH2n+1Br(n = 1, 2, 4, 8, 12, 16 ) on long-chain hydroformylation catalyzed by rhodium-phosphine complexes in aqueous/biphasic system has been investigated. The results show that all the cationic surfactants can greatly improve the reaction rate. The double long-chain cationic surfactants (DLCS) exibit much better acceleration effect than the single long-chain cationic surfactant. The surfactant with smaller cationic head is more favorable for the reaction.The great acceleration of DLCS for higher olefin hydroformylation in aqueous/organic biphasic system is found even without stirring. The very high TOF (turn over frequency defined as the moles of converted olefin per mole Rh per hour) 5617.5h-1 is first observed. By comparison, the single chained cationic surfactant CTAB showed negligible acceleration effect on the reaction without stirring. However, the selectivity towards the aldehyde is lower without stirring than that with stirring.The outstanding acceleration effect of the double-long chain surfactants is attributed to the formation of vesicle, which includes the internal and external aqueous phase and has larger solubilization for olefin. Thus, both the enrichment of rhodium catalyst in the interfacial layer, as well as the transfer rate of olefins from the organic phase to the interface of vesicle are much stronger than the micelle which is...