Tetrahydrofuran appears as a clear colorless liquid with an ethereal odor. Less dense than water. Flash point 6°F. Vapors are heavier than air. Oxolane is a cyclic ether that is butane in which one hydrogen from each methyl group is substituted by an oxygen. It has a role as a polar aprotic solvent. It is a member of oxolanes, a saturated organic heteromonocyclic parent, a cyclic ether and a volatile organic compound.