Liquid phase asymmetric hydrogenation on Pt-containing zeolite Y catalysts

Heterogeneous asymmetric reactions

“…In the 25 years that have passed since their discovery, optimization of catalysts and reaction conditions has enabled the achievement of optical purities as high as 97-98% in EtPy hydrogenation [16][17][18], a result made possible by the resourceful and versatile research carried out at several groups. In order to develop optimal catalyst surfaces, catalyst pretreatment [19][20][21] and the effects of air and other gases [22][23][24][25][26][27][28], ultrasound treatment [17,29], prehydrogenation conditions [22,30], the concentration and impregnation method of modifier [19,29,31,32], particle size and pore size distribution [22,[33][34][35][36][37] and support quality [7,14,21,34,35,[37][38][39] have been studied. The results of these far-reaching studies have been reviewed [2,3,40].…”

Heterogeneous asymmetric hydrogenation over chiral molecule-modified metal particles

“…In the hydrogenation of ethyl pyruvate over cinchonidine-modified Pt particles supported on Y zeolite, doping Ca 2+ , Mg 2+ , Na + , and rare earth metal ions were adapted to modulate the acidity of the support. It was found that increasing the acidity of the zeolites promoted the activity but had minor impact on the enantioselectivity, and accordingly the acidity of the zeolites was assumed to simply enhance Pt dispersion 62 . Among other typical 70 support materials like activated carbon, SiO 2 , Al 2 O 3 , ZrO 2 and TiO 2 , TiO 2 with both acidic and basic sites that favoured the adsorption of CD, provided a higher enantioselectivity for the asymmetric hydrogenation of (E)-α-phenylcinnamic acid over CD-modified Pd particles 59 .…”

“…It was found that increasing the acidity of the zeolites promoted the activity but had minor impact on the enantioselectivity, and accordingly the acidity of the zeolites was assumed to simply enhance Pt dispersion. 62 Among other typical support materials like activated carbon, SiO 2 , Al 2 O 3 , ZrO 2 and TiO 2 , TiO 2 with both acidic and basic sites that favoured the adsorption of CD provided a higher enantioselectivity for the asymmetric hydrogenation of (E)-α-phenylcinnamic acid over CD-modified Pd particles. 59 Basic oxides, such as CaCO 3 and MgO, were superior supports in the asymmetric hydrogenation of isophorone over proline-modified Pd catalysts, although significant kinetic resolution was observed in the reaction network.…”

Heterogeneous Catalytic Enantioselective Hydrogenation of Activated Ketones

“…Various supports are suitable for this purpose; Al 2 O 3 , SiO 2 , TiO 2 , and zeolites give the best results [57][58][59][60][61][62][63][64]. The utilization of clay minerals as catalyst supports has been intensively studied [65][66][67][68][69][70][71][72].…”

“…It has been confirmed that ee values exceeding 90% can be attained using specially prepared Pt/alumina catalysts. In order to develop optimal catalyst surfaces, catalyst pretreatment [47,60,74] and the effects of air and other gases [40,[75][76][77][78][79][80], ultrasound treatment [21,[81][82][83][84][85][86], prehydrogenation conditions [75,87,88], the concentration and impregnation method of modifier [47,[87][88][89][90], particle size and pore size distribution [57][58][59]75,91,92] have been studied.…”