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45-487: 1-Decanol is a straight chain fatty alcohol with ten carbon atoms and the molecular formula C 10 H 21 OH. It is a colorless to light yellow viscous liquid that is insoluble in water and has an aromatic odor. The interfacial tension against water at 20 °C is 8.97 mN/m. Decanol can be prepared by the hydrogenation of decanoic acid , which occurs in modest quantities in coconut oil (about 10%) and palm kernel oil (about 4%). It may also be produced synthetically via

90-433: A Du Pont research group polymerized norbornene to polynorbornene using lithium aluminum tetraheptyl and titanium tetrachloride (a patent by this company on this topic dates back to 1955 ), a reaction then classified as a so-called coordination polymerization . According to the then proposed reaction mechanism a RTiX titanium intermediate first coordinates to the double bond in a pi complex . The second step then

135-438: A 1:2:1 regardless of conversion. The same ratio is found with the higher oligomers. Chauvin also explained how the carbene forms in the first place: by alpha-hydride elimination from a carbon metal single bond. For example, propylene (C3) forms in a reaction of 2-butene (C4) with tungsten hexachloride and tetramethyltin (C1). In the same year Pettit who synthesised cyclobutadiene a few years earlier independently came up with

180-407: A Ru(II) carbene as an effective metal center and in 1992 published the first well-defined, ruthenium-based olefin metathesis catalyst, (PPh 3 ) 2 Cl 2 Ru=CHCH=CPh 2 : The corresponding tricyclohexylphosphine complex (PCy 3 ) 2 Cl 2 Ru=CHCH=CPh 2 was also shown to be active. This work culminated in the now commercially available 1st generation Grubbs catalyst . Schrock entered

225-441: A common name. Olefin metathesis In organic chemistry , olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds . Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of

270-462: A competing mechanism. It consisted of a tetramethylene intermediate with sp hybridized carbon atoms linked to a central metal atom with multiple three-center two-electron bonds . Experimental support offered by Pettit for this mechanism was based on an observed reaction inhibition by carbon monoxide in certain metathesis reactions of 4-nonene with a tungsten metal carbonyl Robert H. Grubbs got involved in metathesis in 1972 and also proposed

315-465: A four-membered metallacycle intermediate to explain the statistical distribution of products found in certain metathesis reactions. This mechanism is today considered the actual mechanism taking place in olefin metathesis. Chauvin's experimental evidence was based on the reaction of cyclopentene and 2-pentene with the homogeneous catalyst tungsten(VI) oxytetrachloride and tetrabutyltin : The three principal products C9, C10 and C11 are found in

360-433: A large-scale feedstock . Animal fats (tallow) were of historic importance, particularly whale oil , however they are no longer used on a large scale. Tallows produce a fairly narrow range of alcohols, predominantly C 16 –C 18 , while plant sources produce a wider range of alcohols from (C 6 –C 24 ), making them the preferred source. The alcohols are obtained from the triglycerides (fatty acid triesters), which form

405-660: A low level of toxicity from inhalation, oral or dermal exposure of fatty alcohols. Fatty alcohols are not very volatile and the acute lethal concentration is greater than the saturated vapor pressure. Longer-chain (C 12 –C 16 ) fatty alcohols produce fewer health effects than short-chain (smaller than C 12 ). Short-chain fatty alcohols are considered eye irritants, while long chain alcohols are not. Fatty alcohols exhibit no skin sensitization. Repeated exposure to fatty alcohols produce low-level toxicity and certain compounds in this category can cause local irritation on contact or low-grade liver effects (essentially linear alcohols have

450-578: A metal halide (MCl x ) using organoaluminium or organotin compounds , e.g. combining MCl x –EtAlCl 2 . A typical catalyst support is alumina . Commercial catalysts are often based on molybdenum and ruthenium. Well-defined organometallic compounds have mainly been investigated for small-scale reactions or in academic research. The homogeneous catalysts are often classified as Schrock catalysts and Grubbs catalysts . Schrock catalysts feature molybdenum(VI)- and tungsten(VI)-based centers supported by alkoxide and imido ligands. Grubbs catalysts, on

495-522: A metallacycle intermediate but one with four carbon atoms in the ring. The group he worked in reacted 1,4-dilithiobutane with tungsten hexachloride in an attempt to directly produce a cyclomethylenemetallacycle producing an intermediate, which yielded products identical with those produced by the intermediate in the olefin metathesis reaction. This mechanism is pairwise: In 1973 Grubbs found further evidence for this mechanism by isolating one such metallacycle not with tungsten but with platinum by reaction of

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540-538: A quasicyclobutane) – metal complex: This particular mechanism is symmetry forbidden based on the Woodward–Hoffmann rules first formulated two years earlier. Cyclobutanes have also never been identified in metathesis reactions, which is another reason why it was quickly abandoned. Then in 1967 researchers led by Nissim Calderon at the Goodyear Tire and Rubber Company described a novel catalyst system for

585-613: A slightly higher rate of occurrence of these effects). No effects on the central nervous system have been seen with inhalation and oral exposure. Tests of repeated bolus dosages of 1-hexanol and 1-octanol showed potential for CNS depression and induced respiratory distress. No potential for peripheral neuropathy has been found. In rats, the no observable adverse effect level ( NOAEL ) ranges from 200 mg/kg/day to 1000 mg/kg/day by ingestion. There has been no evidence that fatty alcohols are mutagenic or cause reproductive toxicity or infertility. Fatty alcohols are effectively eliminated from

630-422: A strained alkene (often a norbornene ) and the release of ring strain drives the reaction. Ring-closing metathesis, conversely, usually involves the formation of a five- or six-membered ring, which is enthalpically favorable; although these reactions tend to also evolve ethylene, as previously discussed. RCM has been used to close larger macrocycles, in which case the reaction may be kinetically controlled by running

675-429: A third development leading up to olefin metathesis, researchers at Phillips Petroleum Company in 1964 described olefin disproportionation with catalysts molybdenum hexacarbonyl , tungsten hexacarbonyl , and molybdenum oxide supported on alumina for example converting propylene to an equal mixture of ethylene and 2-butene for which they proposed a reaction mechanism involving a cyclobutane (they called it

720-466: Is a concerted SNi reaction breaking a CC bond and forming a new alkylidene-titanium bond; the process then repeats itself with a second monomer: Only much later the polynorbornene was going to be produced through ring opening metathesis polymerisation . The DuPont work was led by Herbert S. Eleuterio . Giulio Natta in 1964 also observed the formation of an unsaturated polymer when polymerizing cyclopentene with tungsten and molybdenum halides. In

765-416: Is formally symmetry forbidden and thus has a high activation energy . The Chauvin mechanism involves the [2+2] cycloaddition of an alkene double bond to a transition metal alkylidene to form a metallacyclobutane intermediate. The metallacyclobutane produced can then cycloeliminate to give either the original species or a new alkene and alkylidene. Interaction with the d-orbitals on the metal catalyst lowers

810-408: Is impaired in several inherited human peroxisomal disorders, including adrenoleukodystrophy and Sjögren–Larsson syndrome . Fatty alcohols are relatively benign materials, with LD 50 (oral, rat) ranging from 3.1–4 g/kg for hexanol to 6–8 g/kg for octadecanol. For a 50 kg person, these values translate to more than 100 g. Tests of acute and repeated exposures have revealed

855-453: The Ziegler process , ethylene is oligomerized using triethylaluminium followed by air oxidation. This process affords even-numbered alcohols: Alternatively ethylene can be oligomerized to give mixtures of alkenes, which are subjected to hydroformylation , this process affording odd-numbered aldehyde, which is subsequently hydrogenated. For example, from 1-decene, hydroformylation gives

900-430: The Ziegler process . Decanol is used in the manufacture of plasticizers , lubricants , surfactants and solvents. Its ability to permeate the skin has led to it being investigated as a penetration enhancer for transdermal drug delivery. Like other medium chain fatty alcohols, 1-decanol is able to permeate the skin which can lead to irritation. Fatty alcohol Fatty alcohols became commercially available in

945-507: The 1960s and 1970s various groups reported the ring-opening polymerization of norbornene catalyzed by hydrated trichlorides of ruthenium and other late transition metals in polar, protic solvents. This prompted Robert H. Grubbs and coworkers to search for well-defined, functional group tolerant catalysts based on ruthenium. The Grubbs group successfully polymerized the 7-oxo norbornene derivative using ruthenium trichloride , osmium trichloride as well as tungsten alkylidenes. They identified

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990-435: The 4-membered cycle Chauvin mechanism: In this reaction the ethylene product distribution ( d 4 , d 2 , d 0 ) {\displaystyle (d_{4},d_{2},d_{0})} at low conversion was found to be consistent with the carbene mechanism. On the other hand, Grubbs did not rule out the possibility of a tetramethylene intermediate. The first practical metathesis system

1035-737: The C 11 alcohol: In the Shell higher olefin process , the chain-length distribution in the initial mixture of alkene oligomers is adjusted so as to more closely match market demand. Shell does this by means of an intermediate metathesis reaction. The resultant mixture is fractionated and hydroformylated/hydrogenated in a subsequent step. Fatty alcohols are mainly used in the production of detergents and surfactants. Due to their amphipathic nature, fatty alcohols behave as nonionic surfactants . They find use as co- emulsifiers , emollients and thickeners in cosmetics and food industry . About 50% of fatty alcohols used commercially are of natural origin,

1080-572: The Grubbs group proved that metathesis polymerization of norbornene by Tebbe's reagent is a living polymerization system and a year later Grubbs and Schrock co-published an article describing living polymerization with a tungsten carbene complex While Schrock focussed his research on tungsten and molybdenum catalysts for olefin metathesis, Grubbs started the development of catalysts based on ruthenium, which proved to be less sensitive to oxygen and water and therefore more functional group tolerant. In

1125-414: The activation energy enough that the reaction can proceed rapidly at modest temperatures. Olefin metathesis involves little change in enthalpy for unstrained alkenes. Product distributions are determined instead by le Chatelier's Principle , i.e. entropy . Cross metathesis and ring-closing metathesis are driven by the entropically favored evolution of ethylene or propylene , which can be removed from

1170-409: The air upon release. Modeling shows that each type of fatty alcohol will respond independently upon environmental release. Fish , invertebrates and algae experience similar levels of toxicity with fatty alcohols although it is dependent on chain length with the shorter chain having greater toxicity potential. Longer chain lengths show no toxicity to aquatic organisms. This category of chemicals

1215-985: The body when exposed, limiting possibility of retention or bioaccumulation . Margins of exposure resulting from consumer uses of these chemicals are adequate for the protection of human health as determined by the Organisation for Economic Co-operation and Development (OECD) high production volume chemicals program. Fatty alcohols up to chain length C 18 are biodegradable, with length up to C 16 biodegrading within 10 days completely. Chains C 16 to C 18 were found to biodegrade from 62% to 76% in 10 days. Chains greater than C 18 were found to degrade by 37% in 10 days. Field studies at wastewater treatment plants have shown that 99% of fatty alcohols lengths C 12 –C 18 are removed. Fate prediction using fugacity modeling has shown that fatty alcohols with chain lengths of C 10 and greater in water partition into sediment. Lengths C 14 and above are predicted to stay in

1260-439: The bulk of the oil. The process involves the transesterification of the triglycerides to give methyl esters which are then hydrogenated to produce the fatty alcohols. Higher alcohols (C 20 –C 22 ) can be obtained from rapeseed oil or mustard seed oil . Midcut alcohols are obtained from coconut oil (C 12 –C 14 ) or palm kernel oil (C 16 –C 18 ). Fatty alcohols are also prepared from petrochemical sources. In

1305-453: The dilithiobutane with cis-bis(triphenylphosphine)dichloroplatinum(II) In 1975 Katz also arrived at a metallacyclobutane intermediate consistent with the one proposed by Chauvin He reacted a mixture of cyclooctene , 2-butene and 4-octene with a molybdenum catalyst and observed that the unsymmetrical C14 hydrocarbon reaction product is present right from the start at low conversion. In any of

1350-517: The early 1900s. They were originally obtained by reduction of wax esters with sodium by the Bouveault–Blanc reduction process. In the 1930s catalytic hydrogenation was commercialized, which allowed the conversion of fatty acid esters, typically tallow , to the alcohols. In the 1940s and 1950s, petrochemicals became an important source of chemicals, and Karl Ziegler had discovered the polymerization of ethylene . These two developments opened

1395-424: The metathesis of 2-pentene based on tungsten hexachloride , ethanol , and the organoaluminum compound EtAlMe 2 . The researchers proposed a name for this reaction type: olefin metathesis. Formerly the reaction had been called "olefin disproportionation." In this reaction 2-pentene forms a rapid (a matter of seconds) chemical equilibrium with 2-butene and 3-hexene . No double bond migrations are observed;

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1440-415: The olefin metathesis field in 1979 as an extension of work on tantalum alkylidenes. The initial result was disappointing as reaction of CpTa(=CH−t−Bu)Cl 2 with ethylene yielded only a metallacyclopentane, not metathesis products: But by tweaking this structure to a PR 3 Ta(CHt−bu)(Ot−bu) 2 Cl (replacing chloride by t-butoxide and a cyclopentadienyl by an organophosphine , metathesis

1485-583: The other hand, are ruthenium(II) carbenoid complexes. Many variations of Grubbs catalysts are known. Some have been modified with a chelating isopropoxybenzylidene ligand to form the related Hoveyda–Grubbs catalyst . Olefin metathesis has several industrial applications. Almost all commercial applications employ heterogeneous catalysts using catalysts developed well before the Nobel-Prize winning work on homogeneous complexes. Representative processes include: Molecular catalysts have been explored for

1530-467: The pairwise mechanisms with olefin pairing as rate-determining step this compound, a secondary reaction product of C12 with C6, would form well after formation of the two primary reaction products C12 and C16. In 1974 Casey was the first to implement carbenes into the metathesis reaction mechanism: Grubbs in 1976 provided evidence against his own updated pairwise mechanism: with a 5-membered cycle in another round of isotope labeling studies in favor of

1575-455: The preparation of a variety of potential applications. the manufacturing of high-strength materials, the preparation of cancer-targeting nanoparticles , and the conversion of renewable plant-based feedstocks into hair and skin care products. Some important classes of olefin metathesis include: Hérisson and Chauvin first proposed the widely accepted mechanism of transition metal alkene metathesis. The direct [2+2] cycloaddition of two alkenes

1620-401: The reaction at high dilutions. The same substrates that undergo RCM can undergo acyclic diene metathesis, with ADMET favored at high concentrations. The Thorpe–Ingold effect may also be exploited to improve both reaction rates and product selectivity. Cross-metathesis is synthetically equivalent to (and has replaced) a procedure of ozonolysis of an alkene to two ketone fragments followed by

1665-459: The reaction can be started with the butene and hexene as well and the reaction can be stopped by addition of methanol . The Goodyear group demonstrated that the reaction of regular 2-butene with its all- deuterated isotopologue yielded C 4 H 4 D 4 with deuterium evenly distributed. In this way they were able to differentiate between a transalkylidenation mechanism and a transalkylation mechanism (ruled out): In 1971 Chauvin proposed

1710-456: The reaction mechanism and their discovery of a variety of highly active catalysts , Yves Chauvin , Robert H. Grubbs , and Richard R. Schrock were collectively awarded the 2005 Nobel Prize in Chemistry . The reaction requires metal catalysts . Most commercially important processes employ heterogeneous catalysts . The heterogeneous catalysts are often prepared by in-situ activation of

1755-403: The reaction of one of them with a Wittig reagent . "Olefin metathesis is a child of industry and, as with many catalytic processes, it was discovered by accident." As part of ongoing work in what would later become known as Ziegler–Natta catalysis Karl Ziegler discovered the conversion of ethylene into 1-butene instead of a saturated long-chain hydrocarbon (see nickel effect ). In 1960

1800-459: The remainder being synthetic. Fatty alcohol are converted to their ethoxylates by treatment with ethylene oxide : The resulting fatty alcohol ethoxylates are important surfactants. Another large class of surfactants are the sodium alkylsulfates such as sodium dodecylsulfate (SDS). Five million tons of SDS and related materials are produced annually by sulfation of dodecyl alcohol and related fatty alcohols. The metabolism of fatty alcohols

1845-439: The system because they are gases. Because of this CM and RCM reactions often use alpha-olefins . The reverse reaction of CM of two alpha-olefins, ethenolysis , can be favored but requires high pressures of ethylene to increase ethylene concentration in solution. The reverse reaction of RCM, ring-opening metathesis, can likewise be favored by a large excess of an alpha-olefin, often styrene . Ring-opening metathesis usually involves

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1890-473: The way to synthetic fatty alcohols. Most fatty alcohols in nature are found as waxes , which are esters of fatty acids and fatty alcohols. They are produced by bacteria, plants and animals for purposes of buoyancy, as source of metabolic water and energy, biosonar lenses (marine mammals) and for thermal insulation in the form of waxes (in plants and insects). The traditional sources of fatty alcohols have largely been various vegetable oils , which remain

1935-425: Was established with cis-2-pentene. In another development, certain tungsten oxo complexes of the type W(O)(CHt−Bu)(Cl) 2 (PEt) 3 were also found to be effective. Schrock alkylidenes for olefin metathesis of the type Mo(NAr)(CHC(CH 3 ) 2 R){OC(CH 3 )(CF 3 ) 2 } 2 were commercialized starting in 1990. The first asymmetric catalyst followed in 1993 With a Schrock catalyst modified with

1980-411: Was evaluated under the Organisation for Economic Co-operation and Development (OECD) high production volume chemicals program. No unacceptable environmental risks were identified. This table lists some alkyl alcohols. Note that in general the alcohols with even numbers of carbon atoms have common names, since they are found in nature, whereas those with odd numbers of carbon atoms generally do not have

2025-457: Was introduced in 1978 by Tebbe based on the (what later became known as the) Tebbe reagent . In a model reaction isotopically labeled carbon atoms in isobutene and methylenecyclohexane switched places: The Grubbs group then isolated the proposed metallacyclobutane intermediate in 1980 also with this reagent together with 3-methyl-1-butene: They isolated a similar compound in the total synthesis of capnellene in 1986: In that same year

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