Answer: Hinsberg's reagent (benzenesulfonyl chloride).
- A Hinsberg's reagent (benzenesulfonyl chloride)
- B Lucas reagent, used instead to distinguish primary, secondary, and tertiary alcohols
- C Tollens' reagent, used instead to distinguish aldehydes from ketones
- D Fehling's solution, used instead to detect reducing sugars and aldehydes
Correct answer: A. Hinsberg's reagent (benzenesulfonyl chloride)
Explanation: Hinsberg's reagent (C<sub>6</sub>H<sub>5</sub>SO<sub>2</sub>Cl) reacts differently with primary, secondary, and tertiary amines.
In aniline, the nitrogen's lone pair is pulled into the benzene ring through resonance, leaving less electron density available to accept a proton - which is why aniline is a much weaker base than methylamine, where the lone pair is fully available.
Concept context
Nitrogen-containing organic compounds. Covers classification (primary, secondary, tertiary), basicity comparison, preparation methods, and reactions including diazotization and coupling, key for understanding dyes and pharmaceuticals.