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Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate.Compared to the enantiomeric excess(e.e.)value(71.4%) obtained without the presence of metal cations,obvious e.e.enhancement(up to 82.5%)was resulted from the addition of Zn~(2+) but with a certain decrease in activity.The reaction parameters in the presence of Zn~(2+) were also studied.It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.
Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate. Compared to the enantiomeric excess (ee) value (71.4%) obtained without the presence of metal cations, obvious eeenhancement (up to 82.5%) was wasduced from the addition of Zn ~ (2+) but with a certain decrease in activity. The reaction parameters in the presence of Zn ~ (2+) were also studied .It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.