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Synthesis and Application of Polystyrene Nanospheres Supported Platinum Catalysts in Enantioselective Hydrogenations

“…The use of other modifiers, however, revealed invaluable information regarding important details of the reaction mechanism [11][12][13]. Several enantiodifferentiation models have been proposed to explain the mode of action of cinchona-modified Pt catalysts or analogues thereof [14][15][16][17][18]. The information gained from these studies such as kinetic and spectroscopic investigations were rationalized to coherent mechanistic proposals and the new developments have been summarized in several recent reviews [19][20][21][22][23].…”

Surface Structure of Heterogeneous Catalysts: Cinchona and Tartaric Acid on Solid Surface

“…At present, the effective way to synthesize enantiopure chemicals is via homogeneous catalysis. However, much attention has been paid towards obtaining chiral products by heterogeneous catalysis because of the special advantage of heterogeneous catalysts in handling, separation, stability, and recovery [1][2][3][4][5][6][7][8]. One possible candidate for heterogeneous asymmetry catalysts is the natural chiral metal surfaces in view of the enantioselectivity adsorption of chiral chemicals on them [9][10][11].…”

“…Another strategy promising and demonstrated to be successful to obtain chiral catalysts is via chiral modification of the achiral catalytically active site with chiral auxiliary (modifier) [12][13][14][15]. Two such catalytic systems for enantioselective hydrogenation reactions are Pt/Al 2 O 3 catalysts in the presence of different cinchona alkaloids and tartaric acid (TA) modified Ni catalysts [1][2][3][4][5][6][7][8]14,15]. These catalysts have been shown to be effective for performing enantioselective hydrogenation on a wide range of C@O bondcontaining molecules with high enantiomeric excess of up to 90-95% [1].…”

Ketonok heterogén katalitikus enantioszelektív hidrogénezése cinkona alkaloidok jelenlétében

“…A kinolin gyűrűt hidrogénezve az enantioszelektivitás a telítéssel párhuzamosan csökken [37]. Hasonlóan fenil, naftil, antracil csoportokat tartalmazó amino alkoholok vizsgálata során ebben a sorrendben növekvő enantioszelektivitást tapasztaltak [38].…”

“…Vinil csoportjuk igen gyorsan meghidrogéneződik, így lényegében minden esetben a 10,11dihidro származékok hatását vizsgáljuk. A reakció során az alkaloid kinolin gyűrűje is hidrogéneződhet részben vagy teljesen, ezáltal a módosító adszorpciója gyengül, így hatékonysága csökken [37]. Ez a mellékreakció gyorsan hidrogéneződő szubsztrátok esetén visszaszorul, etilpiruvát esetén például 70% konverzióig nem kimutatható.…”