Liquid/Liquid Biphasic Catalysis Systems Based On PEG And Their Applications

This paper is divided into two parts:In the first part, based on the thermoregulated PEG biphasic system proposed by our research group, the composition of the thermoregulated PEG biphasic system is optimized elaborately. In this system, PEG-400 and n-heptane which are immiscible at any temperature, are chosen as the basic components, and the third component is varied to obtain the thermoregulated PEG biphasic system both with lower catalyst loss and with the character of being biphasic at lower temperature but miscible at higher temperature. It is found that the system of PEG-400/n-heptane/l,4-dioxane pocesses the better separation efficiency. In order to determine the composition of the system with the relatively efficient phase-separation, the phase diagram of this ternary system is studied in detail. On the basis of the optimization of the composition of the thermoregulated PEG biphasic system, the phospite ligand TMPGP with simple structure, simple preparation procedure and containing PEG chains is chosen as the ligand in the Rh-catalyzed hydroformylation of 1-dodecene. The catalytic activity and recycling efficiency of the catalyst are studied in detail. It is found that the conversion of 1 -dodecene and the yield of aldehydes reach up to 96% and 94%, respectively. The catalyst can be recycled 23 times without evident loss of catalytic activity. The results of ICP-AES analysis reveal that the average Rh loss in the product phase is 0.65%(wt) while recycling the catalyst in the hydroformylation of 1-dodecene. This PEG catalysis system is also successfully applied to the hydroformylation of tripropene. Under the optimized reaction conditions, the conversion of tripropene and the yield of aldehydes reach up to 77% and 75%, respectively. The catalyst can be recycled 11 times without obvious loss of catalytic activity and the average Rh loss in the product phase is 0.69%(wt) with the catalyst's phase separation conducted at room temperature. Furthermore, in this paper a new kind of phosphite ligand, TPGP (n≈9), is synthesized by the reaction of PEG-400 with PCl₃. Under the optimized reaction conditions, the conversion of 1-dodecene and the yield of aldehydes are above 96% and 94%, respectively. The catalyst can be recycled 10 times without evident loss of catalytic activity. The highest Rh loss in the product phase is about 1.00% (wt). All these experimental results prove that the transesterification of phosphite ligand TMPGP and PEG has no influence on the catalyst's activity and recycling efficiency in the hydroformylation of higher olefins.