2,4,6-Trimethylpyridine (2,4,6-collidine) is an organic compound which belongs to the
heterocycles (more precisely,
heteroaromatics). It consists of a
pyridine ring substituted with three
methyl group
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in ma ...
s. It belongs to the substance group of the
collidines, a group of six
constitutional isomers
In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct bonds between them. The term metam ...
. 2,4,6-trimethylpyridine is the most well-known isomer of this group.
Properties
The compound has a
refractive index
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium.
The refractive index determines how much the path of light is bent, or ...
of 1.4959 (25 °C).
Preparation
2,4,6-Trimethylpyridine was isolated from
Dippel's oil Dippel's oil (sometimes referred to as bone oil) is a nitrogenous by-product of the destructive distillation of bones. A dark, viscous, tar-like liquid with an unpleasant smell, it is named after its inventor, Johann Konrad Dippel. The oil consist ...
in 1854. A synthesis can be carried out analogously to the Hantzsch's dihydropyridine synthesis from ethyl acetoacetate (as β-ketocarbonyl compound),
acetaldehyde and
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
in the ratio 2: 1: 1.
Use
By oxidation of the methyl groups with
potassium permanganate
Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and , an intensely pink to purple solution.
Potassium permanganate is widely used in the c ...
collidinic acid is obtained.
2,4,6-Trimethylpyridine is used in organic syntheses (for example, for
dehydrohalogenation
In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications.
Dehydrohalogenation from alkyl halid ...
), by binding the formed
hydrogen halide
In chemistry, hydrogen halides (hydrohalic acids when in the aqueous phase) are diatomic, inorganic compounds that function as Arrhenius acids. The formula is HX where X is one of the halogens: fluorine, chlorine, bromine, iodine, or astatine. ...
s.
See also
*
2,6-Dimethylpyridine (lutidine)
References
{{DEFAULTSORT:Trimethylpyridine, 2, 4, 6-
Pyridines
Non-nucleophilic bases