Tetrahydrofuran

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Alias: 1,4-Epoxybutane, Oxolane, Tetramethylene oxide.

Abbreviation: THF.

Molecular formula: C₄H₈O

Molecular weight: 72.11

CAS number: 109-99-9

EINECS number: 203-726-8.

Structural formula:

Physical and Chemical Properties

Colorless transparent liquid with an odor similar to diethyl ether and acetone. Relative density (20℃): 0.889. Boiling point: 66℃, boiling range (65-67℃) with a volume fraction of distillate ≥95%, freezing point: -108.5℃, flash point: -17.2℃, autoignition temperature: 321℃, refractive index: 1.405-1.407, surface tension (20℃): 26.4 mN/m, critical temperature: 268℃, critical pressure: 5.19 MPa, vapor pressure: 15.2 kPa (15℃), 17.2 kPa (20℃), vapor density is 2.5 times that of air. Soluble in water, ethanol, diethyl ether, aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, acetone, benzene, and most other organic solvents.

Vapor can form explosive mixtures with air, with an explosion limit of 1.5%-12% (volume fraction). It can form potentially explosive peroxides upon contact with air or under light. Due to the tendency of THF to form peroxides during storage, industrial products generally contain the antioxidant BHT. Water content ≤0.2%.

LyondellBasell Industries’ specifications for tetrahydrofuran sold in the United States and Europe are: purity 99.90%, color (APHA) 10, water content 0.03%, THF hydroperoxide 0.005%, total impurities 0.05%, oxidation inhibitor 0.025%-0.035%.

Toxicity and Protection

THF is slightly toxic by inhalation and low toxicity by ingestion. The acute oral toxicity LD50 in rats is 2816 mg/kg, and the inhalation LC50 in rats is 61740 mg/m³ (3h). This product is irritating to the skin and mucous membranes. High concentrations have an anesthetic effect; foreign reports indicate that the concentration causing anesthesia in humans is 73800 mg/m³, and the human olfactory threshold is 88.5 mg/m³. Occupational exposure limits: China’s MAC is 300 mg/m³ (1996), and the US OSHA PEL (all industries) 8h TWA is 0.02% (590 mg/m³).

Properties and Uses

Tetrahydrofuran is an important organic chemical and fine chemical raw material.

Its main use in the polyurethane industry is as a monomer raw material for polytetrahydrofuran diol (PTMEG), which is also one of the main uses of THF. A small amount is also used as a solvent.