Salicylaldehyde

Template:Chembox header| Salicylaldehyde
Salicylaldehyde
Chemical name	2-Hydroxybenzaldehyde
Other names	Salicylaldehyde Salicylic aldehyde
Chemical formula	C7H6O2
Molecular mass	122.12 g/mol
CAS number	[90-02-8]
Density	1.146 g/cm3
Melting point	-7 °C
Boiling point	196-197 °C
SMILES	OC1=C(C=O)C=CC=C1
Related compounds	Salicylic acid Benzaldehyde Salicylaldoxime
Template:Chembox header | Disclaimer and references

Salicylaldehyde, or 2-hydroxybenzaldehyde, is the chemical compound with the formula C₆H₄CHO-2-OH. This colourless oily liquid has a bitter almond odor. Salicylaldehyde is a key precursor to a variety chelating agents, some of which are commercially important. It can be prepared from phenol and chloroform by heating with sodium hydroxide in a Reimer-Tiemann reaction.

Salicylaldehyde is a common highly functionalized arene that has often been exploited as a precursor to still other chemicals, which are shown in the figure.

File:SalicylaldDerivs.png

Figure. Illustrative compounds derived from salicylaldehyde. From the left: catechol, benzofuran, a salicylaldehydimine (R = alkyl or aryl), 3-carbethoxycoumarin.

• Salicylaldehyde is converted to chelating ligands via condensation with amines. With ethylenediamine, it condenses to give the popular diprotic ligand H₂salen. Hydroxylamine gives salicylaldoxime.
• oxidation with hydrogen peroxide gives catechol (1,2-dihydroxybenzene).
• condensation with diethyl malonate gives a derivative of the heterocycle coumarin.
• etherification with chloroacetic acid followed by cyclisation gives the heterocycle benzofuran.

General reading

• Merck Index, 11th Edition, 8295.