Aqueous-organic Biphasic Hydroformylation Of Higher Olefins Catalyzed By Thermoregulated Phase-transfer Cobalt Complex

Higher alcohols are important industrial chemicals. Hydroformylation of higher olefins is one of the main routes to produce higher alcohols. At present, homogeneous cobalt carbonyl or its phosphine complex is used as the catalyst in the hydroformylation plants of higher olefins, even though the difficult separation and recovery of the cobalt catalyst is still a problem. So it is of great importance to develop a cobalt catalyst which can be easily separated and recycled.Aqueous-organic biphasic catalysis with cheap nontoxic water as the reaction medium is a method for the heterogenization of homogeneous catalysis. But the insolubility or poor solubility of most organic substrates results in rather low reaction rate. Base on the cloud point of thermoregulated ligands, a concept of the thermoregulated phase-transfer catalysis (TRPTC) has been developed by Jin and co-workers. The TRPTC has been successfully applied in the aqueous-organic biphasic hydroformylation of higher olefins catalyzed by the rhodium complexes. But so far no publication has been referred to the cobalt catalyst in the TRPTC system.In this dissertation, the TRPTC was applied in the hydroformylation of higher olefins catalyzed by the cobalt complex. The thermoregulated phase-transfer cobalt complexes were used as the catalyst. The catalytic performance and the reusability of the catalysts in the aqueous-organic biphasic hydroformylation of higher olefins were investigated.The thermoregulated phosphine ligand L1, containing a polyoxyethylene chain was prepared, as well as two new thermoregulated phosphine ligands L2and L3were designed and prepared according to the feature of phosphines in the homogeneous cobalt-phosphine catalysts (see Fig.2.1). And three thermoregulated phase-transfer cobalt complexes (Co2(CO)8/Li, Co2(CO)8/L2, Co2(CO)8/L3) were generated in situ. The catalytic performance of the three thermoregulated phase-transfer cobalt complexes, the effects of different reaction conditions and the reusability of the catalysts were investigated. The results showed that the activity and the selectivity of the thermoregulated phase-transfer cobalt complex catalysts in the aqueous-organic biphasic system were as high as those of the homogeneous phosphine modified cobalt carbonyl catalysts, and the yield of nonanals and nonanols was up to93%and the linearity reached85%. The hydrofromylation reaction was not influenced by the poor solubility of1-octene. After reaction, the aqueous phase containing the thermoregulated phase-transfer cobalt complex catalyst was reused directly without treatment in the recycling experiment. And after5cycles of the catalysts, the total TON reached365. And the catalytic performance of Co2(CO)8/L1and Co2(CO)8/L2catalysts were also investigated in the hydroformylation of C11-12mixed olefins. The results showed the linear C12-13aldehydes and alcohols were obtained predominately because of the isomerization activity of the catalysts, and the linearity reached69%and the yield of C12-13aldehydes and alcohols was up to86%. After5cycles of the catalysts, the total TON reached187.The formation of the thermoregulated phase-transfer cobalt complex catalyst from the cheap cobalt compounds and the thermoregulated phosphine ligand was explored. It was found that the catalytic activity of the cobalt complex catalysts, formed from cobalt acetate or cobalt acetylacetonate under the hydroformylation conditions, was equal to that of Co2(CO)8/Li catalyst. The preliminary study confirmed that the cobalt carbonyl complexes formed from the thermoregulated phosphine ligand L1and cobalt acetate or cobalt acetylacetonate under the hydroformylation conditions were the same as that from the thermoregulated phosphine ligand L1and Co2(CO)8.