ABSTRACT
Diazonium salts are of particular importance in aromatic chemistry. They undergo reactions with nucleophiles and one-electron reductions. The reactions include replacement of the diazonium group by hydroxyl, halogens, cyanide, hydrogen, sulphur-containing species, aliphatic groups and aromatic groups. Aromatic diazonium salts are moderately stable in aqueous solution at low temperature when present with anions of low nucleophilic power and, in suitable cases, can be isolated as solids. Generally, aromatic diazonium salts are used in solution without the need to isolate or purify them. Amines that are substituted in the nucleus with electron-attracting groups are less easy to diazotize because the nucleophilicity of the amino-nitrogen is reduced. The diazonium cation is a poor electrophile and reacts only with particularly electron-rich aryl compounds such as phenoxide. The electrophilicity of a diazonium salt can be increased by the presence of electron-withdrawing substituents attached to the aromatic nucleus; the 2,4- dinitrobenzenediazonium ion is sufficiently electrophilic to react with anisole.
