PrayogX › Chemistry › Amines and Diazonium Salts

Diazonium chemistry and azo coupling: identifying P, Q, S and T

Walk aniline through acetylation, nitration, hydrolysis and diazotisation, take cumene to salicylic acid by the cumene process and Kolbe-Schmitt, then couple the two and watch the absorption move into the visible.

Sub-topics covered

• Acetylation as a protecting group for aniline
• Nitration of acetanilide and para selectivity
• Diazotisation at 273-278 K
• Reduction of diazonium salts by ethanol
• Cumene process for phenol
• Kolbe-Schmitt reaction
• Phthalein dye test and the free para position
• Azo dyes, conjugation and colour

What it teaches

• A protonated amine is deactivating and meta-directing, which is why aniline is acetylated first
• The acetyl group moderates activation enough to stop nitration at one substitution
• A diazonium salt couples only with a strongly activated ring
• Ethanol reduces a diazonium salt and is itself oxidised to an aliphatic aldehyde
• The phthalein test needs a free position para to the phenolic OH
• Extended push-pull conjugation moves absorption out of the UV into the visible

Simulation ID

• ADV-2026-P2-CHE-Q08 · revision 1

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