Question

Why is Diazotization done at Low Temperature?

Answer 1

Hint: Diazonium salts of amines are often produced by the chemical process known as diazotization. In 1858, the first such reaction was reported by the German industrial scientist Peter Griess. He went on to uncover a multitude of other reactions using diazonium salts.

Complete Step by Step Solution:
In general, these diazonium salts are produced by reacting an aromatic amine with nitrous acid in the addition of another acid. The mechanism of the diazotization process starts with the action of nitrous acid with the other acid, which produces water and nitronium ions.

Consequently, the necessary nitrosonium ion is synthesised. This is now reacting with the aromatic ring linked to the NH₂ group. As a new nitrogen-nitrogen bond is created, the positive charge of the nitrosonium ion is transferred to the nitrogen that is immediately linked to the aromatic ring. Following deprotonation, n-nitrosamine is produced.

By protonation and deprotonation, n-nitrosamine can be transformed into diazohydroxide in the presence of sufficient acid. Now, diazo hydroxide is protonated and water is removed to produce the necessary aryl diazonium ion.

Since diazonium salts generate additional materials at high temperature and give phenol by combining at high temperature with water, keeping the temperature low throughout diazotization and pairing reactions is essential to avoiding a terrible miscalculation.
Therefore, it is necessary to maintain low temperature throughout the diazotization process.

Note: Because of their instability, aryldiazonium salts break down into hydrogen chloride, N₂ gas, and chlorobenzene when heated to high temperatures. However, the salts are never dried and are instead kept in a cool, dry environment.