The role of iodide promoters and the mechanism of ethylene carbonylation catalyzed by molybdenum hexacarbonyl

Chieh Chao Yang, Beata A. Kilos, David G. Barton, Eric Weitz, Justin M. Notestein*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

In limited prior reports, molybdenum hexacarbonyl has been shown to be active in catalyzing ethylene carbonylation promoted by ethyl iodide. Here, we assess the productivity of this reaction with respect to various reaction parameters and provide an understanding of the mechanism by NMR and mass spectrometric studies of isotopically labeled reactants. 13C labeled reactants show that ethyl iodide promotes initiation but is not a participant in the primary catalytic cycle, in contrast to classical mechanisms for alcohol carbonylation with an iodide co-catalyst, such as in the Monsanto process. NMR spectroscopy shows incorporation of only one D from D2O into the carbon backbone of propionic acid products, and in a manner consistent with direct, reversible addition of ethylene to a Mo hydride intermediate. CO migratory insertion and a formal hydroxylation then yield propionic acid. Under the conditions described here, the overall cycle gives propionic acid in high selectivity and requiring low promoter loads.

Original languageEnglish (US)
Pages (from-to)211-219
Number of pages9
JournalJournal of Catalysis
Volume319
DOIs
StatePublished - 2014

Funding

The authors acknowledge the financial support of the Dow Chemical Company . The authors thank Dr. Yuyang Wu at IMSERC, Northwestern University for his technical assistance in NMR. The CleanCat Core facility acknowledges funding from the Department of Energy (DE-AC02-06CH11357) used for the purchase of the gas chromatographs.

Keywords

  • Carbonylation
  • Ethylene
  • Homogeneous catalysis
  • Isotopic labeling
  • Metal carbonyl
  • Molybdenum
  • Promotion

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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