Jump to navigation Jump to search

Template:Chembox new

WikiDoc Resources for Pyridine


Most recent articles on Pyridine

Most cited articles on Pyridine

Review articles on Pyridine

Articles on Pyridine in N Eng J Med, Lancet, BMJ


Powerpoint slides on Pyridine

Images of Pyridine

Photos of Pyridine

Podcasts & MP3s on Pyridine

Videos on Pyridine

Evidence Based Medicine

Cochrane Collaboration on Pyridine

Bandolier on Pyridine

TRIP on Pyridine

Clinical Trials

Ongoing Trials on Pyridine at Clinical

Trial results on Pyridine

Clinical Trials on Pyridine at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Pyridine

NICE Guidance on Pyridine


FDA on Pyridine

CDC on Pyridine


Books on Pyridine


Pyridine in the news

Be alerted to news on Pyridine

News trends on Pyridine


Blogs on Pyridine


Definitions of Pyridine

Patient Resources / Community

Patient resources on Pyridine

Discussion groups on Pyridine

Patient Handouts on Pyridine

Directions to Hospitals Treating Pyridine

Risk calculators and risk factors for Pyridine

Healthcare Provider Resources

Symptoms of Pyridine

Causes & Risk Factors for Pyridine

Diagnostic studies for Pyridine

Treatment of Pyridine

Continuing Medical Education (CME)

CME Programs on Pyridine


Pyridine en Espanol

Pyridine en Francais


Pyridine in the Marketplace

Patents on Pyridine

Experimental / Informatics

List of terms related to Pyridine

Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [1] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.


Pyridine is a chemical compound with the formula C5H5N. It is a liquid with a distinctively putrid, fishy odour. Pyridine is a simple and fundamentally important heterocyclic aromatic organic compound that is structurally related to benzene, wherein one CH group in the six-membered ring is replaced by a nitrogen atom. The pyridine ring occurs in many important compounds, including the nicotinamides. Pyridine is sometimes used as a ligand in coordination chemistry. As a ligand, it is usually abbreviated py.


Pyridinium cation

Pyridine has a lone pair of electrons at the nitrogen atom. Because this lone pair is not delocalized into the aromatic pi-system, pyridine is basic with chemical properties similar to tertiary amines. The pKa of the conjugate acid is 5.30. Pyridine is protonated by reaction with acids and forms a positively charged aromatic polyatomic ion called pyridinium cation. The bond lengths and bond angles in pyridine and the pyridinium ion are almost identical[1] because protonation does not affect the aromatic pi system.

Pyridine as a solvent

Pyridine is widely used as a versatile solvent, since it is polar but aprotic. It is fully miscible with a very broad range of solvents including hexane and water. Deuterated pyridine, called pyridine-d5, is a common solvent for1H NMR spectroscopy.

Role in chemical synthesis

Pyridine is important in industrial organic chemistry, both as a fundamental building block and as a solvent and reagent in organic synthesis.[2] It is used as a solvent in Knoevenagel condensations.

Pyridine-borane, C5H5NBH3 (m.p. 10–11 °C) is a mild reducing agent with improved stability vs NaBH4 in protic solvents and improved solubility in aprotic organic solvents. Pyridine-sulfur trioxide, C5H5NSO3 (mp 175 °C) is a sulfonation agent used to convert alcohols to sulfonates, which in turn undergo C-O bond scission upon reduction with hydride agents.

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.

Preparation and occurrence

Many methods exist in industry and in the laboratory (some of them named reactions) for the synthesis of pyridine and its derivatives:[3]

Organic reactions

In organic reactions pyridine behaves both as a tertiary amine with protonation, alkylation, acylation and N-oxidation at nitrogen and as an aromatic compound with Nucleophilic substitutions.

Safety and Environmental

Pyridine is toxic with LD50 in rats (oral) of 891 mg kg–1. It is volatile and can be absorbed through skin. Available data indicate that "exposure to pyridine in drinking-water led to reduction of sperm motility at all dose levels in mice and increased estrous cycle length at the highest dose level in rats".[6] Currently its evaluations as a possible carcinogenic agent showed there is inadequate evidence in humans for the carcinogenicity of pyridine, albeit there is limited evidence of carcinogenic effects on animals.[6] Effects of an acute pyridine intoxication include dizziness, headache, nausea and anorexia. Further symptoms include abdominal pain and pulmonary congestion.[6] Though resistant to oxidation, pyridine is readily degraded by bacteria, releasing ammonium and carbon dioxide as terminal degradation products.[7]

Related compounds

Structurally or chemically related compounds are

  • DMAP is short for 4-dimethylaminopyridine
  • Bipyridine and viologen are simple polypyridine compounds consisting of two pyridine molecules joined by a single bond
  • Terpyridine, a molecule of three pyridine rings connected together by two single bonds.
  • Quinoline and Isoquinoline have pyridine and a benzene ring fused together.
  • Aniline is a benzene derivative with an attached NH2 group and NOT a pyridine
  • Diazines are compounds with one more carbon replaced by nitrogen such as Pyrazine and Pyramidine
  • Triazines are compounds with two more carbons replaced by nitrogen and a tetrazine has four nitrogen atoms
  • 2,6-Lutidine is a trivial name for 2,6-dimethylpyridine.
  • Collidine is the trivial name for 2,4,6-trimethylpyridine.
  • Pyridinium p-toluenesulfonate (PPTS) is a salt formed by proton exchange between pyridine and p-toluenesulfonic acid
  • 2-Chloropyridine is a toxic environmentally significant component of the breakdown of the pesticide imidacloprid.

See also

External links

Template:Functional Groups


  1. T. M. Krygowski, H. Szatyowicz, and J. E. Zachara J. Org. Chem. 2005 70(22) 8859 - 8865; doi:10.1021/jo051354h.
  2. Sherman, A. R. “Pyridine” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289.
  3. Gilchrist, T.L. (1997). Heterocyclic Chemistry ISBN 0470204818
  4. Ciamician-Dennstedt Rearrangement @ Link
  5. Histamine Antagonists. Basically Substituted Pyridine Derivatives Charles H. Tilford, Robert S. Shelton, and M. G. van Campen J. Am. Chem. Soc.; 1948; 70(12) pp 4001 - 4009; doi:10.1021/ja01192a010
  6. 6.0 6.1 6.2 International Agency for Research on Cancer (IARC) (2000-08-22). "Pyridine Summary & Evaluation" (HTML). IARC Summaries & Evaluations. IPCS INCHEM. Retrieved 2007-01-17.
  7. Sims, G.K. and O'Loughlin, E.J. (1989). "Degradation of pyridines in the environment". CRC Critical Reviews in Environmental Control. 19 (4): 309–340.

Template:SIB cs:Pyridin de:Pyridin hr:Piridin it:Piridina nl:Pyridine fi:Pyridiini sv:Pyridin uk:Піридин

Template:Jb1 Template:WH Template:WS