Kinetics and Mechanism of the Oxidation of Unsaturated Carboxylic Acids by Methyltributylammonium Permanganate in Methylene Chloride Solutions

Article abstract of DOI:10.1021/jo00391a011

The product obtained when permanganate is reduced by unsaturated carboxylic acids under anhydrous conditions is manganese(III).The rate of reaction, which is subject to acid catalysis, exhibits a Hammet ρ value of 1.11 and inverse secondary isotope effects (k_H/k_D = 0.96-0.98) when the hydrogens on the double bond are replaced by deuterium.The involvement of a free-radical process is indicated by the formation of polymer during the oxidation of acrylic and methacrylic acids.The reaction is believed to be initiated by formation of an organometallic complex in which the double bond is a η² ligand on manganese.Rearrangement of this complex results in the formation of a reactive manganate(V) cyclic diester, which undergoes a rapid (free-radical) reduction to manganese(III).