Tetrahydrofuran

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Categories: Ether solvents | Oxygen heterocycles

Tetrahydrofuran

Image:Tetrahydrofuran-scaledBallAndStick.png
IUPAC name	Oxacyclopentane
Other names	THF, tetrahydrofuran, 1,4-epoxybutane, butylene oxide, cyclotetramethylene oxide, oxacyclopentane, diethylene oxide, oxolane, furanidine, hydrofuran, tetra-methylene oxide
Identifiers
CAS number	[109-99-9]
RTECS number	LU5950000
SMILES	C1CCCO1
Properties
Molecular formula	C₄H₈O
Molar mass	72.11 g/mol
Appearance	colorless liquid
Density	0.8892 g/cm³ @ 20 °C, liquid
Melting point	-108.4 °C (164.75 K)
Boiling point	66 °C (339.15 K)
Solubility in water	Miscible
Viscosity	0.48 cP at 25 °C
Structure
Molecular shape	envelope
Dipole moment	1.63 D (gas)
Hazards
MSDS	External MSDS
EU classification	Flammable (F) Irritant (Xi)
NFPA 704	3 2 0
R-phrases	R11, R19, R36/37
S-phrases	S16, S29, S33
Flash point	-14 °C
Related compounds
Related heterocycles	Furan Pyrrolidine Dioxane
Related compounds	Diethyl ether
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

"THF" redirects here. For other uses, see THF (disambiguation).

Tetrahydrofuran, also known as THF, is a heterocyclic organic compound with the formula (CH₂)₄O). It is a colourless low-viscosity liquid with a smell similar to diethyl ether. It is one of the most polar ethers. THF is the fully hydrogenated analog of the aromatic compound furan.

1 Solvent properties
2 Preparation
3 Precautions
4 See also
5 References
6 External links

Solvent properties

THF is an aprotic solvent with a dielectric constant of 7.6. It is a moderately polar, aprotic solvent that dissolves a wide range of nonpolar and polar compounds.

THF can often be substituted for diethyl ether when a higher-boiling solvent is required. Thus THF, like diethyl ether, is often used for hydroborations used to synthesize primary alcohols. Both ethers have an oxygen atom which can coordinate to the electron-deficient boron atom, forming an adduct. Similarly, THF or diethyl ether are often used as solvents for Grignard reagents because of the oxygen atom's ability to coordinate to the magnesium ion component of the Grignard reagent. In addition, the oxygen atom has no acid hydrogen that can undergo acid-base reaction with the Grignard reagent. 2-methyltetrahydrofuran has become a popular THF alternative, based on its similar properties to THF, but having a lower melting point (useful for lower temperature reactions), as well as having a higher boiling point (useful for solvent retention under reflux).

THF is often used in polymer science. For example, it can be used to dissolve rubber prior to determining its molecular mass using gel permeation chromatography.

THF can be polymerized by strong acids to give a linear polymer called poly(tetramethylene ether) glycol (PTMEG),(CAS Registry Number, [25190-06-1], also known as PTMO, polytetramethylene oxide. The primary use of this polymer is to make elastomeric polyurethane fibers like Spandex.^[1].

It is often used industrially to degrease metal parts.

Preparation

THF can be synthesized by catalytic hydrogenation of furan^[2].

The major industrial process for making THF is the acid-catalyzed dehydration of 1,4-butanediol.^[3]. Du Pont developed a process for producing THF by oxidizing n-butane to crude maleic anhydride, followed by catalytic hydrogenation of maleic anhydride to THF.^[3]^[4]

Precautions

THF tends to form peroxides on storage in air. As a result, THF should not be distilled to dryness, which can leave a residue of highly-explosive peroxides. Commercial THF is therefore often inhibited with BHT.

References

^ "Polyethers, Tetrahydrofuran and Oxetane Polymers by Gerfried Pruckmayr, P. Dreyfuss, M. P. Dreyfuss". Kirk‑Othmer Encyclopedia of Chemical Technology. (1996). John Wiley & Sons, Inc.
^ Morrison, Robert Thornton; Boyd, Robert Neilson: Organic Chemistry, 2nd ed., Allyn and Bacon 1972, p 569
^ ^a ^b "Ethers, by Lawrence Karas and W. J. Piel". Kirk‑Othmer Encyclopedia of Chemical Technology. (2004). John Wiley & Sons, Inc. Retrieved on 2007-09-05.
^ Merck Index of Chemicals and Drugs, 9th ed. monograph 8929