CHEMISTRY GUIDE

This page looks at the reaction of the carbon-carbon double bond in alkenes such as ethene with potassium manganate(VII) solution (potassium permanganate solution). Oxidation of alkenes with cold dilute potassium manganate(VII) solution Experimental details Alkenes react with potassium manganate(VII) solution in the cold. The colour change depends on whether the potassium manganate(VII) is used under acidic or alkaline conditions. If the potassium manganate(VII) solution is acidified with dilute sulphuric acid, the purple solution becomes colourless. If the potassium manganate(VII) solution is made slightly alkaline (often by adding sodium carbonate solution), the purple solution first becomes dark green and then produces a dark brown precipitate. Chemistry of the reaction We'll look at the reaction with ethene. Other alkenes react in just the same way. Manganate(VII) ions are a strong oxidising agent, and in the first i...