The unsaturated ether on acidic hydrolysis produces carbonyl compounds as shown below :-
CH₃-CH=CH-O-CH=CH₂; ↓ H₃O⁽⁺⁾; CH₃-CH₂-CH=O and O=CH-CH₃
Based on this, predict the solution/reagent that will help to distinguish "P" and "Q" obtained in the following reaction :-
CH₃-CH=CH-O-C(|(CH₃))=CH₂ →(H₃O⁽⁺⁾) P + Q

Solution

Chemistry ma’am · 3 steps

Each C=C–O end of the ether turns into its own carbonyl; then ask which one is an aldehyde.

1. Read the pattern. In acid, each vinyl group on the oxygen becomes an enol that tautomerises to a carbonyl. The carbon bonded to O becomes the C=O carbon, and the other alkene carbon picks up an H.

   CH₃-CH=CH-O-C(CH₃)=CH₂ →(H₃O⁺, Δ) CH₃CH₂CHO + CH₃COCH₃

2. Identify P and Q. The left half gives CH₃CH₂CHO (propanal), an aldehyde. The right half, CH₂=C(CH₃)-O⁻, gives CH₃COCH₃ (acetone), a ketone.

   Reagent	Propanal	Acetone	Distinguishes?
   Saturated NaHSO₃	adduct forms	adduct forms (methyl ketone)	No
   Fehling solution	red Cu₂O precipitate	no reaction	Yes
   Lucas reagent	no reaction (not an alcohol)	no reaction (not an alcohol)	No
   2,4-DNP	orange precipitate	orange precipitate	No

3. So. Only Fehling solution tells them apart: propanal reduces it to a red precipitate of Cu₂O, while acetone does not. The answer is (b).

The idea to keep. To separate an aldehyde from a ketone, use an oxidation test like Fehling or Tollens. Tests that need only a C=O group, such as 2,4-DNP or bisulphite, react with both.

Answer from the NTA final answer key. Solution by PrepWiser.