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1-Ethoxycyclohex-1-ene (a cyclic enol ether) is treated with aqueous acid (H3O+). What are the products?

1. Ethanol and cyclohexanol
2. Cyclohexanone and acetaldehyde
3. Acetic acid and cyclohexanone
4. Ethanol and cyclohexanone

Correct answer: Ethanol and cyclohexanone

Solution

1-Ethoxycyclohex-1-ene is the vinyl (enol) ether formed between cyclohexanone and ethanol. Under acidic aqueous conditions (H3O+), enol ethers undergo rapid hydrolysis: the double bond is protonated to form an oxocarbenium ion, which is then attacked by water, ultimately giving the ketone and the alcohol. Products: cyclohexanone + ethanol (EtOH).

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