Photocatalytic Asymmetric Hydrogenation of Methyl Acetoacetate with CdS/Modified Raney Nickel

Abstract

Raney Ni modified with (R, R)-tartaric acid (MRNi) was loaded on a CdS particle by solution-phase mixing. Irradiation to this CdS/MRNi photocatalyst in a deaerated methyl acetoacetate (MAA)-ethanol solution leads to the formation of acetaldehyde, hydrogen, and optically active methyl 3-hydroxybutyrate (MHB) with an optical yield of 67%.
It is concluded that the dominant reaction mechanism is not the reduction of MAA by the photocatalytically produced gaseous hydrogen, but the electrochemical reduction of MAA and proton by the photogenerated electron. The hydrogen production site on MRNi seems to be different from the MHB production site, judging from the kinetic behavior of the reaction.