The unsaturated ether on acidic hydrolysis produces carbonyl compounds as shown below:- $\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}=\mathrm{O}$ and $\mathrm{O}=\mathrm{CH}-\mathrm{CH}_{3}$ Based on this, predict the solution / reagent that will help to distinguish "P" and "Q" obtained in the following reaction.

(C) Saturated $\mathrm{NaHSO}_{3}$ solution

JEE Main · 2026 · 24 Jan 2026 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

The unsaturated ether on acidic hydrolysis produces carbonyl compounds as shown below:-

CH_{3} - CH_{2} - CH = O

and

O = CH - CH_{3}

Based on this, predict the solution / reagent that will help to distinguish "P" and "Q" obtained in the following reaction.

Answer: (D)

Acidic hydrolysis cleaves the unsaturated ether at oxygen, and each resulting enol tautomerises to a carbonyl compound. The propenyl side

C H_{3} C H = C H - O -

gives the enol

C H_{3} C H = C H O H

, which rearranges to propanal

C H_{3} C H_{2} C H O

(P); the isopropenyl side

- O - C (C H_{3}) = C H_{2}

gives

C H_{2} = C (C H_{3}) O H

, which rearranges to acetone

C H_{3} C O C H_{3}

(Q). To tell an aldehyde from a ketone, Fehling's solution is used: the aldehyde P reduces it to a brick-red precipitate of

C u_{2} O

while the ketone Q gives no reaction. Fehling's solution distinguishes P and Q.

JEE Main · 2026 · 24 Jan 2026 · Shift 2 · Single correct option