High temperature–pressure aqueous oxidations. IV. A kinetic study of the oxidation and enolization of cyclohexanone in the presence of catalytic metal ions

Abstract

. 67, 165 (1989).The aqueous high pressure-temperature oxidation of cyclohexanone was found to be strongly catalyzed by silver, iron(III), and copper ions but not by aluminum, cobalt, manganese@), or nickel ions. The reactivities of the catalytic ions were inhibited by the acidic oxidation products. Accordingly, initial reaction velocities were determined and used to correlate the kinetic data. A detailed kinetic study of copper ion catalysis has shown that in the presence of that ion the reaction was first order in cyclohexanone, one-half order in copper ion, and zero order in oxygen. The rate of enolization of cyclohexanone appeared to be unaffected by the presence of copper ion under conditions of constant acidity but was strongly catalyzed by both deuterium ion and acetate ion. Further, the rate of oxidation exceeded the rate of enolization at higher copper ion concentrations. These data contrast with the uncatalyzed oxidation, for which the kinetic reaction was first order in cyclohexanone, one-half order in oxygen, and the rate of oxidation was much less than the rate of enolization. The activation energies for the catalyzed and uncatalyzed oxidations were about the same, but the entropies of activation were quite different. From these data it is concluded that the en01 is not a major intermediate for the catalyzed reaction. It is suggested that the copper ion may form an active peroxy complex with the oxygen molecule to serve as the reactive oxidant.Key words: metal ion catalysis, kinetics, cyclohexanone, high temperature oxidation, high pressure oxidation.JOHN W. THOMAS et JAY E. TAYLOR. Can. J. Chem. 67, 165 (1989).On a trouvt que I'oxydation de la cyclohexanone, en milieu aqueux et h des tempkratures et des pressions ClevCes, est fortement catalyste par les ions de l'argent, du fer(II1) et du cuivre, mais pas par les ions du aluminum, du cobalt, du manganbse(I1) et du nickel. Le rtactivitt des ions catalytiques est inhibCe par les produits acides de l'oxydation. On a donc determint les vitesses initiales des rCactions et on les a utilisCes pour Ctablir une corrklation avec les donnCes cinCtiques. Une Ctude cinttique dttaillte de la catalyse par l'ion du cuivre a montrk que, en prCsence de cet ion, la rCaction est du premier ordre en cyclohexanone, d'ordre un demi en ion du cuivre et d'ordre zero en oxygene. I1 semble que, h acidite constante, la vitesse d'Cnolisation de la cyclohexanone n'est pas affectke par la prCsence des ions du cuivre; toutefois, elle est fortement catalyste par l'ions deutCrium et acCtate. De plus, h des concentrations ClevCes d'ions du cuivre, la vitesse d'oxydation est plus ClevCe que la vitesse d'Cnolisation. Ces donnCes sont en opposition avec ceux obtenus lors de l'oxydation non-catalysCe de la cyclohexanone alors que la rCaction cinCtique Ctait du premier ordre en cyclohexanone, d'ordre un demi en oxygitne et que la vitesse d'oxydation Ctait beaucoup plus faible que la vitesse dlCnolisation. Les tnergies d'activation pour les reactions catalystes et non-catalystes sont appr...

Liquid-Phase Cooxidation of Cyclohexane and Cyclohexanone over Supported Cerium Oxide Catalysts

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Kinetics and Mechanism of Wet-Air Oxidation of Nuclear-Fuel-Chelating Compounds

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