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(pĭr`ĭdēn) or


(ăz`ēn), C5H5N, colorless, flammable, toxic liquid with a putrid odor. It melts at −42°C; and boils at 115.5°C;. Chemically, it is a heterocyclic aromatic tertiary amine (see under amino groupamino group,
in chemistry, functional group that consists of a nitrogen atom attached by single bonds to hydrogen atoms, alkyl groups, aryl groups, or a combination of these three. An organic compound that contains an amino group is called an amine.
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). Its molecule resembles that of benzene, one carbon-hydrogen unit in the benzene ring being replaced with a nitrogen molecule. It is miscible with water and with most organic solvents. Its aqueous solution is slightly alkaline. Pyridine is used as a solvent, as a denaturant for alcohol, and as a starting material in the synthesis of other compounds. Compounds that can be derived from pyridine include antihistamines and vitamins. Pyridine is obtained from bone oil or from coal tar by destructive distillation, which decomposes alkaloids that contain it. Alkaloids that contain pyridine include coniine, piperine (the alkaloid in pepper), and nicotine (present in tobacco); free pyridine is present in tobacco smoke.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a heterocyclic compound. Colorless liquid with a characteristic odor. Melting point, — 41.6°C; boiling point, 115.3°C; density, 0.9832 g/cm3 (at 20°C). The structural formula

Pyridine is a weak base that is miscible in all proportions with water and most organic solvents. It forms salts with acids as well as with alkyl halides (RX); the alkyl halide salts are called N-alkyl pyridinium salts and have the general formula C5H5N-RX. Pyridine also forms complexes with FeCl2, S02, S03, Br2, and H20. It is oxidized by peracids (RCOOOH)to give N-oxides.

Pyridine exhibits the properties of an aromatic compound, although—unlike benzene—it does not undergo electrophilic substitution readily: it is nitrated, sulfonated, and brominated only at about 300°C, primarily with the resultant formation of ss-derivatives. Nucleophilic substitution occurs more easily with pyridine than with benzene. For example, pyridine reacts with NaNH2 to give α-aminopyridine and with KOH to give a- hydroxypyridine. Pyridine is reduced by sodium in ethanol or by hydrogen over a nickel catalyst at 120°C to give piperidine. The pyridine ring can be cleaved by, for example, the action of bases on pyridinium salts to form glutaconic dialdehyde (HOCCH=CHCH2COH) or the corresponding glutaconic-dialdehyde derivative. The pyridine nucleus is a structural component of many alkaloids, vitamins, and drugs, including anabasine, nicotine, nicotinic acid, and nikethamide.

Pyridine is toxic, with a maximum permissible vapor concentration in the air of 0.0015 mg/l. Coal tar, which contains about 0.08 percent pyridine, is the major source. A mixture of pyridine and its homologues, the pyridine bases, are extracted with dilute sulfuric acid from the light and medium fractions of the tar oils in coal tar. After neutralization, the desired compounds are separated by distillation.

Pyridine is widely used in industrial organic synthesis as a solvent and in the production of dyes, pesticides, and drugs. Derivatives of pyridine, for example, 2-methyl-5-vinylpyridine, are used in the production of vinylpyridine lattices. Pyridine N-sulfur trioxide (C5H5N -S03) is a mild sulfonating agent.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


(organic chemistry)
C5H5N Organic base; flammable, toxic yellowish liquid, with penetrating aroma and burning taste; soluble in water, alcohol, ether, benzene, and fatty oils; boils at 116°C; used as an alcohol denaturant, solvent, in paints, medicine, and textile dyeing.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The structural study reveals that the complex consists of a neutral [Cu2L(pyridine)6] unit and two lattice water molecules.
Yields are generally higher than reactions carried out with DMF cosolvents, and filtrates appeared cleaner to make seven repeat runs possible with yields ranging higher at up to 98.1 percent, although the melting-point spreads ranged to the lower side more than when using pyridine or DMF as cosolvents.
Sixty basic nitrogen compounds, mostly benzenamine, alkyl aniline, quinolones and pyridines, were identified in the final enriched product, their relative content in the product being 69.50%.
A previous study [5] showed that the strength of the Lewis centers, determined by the pyridine adsorption heat on the centers, can be estimated by the shift of the 1440-1460 and 1590-1630 [cm.sup.-1] bands into the high-frequency region.
Joule, "Six-membered ring systems: pyridines and benzo derivatives," Progress in Heterocyclic Chemistry, vol.
Effect of substituent type on the activities of 1, 2-bis benzimidazolyl benzene (53, 54), 1, 2-bis benzimidazolyl-4-methylbenzene (56, 57), 1,2-bis (benzimidazolyl)-4-chlorobenzene (59, 60), 1,2bis(benzimidazolyl)-4- bromobenzene (62, 63) and 2,6-bis(benzimidazolyl) pyridine (69, 70) vanadium complexes.
When we superimposed the ToCDS GD structure into the ToCDS NAT structure, the conformations of the PLP pyridine ring and His114 of both structures were well conserved (Figure 5(a)).
This report studies Pyridine in Global market, especially in North America, Europe, China, Japan, Southeast Asia and India, focuses on top manufacturers in global market, with sales, price, revenue and market share for each manufacturer, covering Vertellus Specialties , Jubilant Life Sciences , Nanjing Red Sun , Shandong Luba Chemical , Hubei Sanonda , Changchun Group , KOEI Chemical and C-Chem .
Pyridine is a toxic and soluble flammable liquid base with a distinct, strong odor.
They reported that using copper chloride and pyridine as catalysts PPO forms in high yield (85%) at the reaction temperature of 40-50[degrees]C along with a small amount of a byproduct, diphenoquinone (3%) [16, 17].
A fourth success is Jubilant Life Sciences, a leading manufacturer of Pyridine and its numerous derivatives at its plant in Gajraula, Uttar Pradesh, about 120 km from New Delhi.