THF: Properties and Applications in Chemical Synthesis

What is THF and why is it used in organic chemistry?

THF, or tetrahydrofuran, is a cyclic ether with the chemical formula C₄H₈O. It is a colourless, highly flammable liquid with a low boiling point (66 °C) and high solubility in water and many organic solvents. Its strong polarity and aprotic nature make it ideal for dissolving organometallic compounds such as lithium and magnesium reagents. THF is widely used in Grignard reactions, lithium aluminium hydride reductions, and other nucleophilic reactions where solvent stability and solvation power are critical.

How is THF handled and stored safely?

Due to its high flammability and tendency to form explosive peroxides upon prolonged exposure to air, THF must be stored in dark, airtight containers with stabilisers such as BHT (butylated hydroxytoluene). It is also important to test for peroxides before use, especially in large-scale or high-risk applications. THF is regulated under REACH and GHS, with appropriate safety data sheets (SDS) required. Its use in laboratories should follow strict protocols to prevent fire hazards and ensure worker safety.

What are the regulatory and environmental considerations?

THF is classified as a hazardous substance under EU REACH and the UK’s equivalent regulations. It is also listed under the US EPA’s TSCA. While not persistent in the environment, it can contribute to air pollution if released in large quantities. Proper disposal via licensed waste contractors is required. In pharmaceutical and biotech manufacturing, THF must meet USP, EP, or BP specifications to ensure purity and compliance with regulatory standards.

Related concepts

THF is often used alongside other solvents such as diethyl ether, DMSO, and acetonitrile. It is also commonly dried using molecular sieves or distillation over sodium metal to remove water and peroxides.