Salicylaldehyde
IUPAC name	2-Hydroxybenzaldehyde
Other names	Salicylic aldehyde; 2-Hydroxybenzaldehyde; o-Hydroxybenzaldehyde
Identifiers
CAS number	90-02-8 Y
SMILES	OC1=C(C=O)C=CC=C1
Properties
Molecular formula	C7H6O2
Molar mass	122.12 g/mol
Density	1.146 g/cm3
Melting point	-7 °C, 266 K, 19 °F
Boiling point	196-197 °C
Related compounds
Related compounds	Salicylic acid Benzaldehyde Salicylaldoxime
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Salicylaldehyde (2-hydroxybenzaldehyde) is the chemical compound with the formula C₆H₄CHO-2-OH.^[1] Along with 3-hydroxybenzaldehyde and 4-hydroxybenzaldehyde, it is one of the three isomers of hydroxybenzaldehyde. This colorless oily liquid has a bitter almond odor at higher concentration and a characteristic buckwheat aroma at lower concentration. Salycylaldehyde was identified as a characteristic aroma component of buckwheat.^[2] 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 or potassium 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, from the left: catechol, benzofuran, a salicylaldehydimine (R = alkyl or aryl), 3-carbethoxycoumarin.

[edit] Reactions

Salicylaldehyde undergoes a variety of chemical reactions including:

• Salicylaldehyde is converted to chelating ligands via condensation with amines. With ethylenediamine, it condenses to give the diprotic ligand H₂salen. Hydroxylamine gives salicylaldoxime.
• Oxidation with hydrogen peroxide gives catechol (1,2-dihydroxybenzene).^[3]
• Condensation with diethyl malonate gives a derivative of the heterocycle coumarin.^[4]
• Etherification with chloroacetic acid followed by cyclisation gives the heterocycle benzofuran.^[5]

[edit] References