8-Hydroxyquinoline

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8-Hydroxyquinoline (also known as oxine) is an organic compound derived from the heterocycle quinoline. A colorless solid, its conjugate base is a chelating agent, which is used for the quantitative determination of metal ions.

8-Hydroxyquinoline
Skeletal formula of 8-hydroxyquinoline
Ball-and-stick model of the 8-hydroxyquinoline molecule
8-hydroxyquinoline
Names
Preferred IUPAC name
Quinolin-8-ol
Other names
1-Azanaphthalene-8-ol, Fennosan H 30, Hydroxybenzopyridine, Oxybenzopyridine, Oxychinolin, Oxyquinoline, Phenopyridine, Quinophenol, Oxine, 8-Quinolinol
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard100.005.193 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C9H7NO/c11-8-5-1-3-7-4-2-6-10-9(7)8/h1-6,11H checkY
    Key: MCJGNVYPOGVAJF-UHFFFAOYSA-N checkY
  • InChI=1/C9H7NO/c11-8-5-1-3-7-4-2-6-10-9(7)8/h1-6,11H
    Key: MCJGNVYPOGVAJF-UHFFFAOYAG
  • C1=CC2=C(C(=C1)O)N=CC=C2
Properties
C9H7NO
Molar mass145.16 g/mol
AppearanceWhite crystalline powder
Density1.034 g/cm3
Melting point76 °C (169 °F; 349 K)
Boiling point276 °C (529 °F; 549 K)
Pharmacology
G01AC30 (WHO) A01AB07 (WHO) D08AH03 (WHO) R02AA14 (WHO)
Hazards
GHS labelling:
GHS06: ToxicGHS08: Health hazardGHS05: CorrosiveGHS09: Environmental hazard
Danger
H301, H317, H318, H360D, H410
P202, P273, P280, P301+P310, P302+P352, P305+P351+P338
Safety data sheet (SDS)External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

In aqueous solution 8-hydroxyquinoline has a pKa value of ca. 9.9[1] It reacts with metal ions, losing the proton and forming 8-hydroxyquinolinato-chelate complexes.

Tris(8-hydroxyquinolinato)aluminium[2]

The aluminium complex,[3] is a common component of organic light-emitting diodes (OLEDs). Substituents on the quinoline ring affect the luminescence properties.[4]

In its photo-induced excited-state, 8-hydroxyquinoline converts to zwitterionic isomers, in which the hydrogen atom is transferred from oxygen to nitrogen.[5]

Bioactivity

The complexes as well as the heterocycle itself exhibit antiseptic, disinfectant, and pesticide properties,[6][7] functioning as a transcription inhibitor.[8] Its solution in alcohol is used in liquid bandages. It once was of interest as an anti-cancer drug.[9]

A thiol analogue, 8-mercaptoquinoline is also known.[10]

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.[11]

See also

References