Tetrahydrofuran (CAS No. 109‑99‑9; formula C₄H₈O; MW ≈ 72.1 g/mol) is a colorless, volatile, water‑miscible cyclic ether with an ether-like odor, low viscosity, and a boiling point around 66 °C. Industrial-grade THF is stabilized to prevent peroxide formation and serves as a versatile solvent and chemical intermediate.