The
diazonium salts have the general formula RN⁺₂X⁻
where R stands for an aryl group and X- ion may be Cl⁻, Br⁻, HSO⁻₄, BF⁻₄ etc.
Primary
aliphatic amines form highly unstable alkyldiazonium salts.
Primary
aromatic amines form arenediazonium salts which are stable for a short time in
solution at low temperatures (273 - 278 K).
Preparation: Benzenediazonium
chloride is prepared by the reaction of aniline with nitrous acid at 273-278K.
Nitrous
acid is produced in the reaction mixture by the reaction of sodium nitrite with
hydrochloric acid. The conversion of primary aromatic amines into diazonium
salts is known as diazotisation.
Due
to its instability, the diazonium salt is not generally stored and is used
immediately after its preparation.
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