Benzene
From Memory Alpha, the free Star Trek reference
Benzene is an aromatic hydrocarbon with the chemical formula C6H6. It is an industrial solvent and used as an additive in fossil based fuels.
The complex hydrocarbon used on Earth called gasoline is made of such components as benzene, ethylene and acetylene. (VOY: "The 37's")
Yalosians require ten percent of a room's atmosphere to be benzene, as well as sixty percent nitrogen and thirty percent hydrogen fluoride. (DS9: "Improbable Cause")
