Quinaldine or 2-methylquinoline is an organic compound with the formula CH3C9H6N. It is one of the methyl derivatives of the heterocyclic compound quinoline. It is bioactive and is used in the preparation of various dyes. It is a colorless oil but commercial samples can appear colored.[1]

Quinaldine
Names
Preferred IUPAC name
2-Methylquinoline
Other names
Quinaldine, α-methylquinoline, chinaldine, khinaldin
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.896 Edit this at Wikidata
EC Number
  • 202-085-1
UNII
  • InChI=1S/C10H9N/c1-8-6-7-9-4-2-3-5-10(9)11-8/h2-7H,1H3 checkY
    Key: SMUQFGGVLNAIOZ-UHFFFAOYSA-N checkY
  • InChI=1/C10H9N/c1-8-6-7-9-4-2-3-5-10(9)11-8/h2-7H,1H3
  • Cc1nc2ccccc2cc1
Properties
C10H9N
Molar mass 143.19 g/mol
Appearance colorless oil
Density 1.058 g/cm3
Melting point −2 °C (28 °F; 271 K)
Boiling point 248 °C (478 °F; 521 K)
Insoluble
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H312, H319
P264, P270, P280, P301+P312, P302+P352, P305+P351+P338, P312, P322, P330, P337+P313, P363, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
2
0
Flash point 79 °C (174 °F; 352 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Production and reactions

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Quinaldine is recovered from coal tar. It can be prepared from aniline and paraldehyde via Skraup synthesis or from aniline and crotonaldehyde via Doebner-von Miller variation of the Skraup reaction.[1]

Hydrogenation of quinaldine gives 2-methyltetrahydroquinoline. This reduction can be conducted enantioselectively.[2]

Properties

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Quinaldine has critical point at 787 K and 4.9 MPa and its refractive index is 1.8116.[citation needed]

Uses

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Quinaldine is used in manufacturing anti-malaria drugs, dyes and food colorants (e.g., Quinoline Yellows, pinacyanol). It is the precursor to the pH indicator Quinaldine Red.

 
Quinoline Yellow is a popular dye derived from quinaldine.
 
Quinaldine Red, a pH indicating dye.

Quinaldine sulfate is an anaesthetic used in fish transportation.[3] In some Caribbean islands it is used to facilitate the collection of tropical fish from reefs.

References

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  1. ^ a b 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.
  2. ^ Chen, Fei; Ding, Zi-Yuan; He, Yan-Mei; Fan, Qing-Hua (2015). "Synthesis of Optically Active 1,2,3,4-Tetrahydroquinolines via Asymmetric Hydrogenation Using Iridium-Diamine Catalyst". Org. Synth. 92: 213–226. doi:10.15227/orgsyn.092.0213.
  3. ^ Blasiola G. C. Jr. (1977). "Quinaldine sulphate, a new anaesthetic formulation for tropical marine fishes". Journal of Fish Biology. 10 (2): 113–119(7). doi:10.1111/j.1095-8649.1977.tb04048.x.
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