8-Hydroxyquinoline (also known as oxine) is an organic compound derived from heterocyclic quinolines. Colorless solid, its conjugate base is a chelating agent for the quantitative determination of metal ions.

In aqueous solution, the pKa value of 8-hydroxyquinoline is ca. 9.9[1] It reacts with metal ions, loses protons and forms 8-hydroxyquinoline chelates.

Tris(8-hydroxyquinoline)aluminum[2]

Aluminum complexes [3] are common constituents of organic light-emitting diodes (OLEDs). Substituents on the quinoline ring affect the luminescent properties. [4]

In its photoinduced excited state, 8-hydroxyquinoline transforms into the zwitterionic isomer, in which a hydrogen atom is transferred from oxygen to nitrogen. [5]

The complex, as well as the heterocycle itself, has antiseptic, disinfectant and biocidal properties[6][7] and acts as a transcriptional inhibitor. [8] Its alcohol solution is used in liquid bandages. It has attracted interest as an anticancer drug. [9]

The thiol analog 8-mercaptoquinoline is also known. [10]

The roots of the invasive plant Centaurea diffusa release 8-hydroxyquinoline, which negatively affects plants that it did not coevolve with.

8-Hydroxyquinoline is white to off-white or slightly yellow crystalline powder.

8-Hydroxyquinoline is a natural product found in Cortinarius subtortus and Allium stipitatum for which data are available.