4-Methylpyridine is the 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...

 with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 CH₃C₅H₄N. It is one of the three isomers of methylpyridine

Picoline

Picoline refers to three different methylpyridine isomers, all with the chemical formula C6H7N and a molar mass of 93.13 g mol−1. All three are colourless liquids at room temperature and pressure and are miscible with water and most organic solvents...

. This colourless pungent liquid is a building block for the synthesis of other heterocyclic compound

Heterocyclic compound

A heterocyclic compound is a cyclic compound which has atoms of at least two different elements as members of its ring. The counterparts of heterocyclic compounds are homocyclic compounds, the rings of which are made of a single element....

s. Its conjugate acid, the 4-methylpyridinium ion, has a pK_a of 5.98, about 0.7 units above that of 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...

 itself.

Production and uses

4-Methylpyridine is both isolated from coal tar and is synthesized industrially. It forms via the reaction of 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...

 and ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 in the presence of an oxide

Oxide

An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....

 catalyst. The method also affords some 2-methylpyridine

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. Pyridines including 2-picoline are most crudely prepared by the reaction of acetylene and hydrogen cyanide.-Synthesis:2-Picoline was the...

. 4-methylpyridine is of little intrinsic value but is a precursor to other commercially significant species, often of medicinal interest. Ammoxidation

Ammoxidation

In chemistry, ammoxidation is an industrial process for the production of nitriles using ammonia and oxygen. The usual substrates are alkenes. It is sometimes called the Sohio process, acknowledging that ammoxidation was commercialized by Standard Oil of Ohio...

 of 4-methylpyridine gives 4-cyanopyridine, the precursor to a variety of other derivatives such as the antituberculosis drug Isoniazid

Isoniazid

Isoniazid , also known as isonicotinylhydrazine , is an organic compound that is the first-line antituberculosis medication in prevention and treatment. It was first discovered in 1912, and later in 1951 it was found to be effective against tuberculosis by inhibiting its mycolic acid...

(isonicotinic hydrazide).