Answer: Catalyst and dehydrating agent.
- A Reducing agent that converts the acid to an aldehyde
- B Oxidising agent that activates the carbonyl oxygen
- C Catalyst and dehydrating agent
- D Base that deprotonates the carboxylic acid
Correct answer: C. Catalyst and dehydrating agent
Explanation: Sulfuric acid catalyses esterification and removes water formed, shifting equilibrium forward.
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.