Q.What happens when ethylene is passed through cold dilute alkaline Potassium Permanganate ?
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Start your 14-day free trial to unlock the full solution →The question asks what happens when ethylene (ethene) is treated with cold dilute alkaline KMnO4 (Baeyer's reagent).
Ethylene is oxidised (hydroxylated) to ethane-1,2-diol (ethylene glycol), and the purple colour of the KMnO4 is discharged — Baeyer's test for a C=C double bond.
Cold, dilute, alkaline potassium permanganate solution is known as Baeyer's reagent. It is a mild oxidising agent that carries out syn-hydroxylation of a carbon-carbon double bond, adding one -OH group to each of the two doubly-bonded carbons (a 1,2-diol is formed).
When ethylene is passed through it:
CH2=CH2 + H2O + [O] → HO-CH2-CH2-OH (ethane-1,2-diol / ethylene glycol)
The balanced equation is:
3 CH2=CH2 + 2 KMnO4 + 4 H2O → 3 HOCH2-CH2OH + 2 MnO2 + 2 KOH …
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