Tuning the Selectivity of Palladium Catalysts for Hydroformylation and Semihydrogenation of Alkynes: Experimental and Mechanistic Studies

Jiawang Liu, Zhihong Wei, Ji Yang, Yao Ge, Duo Wei, Ralf Jackstell, Haijun Jiao, Matthias Beller

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Here, we describe a selective palladium catalyst system for chemodivergent functionalization of alkynes with syngas. In the presence of an advanced ligand L2 bearing 2-pyridyl substituent as a built-in base, either hydroformylation or semihydrogenation of diverse alkynes occurs with high chemo- and stereoselectivity under comparable conditions. Mechanistic studies, including density functional theory (DFT) calculations, kinetic analysis, and control experiments, revealed that the strength and concentration of acidic cocatalysts play a decisive role in controlling the chemoselectivity. DFT studies disclosed that ligand L2 not only promotes heterolytic activation of hydrogen similar to frustrated Lewis pair (FLP) systems in the hydrogenolysis step for hydroformylation but also suppresses CO coordination to promote semihydrogenation under strong acid conditions. This switchable selectivity provides a strategy to design new catalysts for desired products.

Original languageEnglish
Pages (from-to)12167-12181
Number of pages15
JournalACS Catalysis
Volume10
Issue number20
DOIs
StatePublished - 16 Oct 2020
Externally publishedYes

Keywords

  • alkynes
  • hydroformylation
  • mechanism
  • selectivity
  • semihydrogenation
  • syngas

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