Quinoline 312116 224628793 2008-07-09T18:53:01Z ChemNerd 2246483 {{Chembox new | ImageFile = Quinoline_chemical_structure_part1.png | ImageSize = 200px | ImageFile1 = Quinoline_chemical_structure_part2.png | ImageSize1 = 200px | IUPACName = Quinoline | OtherNames = 1-benzazine, 1-azanaphthalene, benzo[b]pyridine | Section1 = {{Chembox Identifiers | CASNo = 91-22-5 | PubChem = | SMILES = c1cccc2cccnc12 }} | Section2 = {{Chembox Properties | Formula = C<sub>9</sub>H<sub>7</sub>N | MolarMass = 129.16 g/mol | Appearance = | Density = 1.093 g/ml | MeltingPt = &minus;15 °C | BoilingPt = 238 °C | Solubility = Soluble }} }} '''Quinoline''', also known as '''1-azanaphthalene''', '''1-benzazine''', or '''benzo[b]pyridine''', is a [[heterocyclic]] [[aromatic]] [[organic compound]]. It has the formula C<sub>9</sub>H<sub>7</sub>N 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 [[tonne]]s are produced annually according to a report published in 2005.{{Fact|date=February 2008}} 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 dye]]s. Oxidation of quinonline affords [[quinolinic acid]] (pyridine-2,3-dicarboxylic acid), a precursor to the herbicide sold under the name "Assert".<ref name=Hoke>Gerd Collin, Hartmut Höke "Quinoline and Isoquinoline" Ullmann's Encyclopedia of Chemical Technology; 2005 Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a22_465}} </ref> == Isolation and synthesis == Quinoline was first extracted from [[coal tar]] in [[1834]] by [[Friedlieb Ferdinand Runge]].<ref>{{cite encyclopedia | year = 1911 | encyclopedia = [[Encyclopedia Britannica]] | title = Quinoline | url = http://www.1911encyclopedia.org/Quinoline}}</ref> Coal tar remains the principal source of commercial quinoline. It can be synthesized using various methods: *[[Combes quinoline synthesis]] using [[aniline]]s and β-di[[ketone]]s. *[[Conrad-Limpach synthesis]] using [[aniline]]s and β-ketoesters. *[[Doebner-Miller reaction]] using [[aniline]]s 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 == See also == * [[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 ring]]s * [[Niementowski quinoline synthesis]], quinoline derivative synthesis ==Safety== Quinoline has an LD50 of several hundred milligrams per kilogram.<ref name=Hoke/> ==References== <references/> == External links == * {{ICSC|0071|00}} * [http://www.hull.ac.uk/php/chsanb/Heteroweb/Heterocycles%20Lecture%202%20-%20quinolines.pdf Classical methods of synthesizing quinolines] [[Category:Quinolines| ]] [[Category:Hazardous air pollutants]] [[Category:Nitrogen heterocycles]] [[Category:Aromatic compounds]] [[Category:Amines]] [[Category:Simple aromatic rings]] [[Category:Aromatic bases]] [[Category:Amine solvents]] [[de:Chinolin]] [[fr:Quinoléine]] [[it:Chinolina]] [[hu:Kinolin]] [[nl:Chinoline]] [[ja:キノリン]] [[no:Kinolin]] [[pl:Chinolina]] [[ru:Хинолин]] [[fi:Kinoliini]] [[zh:喹啉]]