Tetrahydrofuran distilled pure has many applications as a solvent, reaction medium or starting product for syntheses. Only a few of the many examples of its usefulness are presented below.
Coatings Artificial leather: PVC or polyurethane spread-coating systems contain THF alone or in blends with other solvents. Magnetic tapes: The abrasion resistance of video, computer or audio tapes can be improved by applying coatings derived from polyurethane or PVC in which the solvent phase is a blend of THF and toluene.
Cellophane: The mechanical strength, impermeability to water vapor, heatsealability and printability of cellophane can be improved by applying coatings formulated from poly(vinylidene chloride) (PVDC), in which the solvent phase is a blend of THF and toluene.
Adhesives: Tetrahydrofuran is suitable for the production of PVC adhesives for rigid PVC. It is used as a swelling agent for bonding plasticized PVC film and for fabricating PVC pipe systems. In both cases, the evaporation rate can be regulated by blending the THF with another solvent, such as cyclohexanone. Specialty Coating Systems By virtue of its excellent solvent power, THF allows the preparation of highly concentrated solutions of various polymers. These solutions can be diluted to the appropriate final concentration by adding thinners. Although THF evaporates rapidly, films formed from its solutions have very minimal tendency toward blushing during drying.
Reaction Medium Tetrahydrofuran is a reaction medium, used primarily by the pharmaceutical industry, e. g., in Grignard syntheses or lithium aluminum hydride reductions. In fact, it is the only medium in which many Grignard compounds can be obtained. By Virtue of its good solvent power for alkali metals, THF is a useful reaction medium for the production of organometallic compounds.
Anionic polymerization reactions can be carried out in THF as well. Extractant Some drugs, e. g., alkaloids, can be obtained in the pure form from their natural or synthetic precursors by extraction with THF.
Also, impurities such as fat, wax or substances with a high molecular mass can be removed from compounds that are insoluble in THF.
Starting Material for Syntheses Tetrahydrofuran is the starting material for a number of syntheses. For instance, ethers with a high molecular mass and chains of various lengths can be obtained by polymerization. The oxygen in the pentagonal ring can be replaced by nitrogen or sulfur to yield other five-membered heterocycles such as tetrahydrothiophene or pyrrolidine. The ring can be cleaved with halocarbons, e. g., 1,4-dihalobutane, or by oxidation (succinaldehyde and butyrolactone).
Along with above applications THF also finds wide applications in Pharmaceutical industry.