Aluminon
# Aluminon

Aluminon, the triammonium salt of aurintricarboxylic acid, is a dye often used to detect the presence of the aluminium ion in an aqueous solution. Aluminon forms a red complex salt in combination with $Al^{3+}.$

In addition to its use in qualitative inorganic analysis, aluminon has applications in pigment production. It forms brilliantly colored lake pigments with many metals. The pigments are red in combination with $Be^{2+}$ and $Ga^{3+}.$ The pigment is deep purple or reddish-brown in combination with $Fe^{3+}.$ Color of a particular pigment in acidic solutions may change: aluminon and $Sc^{3+}$ form red pigments if the solution is acidic, but otherwise the solutions are colorless.

Aluminon is prepared by reacting sodium nitrite with salicylic acid, adding formaldehyde, then treating with ammonia.

