Diazonium Salt Formation: Anilines → Ar–N₂⁺ (Key Intermediate for Aryl Substitution)

Learn how anilines form diazonium salts (0–5°C). Nitrous acid chemistry, N-nitrosation, diazotization, and why diazonium is such a versatile handle.

• Reaction: Ar–NH2 → Ar–N2+ (diazonium)
• What it does: Creates a leaving group for aryl substitution
• Typical reagents: NaNO2 + HCl (forms HNO2) at 0–5°C
• Key intermediate: Nitrosonium (NO+) and diazonium ion
• Driving force: Formation of N2 (excellent leaving group later)
• Exam type: Reagent selection
• Exam type: Synthesis planning