Kinetics and mechanism of oxidation of aliphatic and aromatic alcohols by in situ generated bromine in reaction between oxone and bromide ion

Abstract

Oxidation of aliphatic and aromatic alcohols by oxone catalyzed by bromide ions has been studied in acidic medium, to avoid formation of alkoxide. Since no prior protonation equilibrium is involved, the rate of the reaction is independent of pH. The reaction is initiated by the oxidation of bromide to bromine, which abstracts a hydride ion from the alcohol in a rate determining step to form R₁R₂COH⁺ cation. This cation loses a proton to give the corresponding carbonyl compound in a fast step. A mechanism for the bromide ion mediated oxidation is proposed and the rate law is derived based on the mechanism. Effect of relative permittivity, ionic strength and temperature is also studied; these effects also support the proposed mechanism.