Salicylaldehyde

Chembox new
Name = Salicylaldehyde
ImageFile = Salicylaldehyde.png ImageName =
IUPACName = 2-Hydroxybenzaldehyde
OtherNames = Salicylaldehyde
Salicylic aldehyde
Section1 = Chembox Identifiers
CASNo = 90-02-8
SMILES = OC1=C(C=O)C=CC=C1
Section2 = Chembox Properties
Formula = C₇H₆O₂
MolarMass = 122.12 g/mol
Density = 1.146 g/cm³
MeltingPt = -7 °C
BoilingPt = 196-197 °C
Section8 = Chembox Related
OtherCpds = Salicylic acid
Benzaldehyde
Salicylaldoxime

Salicylaldehyde, or 2-hydroxybenzaldehyde, is the chemical compound with the formula C₆H₄CHO-2-OH ["Merck Index", 11th Edition, 8295.] . This colourless 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 [Janes D, Kreft S: Salicylaldehyde is a characteristic aroma component of buckwheat groats, Food Chemistry 2008; 109: 293-298, doi:10.1016/j.foodchem.2007.12.032] . 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, 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). [OrgSynth | author = Dakin, H. D. | title = Catechol | collvol = 1 | collvolpages = 149 | year = 1941 | prep = CV1P0149]
*Condensation with diethyl malonate gives a derivative of the heterocycle coumarin. [OrgSynth | author =Horning, E. C.; Horning, M. G.; Dimmig, D. A. | title = 3-Carbethoxycoumarin | collvol = 3 | collvolpages = 165 | year = 1955 | prep = cv3p0165]
*Etherification with chloroacetic acid followed by cyclisation gives the heterocycle benzofuran. [OrgSynth | author = Burgstahler, A. W.; Worden, L. R. | title = Coumarone | collvol = 5 | collvolpages = 251 | year = 1973 | prep = cv5p0251]

Other hydroxybenzaldehydes

Three isomers exist of hydroxybenzaldehyde with the hydroxyl group in the ortho, meta, or para position.

3-Hydroxybenzaldehyde has been prepared from m-nitrobenzaldehyde in a sequence of nitro group [organic reduction, diazotisation of the amine and its hydrolysis [Organic Syntheses, Coll. Vol. 3, p.453 (1955); Vol. 25, p.55 (1945). http://www.orgsynth.com/orgsyn/orgsyn/prepContent.asp?prep=cv3p0453] [Organic Syntheses, Coll. Vol. 3, p.564 (1955); Vol. 29, p.63 (1949). http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv3p0564]

References