8-Hydroxyquinoline[1]
Identifiers
CAS number  YesY
PubChem
ChemSpider  YesY
UNII  YesY
KEGG  YesY
ChEBI  YesY
ChEMBL  YesY
ATC code G01,A01 D08 R02
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 (169 °F; 349 K)
Boiling point 276 °C (529 °F; 549 K)
Hazards
MSDS External MSDS
Main hazards flammable
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY   YesY/N?)

8-Hydroxyquinoline is an 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 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.[13]

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. ^ "8-Hydroxyquinoline Safety Data". Oxford University. 
  3. ^ "8-Hydroxyquinoline". PAN Pesticides Database. 
  4. ^ Collin, G.; Höke, H. (2005), "Quinoline and Isoquinoline",  
  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) 1956: 1294–1304.  
  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 (39): 7786–7793.  
  7. ^ Phillips, J. P. (1956). "The Reactions of 8-Quinolinol". Chemical Reviews 56 (2): 271–297.  
  8. ^ "8-Hydroxyquinoline". Medical Dictionary Online. 
  9. ^ "8-Hydroxyquinoline". Sigma-Aldrich. Retrieved 2012-05-23. 
  10. ^ Shen, A. Y.; Wu, S. N.; Chiu, C. T. (1999). "Synthesis and Cytotoxicity Evaluation of some 8-Hydroxyquinoline Derivatives". Journal of Pharmacy and Pharmacology 51 (5): 543–548.  
  11. ^ Katakura, R.; Koide, Y. (2006). "Configuration-Specific Synthesis of the Facial and Meridional Isomers of Tris(8-hydroxyquinolinate)aluminum (Alq3)". Inorganic Chemistry 45 (15): 5730–5732.  
  12. ^ Montes, V. A.; Pohl, R.; Shinar, J.; Anzenbacher, P. Jr. (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 12 (17): 4523–4535.  
  13. ^ Vivanco, J.M.; Bais, H.P.; Stermitz, F.R.; Thelen, G.C.; Callaway, R.M. (2004). "Biogeographical variation in community response to root allelochemistry: novel weapons and exotic invasion". Ecology Letters 7 (4): 285–292.