Kinetics and mechanism of cerium(IV) oxidation of primary and secondary alcohols catalysed by chromium(III)

The cerium(IV) oxidation of isobutanol, isoamyl alcohol isopropyl alcohol, and secondary butanol catalysed by chromium(III) was studied in sulphuric and perchloric acid mixture at 30 degrees C. The reaction was found to proceed with the formation of a chromium(IV) intermediate followed by its complexation with alcohol. The complex thus formed decomposed into an aldehyde or ketone by a two-electron hydride ion transfer. The formation constants for complexes were determined from Michaelis-Menten plots. The accelerating effect of [H+] on the reaction is attributed to the formation of active species, HCe(SO4)(3-) and HAlcohol(+), of the oxidant and alcohol, respectively. The activation parameters were also determined and an isokinetic plot was found to be linear. (C) 1998 John Wiley gr Sons, Ltd.