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1999.9 - 2003.7 Nankai University, College of Chemistry, B. S.
2003.9 - 2008.6 Nankai University, SKLEOC, Ph. D.
Different kinds of supports were applied in asymmetric catalysis to make supported-catalysts recyclable and improve the catalytic capability. As a novel support, Carbon Nanotubes (CNTs) have attracted considerable attention, because of their unique structural and electronic properties. However, so far they have been rarely applied in asymmetric catalysis.
It was found that pyrene-modified compounds could be strongly incovalently absorbed onto CNTs via π-π stacking. Based on this property, we designed a novel method for catalyst recycling with CNTs as support.
The pyrene-modified chiral ligand N-(4-(1-pyrenyl)-butyryl)-(3R,4R)-3,4-bis(diphenylphosphino)pyrrolidine (Py-Pyrphos)was synthesized starting from (R,R)-(+)-tartaric acid over 6 steps firstly. The Py-Pyrphos/Rh catalyst was well applied in the asymmetric hydrogenation of a-dehydroamino esters.It was found that the catalyst have different absorption capabilities with Multi-Wall Carbon Nanotubes (MWNTs) in different solvents. By utilizing this interesting property, we performed the hydrogenation in the solvent with weaker absorption capability and recycled the catalyst in another solvent with stronger absorption capability. the pyrene-modified chiral Rh catalyst waseffectively recycled and reused for 9 times via so-called “one-phase catalysis and two-phase separation” concept,without obvious deterioration of enantioselectivity(92–93% ee).
Another pyrene-modified chiral ligand N-(7,7′-di(diphenylphosphinooxy)- (S)-1,1′-spirobiindane-4-yl-methyl)-4-(1-pyrenyl)-butyramide(Py-SDPO) was synthesized from (S)-1,1′-spirobiindane-7,7′-diol (SPINOL) over 7 steps. The Py-SDPO/Ir catalyst, which could be absorbed completely onto MWNTs in THF, was heterogeneously supported by MWNTs to diminished the dimerization of the Ir catalyst and facilitated the reserving of the catalytic reactivity. The MWNTs-supported chiral catalyst, which showed the same enantioselectivity in the asymmetric hydrogenation of quinoline as the corresponding homogeneous catalyst, can be recycled by filtration and reused without deterioration of enantioselectivity. All of the new phosphorus ligands and their intermediates were identified by 1H NMR, 31P NMR, 13C NMR and HRMS.
A series of Single-Wall Carbon Nanotubes (SWNTs) supported Pt nanoparticle catalysts with 5 %, 10 % and 20 % Pt loadings were prepared. These catalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Chemical Hydrogen Absorption. After modified with cinchonidine (Cd), these Pt/SWNTs catalysts were applied in the asymmetric hydrogenation of ethyl pyruvate, and in high activity and moderate enantioselectivity were obtained. The reaction results were rationalized based on the kinetic and the absorption property studies of the Pt/SWNTs.
Keywords: Carbon nanotubes, support, absorption, asymmetric hydrogenation, catalyst recycling.
1. Liang Xing, Jian-Hua Xie, Yong-Sheng Chen, Li-Xin Wang, Qi-Lin Zhou*, Simply modified chiral diphosphine: catalyst recycling via non-covalent absorption on carbon nanotubes, Adv. Synth. Catal. 2008, 350, 1013-1016.
2.Liang Xing, Feng Du, Jia-Jie Liang, Yong-Sheng Chen*, Qi-Lin Zhou*, Preparation of Pt/SWNTs for heterogeneous asymmetric hydrogenation of ethyl pyruvate, J. Mol. Catal. Α: Chem. 2007, 276, 191-196.
3.Yu Fu, Guo-Hua Hou, Jian-Hua Xie, Liang Xing, Li-Xin Wang, Qi-Lin Zhou*, Synthesis of monodentate chiral spiro phosphonites and the electronic effect of ligand in asymmetric hydrogenation, J. Org. Chem. 2004, 69, 8157-8160.
4.Shou-Fei Zhu, Yu Fu, Jian-Hua Xie, Βin Liu, Liang Xing, Qi-Lin Zhou*, Synthesis of chiral 4,4′-disubstituted 1,1′-spirobiindane-7,7′-diols and related phosphoramidites. The substituent effect of SIPHOS ligands in Rh-catalyzed asymmetric hydrogenation, Tetrahedron: Asymmetry 2003, 14, 3219-3224.