Oxidative cleavage of alkene with KMnO4
Abstract
The oxidative cleavage of alkene using a concentrated solution of potassium permanganate at high temperature, leads to the formation of ketone or carboxylic acid depending on the nature of the initial alkene. During this reaction, a C-C bond is oxidatively cleaved, resulting in the formation of two separated carbonyl products.
Keywords
Alkene, Permanganate, Ketone, Carboxylic acid
Category
Alkene
Mechanism
In a strong acidic medium, permanganate can be partially protonated, generating more electrophilic species such as HMnO4. These species react with the alkene via a concerted syn cycloaddition, forming a cyclic manganate(V) ester, while the oxidation state of the manganese is reduced from +VII to +V. This cyclic intermediate is unstable under these harsh conditions and undergoes oxidative cleavage of the C-C bond. During this step, the σ bond between the two carbon breaks and carbonyl groups are formed. The nature of the final products depends on the substitution patterns of the alkene: A disubstituted alkene carbon gives a ketone. A monosubstituted alkene carbon initially forms an aldehyde, which is rapidly further oxidized to a carboxylic acid.
