Salicylaldehyde

Salicylaldehyde

Skeletal formula Ball-and-stick model
Names
IUPAC name 2-Hydroxybenzaldehyde
Other names Salicylic aldehyde; 2-Hydroxybenzaldehyde; o-Hydroxybenzaldehyde
Identifiers
CAS Number	90-02-8 Y
ChEBI	CHEBI:16008 Y
ChEMBL	ChEMBL108925 Y
ChemSpider	13863618 Y
Jmol 3D model	Interactive image
UNII	17K64GZH20 Y
InChI InChI=1S/C7H6O2/c8-5-6-3-1-2-4-7(6)9/h1-5,9H Y Key: SMQUZDBALVYZAC-UHFFFAOYSA-N Y InChI=1/C7H6O2/c8-5-6-3-1-2-4-7(6)9/h1-5,9H Key: SMQUZDBALVYZAC-UHFFFAOYAD
SMILES O=Cc1ccccc1O
Properties
Chemical formula	C7H6O2
Molar mass	122.12 g/mol
Density	1.146 g/cm3
Melting point	−7 °C (19 °F; 266 K)
Boiling point	196 to 197 °C (385 to 387 °F; 469 to 470 K)
Related compounds
Related compounds	Salicylic acid Benzaldehyde Salicylaldoxime
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

Salicylaldehyde (2-hydroxybenzaldehyde) is the organic compound with the formula C₆H₄CHO-2-OH. 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. Salicylaldehyde is a key precursor to a variety chelating agents, some of which are commercially important.

Production

Salicylaldehyde is prepared from phenol and chloroform by heating with sodium hydroxide or potassium hydroxide in a Reimer–Tiemann reaction:

Alternative, it is produced by condensation of phenol or its derivatives with formaldehyde to give hydroxybenzyl alcohol, which is oxidized to the aldehyde.

Salicylaldehydes in general may be prepared from the corresponding phenol by the Duff reaction, or by treatment with paraformaldehyde in the presence of magnesium chloride and a base.

Natural occurrences

Salicylaldehyde was identified as a characteristic aroma component of buckwheat.

It is also one of the components of castoreum, the exudate from the castor sacs of the mature North American beaver (Castor canadensis) and the European beaver (Castor fiber), used in perfumery.

Reactions and applications

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.

Figure. Illustrative compounds derived from salicylaldehyde.

Salicylaldehyde is converted to chelating ligands by condensation with amines. With ethylenediamine, it condenses to give the ligand salen. Hydroxylamine gives salicylaldoxime. Oxidation with hydrogen peroxide gives catechol (1,2-dihydroxybenzene) (Dakin reaction). Condensation with diethyl malonate gives a derivative of the heterocycle coumarin via an aldol condensation. Etherification with chloroacetic acid followed by cyclisation gives the heterocycle benzofuran. The first step in this reaction to the substituted benzofuran is called the Rap–Stoermer condensation after E. Rap (1895) and R. Stoermer (1900).