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 (whereas normal methane has the formula ). In formulas, the group is often abbreviated a ...
s. It belongs to the substance group of the
collidine Collidine is the trivial name used to describe the chemical compounds which are Methyl group, trimethyl derivative (chemistry), derivatives of pyridine. Their chemical properties resemble those of pyridine, although the presence of the methyl groups ...
s, a group of six
constitutional isomers
In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a compound is a compound that contains the same number and type of atoms, but with a different connectivity (i.e. arrangement of bonds) between them. The ...
. 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 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 ...
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 consists ...
in 1854. A synthesis can be carried out analogously to the Hantzsch's dihydropyridine synthesis from ethyl acetoacetate (as β-ketocarbonyl compound),
acetaldehyde
Acetaldehyde (IUPAC systematic name ethanal) is an organic compound, organic chemical compound with the chemical formula, formula , sometimes abbreviated as . It is a colorless liquid or gas, boiling near room temperature. It is one of the most ...
and
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
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, which dissolves in water as K+ and ions to give an intensely pink to purple solution.
Potassium permanganate is widely us ...
collidinic acid
Collidinic acid (pyridine-2,4,6-tricarboxylic acid) is an organic compound that belongs to the heterocycles (more precisely the heteroaromatics). It belongs to the group of pyridinetricarboxylic acids and consists of a pyridine ring which carri ...
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 (chemistry), substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications.
Dehydrohalogen ...
), 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, astatine, or ...
s.
See also
*
2,6-Dimethylpyridine
2,6-Lutidine is a natural heterocyclic compound, heterocyclic aromaticity, aromatic organic compound with the formula (CH3)2C5H3N. It is one of several methyl group, dimethyl-substituted derivative of pyridine, all of which are referred to as Luti ...
(lutidine)
References
{{DEFAULTSORT:Trimethylpyridine, 2, 4, 6-
Pyridines
Non-nucleophilic bases