Evidence of esterification during the oxidation of some aromatic aldehydes by permanganate

Summary The permanganate ion oxidation of PhCHO in HClO₄ medium is first order in MnO _inf4 ^sup- ], but of complex order with respect to aldehyde] as well as H⁺]. The influence of substituents on the reaction rate and mechanism has also been studied in 40% (v/v) aqueous AcOH and convincing evidence favours an ester formation mechanism. Thermodynamic values associated with 11 intermediate ester formation and the activation parameters associated with the disproportionation steps involved have been evaluated.