Answer: Diphenylamine < aniline < ammonia < cyclohexylamine.
- A Diphenylamine < aniline < ammonia < cyclohexylamine
- B Aniline < ammonia < diphenylamine < cyclohexylamine
- C Cyclohexylamine < ammonia < aniline < diphenylamine
- D All equal
Correct answer: A. Diphenylamine < aniline < ammonia < cyclohexylamine
Explanation: Aryl groups decrease basicity through conjugation. Cyclohexylamine (aliphatic) > NH<sub>3</sub> > aniline > diphenylamine.
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.