Pyridinium refers to the charged cation of pyridine. The simplest being the conjugate acid . Many related cations are known involving substituted pyridines, e.g. picolines, lutidines, collidines. They are prepared by treating pyridine with acids.
As pyridine is often used as an organic base in chemical reactions, pyridinium salts are produced in many acid-base reactions. Its salts are often insoluble in the organic solvent, so precipitation of the pyridinium leaving group complex is an indication of the progress of the reaction.
Pyridinium cations are aromatic, as determined through Hückel's rule. They are isoelectronic with benzene.
Other N-substitutions of pyridinium exist. Examples include N-alkyl, N-aryl and N-amino pyridinium species.
thumb|center|Schematic representation of various pyridinium species, without a counter anion.
See also
- Pyridinium chlorochromate
- Pyridinium chloride