any of a class of hetercyclic compounds
- Finnish: kinoliini
- Spanish: quinoleína, quinolina
Quinoline, also known as 1-azanaphthalene, 1-benzazine, or benzo[b]pyridine, is a heterocyclic aromatic organic compound. It has the formula C9H7N and is a colourless hygroscopic liquid with a strong odour. Aged samples, if exposed to light, become yellow and later brown. Quinoline is only slightly soluble in cold water but dissolves readily in hot water and most organic solvents.
Quinoline is mainly used as a building block to other specialty chemicals. Approximately 4 tonnes are produced annually according to a report published in 2005. Its principal use is as a precursor to 8-hydroxyquinoline, which is a versatile chelating agent and precursor to pesticides. Its 2- and 4-methylderivatives are precursors to cyanine dyes. Oxidation of quinonline affords quinolinic acid (pyridine-2,3-dicarboxylic acid), a precursor to the herbicide sold under the name "Assert".
Isolation and synthesisQuinoline was first extracted from coal tar in 1834 by Friedlieb Ferdinand Runge. Coal tar remains the principal source of commercial quinoline. It can be synthesized using various methods:
- Combes quinoline synthesis using anilines and β-diketones.
- Conrad-Limpach synthesis using anilines and β-ketoesters.
- Doebner-Miller reaction using anilines and α,β-unsaturated carbonyl compounds.
- Friedländer synthesis using 2-aminobenzaldehyde and acetaldehyde.
- Skraup synthesis using ferrous sulfate, glycerol, aniline, nitrobenzene, and sulfuric acid.
- Povarov reaction using an aniline, a benzaldehyde and an activated alkene.
- Camps quinoline synthesis utilizing an o-acylaminoacetophenone and hydroxide
- Knorr quinoline synthesis, using a β-ketoanilide and sulfuric acid.
- Gould-Jacobs reaction starting from an aniline and ethyl ethoxymethylenemalonate
- Isoquinoline, an analog with the nitrogen atom in position 2.
- Pyridine, an analog without the fused benzene ring.
- Naphthalene, an analog without the nitrogen atom.
- Indole, an analog with only a five-membered nitrogen ring.
- Simple aromatic rings
- Niementowski quinoline synthesis, quinoline derivative synthesis
SafetyQuinoline has an LD50 of several hundred milligrams per kilogram.
quinoline in German: Chinolin
quinoline in French: Quinoléine
quinoline in Italian: Chinolina
quinoline in Hungarian: Kinolin
quinoline in Dutch: Chinoline
quinoline in Japanese: キノリン
quinoline in Norwegian: Kinolin
quinoline in Polish: Chinolina
quinoline in Russian: Хинолин
quinoline in Finnish: Kinoliini
quinoline in Chinese: 喹啉