Pyrrole, or pyrrol, is a heterocyclic aromatic organic compound, a five-membered ring with the formula C₄H₅N.

Pyrroles are components of larger aromatic rings, including the porphyrins of heme, the chlorins and bacteriochlorins of chlorophyll, and the corrin ring of vitamin B12.

Pyrrole has very low basicity compared to amines and other aromatic compounds like pyridine where the ring nitrogen is not bonded to a hydrogen atom. This is because the lone pair of electrons of the nitrogen atom becomes delocalized in the aromatic ring.

Pyrrole undergoes electrophillic substitution predominantly at the 2 and 5 positions, though the substitution product at positions 3 and 4 is obtained in low yields.

In a 1994 report released by five top cigarette companies, pyrrole is one of the 599 additives to cigarettes. Its use or purpose, however, is unknown, like most cigarette additives. ^*

See also

• Polypyrrole
• Indole, a derivative with a fused benzene ring.
• Thiophene, an analog with a sulfur instead of the nitrogen atom.
• Furan, an analog with an oxygen instead of the nitrogen.
• Arsole, a non-aromatic arsenic analog.
• Pyrrolidine, the saturated hydrogenated derivative
• Simple aromatic rings
• Pyroluria

External links

• Synthesis of pyrroles (overview of recent methods)
• Substitution reaction mechanisms of nitrogen-containing heteroaromatics

References

Nitrogen heterocycles | Simple aromatic rings | Amines

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