4-Methylpyridine is the
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...
with the
formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...
CH
3C
5H
4N. It is one of the three isomers of
methylpyridine Picoline refers to any of three isomers of methylpyridine (CH3C5H4N). They are all colorless liquids with a characteristic smell similar to that of pyridine. They are miscible with water and most organic solvents.
The CAS number of an unspecified ...
. This pungent liquid is a building block for the synthesis of other
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 chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...
s. Its conjugate acid, the 4-methylpyridinium ion, has a p''K''
a of 5.98, about 0.7 units above that of
pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a d ...
itself.
Production and uses
4-Methylpyridine is both isolated from coal tar and is synthesized industrially. It forms via the reaction of
acetaldehyde
Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the mos ...
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 was ...
in the presence of an
oxide
An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...
catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
. The method also affords some
2-methylpyridine
2-Methylpyridine, or 2-picoline, is the compound described with formula C6H7N. 2-Picoline is a colorless liquid that has an unpleasant odor similar to pyridine. It is mainly used to make vinylpyridine and the agrichemical nitrapyrin.
Synthesis
2 ...
.
4-Methylpyridine is of little intrinsic value but is a precursor to other commercially significant species, often of medicinal interest. For example,
ammoxidation of 4-methylpyridine gives 4-cyanopyridine, the precursor to a variety of other derivatives such as the antituberculosis drug
isoniazid.
[
]
Toxicity
Like most alkylpyridines, the LD50 of 2-methylpyridine is modest, being 1290 mg/kg (oral, rat).[
]
References
{{DEFAULTSORT:Methylpyridine, 4-
4-Pyridyl compounds