title: Unsupported Nanoporous Gold Catalyst for Chemoselective Hydrogenation Reactions under Low Pressure: Effect of Residual Silver on the Reaction.
abstract: For the first time, H-H dissociation on an unsupported nanoporous gold (AuNPore) surface is reported for chemoselective hydrogenation of C≡C, C═C, C═N, and C═O bonds under mild conditions (8 atm H2 pressure, 90 °C). Silver doping in AuNPore, which was inevitable for its preparation through a process of dealloying of Au-Ag alloy, exhibited a remarkable difference in catalytic activity between two catalysts, Au>99Ag1NPore and Au90Ag10NPore.The former was more active and the latter less active in H2 hydrogenation, while the reverse tendency was observed for O2 oxidation. This marked contrast between H2 reduction and O2 oxidation is discussed. Further, Au>99Ag1NPore showed a high chemoselectivity toward reduction of terminal alkynes in the presence of internal alkynes which was not achieved using supported gold nanoparticle catalysts and other previously known methods. Reductive amination, which has great significance in synthesis of amines due to its atom-economical nature, was also realized using Au>99Ag1NPore, and the Au>99Ag1NPore/H2 system showed a preference for the reduction of aldehydes in the presence of imines. In addition to this high chemoselectivity, easy recovery and high reusability of AuNPore make it a promising heterogeneous catalyst for hydrogenation reactions.
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116023, China.|WPI-Advanced Institute for Materials Research, Tohoku University , Sendai 980-8577, Japan.
authors.forename: Balaram S
authors.initials: BS
authors.lastname: Takale
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116023, China.
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116023, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116023, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Bao
authors.affiliation: WPI-Advanced Institute for Materials Research, Tohoku University , Sendai 980-8577, Japan.
authors.forename: Tienan
authors.initials: T
authors.lastname: Jin
authors.affiliation: Office of Society-Academia Collaboration for Innovation, Kyoto University , Uji, Kyoto 611-0011, Japan.
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Minato
authors.affiliation: State Key Laboratory of Fine Chemicals, Dalian University of Technology , Dalian 116023, China.|WPI-Advanced Institute for Materials Research, Tohoku University , Sendai 980-8577, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Yamamoto