A vinyl functionalized biphephos ligand with high steric hindrance was copolymerized with tris(4-vinphenyl)phosphane and other ligands to afford efficient porous organic copolymers (POPs) through the solvothermal synthesis technique. By employing the copolymer self-supported heterogeneous Rh/CPOL-bp&P catalysts, the hydroformylation of propene to linear-butaldehyde can be performed efficiently in a continuous fixed-bed reactor with high regioselectivity (l/b > 24), activity (TOF > 1200 h−1) and stability (over 1000 h) under mild conditions (70 °C, 0.5 MPa), which represents a substantial improvement in the efficiency of this important industrial process. EXAFS and HAADF-STEM showed that the Rh was a single atom dispersion, which explained well the high efficiency of the Rh/CPOL-bp&P catalysts. Compared with liquid–liquid biphasic (LLB) and ionic liquid (IL) systems, this highly efficient solvent free system has the advantages of simple operability, and almost no waste emission, which meets the demands of green industrial processing.
11 May 2017 in ACS Sustainable Chemistry & Engineering
Vinyl functionalized Biphephos ligand, denoted as vinyl biphephos, has been succesfully synthesized. Copolymerization of vinyl biphephos with tris(4-vinphenyl) phosphane can afford an efficient Porous Organic Polymer (POP), CPOL-bp&PPh3. The ultimately formed Rh/CPOL-bp&PPh3 heterogeneous catalyst showed excellent performance in converting terminal olefins to the corresponding linear aldehydes with high regioselectivity (l/b = 96 : 4–98 : 2), activity and stability, even better than the comparable homogeneous Rh + vinyl biphephos system. Notably, isomerizing hydrofromylation of internal olefins (2-heptene, 2-octene, trans-3-hexene) was also performed with high regioselectivity (l/b = 92 : 8–93 : 7) using the Rh/CPOL-bp&PPh3 heterogeneous catalyst.
8 September 2016 in Journal of Materials Chemistry A
Phosphonium salt and ZnX2–PPh3integrated POPs have been successful synthesized and were employed in cooperative catalytic preparation of cyclic carbonates.
Revealing key factors that modulate the regioselectivity in heterogeneous hydroformylation requires identifying and monitoring the dynamic evolution of the truly active center under real reaction conditions. However, unambiguous in situ characterizations are still lacking. Herein, we elaborately construct a series of Rh-POPs catalysts for propylene hydroformylation which exhibited tunable regioselectivity. Multi-technique approaches reveal the unique microenvironment of the diverse HRh(CO)(PPh3-frame)2 sites with distinct P-Rh-P bite angles ranging from 90° to 120° and 158° to 168°, respectively. In situ time-resolved XAFS, FT-IR, and quasi-in situ Solid-state NMR experiments combined with DFT calculations explain the dynamic evolution of the electronic and coordinate state of the distinct active sites induced by hemilabile PPh3-frame ligands and further disclose the regulatory mechanism of regioselectivity. These state-of-the-art techniques and multiscale analysis advance the understanding of how hemilabile coordination influences regioselectivity and will provide a new thought to modulate the regioselectivity in future industrial processes.