Insights into the palladium(ll)-catalyzed wacker-type oxidation of styrene with hydrogen peroxide and tert-butyl hydroperoxide

Manting Mu, Katherine L. Walker, Goar Sánchez-Sanz, Robert M. Waymouth*, Cristina Trujillo*, Mark J. Muldoon*, Max García-Melchor*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
36 Downloads (Pure)

Abstract

Wacker oxidations are ubiquitous in the direct synthesis of carbonyl compounds from alkenes. While the reaction mechanism has been widely studied under aerobic conditions, much less is known about such processes promoted with peroxides. Here, we report an exhaustive mechanistic investigation of the Wacker oxidation of styrene using hydrogen peroxide (H2O2) and tert-butyl hydroperoxide (TBHP) as oxidants by combining density functional theory and microkinetic modeling. Our results with H2O2 uncover a previously unreported reaction pathway that involves an intermolecular proton transfer assisted by the counterion [OTf] present in the reaction media. Furthermore, we show that when TBHP is used as an oxidant instead of H2O2, the reaction mechanism switches to an intramolecular protonation sourced by the HOtBu moiety generated in situ. Importantly, these two mechanisms are predicted to outcompete the 1,2-hydride shift pathway previously proposed in the literature and account for the level of D incorporation in the product observed in labeling experiments with α-d-styrene and D2O2. We envision that these insights will pave the way for the rational design of more efficient catalysts for the industrial production of chemical feedstocks and fine chemicals.

Original languageEnglish
Pages (from-to)1567-1574
Number of pages8
JournalACS Catalysis
Volume14
Issue number3
Early online date16 Jan 2024
DOIs
Publication statusPublished - 02 Feb 2024

Bibliographical note

Funding Information:
The authors are grateful to the Irish Research Council (M.M. GOIPG/2021/88) and the National Science Foundation (RMW, NSF CHE-2101256) for financial support. The authors also acknowledge the DJEI/DES/SFI/HEA Irish Centre for High-End Computing (ICHEC) for the generous provision of computational resources.

Publisher Copyright:
© 2024 The Authors. Published by American Chemical Society

Keywords

  • density functional theory
  • enol−enolate
  • hydride
  • microkinetic modeling
  • palladium
  • proton shuttle
  • reaction mechanisms
  • Wacker oxidation

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry

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