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| Names | |||
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| Preferred IUPAC name Oxolane[1] | |||
| Systematic IUPAC name 1,4-Epoxybutane 1-Oxacyclopentane | |||
Other names
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| Identifiers | |||
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3D model (JSmol) | |||
| Abbreviations | THF | ||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.003.389 | ||
| RTECS number |
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| UNII | |||
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| Properties | |||
| C4H8O | |||
| Molar mass | 72.107 g·mol−1 | ||
| Appearance | Colorless liquid | ||
| Odor | Ether-like[2] | ||
| Density | 0.8876 g/cm3 at 20 °C, liquid[3] | ||
| Melting point | −108.4 °C (−163.1 °F; 164.8 K) | ||
| Boiling point | 66 °C (151 °F; 339 K)[4][3] | ||
| Miscible | |||
| Vapor pressure | 132 mmHg at 20 °C[2] | ||
Refractive index (nD) | 1.4073 at 20 °C[3] | ||
| Viscosity | 0.48 cP at 25 °C | ||
| Structure | |||
| Envelope | |||
| 1.63 D (gas) | |||
| Hazards | |||
| GHS labelling: | |||
   [5] | |||
| Danger | |||
| H225,H302,H319,H335,H351[5] | |||
| P210,P280,P301+P312+P330,P305+P351+P338,P370+P378,P403+P235[5] | |||
| NFPA 704 (fire diamond) | |||
| Flash point | −14 °C (7 °F; 259 K) | ||
| Explosive limits | 2–11.8%[2] | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) |
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LC50 (median concentration) | 21000 ppm (rat, 3 h)[6] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 200 ppm (590 mg/m3)[2] | ||
REL (Recommended) | TWA 200 ppm (590 mg/m3) ST 250 ppm (735 mg/m3)[2] | ||
IDLH (Immediate danger) | 2000 ppm[2] | ||
| Related compounds | |||
Relatedheterocycles | Furan Pyrrolidine Dioxane | ||
Related compounds | Diethyl ether | ||
| Supplementary data page | |||
| Tetrahydrofuran (data page) | |||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Tetrahydrofuran (THF), oroxolane, is anorganic compound with the formula (CH2)4O. The compound is classified asheterocyclic compound, specifically a cyclicether. It is a colorless, water-miscible organic liquid with lowviscosity. It is mainly used as aprecursor to polymers.[8] Beingpolar and having a wide liquid range, THF is a versatilesolvent. It is an isomer of another solvent,butanone.
About 200,000tonnes of tetrahydrofuran are produced annually.[9] The most widely used industrial process involves the acid-catalyzed dehydration of1,4-butanediol.Ashland/ISP is one of the biggest producers of this chemical route. The method is similar to the production ofdiethyl ether fromethanol. The butanediol is derived fromcondensation ofacetylene withformaldehyde followed byhydrogenation.[8]DuPont developed a process, for producing THF byoxidizingn-butane to crudemaleic anhydride, followed by catalytic hydrogenation.[10] A third major industrial route entailshydroformylation ofallyl alcohol followed by hydrogenation to1,4-butanediol.
THF can also be synthesized by catalytic hydrogenation offuran.[11][12] This allowscertain sugars to be converted to THF via acid-catalyzed digestion tofurfural anddecarbonylation to furan,[13] although this method is not widely practiced. THF is thus derivable from renewable resources.
In the presence ofstrong acids, THF converts to a linear polymer calledpoly(tetramethylene ether) glycol (PTMEG), also known as polytetramethylene oxide (PTMO):
This polymer is primarily used to makeelastomericpolyurethane fibers likespandex.[14]
The other main application of THF is as an industrial solvent forpolyvinyl chloride (PVC) and invarnishes.[8] It is anaproticsolvent with adielectric constant of 7.6. It is a moderately polar solvent and can dissolve a wide range of nonpolar and polar chemical compounds.[15] THF is water-miscible and can form solidclathrate hydrate structures with water at low temperatures.[16]
THF has been explored as a miscible co-solvent in aqueous solution to aid in the liquefaction and delignification of plantlignocellulosic biomass for production of renewable platform chemicals andsugars as potential precursors tobiofuels.[17] Aqueous THF augments the hydrolysis ofglycans from biomass and dissolves the majority of biomass lignin making it a suitable solvent for biomass pretreatment.
THF is often used in polymer science. For example, it can be used to dissolvepolymers prior to determining their molecular mass usinggel permeation chromatography. THF dissolves PVC as well, and thus it is the main ingredient in PVC adhesives. It can be used to liquefy old PVC cement and is often used industrially todegrease metal parts.
THF is used as a component in mobile phases forreversed-phase liquid chromatography. It has a greater elution strength thanmethanol oracetonitrile, but is less commonly used than these solvents.
THF is used as a solvent in 3D printing when printing withPLA,PETG and substantially similar filaments. It can be used to clean clogged 3D printer parts, to remove extruder lines and add a shine to the finished product as well as tosolvent weld printed parts.
In the laboratory, THF is a popular solvent when its water miscibility is not an issue. It is morebasic than diethyl ether[18] and forms strongercomplexes withLi+,Mg2+, andboranes. It is a popular solvent forhydroboration reactions and fororganometallic compounds such asorganolithium andGrignard reagents.[19] Thus, while diethyl ether remains the solvent of choice for some reactions (e.g., Grignard reactions), THF fills that role in many others, where strong coordination is desirable and the precise properties of ethereal solvents such as these (alone and in mixtures and at various temperatures) allows fine-tuning modern chemical reactions.
Commercial THF contains substantial water that must be removed for sensitive operations, e.g. those involvingorganometallic compounds. Although THF is traditionally dried bydistillation from an aggressivedesiccant such as elementalsodium,molecular sieves have been shown to be superior water scavengers.[20]
In the presence of asolid acid catalyst, THF reacts withhydrogen sulfide to givetetrahydrothiophene.[21]
THF is a Lewis base that bonds to a variety ofLewis acids such asI2,phenols,triethylaluminum andbis(hexafluoroacetylacetonato)copper(II). THF has been classified in theECW model and it has been shown that there is no one order of base strengths.[23] Many complexes are of the stoichiometry MCl3(THF)3.[24]
THF is a relatively acutely nontoxic solvent, with themedian lethal dose (LD50) comparable to that foracetone. However, chronic exposure is suspected of causing cancer.[5][25] Reflecting its remarkable solvent properties, it penetrates the skin, causing rapid dehydration. It is highly flammable. THF dissolves or penetrates most polymer glove materials in a very short period of time; onlyLinear low-density polyethylene (LLDPE) laminated gloves are capable of protecting against it for long time periods, similar to most ketones.[26]Polyvinyl alcohol (PVA) coated gloves are capable of providing protection for nearly an hour, but because PVA is water soluble they are only effective in low humidity environments and when working with anhydrous solvents.[27] Even very thick nitrile or nitrile-neoprene gloves degrade in under 10 minutes.[28]
One danger posed by THF is its tendency to form the explosive compound 2-hydroperoxytetrahydrofuran upon reaction with air:
To minimize this problem, commercial supplies of THF are often stabilized withbutylated hydroxytoluene (BHT). Distillation of THF to dryness is unsafe because the explosive peroxides can concentrate in the residue.[citation needed]
The tetrahydrofuran ring is found in diverse natural products includinglignans,acetogenins, andpolyketide natural products.[29] Diverse methodology has been developed for the synthesis of substituted THFs.[30]
Tetrahydrofuran is one of the class of five-memberedsaturated carbon/oxygen rings calledoxolanes. There are seven possible structures, namely,[31]
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