An alcohol is heated with aqueous KOH under reflux. What is the product?

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Multiple Choice

An alcohol is heated with aqueous KOH under reflux. What is the product?

The key idea is dehydration of an alcohol to form an alkene when heated with a base. Under reflux with a strong base like KOH, the hydroxyl group can be set up to leave as water, and a β-hydrogen is removed by the base to form the carbon–carbon double bond. This elimination step converts the alcohol into the corresponding alkene. The exact alkene produced depends on the structure of the starting alcohol (the more substituted alkene is usually favored, per Zaitsev’s rule). There isn’t a halogen source present to form a haloalkane, and there isn’t an oxidizing condition to produce a carboxylic acid, so those products aren’t expected under these conditions. The main outcome is the alkene.

The key idea is dehydration of an alcohol to form an alkene when heated with a base. Under reflux with a strong base like KOH, the hydroxyl group can be set up to leave as water, and a β-hydrogen is removed by the base to form the carbon–carbon double bond. This elimination step converts the alcohol into the corresponding alkene. The exact alkene produced depends on the structure of the starting alcohol (the more substituted alkene is usually favored, per Zaitsev’s rule).

There isn’t a halogen source present to form a haloalkane, and there isn’t an oxidizing condition to produce a carboxylic acid, so those products aren’t expected under these conditions. The main outcome is the alkene.

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