Quinoline

Overview
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.

As it ages, if exposed to light, the liquid tends to become yellow and later brown. It is only slightly soluble in water but dissolves readily in many organic solvents.

Quinoline is an intermediate in metallurgical processes and in dye, polymer, and agrochemical production. It is also a preservative, disinfectant, and solvent.

It is toxic: short-term exposure to the vapour causes irritation of the nose, eyes, and throat as well as dizziness and nausea. Longer-term effects are uncertain, but quinoline has been linked to liver damage.

Isolation and synthesis
Quinoline is naturally found in coal tar and was first extracted from this source in 1834 by F. Runge. It can be prepared 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