The liquid-phase oxidation of 2,6-di-tert-butylphenol(BOH) was studied using a heterogeneous polymer-supported Cu(II) catalyst, basic Cu(II)-poly(4-vinylpyridine) (Cu(II)-PVP) catalyst. The only oxidation product was 3,3′,5,5′-tetramethyl-4,4'-diphenoquinone. The oxidation reaction of BOH did not proceed by the presence of only the Cu(II)-PVP catalyst itself, but was significantly promoted by adding an inorganic base such as KOH in the solvent. The added KOH was found to have the role of generating the corresponding phenolate anion by dissociating the BOH molecule. The turnover number (mole of absorbed OZ molecule per unit time and unit mole of Cu(II)) with the basic Cu(II)-PVP catalyst in the BOH oxidation passed through a maximum with the variation in the pyridine/Cu(II) mole ratios (ligand ratio). From the dependence of the reaction rate on the Cu(II) concentration of the Cu(II)-PVP catalyst, it was found that the reaction order of the Cu(II) concentration was changed from second- to first-order with an increase in the Cu(II) amount in the Cu(II)-PVP. On the basis of the kinetic results it is assumed that the rate-determining step in the BOH oxidation catalyzed by the basic Cu(II)-PVP changed from the reoxidation step of the dinuclear Cu(I) complex with an oxygen molecule to the BOH oxidation step by the mononuclear Cu(II) complex with an increase in the Cu(II) amount in the Cu(II)-PVP catalyst. Since the catalytic activity of the used Cu(II)-PVP catalyst almost remained intact, it was found possible to re-use the Cu(II)-PVP catalyst. © 1992.
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