Quinoline
| |||
| |||
| Names | |||
|---|---|---|---|
| IUPAC name
quinoline
| |||
Systematic IUPAC name
| |||
Other names
| |||
| Identifiers | |||
3D model (JSmol)
|
|||
| 3DMet | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.001.865 | ||
| EC Number |
| ||
| KEGG | |||
| MeSH | Quinolines | ||
PubChem CID
|
|||
| RTECS number |
| ||
| UNII | |||
| UN number | 2656 | ||
CompTox Dashboard (EPA)
|
|||
| |||
| |||
| Properties | |||
| C9H7N | |||
| Molar mass | 129.16 g/mol | ||
| Appearance | yellowish oily liquid | ||
| Density | 1.093 g/mL | ||
| Melting point | −15 °C (5 °F; 258 K) | ||
| Boiling point | 237 °C (459 °F; 510 K) /760 mm Hg, 108 to 110 °C/11 mm Hg | ||
| Slightly soluble | |||
| Solubility | Soluble in alcohol, ether, and carbon disulfide | ||
| Acidity (pKa) | 4.85[2] | ||
| Thermochemistry | |||
Std enthalpy of
formation (ΔfH⦵298) |
174.9 kJ mol−1 | ||
| Hazards | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 101 °C (214 °F; 374 K) | ||
| 400 °C (752 °F; 673 K) | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
|
331 mg/kg | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |||
Quinoline is a heterocyclic aromatic organic compound with the chemical formula C9H7N. It is a colorless hygroscopic liquid with a strong odor. Aged samples, especially 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 itself has few applications, but many of its derivatives are useful in diverse applications. A prominent example is quinine, an alkaloid found in plants. 4-Hydroxy-2-alkylquinolines (HAQs) are involved in antibiotic resistance.
Occurrence and isolation
Quinoline was first extracted from coal tar in 1834 by Friedlieb Ferdinand Runge.[3] Coal tar remains the principal source of commercial quinoline.[4]
Like other nitrogen heterocyclic compounds, such as pyridine derivatives, quinoline is often reported as an environmental contaminant associated with facilities processing oil shale or coal, and has also been found at legacy wood treatment sites. Owing to its relatively high solubility in water, quinoline has significant potential for mobility in the environment, which may promote water contamination. Quinoline is readily degradable by certain microorganisms, such as Rhodococcus species Strain Q1, which was isolated from soil and paper mill sludge.[5]
Quinolines are present in small amounts in crude oil within the virgin diesel fraction. It can be removed by the process called hydrodenitriification.
Synthesis
Quinolines are often synthesized from simple anilines using a number of named reactions.
Going clockwise from top these are:
- Combes quinoline synthesis using anilines and β-diketones.
- Conrad-Limpach synthesis using anilines and β-ketoesters.
- Doebner reaction using anilines with an aldehyde and pyruvic acid to form quinoline-4-carboxylic acids
- Doebner-Miller reaction using anilines and α,β-unsaturated carbonyl compounds.
- Gould-Jacobs reaction starting from an aniline and ethyl ethoxymethylenemalonate
- Skraup synthesis using ferrous sulfate, glycerol, aniline, nitrobenzene, and sulfuric acid.
A number of other processes exist, which require specifically substituted anilines or related compounds:
- Camps quinoline synthesis utilizing an o-acylaminoacetophenone and hydroxide
- Friedländer synthesis using 2-aminobenzaldehyde and acetaldehyde.
- Knorr quinoline synthesis, using a β-ketoanilide and sulfuric acid.
- Niementowski quinoline synthesis, using anthranilic acid and ketones.
- Pfitzinger reaction using an isatin with base and a carbonyl compound to yield substituted quinoline-4-carboxylic acids
- Povarov reaction using an aniline, a benzaldehyde and an activated alkene.
Applications
Quinoline is used in the manufacture of dyes, the preparation of hydroxyquinoline sulfate and niacin. It has also used as a solvent for resins and terpenes.
Quinoline is mainly used as a feedstock in the production of other specialty chemicals. Approximately 4 tonnes are produced annually according to a report published in 2005.[4] Its principal use is as a precursor to 8-hydroxyquinoline, which is a versatile chelating agent and precursor to pesticides. Its 2- and 4-methyl derivatives are precursors to cyanine dyes. Oxidation of quinoline affords quinolinic acid (pyridine-2,3-dicarboxylic acid), a precursor to the herbicide sold under the name "Assert".[4]
See also
- Isoquinoline, an analog with the nitrogen atom in position 2.
- Pyridine, an analog without the fused benzene ring.
- Naphthalene, an analog with a carbon instead of the nitrogen.
- Indole, an analog with only a five-membered nitrogen ring.
- Simple aromatic rings
- Niementowski quinoline synthesis, quinoline derivative synthesis
- Lindlar catalyst, quinoline prevents formation of alkanes
- Pyrroloquinoline quinone (PQQ), a redox cofactor and controversial nutritional supplement
References
- ^ "QUINOLINE (BENZOPYRIDINE)". Chemicalland21.com. Retrieved 2012-06-14.
- ^ Brown, H.C., et al., in Baude, E.A. and Nachod, F.C., Determination of Organic Structures by Physical Methods, Academic Press, New York, 1955.
- ^ "Quinoline". Encyclopædia Britannica. 1911.
- ^ a b c Gerd Collin; Hartmut Höke. "Quinoline and Isoquinoline". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a22_465. ISBN 978-3527306732.
- ^ O'Loughlin, Edward J.; Kehrmeyer, Staci R.; Sims, Gerald K. (1996). "Isolation, characterization, and substrate utilization of a quinoline-degrading bacterium". International Biodeterioration & Biodegradation. 38 (2): 107. doi:10.1016/S0964-8305(96)00032-7.