Salicylaldehyde

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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
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.

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).^[1]
condensation with diethyl malonate gives a derivative of the heterocycle coumarin.^[2]
etherification with chloroacetic acid followed by cyclisation gives the heterocycle benzofuran.^[3]

[edit] References

^ Dakin, H. D. "Catechol" Organic Syntheses, Collected Volume 1, p.149 (1941).http://www.orgsyn.org/orgsyn/pdfs/CV1P0149.pdf
^ Horning, E. C.; Horning, M. G.; Dimmig, D. A. "3-Carbethoxycoumarin" Organic Syntheses, Collected Volume 3, p.165 (1955).http://www.orgsyn.org/orgsyn/pdfs/CV3P0165.pdf
^ Burgstahler, A. W.; Worden, L. R. "Coumarone" Organic Syntheses, Collected Volume 5, p.251 (1973).http://www.orgsyn.org/orgsyn/pdfs/CV5P0251.pdf