Kinetics and mechanism of the oxidation of a substituted phenol by a superoxochromium(III) ion.
A superoxochromium(III) ion, CraqOO2+, abstracts the hydrogen atom from the hydroxylic group of a substituted, cationic phenol (ArOH), kCrOO = 1.24 M-1 s-1 in acidic aqueous solution at 25 degrees C. The reaction has a large kinetic isotope effect, kArOH/kArOD approximately 12 and produces ArO., which also reacts with CraqOO2+ in a rapid second step, kArO = 1.26 x 10(4) M-1 s-1. The final oxidation product is an o-quinone, which was identified by its behavior on a cation-exchange resin, UV-visible spectrum, and reaction with iodide ions. This work has extended to three the types of element-hydrogen bonds that react with CraqOO2+ about 10(2) times more slowly than with CraqO2+. The mechanistic implications of these findings are discussed.
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Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA.
Bakac
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D002857:Chromium / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D011809:Quinones / Q000737:chemistry
D010636:Phenols; D011809:Quinones; D002857:Chromium; D010100:Oxygen