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Pyridine

Pyridine
Names Preferred IUPAC name
Pyridine
Systematic IUPAC name
Azabenzene
Other names
Azine
Azinine
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard100.003.464EC Number
  • 203-809-9
KEGG
UNII
  • InChI=1S/C5H5N/c1-2-4-6-5-3-1/h1-5H
    Key: JUJWROOIHBZHMG-UHFFFAOYSA-N
  • InChI=1/C5H5N/c1-2-4-6-5-3-1/h1-5H
    Key: JUJWROOIHBZHMG-UHFFFAOYAY
  • c1ccncc1
Properties C5H5NMolar mass79.102 g·mol Appearance Colorless liquid OdorNauseating, fish-like Density0.9819 g/mL (20 °C) Melting point−41.63 °C (−42.93 °F; 231.52 K) Boiling point115.2 °C (239.4 °F; 388.3 K) Miscible log P0.65 Vapor pressure16 mmHg (20 °C) Acidity (pKa) 5.23 (pyridinium) Conjugate acidPyridinium−48.7·10 cm/mol Thermal conductivity0.166 W/(m·K) 1.5095 (20 °C) Viscosity0.879 cP (25 °C) 2.215 D Thermochemistry 132.7 J/(mol·K) 100.2 kJ/mol −2.782MJ/mol Hazards Occupational safety and health (OHS/OSH):
Main hazards
Low to moderate hazard GHS labelling: DangerH225, H302, H312, H315, H319, H332P210, P280, P301+P312, P303+P361+P353, P304+P340+P312, P305+P351+P338NFPA 704 (fire diamond)
2
3
0
Flash point20 °C (68 °F; 293 K) 482 °C (900 °F; 755 K) Explosive limits1.8–12.4% 5 ppm (TWA) Lethal dose or concentration (LD, LC): 891 mg/kg (rat, oral)
1500 mg/kg (mouse, oral)
1580 mg/kg (rat, oral) 9000 ppm (rat, 1 hr) NIOSH (US health exposure limits):
PEL (Permissible)
TWA 5 ppm (15 mg/m)
REL (Recommended)
TWA 5 ppm (15 mg/m)
IDLH (Immediate danger)
1000 ppm Related compounds
Related amines
Picoline
Quinoline
Related compounds
Aniline
Pyrimidine
PiperidineSupplementary data page Pyridine (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Pyridine is a basicheterocyclicorganic compound with the chemical formulaC5H5N. It is structurally related to benzene, with one methine group(=CH−) replaced by a nitrogen atom (=N−). It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow. The pyridine ring occurs in many commercial compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide.

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