Functional phenoxazinone synthase models

Kinetic studies on the copper-catalyzed oxygenation of 2-aminophenol

Tamás Horváth, J. Kaizer, G. Speier

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Abstract

Several copper compounds (CuCl, CuCl2, CuSO4, Cu(NO3)2, Cu(OAc)2, Cu(OCH3) 2, and Cu(OCH3)(Cl)) have been used as catalysts for the oxidation of 2-aminophenol with dioxygen at 60°C in DMF to 2-aminophenoxazine-3-one; a comparison of their activities was made through kinetic measurements. Stronger coordinating donor N-ligands (bpy, phen) accelerate the reaction rate remarkably and the amount of ligand influences the molecularity of the CuCl-catalyzed reaction. The overall second order rate equation was found at CuCl to phen ratio of 1:0 (k2/60°C=11. 3±0.5×102mol-3l3s-1), while the reaction is zero order with respect to 2-aminophenol concentration at a CuCl to phen ratio of 1:2 (k0/60°C=13.9±0. 7×10-2mol-3l3s-1). The kinetics of the CuCl(phen)-catalyzed reaction measured at 60°C resulted in a rate equation with first order dependence on copper, dioxygen and 2-aminophenol. The rate constant, activation enthalpy, and entropy at 333.16K are as follows: kobs=2.42±0.22mol-2dm 6s-1, Ea=25±1kJmol-1, ΔH=22±1kJmol-1 and ΔS =-170±13Jmol-1K-1. The catalytic systems investigated can be viewed as functional models of the enzyme phenoxazinone synthase.

Original languageEnglish
Pages (from-to)9-15
Number of pages7
JournalJournal of Molecular Catalysis A: Chemical
Volume215
Issue number1-2
DOIs
Publication statusPublished - Jun 14 2004

Fingerprint

Oxygenation
oxygenation
Copper
Ligands
Copper compounds
copper
Kinetics
kinetics
Oxygen
copper compounds
Reaction rates
Enthalpy
Rate constants
ligands
Entropy
Enzymes
Chemical activation
Oxidation
Catalysts
enzymes

Keywords

  • 2-Aminophenol
  • Dioxygen
  • Kinetic studies
  • Oxygenation
  • Phenoxazinone

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology

Cite this

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title = "Functional phenoxazinone synthase models: Kinetic studies on the copper-catalyzed oxygenation of 2-aminophenol",
abstract = "Several copper compounds (CuCl, CuCl2, CuSO4, Cu(NO3)2, Cu(OAc)2, Cu(OCH3) 2, and Cu(OCH3)(Cl)) have been used as catalysts for the oxidation of 2-aminophenol with dioxygen at 60°C in DMF to 2-aminophenoxazine-3-one; a comparison of their activities was made through kinetic measurements. Stronger coordinating donor N-ligands (bpy, phen) accelerate the reaction rate remarkably and the amount of ligand influences the molecularity of the CuCl-catalyzed reaction. The overall second order rate equation was found at CuCl to phen ratio of 1:0 (k2/60°C=11. 3±0.5×102mol-3l3s-1), while the reaction is zero order with respect to 2-aminophenol concentration at a CuCl to phen ratio of 1:2 (k0/60°C=13.9±0. 7×10-2mol-3l3s-1). The kinetics of the CuCl(phen)-catalyzed reaction measured at 60°C resulted in a rate equation with first order dependence on copper, dioxygen and 2-aminophenol. The rate constant, activation enthalpy, and entropy at 333.16K are as follows: kobs=2.42±0.22mol-2dm 6s-1, Ea=25±1kJmol-1, ΔH‡=22±1kJmol-1 and ΔS ‡=-170±13Jmol-1K-1. The catalytic systems investigated can be viewed as functional models of the enzyme phenoxazinone synthase.",
keywords = "2-Aminophenol, Dioxygen, Kinetic studies, Oxygenation, Phenoxazinone",
author = "Tam{\'a}s Horv{\'a}th and J. Kaizer and G. Speier",
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TY - JOUR

T1 - Functional phenoxazinone synthase models

T2 - Kinetic studies on the copper-catalyzed oxygenation of 2-aminophenol

AU - Horváth, Tamás

AU - Kaizer, J.

AU - Speier, G.

PY - 2004/6/14

Y1 - 2004/6/14

N2 - Several copper compounds (CuCl, CuCl2, CuSO4, Cu(NO3)2, Cu(OAc)2, Cu(OCH3) 2, and Cu(OCH3)(Cl)) have been used as catalysts for the oxidation of 2-aminophenol with dioxygen at 60°C in DMF to 2-aminophenoxazine-3-one; a comparison of their activities was made through kinetic measurements. Stronger coordinating donor N-ligands (bpy, phen) accelerate the reaction rate remarkably and the amount of ligand influences the molecularity of the CuCl-catalyzed reaction. The overall second order rate equation was found at CuCl to phen ratio of 1:0 (k2/60°C=11. 3±0.5×102mol-3l3s-1), while the reaction is zero order with respect to 2-aminophenol concentration at a CuCl to phen ratio of 1:2 (k0/60°C=13.9±0. 7×10-2mol-3l3s-1). The kinetics of the CuCl(phen)-catalyzed reaction measured at 60°C resulted in a rate equation with first order dependence on copper, dioxygen and 2-aminophenol. The rate constant, activation enthalpy, and entropy at 333.16K are as follows: kobs=2.42±0.22mol-2dm 6s-1, Ea=25±1kJmol-1, ΔH‡=22±1kJmol-1 and ΔS ‡=-170±13Jmol-1K-1. The catalytic systems investigated can be viewed as functional models of the enzyme phenoxazinone synthase.

AB - Several copper compounds (CuCl, CuCl2, CuSO4, Cu(NO3)2, Cu(OAc)2, Cu(OCH3) 2, and Cu(OCH3)(Cl)) have been used as catalysts for the oxidation of 2-aminophenol with dioxygen at 60°C in DMF to 2-aminophenoxazine-3-one; a comparison of their activities was made through kinetic measurements. Stronger coordinating donor N-ligands (bpy, phen) accelerate the reaction rate remarkably and the amount of ligand influences the molecularity of the CuCl-catalyzed reaction. The overall second order rate equation was found at CuCl to phen ratio of 1:0 (k2/60°C=11. 3±0.5×102mol-3l3s-1), while the reaction is zero order with respect to 2-aminophenol concentration at a CuCl to phen ratio of 1:2 (k0/60°C=13.9±0. 7×10-2mol-3l3s-1). The kinetics of the CuCl(phen)-catalyzed reaction measured at 60°C resulted in a rate equation with first order dependence on copper, dioxygen and 2-aminophenol. The rate constant, activation enthalpy, and entropy at 333.16K are as follows: kobs=2.42±0.22mol-2dm 6s-1, Ea=25±1kJmol-1, ΔH‡=22±1kJmol-1 and ΔS ‡=-170±13Jmol-1K-1. The catalytic systems investigated can be viewed as functional models of the enzyme phenoxazinone synthase.

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KW - Dioxygen

KW - Kinetic studies

KW - Oxygenation

KW - Phenoxazinone

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M3 - Article

VL - 215

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EP - 15

JO - Journal of Molecular Catalysis A: Chemical

JF - Journal of Molecular Catalysis A: Chemical

SN - 1381-1169

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