Kinetics and mechanism of the ferroxime(II)-catalysed biomimetic oxidation of 2-aminophenol by dioxygen. A functional phenoxazinone synthase model.
[Fe(Hdmg)(2)(MeIm)(2)](1), referred to as ferroxime(II), is the precursor of a selective catalyst for the oxidative dehydrogenation of 2-aminophenol (Hap) to 2-amino-3H-phenoxazine-3-one (apx) by dioxygen under ambient conditions. The superoxoferroxime(III) species has been detected by ES-MS, and a 4-substituted 2-aminophenoxyl free radical by the ESR technique. The kinetics of the reaction was followed spectrophotometrically and by monitoring dioxygen uptake at constant pressure. According to the proposed mechanism, solvolysis of 1 is followed by O(2) binding to afford a superoxoferroxime, which abstracts an H-atom from Hap in the rate-determining step via an H-bonded intermediate, generating the free radical. This is supported by the observed primary deuterium kinetic isotope effect of 2.63. The system studied is a functional phenoxazinone synthase model.
Simándi
Tatiana M
TM
Chemical Research Center, Institute of Chemistry, Hungarian Academy of Sciences, P.O. Box 17, H-1525 Budapest, Hungary. simandi@chemres.hu
Simándi
László I
LI
Gyor
Miklós
M
Rockenbauer
Antal
A
Gömöry
Agnes
A
D000627:Aminophenols / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry*; D002384:Catalysis; D003609:Dactinomycin / Q000096:biosynthesis; D004578:Electron Spin Resonance Spectroscopy; D005296:Ferrous Compounds / Q000737:chemistry*; D007554:Isotopes; D007700:Kinetics; D008954:Models, Biological; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D010100:Oxygen / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
D000627:Aminophenols; D005296:Ferrous Compounds; D007554:Isotopes; C502342:ferroxime(II); D003609:Dactinomycin; C027667:2-aminophenol; D010088:Oxidoreductases; C023944:2-aminophenol oxidase; D010100:Oxygen