Multiphase heterogeneous catalytic enantioselective hydrogenation of acetophenone over cinchona-modified Pt/C

Abstract

The multiphase heterogeneous enantioselective hydrogenation of acetophenone in the presence of cinchona-modified Pt/C was investigated. The system demonstrated the feasibility of this reaction on non-activated ketones. The reaction proceeded selectively, at room temperature and atmospheric pressure, towards the formation of 1-phenylethanol, with up to 20% ee (enantiomeric excess) of either enantiomer depending on the modifier used. A mode of action of the modifier is proposed to account for the mechanism. A comparison with other systems indicates that the investigated system likely acts by a different mechanism, and that it is quite specific for acetophenone.

Hydrodechlorination and Hydrogenation over Raney–Ni under Multiphase Conditions: Role of Multiphase Environment in Reaction Kinetics and Selectivity

“…The selectivity, kinetics, and synthetic (10,11) and environmental applications (12) of the multiphase systems have been amply studied for charcoal-supported Pt and Pd catalysts. Some mechanistic hypotheses on the mode of action of the multiphase environment have been proposed as well (7).…”

Multiphasic Heterogeneous Catalysis Mediated by Catalyst‐Philic Liquid Phases

“…85 The idea was to employ chiral phase transfer agents derived from chincona alkaloids in place of A336, coupled with Pt/C as catalyst. A rapid screening, however, demonstrated that the pure alkaloids chincona and chinconidine were more active than the corresponding ammonium salt in promoting a degree of enantioselectivity in the reduction of acetophenone (Fig.…”

Hydrogenation of Acetophenone in the Presence of Ru Catalysts Supported on Amine Groups Functionalized Polymer

“…According to the literature, in biphasic IO/H 2 O solvent system a variety of catalytic reductions can effectively proceed under mild conditions (ca. 50°C, atmospheric pressure of hydrogen) and their selectivity can be modified [24][25][26][27]. Thus, Marques et al [24] demonstrate that hydrogenation of propiophenone on Pd/C catalyst in conventional ethanol solvent produces propylbenzene as the final product, while in the biphasic IO/H 2 O system propiophenone is almost selectively reduced to 1-phenyl-1-propanol [24].…”

“…In contrast, on Pt/C catalyst and in IO/H 2 O system, the hydrogenation of acetophenone and propiophenone proceeds towards the full reduction products, ethyl benzene and ethyl cyclohexane, respectively [25,26]. Biphasic IO/H 2 O system is also successfully used for enantioselective hydrogenation of ACT in the presence of cinchona-modified Pt/C catalyst [27]. Moreover, our preliminary catalytic data demonstrate the advantage of biphasic IO/H 2 O solvent system in hydrogenation of ACT in the presence of Ru-catalysts supported on methacrylate-styrene gel-type resin (FCN) (Scheme 2).…”