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Tetrahydrofuran

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Tetrahydrofuran ( THF ), or oxolane , is an organic compound with the formula (CH 2 ) 4 O. The compound is classified as heterocyclic compound , specifically a cyclic ether . It is a colorless, water- miscible organic liquid with low viscosity . It is mainly used as a precursor to polymers. Being polar and having a wide liquid range, THF is a versatile solvent . It is an isomer of another solvent, butanone .

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46-439: About 200,000 tonnes of tetrahydrofuran are produced annually. The most widely used industrial process involves the acid-catalyzed dehydration of 1,4-butanediol . Ashland/ISP is one of the biggest producers of this chemical route. The method is similar to the production of diethyl ether from ethanol . The butanediol is derived from condensation of acetylene with formaldehyde followed by hydrogenation . DuPont developed

92-973: A distinct subfield culminated in the Nobel Prizes to Ernst Fischer and Geoffrey Wilkinson for work on metallocenes . In 2005, Yves Chauvin , Robert H. Grubbs and Richard R. Schrock shared the Nobel Prize for metal-catalyzed olefin metathesis . Subspecialty areas of organometallic chemistry include: Organometallic compounds find wide use in commercial reactions, both as homogenous catalysts and as stoichiometric reagents . For instance, organolithium , organomagnesium , and organoaluminium compounds , examples of which are highly basic and highly reducing, are useful stoichiometrically but also catalyze many polymerization reactions. Almost all processes involving carbon monoxide rely on catalysts, notable examples being described as carbonylations . The production of acetic acid from methanol and carbon monoxide

138-684: A heated substrate via metalorganic vapor phase epitaxy (MOVPE) process in the production of light-emitting diodes (LEDs). Organometallic compounds undergo several important reactions: The synthesis of many organic molecules are facilitated by organometallic complexes. Sigma-bond metathesis is a synthetic method for forming new carbon-carbon sigma bonds . Sigma-bond metathesis is typically used with early transition-metal complexes that are in their highest oxidation state. Using transition-metals that are in their highest oxidation state prevents other reactions from occurring, such as oxidative addition . In addition to sigma-bond metathesis, olefin metathesis

184-519: A large cask, or tun . A full tun, standing about a metre high, could easily weigh a tonne. See also the common German word de:Mülltonne (literal translation: garbage drum ). The spelling tonne pre-dates the introduction of the SI in 1960; it has been used with this meaning in France since 1842, when there were no metric prefixes for multiples of 10 and above, and is now used as the standard spelling for

230-605: A lesser extent to a long ton of 2,240 lb (1,016 kg), with the term tonne rarely used in speech or writing. Both terms are acceptable in Canadian English . Ton and tonne are both derived from a Germanic word in general use in the North Sea area since the Middle Ages (cf. Old English and Old Frisian tunne , Old High German and Medieval Latin tunna , German and French tonne ) to designate

276-435: A mixed-valence iron-cyanide complex, was first prepared in 1706 by paint maker Johann Jacob Diesbach as the first coordination polymer and synthetic material containing a metal-carbon bond. ) The abundant and diverse products from coal and petroleum led to Ziegler–Natta , Fischer–Tropsch , hydroformylation catalysis which employ CO, H 2 , and alkenes as feedstocks and ligands. Recognition of organometallic chemistry as

322-462: A process for producing THF by oxidizing n -butane to crude maleic anhydride , followed by catalytic hydrogenation. A third major industrial route entails hydroformylation of allyl alcohol followed by hydrogenation to 1,4-butanediol . THF can also be synthesized by catalytic hydrogenation of furan . This allows certain sugars to be converted to THF via acid-catalyzed digestion to furfural and decarbonylation to furan, although this method

368-438: A shine to the finished product as well as to solvent weld printed parts. In the laboratory, THF is a popular solvent when its water miscibility is not an issue. It is more basic than diethyl ether and forms stronger complexes with Li , Mg , and boranes . It is a popular solvent for hydroboration reactions and for organometallic compounds such as organolithium and Grignard reagents . Thus, while diethyl ether remains

414-513: Is methylcobalamin (a form of Vitamin B 12 ), which contains a cobalt - methyl bond. This complex, along with other biologically relevant complexes are often discussed within the subfield of bioorganometallic chemistry . Many complexes feature coordination bonds between a metal and organic ligands . Complexes where the organic ligands bind the metal through a heteroatom such as oxygen or nitrogen are considered coordination compounds (e.g., heme A and Fe(acac) 3 ). However, if any of

460-542: Is an aprotic solvent with a dielectric constant of 7.6. It is a moderately polar solvent and can dissolve a wide range of nonpolar and polar chemical compounds. THF is water-miscible and can form solid clathrate hydrate structures with water at low temperatures. THF has been explored as a miscible co-solvent in aqueous solution to aid in the liquefaction and delignification of plant lignocellulosic biomass for production of renewable platform chemicals and sugars as potential precursors to biofuels . Aqueous THF augments

506-940: Is catalyzed via metal carbonyl complexes in the Monsanto process and Cativa process . Most synthetic aldehydes are produced via hydroformylation . The bulk of the synthetic alcohols, at least those larger than ethanol, are produced by hydrogenation of hydroformylation-derived aldehydes. Similarly, the Wacker process is used in the oxidation of ethylene to acetaldehyde . Almost all industrial processes involving alkene -derived polymers rely on organometallic catalysts. The world's polyethylene and polypropylene are produced via both heterogeneously via Ziegler–Natta catalysis and homogeneously, e.g., via constrained geometry catalysts . Most processes involving hydrogen rely on metal-based catalysts. Whereas bulk hydrogenations (e.g., margarine production) rely on heterogeneous catalysts, for

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552-749: Is generally highly covalent . For highly electropositive elements, such as lithium and sodium, the carbon ligand exhibits carbanionic character, but free carbon-based anions are extremely rare, an example being cyanide . Most organometallic compounds are solids at room temperature, however some are liquids such as methylcyclopentadienyl manganese tricarbonyl , or even volatile liquids such as nickel tetracarbonyl . Many organometallic compounds are air sensitive (reactive towards oxygen and moisture), and thus they must be handled under an inert atmosphere . Some organometallic compounds such as triethylaluminium are pyrophoric and will ignite on contact with air. As in other areas of chemistry, electron counting

598-546: Is highly flammable. 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 with butylated hydroxytoluene (BHT). Distillation of THF to dryness is unsafe because the explosive peroxides can concentrate in the residue. The tetrahydrofuran ring is found in diverse natural products including lignans , acetogenins , and polyketide natural products. Diverse methodology has been developed for

644-501: Is little need to distinguish between metric and other tons, and the unit is spelled either as ton or tonne with the relevant prefix attached. A metric ton unit (mtu) can mean 10 kg (22 lb) within metal trading, particularly within the United States. It traditionally referred to a metric ton of ore containing 1% (i.e. 10 kg) of metal. The following excerpt from a mining geology textbook describes its usage in

690-453: Is not widely practiced. THF is thus derivable from renewable resources. In the presence of strong acids , THF converts to a linear polymer called poly(tetramethylene ether) glycol (PTMEG), also known as polytetramethylene oxide (PTMO): This polymer is primarily used to make elastomeric polyurethane fibers like Spandex . The other main application of THF is as an industrial solvent for polyvinyl chloride (PVC) and in varnishes . It

736-456: Is often used industrially to degrease metal parts. THF is used as a component in mobile phases for reversed-phase liquid chromatography . It has a greater elution strength than methanol or acetonitrile , but is less commonly used than these solvents. THF is used as a solvent in 3D printing when printing with PLA , PETG and substantially similar filaments. It can be used to clean clogged 3D printer parts, to remove extruder lines and add

782-583: Is shared between ( delocalized ) a carbon atom and an atom more electronegative than carbon (e.g. enolates ) may vary with the nature of the anionic moiety, the metal ion, and possibly the medium. In the absence of direct structural evidence for a carbon–metal bond, such compounds are not considered to be organometallic. For instance, lithium enolates often contain only Li-O bonds and are not organometallic, while zinc enolates ( Reformatsky reagents ) contain both Zn-O and Zn-C bonds, and are organometallic in nature. The metal-carbon bond in organometallic compounds

828-400: Is the joule . One tonne of TNT is approximately equivalent to 4.2 gigajoules. In the petroleum industry the tonne of oil equivalent (toe) is a unit of energy : the amount of energy released by burning one tonne of crude oil , approximately 42 GJ. There are several slightly different definitions. This is ten times as much as a tonne of TNT because atmospheric oxygen is used. Like

874-481: Is the mass of one cubic metre of pure water at 4 °C (39 °F). As a non-SI unit, the use of SI metric prefixes with the tonne does not fall within the SI standard. For multiples of the tonne, it is more usual to speak of thousands or millions of tonnes. Kilotonne, megatonne, and gigatonne are more usually used for the energy of nuclear explosions and other events in equivalent mass of TNT , often loosely as approximate figures. When used in this context, there

920-1275: Is the study of organometallic compounds , chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal , including alkali , alkaline earth , and transition metals , and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide ( metal carbonyls ), cyanide , or carbide , are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term " metalorganic compound " refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides , dialkylamides, and metal phosphine complexes are representative members of this class. The field of organometallic chemistry combines aspects of traditional inorganic and organic chemistry . Organometallic compounds are widely used both stoichiometrically in research and industrial chemical reactions, as well as in

966-465: Is traditionally dried by distillation from an aggressive desiccant such as elemental sodium , molecular sieves have been shown to be superior water scavengers. In the presence of a solid acid catalyst , THF reacts with hydrogen sulfide to give tetrahydrothiophene . THF is a Lewis base that bonds to a variety of Lewis acids such as I 2 , phenols , triethylaluminum and bis(hexafluoroacetylacetonato)copper(II) . THF has been classified in

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1012-466: Is used as a proxy for energy, usually of explosions (TNT is a common high explosive ). Prefixes are used: kiloton(ne), megaton(ne), gigaton(ne), especially for expressing nuclear weapon yield , based on a specific combustion energy of TNT of about 4.2  MJ / kg (or one thermochemical calorie per milligram ). Hence, 1 t TNT = approx. 4.2  GJ , 1 kt TNT = approx. 4.2  TJ , 1 Mt TNT = approx. 4.2  PJ . The SI unit of energy

1058-1150: Is used to synthesize various carbon-carbon pi bonds . Neither sigma-bond metathesis or olefin metathesis change the oxidation state of the metal. Many other methods are used to form new carbon-carbon bonds, including beta-hydride elimination and insertion reactions . Organometallic complexes are commonly used in catalysis. Major industrial processes include hydrogenation , hydrosilylation , hydrocyanation , olefin metathesis , alkene polymerization , alkene oligomerization , hydrocarboxylation , methanol carbonylation , and hydroformylation . Organometallic intermediates are also invoked in many heterogeneous catalysis processes, analogous to those listed above. Additionally, organometallic intermediates are assumed for Fischer–Tropsch process . Organometallic complexes are commonly used in small-scale fine chemical synthesis as well, especially in cross-coupling reactions that form carbon-carbon bonds, e.g. Suzuki-Miyaura coupling , Buchwald-Hartwig amination for producing aryl amines from aryl halides, and Sonogashira coupling , etc. Natural and contaminant organometallic compounds are found in

1104-454: Is useful for organizing organometallic chemistry. The 18-electron rule is helpful in predicting the stabilities of organometallic complexes, for example metal carbonyls and metal hydrides . The 18e rule has two representative electron counting models, ionic and neutral (also known as covalent) ligand models, respectively. The hapticity of a metal-ligand complex, can influence the electron count. Hapticity (η, lowercase Greek eta), describes

1150-413: Is usually pronounced the same as ton ( / t ʌ n / ), but the final "e" can also be pronounced, i.e. " tunnie " ( / ˈ t ʌ n i / ). In Australia, the common and recommended pronunciation is / t ɒ n / . In the United States, metric ton is the name for this unit used and recommended by NIST; an unqualified mention of a ton typically refers to a short ton of 2,000 lb (907.2 kg) and to

1196-558: The ECW model and it has been shown that there is no one order of base strengths. Many complexes are of the stoichiometry MCl 3 (THF) 3 . THF is a relatively acutely nontoxic solvent, with the median lethal dose (LD 50 ) comparable to that for acetone . However, chronic exposure is suspected of causing cancer. Reflecting its remarkable solvent properties, it penetrates the skin, causing rapid dehydration. THF readily dissolves latex and thus should be handled with nitrile rubber gloves. It

1242-412: The gram and the kilogram, the tonne gave rise to a (now obsolete) force unit of the same name, the tonne-force, equivalent to about 9.8 kilonewtons . The unit is also often called simply "tonne" or "metric ton" without identifying it as a unit of force. In contrast to the tonne as a mass unit, the tonne-force is not accepted for use with SI. Organometallic compound Organometallic chemistry

1288-476: The isolobal principle . A wide variety of physical techniques are used to determine the structure, composition, and properties of organometallic compounds. X-ray diffraction is a particularly important technique that can locate the positions of atoms within a solid compound, providing a detailed description of its structure. Other techniques like infrared spectroscopy and nuclear magnetic resonance spectroscopy are also frequently used to obtain information on

1334-405: The tesla , megatesla, and millitesla, respectively, while Mt and mt are SI-compatible symbols for the megatonne (one teragram) and millitonne (one kilogram). If describing TNT equivalent units of energy, one megatonne of TNT is equivalent to approximately 4.184 petajoules . In English, tonne is an established spelling alternative to metric ton . In the United States and United Kingdom, tonne

1380-415: The United States to distinguish it from the non-metric units of the short ton ( United States customary units ) and the long ton ( British imperial units ). It is equivalent to approximately 2,204.6 pounds , 1.102 short tons, and 0.984 long tons. The official SI unit is the megagram ( Mg ), a less common way to express the same amount. The BIPM symbol for the tonne is t, adopted at the same time as

1426-416: The electron donating interactions of the ligand. Many organometallic compounds do not follow the 18e rule. The metal atoms in organometallic compounds are frequently described by their d electron count and oxidation state . These concepts can be used to help predict their reactivity and preferred geometry . Chemical bonding and reactivity in organometallic compounds is often discussed from the perspective of

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1472-412: The environment. Some that are remnants of human use, such as organolead and organomercury compounds, are toxicity hazards. Tetraethyllead was prepared for use as a gasoline additive but has fallen into disuse because of lead's toxicity. Its replacements are other organometallic compounds, such as ferrocene and methylcyclopentadienyl manganese tricarbonyl (MMT). The organoarsenic compound roxarsone

1518-486: The hydrolysis of glycans 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 dissolve polymers prior to determining their molecular mass using gel 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

1564-452: The ligands form a direct metal-carbon (M-C) bond, then the complex is considered to be organometallic. Although the IUPAC has not formally defined the term, some chemists use the term "metalorganic" to describe any coordination compound containing an organic ligand regardless of the presence of a direct M-C bond. The status of compounds in which the canonical anion has a negative charge that

1610-522: The metric mass measurement in most English -speaking countries. In the United States, the unit was originally referred to using the French words millier or tonneau , but these terms are now obsolete. The British imperial and United States customary units are comparable to the tonne and the spelling of ton in English is the same, though they differ in mass. One tonne is equivalent to: A tonne

1656-566: The number of contiguous ligands coordinated to a metal. For example, ferrocene , [(η -C 5 H 5 ) 2 Fe], has two cyclopentadienyl ligands giving a hapticity of 5, where all five carbon atoms of the C 5 H 5 ligand bond equally and contribute one electron to the iron center. Ligands that bind non-contiguous atoms are denoted the Greek letter kappa, κ. Chelating κ2-acetate is an example. The covalent bond classification method identifies three classes of ligands, X,L, and Z; which are based on

1702-482: The particular case of tungsten: Tungsten concentrates are usually traded in metric tonne units (originally designating one tonne of ore containing 1% of WO 3 , today used to measure WO 3 quantities in 10 kg units. One metric tonne unit (mtu) of tungsten (VI) contains 7.93 kilograms of tungsten. In the case of uranium , MTU is sometimes used in the sense of metric ton of uranium (1,000 kg [2,200 lb]). The tonne of trinitrotoluene (TNT)

1748-469: The production of fine chemicals such hydrogenations rely on soluble (homogenous) organometallic complexes or involve organometallic intermediates. Organometallic complexes allow these hydrogenations to be effected asymmetrically. Many semiconductors are produced from trimethylgallium , trimethylindium , trimethylaluminium , and trimethylantimony . These volatile compounds are decomposed along with ammonia , arsine , phosphine and related hydrides on

1794-594: The result of hydroboration and carboboration reactions. Tetracarbonyl nickel and ferrocene are examples of organometallic compounds containing transition metals . Other examples of organometallic compounds include organolithium compounds such as n -butyllithium (n-BuLi), organozinc compounds such as diethylzinc (Et 2 Zn), organotin compounds such as tributyltin hydride (Bu 3 SnH), organoborane compounds such as triethylborane (Et 3 B), and organoaluminium compounds such as trimethylaluminium (Me 3 Al). A naturally occurring organometallic complex

1840-439: The role of catalysts to increase the rates of such reactions (e.g., as in uses of homogeneous catalysis ), where target molecules include polymers, pharmaceuticals, and many other types of practical products. Organometallic compounds are distinguished by the prefix "organo-" (e.g., organopalladium compounds), and include all compounds which contain a bond between a metal atom and a carbon atom of an organyl group . In addition to

1886-457: 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 involving organometallic compounds . Although THF

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1932-738: The structure and bonding of organometallic compounds. Ultraviolet-visible spectroscopy is a common technique used to obtain information on the electronic structure of organometallic compounds. It is also used monitor the progress of organometallic reactions, as well as determine their kinetics . The dynamics of organometallic compounds can be studied using dynamic NMR spectroscopy . Other notable techniques include X-ray absorption spectroscopy , electron paramagnetic resonance spectroscopy , and elemental analysis . Due to their high reactivity towards oxygen and moisture, organometallic compounds often must be handled using air-free techniques . Air-free handling of organometallic compounds typically requires

1978-406: The synthesis of substituted THFs. Tetrahydrofuran is one of the class of pentic cyclic ethers called oxolanes . There are seven possible structures, namely, Tonne The tonne ( / t ʌ n / or / t ɒ n / ; symbol:  t ) is a unit of mass equal to 1,000  kilograms . It is a non-SI unit accepted for use with SI . It is also referred to as a metric ton in

2024-474: The traditional metals ( alkali metals , alkali earth metals , transition metals , and post transition metals ), lanthanides , actinides , semimetals, and the elements boron , silicon , arsenic , and selenium are considered to form organometallic compounds. Examples of organometallic compounds include Gilman reagents , which contain lithium and copper , and Grignard reagents , which contain magnesium . Boron-containing organometallic compounds are often

2070-493: The unit in 1879. Its use is also official for the metric ton in the United States, having been adopted by the United States National Institute of Standards and Technology (NIST). It is a symbol, not an abbreviation, and should not be followed by a period . Use of lower case is significant, and use of other letter combinations can lead to ambiguity. For example, T, MT, mT, are the SI symbols for

2116-519: The use of laboratory apparatuses such as a glovebox or Schlenk line . Early developments in organometallic chemistry include Louis Claude Cadet 's synthesis of methyl arsenic compounds related to cacodyl , William Christopher Zeise 's platinum-ethylene complex , Edward Frankland 's discovery of diethyl- and dimethylzinc , Ludwig Mond 's discovery of Ni(CO) 4 , and Victor Grignard 's organomagnesium compounds. (Although not always acknowledged as an organometallic compound, Prussian blue ,

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