Tetrahydrofuran Description

Tetrahydrofuran, or THF is a colorless, volatile cycloaliphatic ether with an odor characteristic of acetone. It is chemically neutral, highly polar and miscible with water. Synthetically derived THF is made by eliminating water from 1,4-butanediol. THF has excellent solvent power for numerous organic substances. It is miscible with water and all common  organic solvents.

Chief among its uses is the production of certain polymers. THF is used as a precursor to the formation of many complex polymers, as its solvent properties allow for the mixing and combining of simple polymers in solution. When mixed with acids, tetrahydrofuran itself can be polymerized, and the resulting polymers have many uses, such as the manufacture of urethanes and polyurethanes. Some of these materials are very common in everyday products, like certain fabrics with elastic properties.

Its strong solvent properties make tetrahydrofuran highly suitable for many other uses, as well. It is used in making adhesives that are used with polyvinyl chloride (PVC) and for improving certain qualities of other materials, such as cellophanes and magnetic tapes, although this usage is becoming less common in the digital age as these tapes are phased out in favor of digital recording and storage media. THF is a key component in the manufacture of a class of protective coatings and is used in the production and extraction of many organic and organometallic compounds, including some drugs.

Since THF is very soluble in water and has a relatively low boiling point, signficant amounts are often released into the environment, causing contamination problems. It is not considered to be readily degradable, and concerns of environmental contamination have been raised.

Bernhardt and Diekmann performed studied the pathway for THF degradation by Rhodococcus ruber DSM 44190. The pathway shown below is hypothetical. Not all intermediates were detected(e.g. 2-hydroxytetrahydrofuran). In fact, the isomerization of this chemcial might occur spontaneously and not require an enzyme. However, degradation experiments using the same organism were performed with a similar compound, 2,5-dimethyltetrahydrofuran, and those data support the proposed tetrahydrofuran(CAS No. 109-99-9) pathway.

THF can be potentially dangerous and must be handled under strictly controlled conditions for safety. It can form dangerous flammable chemicals called peroxides when exposed to air, which can ignite or explode very easily. For this reason, additives such as BHT are mixed with tetrahydrofuran to stabilize it, which reduces its tendency to spontaneously form these dangerous peroxides. THF is also stored in sealed containers with pure nitrogen gas to prevent it from reacting with air. It is also highly flammable and can give off toxic materials as a by-product of burning.

All about Tetrahydrofuran

Tetrahydrofuran, or THF, is a common organic solvent of the ether family. A colorless, somewhat volatile liquid at room temperature, it is similar to diethyl ether, the chemical once widely used as an anesthetic, with a similar odor, but does not share its anesthetic properties. It has the chemical formula (CH2)4O and is known by a number of other names, most of which have fallen out of common use. It is popular as a solvent, as it is soluble in most other common solvents like water, alcohols, esters, and acetone, is chemically inactive, and acts as a strong solvent on many materials, particularly organics. Tetrahydrofuran is used extensively in the manufacture of many polymers as well as other products such as certain adhesives and pharmaceuticals.

Production
Tetrahydrofuran was traditionally produced using the Furfural process where furfural, extracted from corn husks, is used as the raw material in production.  However, the disadvantage of this method is that supply depended on agricultural conditions and, could not therefore be relied upon, so a move was made to the fully synthetic Reppe process.

In the Reppe process, ethyne and formaldehyde are used as the raw materials that produce 1,4 butanediol, at the first step.  Tetrahydrofuran can then be obtained by dehydration under the existence of an acidic ion exchange resin.  This is currently the main method of extraction employed throughout the world.

The world annual production of tetrahydrofuran is approximately 200,000 tonnes and it is predicted that demand and production will grow as the Chinese economy continues to expand.

General Uses
Magnetic Tape:
Solvents are needed to dissolve the raw binder polymers and to provide a fluid medium for the pigment dispersion in the magnetic tape paint. THF, with its high purity, excellent solvency power and favorable conductivity value, is fast becoming the solvent of choice.

Adhesives: THF solvents can be used to join rigid plastic pipe and in compounded cements for leather, plastic sheet film extrusions and for molded plastic parts assemblies. The combined advantages of rapid solvent activity, minimum gelation and lower relative viscosities for resin solutions, makes it an attractive solvent choice.

Reaction Solvent: THF is stable under very strongly basic conditions and is therefore the choice for numerous specialty syntheses which involve complex catalysts and Grignard reagents. Also, this product is a preferred solvent for anionic polymerization.

PVC Cements: THF-PVC formulations meet NSF standards. THF solvent cements can be formulated with additional solvents and inorganic fillers to control set time. It can also function as a PVC-type cleaner before joint formation.

Storage
This cousin to common ether can be potentially dangerous and must be handled under strictly controlled conditions for safety. It can form dangerous flammable chemicals called peroxides when exposed to air, which can ignite or explode very easily. For this reason, additives such as BHT are mixed with tetrahydrofuran to stabilize it, which reduces its tendency to spontaneously form these dangerous peroxides. THF is also stored in sealed containers with pure nitrogen gas to prevent it from reacting with air. It is also highly flammable and can give off toxic materials as a by-product of burning.  It should be stored in tightly sealed metal drums and/or amber glass containersstored and stored in a cool, dry, and well-ventilated area that is free from the risk of ignition.