The Kinetics of the Autoxidation of Aldehydes in the Presence of Cobalt(II) and Cobalt(III) Acetate in Acetic Acid Solution

Abstract

The mechanism of the autoxidation of several aldehydes in the presence of Co11 and Co111 acetate was investigated in rapidly stirred acetic acid solutions. The kinetic parameters were determined. In the presence of Co" acetate the autoxidation of an aldehyde is inhibited by reduction of the chain carrying acylperoxy radicals by Co", while Co111 acetate, formed by this reaction, contributes to the initiation by oxidation of the aldehyde to acyl radicals. These combined effects explain the autocatalytic conversion of Co" into Co"1 acetate. In the absence of Co" acetate, the corresponding peracid is formed as the first stable product of the aldehyde autoxidation. Co1" acetate catalyzes the decomposition of these peracids with formation of acylperoxy radicals, which initiate a very fast autocatalytic oxidation of the aldehyde. At high concentrations Co1" acetate also participates in chain termination by oxidizing acyl radicals.

The Autoxidation of Methyl Linoleate and Methyl Linolenate in the Presence of Cobalt(II) and Cobalt(III) Naphthanate in n-Heptane Solution

“…The stoichiometry observed (13) requires that the decomposition of the Com complex ultimately also leads to the oxidation of the methyl ester concerned. This explanation is similar to the one given for the oxidation of aldehydes by cobalt(III) acetate in acetic acid solutions, as has been discussed in a previous paper (Hendriks et al, 1978). It should be noted that reaction 2 contributes to the initiation of the autoxidation of the methyl esters in aerobic solutions.…”

Kinetics and mechanism of the catalyzed epoxidation of oleic acid with oxygen in the presence of benzaldehyde

“…The mechanism of epoxidation of oleic acid with oxygen in the presence of aldehyde using Co3+ ion as the catalyst is proposed based on the mechanism of producing peroxides from aldehydes (Chou and Lin, 1983; Chou and Lee, 1985;Wang, 1984; Maslov and Blyumberg, 1976;Hendriks et al, 1977Hendriks et al, , 1978 and the mechanism of epoxidation of unsaturated compounds by peroxides (Dryuk, 1976). The proposed mechanism will be confirmed by the experimental data in this work.…”

Aerobic oxidation of benzyl alcohol in a slug flow microreactor: Influence of liquid film wetting on mass transfer

“…At low catalyst concentrations ( C Co of ca. 10 mM and below), the reaction was reported of second order in cobalt concentration 50,51 . Hence, for the other experiments in this work, an excessive amount of catalyst was used ( C Co = 30 mM) to exclude its influence on kinetics.…”