Diazonium salts: Diazonium salts have the general formula

(R/Ar—N₂⁺Cl^-) where R stands for the alkyl group and Ar stands for the aryl group. The structure is given below:

Formation of Diazonium salts:

Diazonium salt is obtained by treating aromatic amine(aniline) dissolved in dil. HCl with HNO₂ at 273-278K (0° -5° C)

Diazonium salts of aromatic amines are more stable than those of aliphatic amines.

Explanation:

Aromatic amine form arenediazonium salts, which are stable for a short time in solution at low temperature(273-278K).The diazonium salts of aromatic amines are more stable due to the dispersal of the positive charge on the benzene ring (resonance) as shown below:

The aliphatic amines, on the other hand, form highly unstable alkane diazonium salt (R—N₂⁺Cl^-). They rapidly decompose even at low temperature(<272-278K) forming carbocation and nitrogen gas.

Hence, diazonium salts of aromatic amine are much more stable than aliphatic diazonium salts.

Note: Carbocation is an ion in which carbon atom consists of positive charge