Key Idea

Unsaturated ethers (enol ethers) on acidic hydrolysis give carbonyl compounds (aldehydes/ketones).

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Why does this happen?

Unsaturated ethers are basically enol forms of carbonyl compounds.

General structure:$$R – CH = CH – OR’$$

Under acidic conditions:

1. Protonation of ether oxygen
2. Formation of unstable enol
3. Tautomerism (enol → carbonyl)

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🔹 Important Reaction

Example:$$CH_2 = CH – OCH_3 \xrightarrow{H^+, H_2O} CH_3CHO + CH_3OH$$

Product:

• Aldehyde/Ketone (carbonyl compound)
• Alcohol

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🔹 Mechanism Shortcut (Exam Trick ⚡)

• Break C–O bond
• Form enol
• Enol → carbonyl (keto form)

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One-line Concept (for revision)

Unsaturated ether + acidic hydrolysis → enol → carbonyl compound

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Important for Exams

• Only vinyl / allyl ethers show this behavior
• Due to keto-enol tautomerism
• Very common in mechanism-based questions