Salicylaldehyde
From Wikipedia, the free encyclopedia
| Salicylaldehyde | |
|---|---|
 |
|
| IUPAC name | 2-Hydroxybenzaldehyde |
| Other names | Salicylaldehyde Salicylic aldehyde |
| Identifiers | |
| CAS number | [90-02-8] |
| 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 |
| Boiling point |
196-197 °C |
| Related compounds | |
| Related compounds | Salicylic acid Benzaldehyde Salicylaldoxime |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
Salicylaldehyde, or 2-hydroxybenzaldehyde, is the chemical compound with the formula C6H4CHO-2-OH[1]. 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 [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 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).[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] Other hydroxybenzaldehydes
Three isomers exist of hydroxybenzaldehyde with the hydroxyl group in the ortho, meta, or para position.
| ortho-hydroxybenzaldehyde | meta-hydroxybenzaldehyde | para-hydroxybenzaldehyde | |
| Synonyms | salisylaldehyde | 3-hydroxybenzaldehyde | 4-hydroxybenzaldehyde |
| CAS number | [90-02-8] | [100-83-4] | [123-08-0] |
| Appearance | colorless oily liquid | light-tan crystals | yellow to tan powder |
| Density | 1.146 g/cm3 | 1.226 ± 0.06 g/cm3 | |
| Melting point | -7 °C | 100-103 °C | 112-116 °C |
| Boiling point | 196-197 °C | 191 °C 50 mm Hg | 310.00 - 311.00 °C |
| hydroxybenzaldehydes[6][7]. | |||
3-Hydroxybenzaldehyde has been prepared from m-nitrobenzaldehyde in a sequence of nitro group [[organic reduction, diazotisation of the amine and its hydrolysis[8][9]
[edit] References
- ^ Merck Index, 11th Edition, 8295.
- ^ 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
- ^ Dakin, H. D. (1941). "Catechol". Org. Synth.; Coll. Vol. 1: 149.
- ^ Horning, E. C.; Horning, M. G.; Dimmig, D. A. (1955). "3-Carbethoxycoumarin". Org. Synth.; Coll. Vol. 3: 165.
- ^ Burgstahler, A. W.; Worden, L. R. (1973). "Coumarone". Org. Synth.; Coll. Vol. 5: 251.
- ^ Sigma-Aldrich.com
- ^ 4-hydroxybenzaldehyde - 123-08-0
- ^ 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
