Here are the essential concepts you must grasp in order to answer the question correctly.
Protonation of Aniline
Protonation of aniline involves the addition of a proton (H+) to the nitrogen atom of the aniline molecule, forming an anilinium ion. This process significantly reduces the electron density on the benzene ring because the lone pair on nitrogen, which would otherwise donate electrons to the ring, is now involved in bonding with the proton. This electron withdrawal makes the ring less reactive towards electrophilic aromatic substitution.
Recommended video:
Protection of Aniline Derivatives
Electrophilic Aromatic Substitution (EAS)
Electrophilic aromatic substitution is a reaction where an electrophile replaces a hydrogen atom on an aromatic ring. The reactivity and position of substitution depend on the substituents already present on the ring. Electron-donating groups activate the ring and direct substitution to ortho and para positions, while electron-withdrawing groups deactivate the ring and direct substitution to the meta position.
Recommended video:
Meta-Directing Effect
The meta-directing effect occurs when a substituent on an aromatic ring withdraws electron density, making the ortho and para positions less favorable for electrophilic attack. In the case of protonated aniline, the positive charge on the nitrogen withdraws electrons from the ring, stabilizing the meta position for substitution. This effect is due to the reduced electron density at the ortho and para positions, making them less reactive towards electrophiles.
Recommended video:
Directing Effects in Substituted Pyrroles, Furans, and Thiophenes Concept 1
05:15
