Effect of different carboxylic acids on the aromatic hydroxylation with H2O2 in the presence of an iron aminopyridine complex

Nikolay V. Tkachenko, Oleg Y. Lyakin, Alexandra M. Zima, Evgenii P. Talsi, Konstantin P. Bryliakov

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

In this contribution, the effect of the structure of the catalytic additive – carboxylic acid – on the catalytic performance of the iron based catalyst [(PDP)Fe(OTf)2], 2 (PDP = N,N′-bis(2-pyridylmethyl)-(S,S)-2,2′-bipyrrolidine) in the selective aromatic oxidation of alkylbenzenes with H2O2 is presented. Eight (linear and branched) carboxylic acids have been tested; in the presence of 2-ethylhexanoic acid, the system [(PDP)Fe(OTf)2]/RCOOH/H2O2 has demonstrated the highest substrate conversion and the highest selectivity for oxygen incorporation into the aromatic ring (up to > 99%) at the same time. Low-temperature EPR spectroscopic study of the system [(PDP)Fe(OTf)2]/2-ethylhexanoic acid/H2O2 witness the presence of the low-spin perferryl intermediate 2aEHA with small g-factor anisotropy (g1 = 2.069, g2 = 2.007, g3 = 1.963), which directly reacts with benzene at −80 °C with the rate constant k2 = 0.6 M−1s−1, and with toluene with k2 > 1 M−1s−1, thus giving evidence for its key role in the selective oxygenation of aromatic substrates.

Original languageEnglish
Pages (from-to)130-134
Number of pages5
JournalJournal of Organometallic Chemistry
Volume871
DOIs
Publication statusPublished - 15 Sep 2018

Keywords

  • Aromatic oxidation
  • Electrophilic substitution
  • Hydrogen peroxide
  • Intermediates
  • Iron
  • Oxidation
  • OXIDATION
  • BENZENE
  • EPR
  • REACTIVITY
  • EPOXIDATION
  • HYDROGEN-PEROXIDE
  • SELECTIVITY
  • CATALYSTS
  • FE

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