Thiophene
Chemical name	Thiophene
Chemical formula	C4H4S
Molecular mass	84.14 g/mol
Density	1.051 g/ml
Melting point	-38.2 °C
Boiling point	84.4 °C
CAS number	110-02-1
SMILES	C1=CC=CS1

Thiophene is a heterocyclic aromatic organic compound. It is a clear colorless lachrymatory liquid with a strong and very unpleasant odor. Thiophene is often found naturally occurring in petroleum in concentrations up to several percent.

Thiophene is aromatic because one of the two electron pairs of the sulfur atom contributes to the delocalized pi electron system, in a manner analogous to the compound furan.

See also

• Pyrrole, an analog with a nitrogen atom instead of the sulfur atom.
• Furan, an analog with an oxygen instead of the sulfur atom.
• Simple aromatic rings