8-Hydroxyquinoline

8-Hydroxyquinoline[1]
Identifiers
CAS number 148-24-3
PubChem 1923
ChemSpider 1847 Y
UNII 5UTX5635HP Y
KEGG D05321 Y
ChEBI CHEBI:48981 Y
ChEMBL CHEMBL310555 Y
ATC code G01AC30,A01AB07 D08AH03 R02AA14
Jmol-3D images Image 1
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
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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 colorless compound is widely used commercially, although under a variety of names.[2][3]

Contents

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 and salen. 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] Its solution in alcohol is used as liquid bandages. It once was of interest as an anti-cancer drug.[9]

The reaction of 8-hydroxyquinoline with aluminium(III) [10] 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.[11]

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

  1. ^ Nanjing Odyssey Chemicals
  2. ^ Oxford University 8-hydroxyquinoline Safety Data
  3. ^ Pesticide Database
  4. ^ Gerd Collin, Hartmut Höke "Quinoline and Isoquinoline" Ullmann's Encyclopedia of Chemical Technology; 2005 Wiley-VCH, Weinheim.10.1002/14356007.a22 465
  5. ^ Albert, A.; Phillips, J. N. (1956). "264. Ionization constants of heterocyclic substances. Part II. Hydroxy-derivatives of nitrogenous six-membered ring-compounds". Journal of the Chemical Society (Resumed): 1294. doi:10.1039/JR9560001294.  edit
  6. ^ Bardez, E.; Devol, I.; Larrey, B.; Valeur, B. (1997). "Excited-State Processes in 8-Hydroxyquinoline:  Photoinduced Tautomerization and Solvation Effects". The Journal of Physical Chemistry B 101: 7786. doi:10.1021/jp971293u.  edit
  7. ^ Phillips, J. P. (1956). "The Reactions of 8-Quinolinol". Chemical Reviews 56 (2): 271. doi:10.1021/cr50008a003. 
  8. ^ Medical Dictionary Online
  9. ^ Shen AY, Wu SN, Chiu CT (1999). "Synthesis and cytotoxicity evaluation of some 8-hydroxyquinoline derivatives". J. Pharm. Pharmacol. 51 (5): 543–8. doi:10.1211/0022357991772826. PMID 10411213. 
  10. ^ Katakura, R.; Koide, Y. “Configuration-Specific Synthesis of the Facial and Meridional Isomers of Tris(8-hydroxyquinolinate)aluminum (Alq3)” Inorganic Chemistry 2006 volume 45,pp 5730-5732. doi:10.1021/ic060594s
  11. ^ Victor A. Montes, Radek Pohl, Joseph Shinar, Pavel Anzenbacher Jr. "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 2006, Volume 12, pp. p 4523-4535. doi:10.1002/chem.200501403