Rhenium-Loaded TiO2: A Highly Versatile and Chemoselective Catalyst for the Hydrogenation of Carboxylic Acid Derivatives and the N-Methylation of Amines Using H2 and CO2

Takashi Toyao, S. M.A.H. Siddiki, Yoshitsugu Morita, Takashi Kamachi, Abeda S. Touchy, Wataru Onodera, Kenichi Kon, Shinya Furukawa, Hiroko Ariga, Kiyotaka Asakura, Kazunari Yoshizawa, Ken Ichi Shimizu

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)

Abstract

Herein, we report a heterogeneous TiO2-supported Re catalyst (Re/TiO2) that promotes various selective hydrogenation reactions, which includes the hydrogenation of esters to alcohols, the hydrogenation of amides to amines, and the N-methylation of amines, by using H2 and CO2. Initially, Re/TiO2 was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (pH2 =5 MPa, =5 MPa, T=180 °C), which revealed a superior performance over other catalysts that we tested in this study. In contrast to other typical heterogeneous catalysts, hydrogenation reactions with Re/TiO2 did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings is ascribed to the higher affinity of Re towards the COOCH3 group than to the benzene ring. Moreover, Re/TiO2 showed a wide substrate scope for the hydrogenation reaction (19 examples). Subsequently, this Re/TiO2 catalyst was applied to the hydrogenation of amides, the N-methylation of amines, and the N-alkylation of amines with carboxylic acids or esters.

Original languageEnglish
Pages (from-to)14848-14859
Number of pages12
JournalChemistry - A European Journal
Volume23
Issue number59
DOIs
Publication statusPublished - Oct 20 2017

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

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