Illustrated Glossary of Organic Chemistry

Nitrosonium cation: NO⁺. A reactive intermediate in the amine diazotization reaction mechanism.

Resonance contributors for the nitrosonium cation.


The nitrosonium cation is a reactive intermediate in the amine diazotization reaction mechanism. The reaction begins with protonation of nitrite ion (NO₂^-) to form nitrous acid (HONO). Nitrous acid is then protonated and water leaves to form the nitrosonium cation. The nitrosonium cation then reacts with a primary amine such as aniline (PhNH₂) to form the corresponding diazonium cation.