Oxidation of Alkenes with KMnO4

Alkenes are unsaturated hydrocarbons having Pi (π)-bond(s) between the carbon atoms, so they are easily oxidized by cold dilute alkaline solution of KMnO₄.

When an alkaline solution of KMnO₄ (Baeyer’s Reagent) is added to an alkene, the purple colour of KMnO₄ gets discharged. This reaction is used to test unsaturation in hydrocarbons.

On treatment with hot alkaline KMnO₄ the alkene gets oxidized to ketones or further to acids depending upon its structure. This happens due to the breaking of carbon-carbon double bond.