Pyrrole

Pyrrole
Explicit structural formula of pyrrole, with aromaticity indicated by dashed bonds	Numbered skeletal formula of pyrrole
Ball-and-stick model of the pyrrole molecule	Space-filling model of the pyrrole molecule
Names
	Preferred IUPAC name 1H-Pyrrole
	Other names Azole; Imidole;
Identifiers
CAS Number	109-97-7 ;
3D model (JSmol)	Interactive image; Interactive image;
Beilstein Reference	1159
ChEBI	CHEBI:19203 ;
ChEMBL	ChEMBL16225 ;
ChemSpider	7736 ;
ECHA InfoCard	100.003.387
EC Number	203-724-7;
Gmelin Reference	1705
PubChem CID	8027;
RTECS number	UX9275000;
UNII	86S1ZD6L2C ;
UN number	1992, 1993
CompTox Dashboard (EPA)	DTXSID5021910 ;
	InChI InChI=1S/C4H5N/c1-2-4-5-3-1/h1-5H Key: KAESVJOAVNADME-UHFFFAOYSA-N ; InChI=1/C4H5N/c1-2-4-5-3-1/h1-5H;
	SMILES N1C=CC=C1; [nH]1cccc1;
Properties
Chemical formula	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.)
Magnetic susceptibility (χ)	−47.6×10−6 cm3 mol−1
Viscosity	0.001225 Pa s
Thermochemistry
Heat capacity (C)	1.903 J K−1 mol−1
Std enthalpy of; formation (ΔfH⦵298)	108.2 kJ mol−1 (gas)
Std enthalpy of; combustion (ΔcH⦵298)	2242 kJ mol−1
Hazards
NFPA 704 (fire diamond)	2 2 0
Flash point	33.33 °C (91.99 °F; 306.48 K)
Autoignition; temperature	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). verify (what is ?) Infobox references

Pyrrole is a heterocyclic, aromatic, organic compound, a five-membered ring with the formula C₄H₄NH.^[3] 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.^[4]

Pyrroles are components of more complex macrocycles, including the porphyrinogens and products derived therefrom, including porphyrins of heme, the chlorins, bacteriochlorins, and chlorophylls.^[5]

^ William M. Haynes (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton: CRC Press. pp. 3–478. ISBN 978-1-4987-5429-3.
^ International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 141. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
^ Loudon, Marc G. (2002). "Chemistry of Naphthalene and the Aromatic Heterocycles". Organic Chemistry (4th ed.). New York: Oxford University Press. pp. 1135–1136. ISBN 978-0-19-511999-2.
^ Cox, Michael; Lehninger, Albert L.; Nelson, David R. (2000). Lehninger Principles of Biochemistry. New York: Worth Publishers. ISBN 978-1-57259-153-0.
^ Jusélius, Jonas; Sundholm, Dage (2000). "The aromatic pathways of porphins, chlorins and bacteriochlorins". Phys. Chem. Chem. Phys. 2 (10): 2145–2151. Bibcode:2000PCCP....2.2145J. doi:10.1039/b000260g.

[crc97-1] William M. Haynes (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton: CRC Press. pp. 3–478. ISBN 978-1-4987-5429-3.

[2] International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 141. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.

[3] Loudon, Marc G. (2002). "Chemistry of Naphthalene and the Aromatic Heterocycles". Organic Chemistry (4th ed.). New York: Oxford University Press. pp. 1135–1136. ISBN 978-0-19-511999-2.

[4] Cox, Michael; Lehninger, Albert L.; Nelson, David R. (2000). Lehninger Principles of Biochemistry. New York: Worth Publishers. ISBN 978-1-57259-153-0.

[Jonas_Jusélius_and_Dage_Sundholm_2000_2145–2151-5] Jusélius, Jonas; Sundholm, Dage (2000). "The aromatic pathways of porphins, chlorins and bacteriochlorins". Phys. Chem. Chem. Phys. 2 (10): 2145–2151. Bibcode:2000PCCP....2.2145J. doi:10.1039/b000260g.

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