Hydroxyquinoline

Hydroxyquinoline

Template:Chembox ChEMBL
8-Hydroxyquinoline[1]
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Identifiers
CAS number 148-24-3 YesY
PubChem 1923
ChemSpider 1847 YesY
UNII 5UTX5635HP YesY
KEGG D05321 YesY
ChEBI CHEBI:48981 YesY
ATC code AA14
Jmol-3D images Image 2
Properties
Molecular formula C9H7NO
Molar mass 145.16 g/mol
Appearance White crystalline needles
Density 1.034 g/cm3
Melting point

76 °C, 349 K, 169 °F

Boiling point

276 °C, 549 K, 529 °F

Hazards
MSDS External MSDS
Main hazards flammable
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

8-Hydroxyquinoline is an organic compound with the formula C9H7NO. It is a derivative of the heterocycle quinoline by placement of an OH group on carbon number 8. This light yellow compound is widely used commercially, although under a variety of names.[2][3]

Synthesis

It is usually prepared from quinoline-8-sulfonic acid and from a Skraup synthesis from 2-aminophenol.[4]

As a chelating agent

8-Hydroxyquinoline is a monoprotic bidentate chelating agent. Related ligands are the Schiff bases derived from salicylaldehyde, such as salicylaldoxime, salen and salicylaldehyde isonicotinoylhydrazone (SIH). In neutral solution, the hydroxyl is in the protonated form (pKa=9.89) and the nitrogen is not protonated (pKa=5.13).[5] However, an excited-state zwitterionic isomer exists in which H+ is transferred from the oxygen (giving an oxygen anion) to the nitrogen (giving a protonated nitrogen cation).[6]

Applications

The complexes as well as the heterocycle itself exhibit antiseptic, disinfectant, and pesticide properties,[7][8] functioning as a transcription inhibitor.[9] Its solution in alcohol is used in liquid bandages. It once was of interest as an anti-cancer drug.[10]

The reaction of 8-hydroxyquinoline with aluminium(III)[11] results in Alq3, a common component of organic light-emitting diodes (OLED's). Variations in the substituents on the quinoline rings affect its luminescence properties.[12]

The roots of the invasive plant Centaurea diffusa release 8-hydroxyquinoline, which has a negative effect on plants that have not co-evolved with it.

Hydroxyquinoline was used as a stabilizer of hydrogen peroxide in a rocket fuel oxidizer (T-Stoff) for the German Messerschmitt Me 163 Komet in World War 2.

References