Oxidative Cleavage using Acidic $$\text{KMnO}_4$$

$$\text{R--CH=CH}_2 \xrightarrow{\text{KMnO}_4 / \text{H}^+, \Delta} \text{R--COOH} + \text{CO}_2 + \text{H}_2\text{O}$$

$$\text{R}_2\text{C=CH--R'} \xrightarrow{\text{KMnO}_4 / \text{H}^+, \Delta} \text{R}_2\text{C=O} + \text{R'--COOH}$$

Concept: Vigorous oxidation of alkenes using hot acidic potassium permanganate breaks both the $$\sigma$$ and $$\pi$$ bonds of the double bond, cleaving the molecule into smaller oxidized fragments depending on the substitution pattern of the alkene carbons.

Cleavage Rules for Carbon Atoms:

• Terminal Carbon ($$=\text{CH}_2$$): Fully oxidized to carbonic acid, which decomposes to carbon dioxide and water ($$\text{CO}_2 + \text{H}_2\text{O}$$).
• Monosubstituted Carbon ( $$=\text{CH--R}$$ ): Oxidized to a carboxylic cid ($$\text{R--COOH}$$).
• Disubstituted Carbon ($$=\text{CR}_2$$): Oxidized to a ketone ($$\text{R}_2\text{C=O}$$).