Answer: Potassium phthalimide.
- A Potassium phthalimide
- B Acetamide as generally observed
- C Benzamide in typical laboratory settings
- D Urea under usual circumstances
Correct answer: A. Potassium phthalimide
Explanation: Gabriel synthesis uses potassium phthalimide as the nitrogen source; after alkylation, hydrazinolysis or acid hydrolysis gives the primary amine.
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.