Answer: They further reduce electron density on nitrogen via induction and resonance.
- A They further reduce electron density on nitrogen via induction and resonance
- B They increase steric strain around the nitrogen lone pair as frequently described
- C They react directly with the nitrogen to form a covalent adduct in most textbook accounts
- D They oxidise the nitrogen lone pair to a nitroso state during normal conditions
Correct answer: A. They further reduce electron density on nitrogen via induction and resonance
Explanation: EWGs like -NO<sub>2</sub>, -Cl withdraw electron density from the ring and from nitrogen, reducing its ability to donate lone pair.
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.