2213-32-3Relevant articles and documents
Cross-linked polymer coated Pd nanocatalysts on SiO2 support: Very selective and stable catalysts for hydrogenation in supercritical CO 2
Wu, Tianbin,Jiang, Tao,Hu, Baoji,Han, Buxing,He, Jinling,Zhou, Xiaosi
, p. 798 - 803 (2009)
Using greener solvents, enhancing the selectivity and stability of catalysts is an important aspect of green chemistry. In this work, we developed a route to immobilize Pd nanoparticles on the surface of silica particles with cross-linked polystyrene coating by one-step copolymerization, and Pd(0) nanocatalysts supported on the silica particle supports with cross-linked polystyrene coating were successfully prepared. The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), plasma optical emission spectroscopy, and thermogravimetric analysis (TGA), and were used for hydrogenation of 2,4-dimethyl-1,3-pentadiene to produce 2,4-dimethyl-2-pentene and allyl alcohol to produce 1-propanol. It was found that the selectivity of the reaction was enhanced significantly by the polymer coating, and the catalysts were very stable due to the insoluble nature of the cross-linked polymers. Supercritical (sc)CO2 can accelerate the reaction rates of the reactions catalyzed by the specially designed catalysts significantly. The excellent combination of polymer coating and scCO2 has wide potential applications in catalysis.
Dimerization method for high activity and selectivity propylene
-
Paragraph 0114; 0115; 0116; 0118-0121; 0124-0139; 0142-0153, (2017/06/02)
The invention provides a dimerization method for high activity and selectivity propylene. The method includes the following steps that methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) is used as a catalyst promoter, and the propylene is subjected to a dimerization reaction under the catalytic action of an ethylidene bridged substituted diindene titanium group metal complex catalyst; and the ethylidene bridged substituted diindene titanium group metal complex catalyst is an internal compensation (meso-) ethylidene bridged substituted diindene titanium group metal complex catalyst or a racemization (rac-) ethylidene bridged substituted diindene titanium group metal complex catalyst. Compared with the prior art, the dimerization method provided by the invention is high in catalytic activity and high in dimerization selectivity, the rate can reach 99%, numerous follow-up operation steps in separation of products with the high degree of polymerization are omitted, the industrialization cost is reduced, and the industrial production needs can be met.
Water-Enabled Catalytic Asymmetric Michael Reactions of Unreactive Nitroalkenes: One-Pot Synthesis of Chiral GABA-Analogs with All-Carbon Quaternary Stereogenic Centers
Sim, Jae Hun,Song, Choong Eui
supporting information, p. 1835 - 1839 (2017/02/05)
Water enables new catalytic reactions for otherwise unreactive substrate systems. Under the “on water” reaction conditions, extremely unreactive β,β-disubstituted nitroalkenes smoothly underwent enantioselective Michael addition reactions with dithiomalonates using a chiral squaramide catalyst, affording both enantiomers of highly enantioenriched Michael adducts with all-carbon-substituted quaternary centers. The developed “on water” protocol was successfully applied for the scalable one-pot syntheses of chiral GABA analogs with all-carbon quaternary stereogenic centers at the β-position, which might show highly interesting pharmaceutical properties.