Tetrahydrofuran (THF) is colorless, miscible with water, and has a small viscous organic liquid at ambient temperature and pressure. This type of annular ether can be written in the chemical style (CH2) 4O. Because of its liquid range is very long, it is a commonly used medium polar non-proton solvent. Its main use is the precursor of polymers. Although the odor and chemical properties of THF are similar to those of ethyl ether, the anesthetic effect is poor.