Pyridine is a clear liquid with a strong and very unpleasant odor. Pyridine is a simple heterocyclic aromatic organic compound that is structurally related to benzene, with one CH group in the six-membered ring replaced by a nitrogen atom. Pyridine is obtained from crude coal tar or is synthesized from acetaldehyde and ammonia.

Pyridine has an equatorial lone pair of electrons at the nitrogen atom that does not participate in the aromatic pi-system. This makes pyridine a basic compound with chemical properties similar to tertiary amines. Pyridine is protonated by reaction with acids and forms a positively charged aromatic polyatomic ion called pyridinium cation.

Pyridine is widely used as a solvent and reagent in organic chemistry and it is also a starting material in the synthesis of compounds used as an intermediate in making insecticides, herbicides, pharmaceuticals, food flavorings, dyes, rubber chemicals, adhesives, paints, explosives and disinfectants. Pyridine is also used as a denaturant for antifreeze mixtures, for ethyl alcohol, and for fungicides, and as a dyeing aid for textiles.

Pyridine is a harmful substance if inhaled, ingested or absorbed through skin, it is known to reduce male fertility and is considered carcinogenic as well. Common symptoms of exposure to pyridine include: headache, coughing, asthmatic breathing, laryngitis, nausea and vomiting.

See also

Structurally or chemically related compounds:

• Pyrimidine and
• Pyrazine, aromatic molecules with two nitrogen atoms in the ring.
• Quinoline and
• Isoquinoline, pyridine and a benzene ring fused together.
• Aniline, benzene with an attached NH₂ group.
• Simple aromatic rings