8-Hydroxyquinoline

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title: "8-Hydroxyquinoline" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["antiseptics", "quinolinols"] topic_path: "general/antiseptics" source: "https://en.wikipedia.org/wiki/8-Hydroxyquinoline" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| Reference = | ImageFile_Ref = | ImageFile = 8-Hydroxychinolin.svg | ImageSize = 150px | ImageAlt = Skeletal formula of 8-hydroxyquinoline | ImageFile1 = 8-Hydroxyquinoline 3D ball.png | ImageSize1 = 160px | ImageAlt1 = Ball-and-stick model of the 8-hydroxyquinoline molecule | ImageFile2 = 8-Hydroxychinolin.jpg | ImageSize2 = 150px | ImageAlt2 = 8-hydroxyquinoline | PIN = Quinolin-8-ol | OtherNames = 1-Azanaphthalene-8-ol, Fennosan H 30, Hydroxybenzopyridine, Oxybenzopyridine, Oxychinolin, Oxyquinoline, Phenopyridine, Quinophenol, Oxine, 8-Quinolinol |Section1={{Chembox Identifiers | KEGG_Ref = | KEGG = D05321 | InChI = 1/C9H7NO/c11-8-5-1-3-7-4-2-6-10-9(7)8/h1-6,11H | InChIKey = MCJGNVYPOGVAJF-UHFFFAOYAG | ChEMBL_Ref = | ChEMBL = 310555 | StdInChI_Ref = | StdInChI = 1S/C9H7NO/c11-8-5-1-3-7-4-2-6-10-9(7)8/h1-6,11H | StdInChIKey_Ref = | StdInChIKey = MCJGNVYPOGVAJF-UHFFFAOYSA-N | CASNo_Ref = | CASNo = 148-24-3 | PubChem = 1923 | ChemSpiderID_Ref = | ChemSpiderID = 1847 | UNII_Ref = | UNII = 5UTX5635HP | ChEBI_Ref = | ChEBI = 48981 | SMILES = C1=CC2=C(C(=C1)O)N=CC=C2 |Section2={{Chembox Properties | Formula = C9H7NO | MolarMass = 145.16 g/mol | Appearance = White crystalline powder | Density = 1.034 g/cm3 | MeltingPtC = 76 | BoilingPtC = 276 | Solubility = |Section6={{Chembox Pharmacology | ATCCode_prefix = G01 | ATCCode_suffix = AC30 | ATC_Supplemental =
|Section7={{Chembox Hazards | GHSPictograms = | GHSSignalWord = Danger | HPhrases = | PPhrases = | ExternalSDS = External MSDS | FlashPt = | AutoignitionPt =

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.

In aqueous solution 8-hydroxyquinoline has a pKa value of ca. 9.9 It reacts with metal ions, losing the proton and forming 8-hydroxyquinolinato-chelate complexes. ::figure[src="https://upload.wikimedia.org/wikipedia/commons/e/e2/Mer-tris(8-hydroxyquinoline)aluminium(III)-from-xtal-2000-CM-3D-ellipsoids.png" caption="s2cid=96135270 }}"] ::

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

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

History

8-hydroxyquinoline was first obtained by Hugo Weidel and his student Albert Cobenzl in 1880. They decarboxylated so-called oxycinchoninic acid (from cinchonine) and characterized the resulting compound as melting at about 70°C. They identified that the hydroxy group is on the benzene ring (but not its particular place) and called the compound oxyquinoline and α-quinophenol.

In the following year more chemists found other ways to make the compound. Zdenko Hans Skraup discovered a way to synthesize substituted quinolines from substituted phenols and described three isomers of oxyquinoline, identifying the structure of 8-hydroxyquinoline. and his student Karl Bedall made the compound from a sulphonic acid independently at about the same time, but misidentified its structure.

By 1888 azo dyes were made from the compound.

In the 1920s insoluble chelates of 8-hydroxyquinoline were discovered.

Bioactivity

The complexes as well as the heterocycle itself exhibit antiseptic, disinfectant, and pesticide properties, functioning as a transcription inhibitor.{{cite web |title=8-Hydroxyquinoline |url=http://www.sigmaaldrich.com/US/en/product/sial/h6878 |access-date=2022-02-15 |publisher=Sigma-Aldrich}} Its solution in alcohol is used in liquid bandages. It once was of interest as an anti-cancer drug.

A thiol analogue, 8-mercaptoquinoline is also known.

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.

References

References

  1. (1956). "264. Ionization Constants of Heterocyclic Substances. Part II. Hydroxy-Derivatives of Nitrogenous Six-Membered Ring-Compounds". Journal of the Chemical Society (Resumed).
  2. (2002). "The structure of the blue luminescent δ-phase of tris(8-hydroxyquinoline)aluminium(III) (Alq3)". Chemical Communications.
  3. (2006). "Configuration-Specific Synthesis of the Facial and Meridional Isomers of Tris(8-hydroxyquinolinate)aluminum (Alq3)". Inorganic Chemistry.
  4. (2006). "Effective Manipulation of the Electronic Effects and Its Influence on the Emission of 5-Substituted Tris(8-quinolinolate) Aluminum(III) Complexes". Chemistry: A European Journal.
  5. (1997). "Excited-State Processes in 8-Hydroxyquinoline: Photoinduced Tautomerization and Solvation Effects". The Journal of Physical Chemistry B.
  6. (1880). "Über Derivate der Cinchoninsäure und des Chinolins". Monatshefte für Chemie und verwandte Teile anderer Wissenschaften.
  7. "Verfahren zur Darstellung der Oxychinoline durch Behandlung von Mononitro- und Monamido-Phenolen mit Glycerin und Schwefelsäure".
  8. (1881). "Ueber Oxychinolin aus Chinolinsulfosäure". Berichte der Deutschen Chemischen Gesellschaft.
  9. Fischer, Otto. (1882). "Zur Geschichte der Oxychinoline". Berichte der Deutschen Chemischen Gesellschaft.
  10. (1888). "Journal of the Society of Dyers and Colourists". Society of Dyers and Colourists.
  11. Berg, R.. (1927). "Neue Wege zur Bestimmung und Trennung der Metalle mit Hilfe von o-Oxychinolin". Zeitschrift für analytische Chemie.
  12. Phillips, J. P.. (1956). "The Reactions of 8-Quinolinol". Chemical Reviews.
  13. "8-Hydroxyquinoline". Medical Dictionary Online.
  14. (1999). "Synthesis and Cytotoxicity Evaluation of some 8-Hydroxyquinoline Derivatives". Journal of Pharmacy and Pharmacology.
  15. (2005). "Structural Chemistry of Complexes of (n-1)d10ns Metal Ions with β-N-Donor Substituted Thiolate Ligands (m=0, 2)". Coordination Chemistry Reviews.
  16. (2004). "Biogeographical variation in community response to root allelochemistry: novel weapons and exotic invasion". Ecology Letters.

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antisepticsquinolinols