Oxidation studies. III. Oxidation of ketone by ceric ions in perchloric acid

Abstract

The oxidation of aliphatic unsymmetrical ketones-n-propyl methyl ketone and isobutyl methyl ketone and cyclic ketone-cyclohexanone by ceric perchlorate in perchloric acid (≈0.5-2.0 M) was studied in the temperature range 10°-30°C. The kinetics of the reactions were followed by measuring rate of Ce⁴⁺ disappearance effecting variations in [Ce⁴⁺], [Ketone], [HClO₄], ionic strength μ, temperature, etc., and the reactions were found to be 2nd order-first order each with respect to [Ce⁴⁺] and [ketone]. No evidence for complex formation between Ce⁴⁺ and ketone was obtained from kinetics or by an independent absorptiometric method. Ce⁴⁺ (αq) and enol of the ketones were the active species for oxidation. Correlations between rates of enolisation of ketones and oxidation of the latter by Ce⁴⁺ were observed. The rate constants and their thermodynamic data were calculated and discussed. A mechanism based on the concept of oxidation as a process of successive hydroxylation of organic molecules is proposed.