Quinaldine or 2-methylquinoline is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula CH₃C₉H₆N. It is one of the methyl derivatives of the

heterocyclic compound A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...

quinoline 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 sl ...

. It is bioactive and is used in the preparation of various dyes. It is a colorless oil but commercial samples can appear colored.

Production and reactions

Quinaldine is recovered from

coal tar Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote. It has both medical and industrial uses. Medicinally it is a topical medication applied to skin to treat psoria ...

. It can be prepared from

aniline Aniline (From , meaning ' indigo shrub', and ''-ine'' indicating a derived substance) is an organic compound with the formula . Consisting of a phenyl group () attached to an amino group (), aniline is the simplest aromatic amine. It is an in ...

and

paraldehyde Paraldehyde is the cyclic trimer (chemistry), trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane, with a methyl group substituted for a hydrogen atom at each carbon. The corresponding tetramer is metaldehyde. A colo ...

via Skraup synthesis or from aniline and

crotonaldehyde Crotonaldehyde is a chemical compound with the formula CH3CH=CHCHO. The compound is usually sold as a mixture of the ''E''- and ''Z''-isomers, which differ with respect to the relative position of the methyl and formyl groups. The ''E''-isomer i ...

via Doebner-von Miller variation of the

Skraup reaction The Skraup synthesis is a chemical reaction used to synthesize quinolines. It is named after the Czech chemist Zdenko Hans Skraup (1850–1910). In the archetypal Skraup reaction, aniline is heated with sulfuric acid, glycerol, and an oxidizing a ...

Hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or Saturated ...

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

Properties

Quinaldine has critical point at 787 K and 4.9 MPa and its

refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

is 1.8116.

Uses

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 SS

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

References

External links

MSDS at Science Lab

* {{cite EB1911 , wstitle=Quinoline , volume=22 , pages=758–760 Quinolines Methyl compounds