Question:

But-2-ene on reaction with alkaline \(\mathrm{KMnO_4}\) at elevated temperature followed by acidification will give :

Show Hint

Hot alkaline \(\mathrm{KMnO_4}\) cleaves the C=C bond oxidatively; each \(\mathrm{CH_3CH=}\) fragment becomes \(\mathrm{CH_3COOH}\) after acidification.
Updated On: Nov 5, 2026
  • one molecule of \(\mathrm{CH_3CHO}\) and one molecule of \(\mathrm{CH_3COOH}\)
  • 2 molecules of \(\mathrm{CH_3COOH}\)
  • 2 molecules of \(\mathrm{CH_3CHO}\)
Show Solution
collegedunia
Verified By Collegedunia

The Correct Option is B

Solution and Explanation

But-2-ene is \(\mathrm{CH_3{-}CH=CH{-}CH_3}\), symmetrical.
Cold dilute alkaline \(\mathrm{KMnO_4}\) would only hydroxylate it to butane-2,3-diol (option 3), but at elevated temperature the strong oxidant cleaves the double bond.
Each \(\mathrm{CH_3CH=}\) carbon is oxidised to the carboxylate \(\mathrm{CH_3COO^-}\) (an aldehyde intermediate is oxidised further under these conditions); acidification gives \(\mathrm{CH_3COOH}\).
So one mole of but-2-ene gives 2 molecules of acetic acid.
Answer: (2) 2 molecules of \(\mathrm{CH_3COOH}\)
Was this answer helpful?
0
0