Pyridine

Names
Preferred IUPAC name Pyridine[1]
Systematic IUPAC name Azabenzene
Other names Azine Azinine
Identifiers
CAS Number	110-86-1 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:16227 N
ChEMBL	ChEMBL266158 Y
ChemSpider	1020 Y
ECHA InfoCard	100.003.464
EC Number	203-809-9
KEGG	C00747 Y
PubChem CID	1049
UNII	NH9L3PP67S Y
CompTox Dashboard (EPA)	DTXSID9021924
InChI InChI=1S/C5H5N/c1-2-4-6-5-3-1/h1-5H Y Key: JUJWROOIHBZHMG-UHFFFAOYSA-N Y InChI=1/C5H5N/c1-2-4-6-5-3-1/h1-5H Key: JUJWROOIHBZHMG-UHFFFAOYAY
SMILES c1ccncc1
Properties
Chemical formula	C5H5N
Molar mass	79.102 g·mol−1
Appearance	Colorless liquid[2]
Odor	Nauseating, fish-like[3]
Density	0.9819 g/mL (20 °C)[4]
Melting point	−41.63 °C (−42.93 °F; 231.52 K)[4]
Boiling point	115.2 °C (239.4 °F; 388.3 K)[4]
Solubility in water	Miscible[4]
log P	0.65[5]
Vapor pressure	16 mmHg (20 °C)[3]
Acidity (pKa)	5.23 (pyridinium)[6]
Conjugate acid	Pyridinium
Magnetic susceptibility (χ)	−48.7·10−6 cm3/mol[7]
Thermal conductivity	0.166 W/(m·K)[8]
Refractive index (nD)	1.5095 (20 °C)[4]
Viscosity	0.879 cP (25 °C)[9]
Dipole moment	2.215 D[10]
Thermochemistry[11]
Heat capacity (C)	132.7 J/(mol·K)
Std enthalpy of formation (ΔfH⦵298)	100.2 kJ/mol
Std enthalpy of combustion (ΔcH⦵298)	−2.782 MJ/mol
Hazards[15]
Occupational safety and health (OHS/OSH):
Main hazards	Low to moderate hazard[13]
GHS labelling:
Pictograms	[12]
Signal word	Danger
Hazard statements	H225, H302, H312, H315, H319, H332[12]
Precautionary statements	P210, P280, P301+P312, P303+P361+P353, P304+P340+P312, P305+P351+P338[12]
NFPA 704 (fire diamond)	2 3 0
Flash point	20 °C (68 °F; 293 K)[16]
Autoignition temperature	482 °C (900 °F; 755 K)[16]
Explosive limits	1.8–12.4%[3]
Threshold limit value (TLV)	5 ppm (TWA)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	891 mg/kg (rat, oral) 1500 mg/kg (mouse, oral) 1580 mg/kg (rat, oral)[14]
LC50 (median concentration)	9000 ppm (rat, 1 hr)[14]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 5 ppm (15 mg/m3)[3]
REL (Recommended)	TWA 5 ppm (15 mg/m3)[3]
IDLH (Immediate danger)	1000 ppm[3]
Related compounds
Related amines	Picoline Quinoline
Related compounds	Aniline Pyrimidine Piperidine
Supplementary data page
Pyridine (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is YN ?) Infobox references

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 (=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. due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity.^{[page needed][17]} The pyridine ring occurs in many important 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.^[2]

Properties

Physical properties

Pyridine is diamagnetic. Its critical parameters are: pressure 5.63 MPa, temperature 619 K and volume 248 cm³·mol⁻¹.^[19] In the temperature range 340–426 °C its vapor pressure p can be described with the Antoine equation

${\displaystyle \log _{10}p=A-{\frac {B}{C+T}}}$

where T is temperature, A = 4.16272, B = 1371.358 K and C = −58.496 K.^[20]

Zdroj:https://en.wikipedia.org?pojem=Pyridine
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