Pyridine

Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH−) replaced by a nitrogen atom. The pyridine ring occurs in many important compounds, including azines and the vitamins niacin and pyridoxine.

Pyridine was discovered in 1849 by the Scottish chemist Thomas Anderson as one of the constituents of bone oil. Two years later, Anderson isolated pure pyridine through fractional distillation of the oil. It is a colorless, highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell.

Pyridine is used as a solvent in the chemical industry and for denaturing alcohols. It is also an important raw material for the synthesis of agrochemicals and pharmaceuticals.

History

Pyridine was discovered in 1849 by the Scottish chemist Thomas Anderson as one of the constituents of bone oil. In 1851, Anderson isolated pure pyridine through fractional distillation of the oil. The name "pyridine" was coined in 1851 by the German chemist August Wilhelm von Hofmann, who prepared it by the dry distillation of picoline.

Properties

Pyridine is a colorless, highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is soluble in water and virtually all organic solvents. It is weakly basic, forming salts with mineral acids. Pyridine is especially noted for its basicity and nucleophilicity.

Uses

Pyridine is used as a solvent in the chemical industry and for denaturing alcohols. It is also an important raw material for the synthesis of agrochemicals and pharmaceuticals. Pyridine derivatives, such as pyridine-3-sulfonic acid, are used as a precursor for the herbicide paraquat.

Safety

Pyridine is harmful if swallowed, inhaled, or absorbed through the skin. It is also a flammable liquid and vapor.

See also

• Quinoline
• Pyrrole
• Pyrrolidine
• Piperidine

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