Pyrrole

Pyrrole is a heterocyclic, aromatic, organic compound, a five-membered ring with the formula C4H4NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3. Porphobilinogen, a trisubstituted pyrrole, is the biosynthetic precursor to many natural products such as heme.

Pyrrole
Names
Preferred IUPAC name
1H-Pyrrole
Other names
  • Azole
  • Imidole
Identifiers
3D model (JSmol)
1159
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.387
EC Number
  • 203-724-7
1705
RTECS number
  • UX9275000
UNII
UN number 1992, 1993
  • InChI=1S/C4H5N/c1-2-4-5-3-1/h1-5H Y
    Key: KAESVJOAVNADME-UHFFFAOYSA-N Y
  • InChI=1/C4H5N/c1-2-4-5-3-1/h1-5H
  • N1C=CC=C1
  • [nH]1cccc1
Properties
C4H5N
Molar mass 67.091 g·mol−1
Density 0.967 g cm−3
Melting point −23 °C (−9 °F; 250 K)
Boiling point 129 to 131 °C (264 to 268 °F; 402 to 404 K)
Vapor pressure 7 mmHg at 23 °C
Acidity (pKa) 17.5 (for the N−H proton)
Basicity (pKb) 13.6 (pKa 0.4 for C.A.)
−47.6×10−6 cm3 mol−1
Viscosity 0.001225 Pa s
Thermochemistry
1.903 J K−1 mol−1
108.2 kJ mol−1 (gas)
2242 kJ mol−1
Hazards
NFPA 704 (fire diamond)
2
2
0
Flash point 33.33 °C (91.99 °F; 306.48 K)
550 °C (1,022 °F; 823 K)
Explosive limits 3.1–14.8%
Safety data sheet (SDS) Chemical Safety Data
Related compounds
Related compounds
 Phosphole, arsole, bismole, stibole
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

Pyrroles are components of more complex macrocycles, including the porphyrinogens and products derived therefrom, including porphyrins of heme, the chlorins, bacteriochlorins, and chlorophylls.

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