Tetrahydrofuran 109-99-9 | 99.90% High-Purity Solvent for Synthesis and Coatings
September 30, 2026 · Product Guide
Basic information
| Item | Value |
|---|---|
| Product name | Tetrahydrofuran |
| Synonyms | THF; oxolane; butylene oxide; 1,4-epoxybutane; tetramethylene oxide |
| CAS number | 109-99-9 |
| Molecular formula | C4H8O |
| Molecular weight | 72.11 g/mol |
| Appearance | Colorless, mobile liquid |
| Assay / Purity | 99.90% min (typical commercial grade) |
| Solubility | Miscible with water, alcohols, ketones, esters, ethers, aromatic hydrocarbons |
| Boiling point | 66 °C |
| Flash point | -14 °C (closed cup) |
| Packaging | 180 kg/drum |
| HS code | 2932.11.00 |
| Storage | Cool, dry, well-ventilated area; away from ignition sources; under nitrogen; protect from light |
| Main uses | Solvent for polymers and resins; reaction medium for organometallic and pharmaceutical synthesis; precursor to polytetramethylene ether glycol (PTMEG); coatings, adhesives, inks |
1. Overview
Tetrahydrofuran is a cyclic ether with the formula C4H8O. It is a colorless, low-viscosity liquid that is water-miscible and acts as an aprotic solvent of moderate polarity. Its ability to dissolve a wide range of polar and nonpolar compounds makes it a versatile reaction medium for organic synthesis, polymer processing, and formulation of coatings and adhesives. The high purity grade (99.90%) is essential for reproducible performance in sensitive applications.
Industrially, tetrahydrofuran is a key building block in the production of polyurethane elastomers, spandex fibers, and thermoplastic polyurethanes via its role as a precursor to polytetramethylene ether glycol (PTMEG). It is also a preferred solvent in pharmaceutical manufacturing, electronics cleaning, and lithium-ion battery electrode fabrication. Its miscibility with water and organic solvents allows formulators to adjust drying rates and solubility profiles without phase separation.
2. Manufacturing and supply
Tetrahydrofuran is produced commercially by acid-catalyzed dehydration of 1,4-butanediol or by the Reppe process from acetylene and formaldehyde. The crude product undergoes multiple distillation steps to reach the 99.90% assay required for demanding applications. Typical commercial grade is stabilized with a phenolic antioxidant to inhibit peroxide formation during storage and transport. Supply is available in 180 kg drums, and larger bulk quantities can be arranged. Quality control includes gas chromatography for purity, water content by Karl Fischer titration, and peroxide testing.
3. How it works
- Solvency: Tetrahydrofuran has a moderate dielectric constant and a strong dipole moment, enabling it to solvate both polar and nonpolar species. It dissolves many polymers—such as PVC, polyurethane, and polyvinylidene fluoride (PVDF)—that are insoluble in simpler hydrocarbons.
- Aprotic nature: As an aprotic solvent, it lacks acidic protons, so it does not quench strong bases. This makes it the solvent of choice for Grignard and organolithium reactions, where reactive intermediates must survive.
- Water miscibility: Complete miscibility with water allows homogeneous reactions and solvent exchange. However, it also forms a low-boiling azeotrope (about 95% THF / 5% water at 64 °C), which affects drying and recovery operations.
- Low viscosity: The low viscosity (0.48 mPa·s at 25 °C) improves mass transfer in reactions, pumping, and coating flow, leading to uniform films and faster processing.
- Peroxide formation: On exposure to air and light, tetrahydrofuran can form explosive peroxides. Stabilizers and regular testing are necessary to manage this hazard.
4. Application areas in detail
Pharmaceutical and fine chemical synthesis
Tetrahydrofuran is a workhorse solvent for pharmaceutical API synthesis. It is used in Grignard reactions, hydride reductions, and peptide coupling steps. Downstream products include antihistamines, antibiotics, steroids, and other active pharmaceutical ingredients. Its aprotic character and water miscibility allow reactions to be run at low temperatures and then quenched into water for easy workup. It is also used in tablet coating formulations and in the preparation of amorphous solid dispersions for poorly soluble drugs.
Polymer and resin production
A major outlet is the polymerization of tetrahydrofuran to polytetramethylene ether glycol (PTMEG), a key intermediate for polyurethane elastomers, spandex (elastane) fibers, thermoplastic polyurethanes (TPU), and polyurethane foams used in footwear, automotive seating, and medical devices. Tetrahydrofuran also serves as a solvent for solution casting of polymer films and membranes, including PVDF membranes for water filtration and polyethersulfone hollow fibers. In PVC processing, it is used in cements and topcoats that bond or finish pipe, fittings, and profiles.
Coatings, adhesives, and inks
In the coatings industry, tetrahydrofuran dissolves vinyl resins, cellulosic esters, and acrylics to produce coatings with good flow and leveling. It is found in flexible packaging adhesives, pressure-sensitive adhesives, and reactive polyurethane adhesives. Printing inks—especially those for flexographic and gravure processes—use tetrahydrofuran as a fast-evaporating solvent that ensures sharp print quality on plastic films. Its water miscibility allows formulators to balance drying speed and viscosity without adding co-solvents that would separate.
Electronics and battery manufacturing
High-purity tetrahydrofuran is used in electronics manufacturing for cleaning residues from printed circuit boards, stripping photoresists, and as a carrier solvent for specialty electronic chemicals. In lithium-ion battery production, it is a preferred solvent for dissolving PVDF binder to create electrode slurries. These slurries are coated onto current collectors to form cathodes and anodes. The solvent must be free of water and metal ions to avoid cell degradation. Its low viscosity and volatility help produce uniform, crack-free electrode coatings.
Laboratory and analytical applications
Tetrahydrofuran is a common mobile phase in gel permeation chromatography (GPC) for polymer molecular weight determination. It is also used as a solvent for nuclear magnetic resonance (NMR) spectroscopy and for air-sensitive organometallic chemistry. In research laboratories, it enables the preparation of samples that are insoluble in other solvents. Its consistent purity grade is critical to avoid baseline drift and column damage in analytical instruments.
Other industrial uses
Beyond the main areas, tetrahydrofuran serves as an extraction solvent in the purification of natural products and as a reaction medium for hydroboration and other transformations. It is used in the manufacture of agrochemicals, dyes, and pigments. In some formulations, it acts as a coupling solvent to homogenize systems that contain both aqueous and organic phases, such as in cleaning concentrates and agrochemical emulsifiable concentrates.
5. Comparison with alternatives
| Alternative | Key difference | Practical implication |
|---|---|---|
| 1,4-Dioxane | Higher boiling point (101 °C), also water-miscible, but classified as a probable carcinogen | Choose 1,4-dioxane only when higher temperature is needed; tetrahydrofuran is preferred for lower-temperature reactions and easier recovery |
| Dimethylformamide (DMF) | Higher polarity, higher boiling point (153 °C), water-miscible, but toxic and difficult to remove | Tetrahydrofuran offers lower toxicity and easier stripping, but DMF may be needed for very polar substrates |
| Dimethyl sulfoxide (DMSO) | Very high polarity, high boiling point, strong solvation, but difficult to dry and remove | Use tetrahydrofuran for volatile systems and organometallic reactions; DMSO for high-polarity, high-temperature chemistry |
| Acetonitrile | Similar aprotic polarity, water-miscible, but higher toxicity and higher cost | Tetrahydrofuran is often more economical and provides better polymer solubility, though acetonitrile is preferred in HPLC |
| Dichloromethane | Lower polarity, not water-miscible, low boiling point, but toxic and regulated | Tetrahydrofuran provides water miscibility and higher solvency for polar polymers; dichloromethane is chosen for nonpolar extractions |
| Toluene | Nonpolar, not water-miscible, higher boiling point, less toxic | Tetrahydrofuran is required for polar or water-miscible systems; toluene is used for nonpolar reactions and azeotropic drying |
| 2-Methyltetrahydrofuran | Bio-based, higher boiling point (80 °C), less water-miscible, lower peroxide risk | 2-Methyltetrahydrofuran is a greener alternative for some reactions, but tetrahydrofuran remains preferred when full water miscibility and lower viscosity are needed |
Tetrahydrofuran is chosen when a water-miscible, aprotic solvent of moderate polarity and low viscosity is required, especially for organometallic reactions, polymer dissolution, and coating formulations. Alternatives may be selected for higher temperature, lower toxicity, or bio-based sourcing, but they often compromise on solvency, recovery, or reactivity.
6. Handling, storage and compliance
Store tetrahydrofuran in a cool, dry, well-ventilated area away from heat, sparks, and open flames. Keep containers tightly closed and under a nitrogen blanket to prevent peroxide formation. Protect from direct sunlight. Use grounded equipment and avoid static discharge. Personal protective equipment includes chemical splash goggles, a face shield, impervious gloves (butyl rubber or equivalent), and flame-retardant clothing. Respiratory protection may be needed if ventilation is inadequate.
Transport classification: UN 2056, Class 3 (flammable liquid), Packing Group II. It is regulated as a VOC in many jurisdictions and may be subject to reporting under chemical inventory and air quality regulations. Consult local regulations for permissible exposure limits, storage thresholds, and waste disposal. Spills should be absorbed with inert material and disposed of according to hazardous waste rules.
FAQ
Q1. What is the CAS number of tetrahydrofuran? Tetrahydrofuran has the CAS number 109-99-9. This identifier is used for regulatory, safety, and inventory purposes worldwide.
Q2. Is tetrahydrofuran miscible with water? Yes, tetrahydrofuran is fully miscible with water in all proportions. This property enables homogeneous reactions and simplifies workup by water quenching.
Q3. What is the typical purity of commercial tetrahydrofuran? The typical commercial grade is 99.90% assay, often stabilized with a phenolic antioxidant. Higher purity grades are available for electronics and pharmaceutical applications.
Q4. How should tetrahydrofuran be stored to prevent peroxide formation? Store under nitrogen, away from light and heat, and test for peroxides regularly. Stabilizers such as butylated hydroxytoluene are added to commercial grades to inhibit peroxide formation.
Q5. What are the main industrial uses of tetrahydrofuran? Major uses include the production of polytetramethylene ether glycol (PTMEG) for polyurethane and spandex, as a solvent for PVC and PVDF, in pharmaceutical synthesis, and in lithium-ion battery electrode manufacturing.
Q6. Is tetrahydrofuran a VOC? Yes, tetrahydrofuran is classified as a volatile organic compound (VOC) in many regions. Its use may be subject to emission controls and reporting requirements.
Q7. What is the flash point of tetrahydrofuran? The flash point is approximately -14 °C (closed cup). It is highly flammable and must be handled with appropriate fire precautions.
Q8. Can tetrahydrofuran be used in lithium-ion battery production? Yes, high-purity tetrahydrofuran is used to dissolve PVDF binder for electrode slurries. It must be free of water and metal ions to ensure battery performance.