Hydroformylation of Higher Olefins Catalyzed by Thermoregulated Phase-separation

The solubility of nonionic tension-active phosphine ligand P [p-C₆H₄O (CH₂CH₂O)_nH]₃ (PETPP, n=6-12, N=3n) in different solvents was investigated. It was found that PETPP(N=18-36) possesses a distinct critical solution temperature(CST) in toluene. A novel concept(Thermoregulated Phase-separable Catalysis, TPSC) based on CST of PETPP for separating a catalyst from the reaction mixture is presented. TPSC system involves only the organic phase, while no water was added. At room temperature (t<CST), the catalyst(PETPP/Rh complex) is insoluble in organic solvent. When being heated to t>CST, the catalyst is soluble in organic solvent. At the reaction temperature(t>CST), the reaction proceeds homogeneously. After the completion of the reaction, on cooling to room temperature(t< CST), the catalyst precipitates from the organic phase. Thus, by decantation, the products could be easily separated from the catalyst. The concept is introduced in the hydroformylation of higher olefins catalyzed by PETPP/Rh complex. The temperature, total pressure, molar ratio of PETPP to rhodium, different N values of PETPP and recycling efficiency of the catalyst on the hydroformylation of 1-decene were investigated. Under the condition: t = 130°C, p=6.0 MPa[V(H₂)/V(CO)=1/1], the conversion of 1-decene and yield of aldehyde reached up to 98.6% and 96.0%, respectively: After recycling use of the catalyst for 10 times, the conversion of 1-decene was still more than 94.9%.