Salicylaldehyde azine is used in the preparation of 2-oxo-2H-1-benzopyran-3-carboxylic acid 2-(2-oxo-2H-1-benzopyran-3-carbonyl)hydrazide by reacting with propadienedione . It has anthelmintic activity.
Salicylic acid can be synthesized from salicylaldehyde using KMnO4 without oxidising the hydroxy group (−OH). The hydroxy group that attached to the benzene isn't oxidized, because the C atom that bonded with the hydroxy has already use 2 electrons for sigma bonding and 1 electron for pi bonding.
Salicylaldehyde is converted to chelating ligands by condensation with amines. With ethylenediamine, it condenses to give the ligand salen. Hydroxylamine gives salicylaldoxime. Condensation with diethyl malonate gives 3-carbethoxycoumarin (a derivative of coumarin) by an aldol condensation.
