Tetrahydrofuran

Cyclic chemical compound, (CH2)4O

Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water-miscible organic liquid with low viscosity. It is mainly used as a precursor to polymers.

From Wikipedia, under CC BY-SA. More on occurri.