Insight into catalyst speciation and hydrogen co-evolution during enantioselective formic acid-driven transfer hydrogenation with bifunctional ruthenium complexes from multi-technique operando reaction monitoring

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Abstract

Transfer hydrogenation of acetophenone from formic acid/triethylamine mixtures catalysed by the Ikariya-Noyori complex [(mesitylene)RuCl(R,R)-(TsDPEN)] has been investigated using simultaneous high-resolution FlowNMR and FlowUV-Vis spectroscopies coupled with on-line sampling head-space mass spectrometry and chiral high-performance liquid chromatography using an integrated, fully automated recirculating flow setup. In line with previous observations, the combined results show a gradual switch from formic acid dehydrogenation to hydrogen transfer mediated by the same Ru-hydride complex, and point to a Ru-formate species as the major catalyst intermediate. Hydrogen bonding in the formic acid/triethylamine mixture emerges as a sensitive 1H NMR probe for the transfer hydrogenation activity of the system and can be used to locate optimum reaction conditions.

Original languageEnglish
Pages (from-to)45-57
JournalFaraday Discussions
Volume220
Early online date11 Jun 2019
DOIs
Publication statusPublished - 11 Jun 2019

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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