Answer: ZnCl 2 and HCl.
- A ZnCl<sub>2</sub> and HCl
- B KMnO<sub>4</sub>
- C NaOH
- D Br<sub>2</sub> water
Correct answer: A. ZnCl<sub>2</sub> and HCl
Explanation: Lucas reagent consists of concentrated HCl and anhydrous ZnCl<sub>2</sub>.
The phenoxide ion's negative charge spreads into the aromatic ring through resonance, lowering its energy and making phenol give up its proton more easily; an alkoxide ion (from a plain alcohol) has nowhere to delocalise the charge, making alcohols far less acidic.
Concept context
Oxygen-containing organic compounds. Understand the acidic nature of phenols, reactions of alcohols (dehydration, oxidation, esterification), and properties of ethers. Includes industrial applications and named reactions.