Quinoline
Overview
 
Quinoline is a heterocyclic aromatic organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

. It has the formula C9H7N 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.
Encyclopedia
Quinoline is a heterocyclic aromatic organic compound
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

. It has the formula C9H7N 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
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...

s are produced annually according to a report published in 2005. Its principal use is as a precursor to 8-hydroxyquinoline
8-Hydroxyquinoline
8-Hydroxyquinoline is an organic compound with the formula C9H7NO. It is a derivative of the heterocycle quinoline by placement of an OH group on carbon number 8...

, which is a versatile chelating agent and precursor to pesticides. Its 2-
Quinaldine
Quinaldine or 2-methylquinoline is a simple derivative of a heterocyclic compound quinoline.Quinaldine has critical point at 787 K and 4.9 MPa and its refractive index is 1.8116....

 and 4-methyl
Lepidine
Lepidine, or 4-methylquinoline, is a heterocyclic aromatic organic compound. Its methyl group is fairly acidic, allowing for condensations to occur at this position, especially when the nitrogen is quaternized. It is used in the preparation of certain dyes....

 derivatives are precursors to cyanine dyes. Oxidation of quinoline affords quinolinic acid
Quinolinic acid
Quinolinic acid is a dicarboxylic acid. It may be prepared by the oxidation of quinoline, either electrochemically, or with acidic hydrogen peroxide.Quinolinic acid is a downstream kynurenine pathway metabolite of tryptophan...

 (pyridine-2,3-dicarboxylic acid), a precursor to the herbicide sold under the name "Assert".

Like other nitrogen heterocylic 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 high water solubility quinoline has significant potential for mobility in the environment, which may promote water contamination. Fortunately, quinoline is readily degradable by certain microorganisms, such as Rhodococcus species Strain Q1, which was isolated from soil and paper mill sludge.

Isolation and synthesis

Quinoline was first extracted from coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...

 in 1834 by Friedlieb Ferdinand Runge. Coal tar remains the principal source of commercial quinoline. It can be synthesized using various methods:
  • Combes quinoline synthesis
    Combes quinoline synthesis
    The Combes quinoline synthesis is a chemical reaction involving the condensation of unsubstituted anilines with β-diketones to form substituted quinolines after an acid-catalyzed ring closure of an intermediate Schiff base .-See also:*Conrad-Limpach reaction*Doebner reaction*Doebner-Miller...

     using aniline
    Aniline
    Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...

    s and β-diketone
    Ketone
    In organic chemistry, a ketone is an organic compound with the structure RCR', where R and R' can be a variety of atoms and groups of atoms. It features a carbonyl group bonded to two other carbon atoms. Many ketones are known and many are of great importance in industry and in biology...

    s.
  • Conrad-Limpach synthesis
    Conrad-Limpach synthesis
    The Conrad-Limpach synthesis is the chemical reaction of anilines with β-ketoesters to form 4-hydroxyquinolines via a Schiff base .Several reviews have been published.-References:...

     using aniline
    Aniline
    Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...

    s and β-ketoesters.
  • Doebner-Miller reaction
    Doebner-Miller reaction
    The Doebner-Miller reaction is the organic reaction of an aniline with α,β-unsaturated carbonyl compounds to form quinolines.This reaction is also known as the Skraup-Doebner-Von Miller quinoline synthesis, and is named after the Czech chemist Zdenko Hans Skraup , and the Germans Oscar Döbner and...

     using aniline
    Aniline
    Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...

    s and α,β-unsaturated carbonyl
    Carbonyl
    In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....

     compounds.
  • Friedländer synthesis
    Friedländer synthesis
    The Friedländer synthesis is the chemical reaction of 2-aminobenzaldehydes with ketones to form quinoline derivatives. It is named after German chemist Paul Friedländer ....

     using 2-aminobenzaldehyde and acetaldehyde
    Acetaldehyde
    Acetaldehyde is an organic chemical compound with the formula CH3CHO or MeCHO. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale industrially. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants as part...

    .
  • Skraup synthesis using ferrous sulfate, glycerol
    Glycerol
    Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

    , aniline
    Aniline
    Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...

    , nitrobenzene
    Nitrobenzene
    Nitrobenzene is an organic compound with the chemical formula C6H5NO2. It is a water-insoluble pale yellow oil with an almond-like odor. It freezes to give greenish-yellow crystals. It is produced on a large scale as a precursor to aniline. Although occasionally used as a flavoring or perfume...

    , and sulfuric acid
    Sulfuric acid
    Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

    .
  • Povarov reaction
    Povarov reaction
    The Povarov reaction is an organic reaction described as a formal cycloaddition between an aromatic imine and an alkene. The imine in this organic reaction is a condensation reaction product from an aniline type compound and a benzaldehyde type compound . The alkene must be electron rich which...

     using an aniline
    Aniline
    Aniline, phenylamine or aminobenzene is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the prototypical aromatic amine. Being a precursor to many industrial chemicals, its main use is in the manufacture of precursors to polyurethane...

    , a benzaldehyde
    Benzaldehyde
    Benzaldehyde is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. This colorless liquid has a characteristic pleasant almond-like odor...

     and an activated alkene
    Alkene
    In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

    .
  • Camps quinoline synthesis
    Camps quinoline synthesis
    The Camps quinoline synthesis is a chemical reaction whereby an o-acylaminoacetophenone is transformed into two different hydroxyquinolines using hydroxide ion....

     utilizing an o-acylaminoacetophenone and hydroxide
  • Knorr quinoline synthesis
    Knorr quinoline synthesis
    The Knorr quinoline synthesis is an intramolecular organic reaction converting a β-ketoanilide to a 2-hydroxyquinoline using sulfuric acid. This reaction was first described by Ludwig Knorr in 1886...

    , using a β-ketoanilide and sulfuric acid.
  • Gould-Jacobs reaction
    Gould-Jacobs reaction
    The Gould-Jacobs reaction is an organic synthesis for the preparation of quinolines. In this reaction aniline or an aniline derivative first reacts with malonic acid derivative ethyl ethoxymethylenemalonate with substitution of the ethoxy group by nitrogen. A benzannulation takes place by...

     starting from an aniline and ethyl ethoxymethylenemalonate
  • Niementowski quinoline synthesis
    Niementowski quinoline synthesis
    The Niementowski quinoline synthesis is the chemical reaction of anthranilic acids and ketones to form γ-hydroxyquinoline derivatives.Several reviews have been published.-See also:* Camps quinoline synthesis* Friedländer synthesis...

    , using anthranilic acid and ketones.

Applications

In manufacturing of dyes, preparation of hydroxyquinoline sulfate and niacin. Solvent for resins and terpenes.

See also

  • Isoquinoline
    Isoquinoline
    Isoquinoline is a heterocyclic aromatic organic compound. It is a structural isomer of quinoline. Isoquinoline and quinoline are benzopyridines, which are composed of a benzene ring fused to a pyridine ring. In a broader sense, the term isoquinoline is used to make reference to isoquinoline...

    , an analog with the nitrogen atom in position 2.
  • Pyridine
    Pyridine
    Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one C-H group replaced by a nitrogen atom...

    , an analog without the fused benzene
    Benzene
    Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....

     ring.
  • Naphthalene
    Naphthalene
    Naphthalene is an organic compound with formula . It is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings...

    , an analog without the nitrogen atom.
  • Indole
    Indole
    Indole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. Indole is a popular component of fragrances and the precursor to many pharmaceuticals. Compounds that contain an...

    , an analog with only a five-membered nitrogen ring.
  • Simple aromatic ring
    Simple aromatic ring
    Simple aromatic rings, also known as simple arenes or simple aromatics, are aromatic organic compounds that consist only of a conjugated planar ring system with delocalized pi electron clouds. Many simple aromatic rings have trivial names. They are usually found as substructures of more complex...

    s
  • Niementowski quinoline synthesis
    Niementowski quinoline synthesis
    The Niementowski quinoline synthesis is the chemical reaction of anthranilic acids and ketones to form γ-hydroxyquinoline derivatives.Several reviews have been published.-See also:* Camps quinoline synthesis* Friedländer synthesis...

    , quinoline derivative synthesis
  • Lindlar catalyst
    Lindlar catalyst
    A Lindlar catalyst is a heterogeneous catalyst that consists of palladium deposited on calcium carbonate and treated with various forms of lead. The lead additive serves to deactivate the palladium sites. A variety of "catalyst poisons" have been used including lead acetate and lead oxide. The...

    , quinoline prevents formation of alkanes

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK