An aqueous solution of potassium Permanganate is known as Baeyer’s reagent.
Alkenes on reaction with cold, dilute, an aqueous potassium permanganate solution (Baeyer’s reagent) produce vicinal glycols. Decolorisation of KMnO4 solution is used as a test for unsaturation.
The Baeyer test for unsaturation is for determining the presence of carbon-carbon double-bonded compounds, called alkenes or carbon-carbon triple bonded compounds, called alkyne bonds. The Baeyer test uses dilute Pottasium Permanganate to Oxidize the carbon-carbon double or triple bond. It’s called oxidation because the double bond is replaced by a hydroxy group (an OH group). An alkene is replaced with a diol because the purple Potassium permanganate goes colourless.
- The reaction is important because it doesn’t work on alkanes (compounds with carbon-carbon single bonds) or aromatic compounds.