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Pages in category "Monomers"
The following 112 pages are in this category, out of 112 total. This list may not reflect recent changes (learn more).
|Wikimedia Commons has media related to Polymer chemistry.|
The following 112 pages are in this category, out of 112 total. This list may not reflect recent changes (learn more).
1. Cyanoacrylate – Cyanoacrylates are a family of strong fast-acting adhesives with industrial, medical, and household uses. Cyanoacrylate adhesives have a shelf life if not used, about one year from manufacture if unopened. Cyanoacrylates include methyl 2-cyanoacrylate, ethyl-2-cyanoacrylate, n-butyl cyanoacrylate and 2-octyl cyanoacrylate, Octyl cyanoacrylate was developed to address toxicity concerns and to reduce skin irritation and allergic response. Cyanoacrylate adhesives are sometimes known generically as instant glues, power glues or superglues, the abbreviation CA is commonly used for industrial grades. The original patent for cyanoacrylate was filed in 1942 by Goodrich Company, as an outgrowth of a search for materials suitable for clear plastic gun sights for the war effort. In 1942, a team of scientists headed by Harry Coover Jr. stumbled upon a formulation that stuck to everything with which it came in contact. The team quickly rejected the substance for the application, but in 1951, while working as researchers for Eastman Kodak, Coover. The two realized the commercial potential, and a form of the adhesive was first sold in 1958 under the title Eastman #910. During the 1960s, Eastman Kodak sold cyanoacrylate to Loctite, which in turn repackaged and distributed it under a different brand name Loctite Quick Set 404, in 1971 Loctite developed its own manufacturing technology and introduced its own line of cyanoacrylate, called Super Bonder. Loctite quickly gained market share, and by the late 1970s it was believed to have exceeded Eastman Kodaks share in the North American industrial cyanoacrylate market, National Starch and Chemical Company purchased Eastman Kodak’s cyanoacrylate business and combined it with several acquisitions made throughout the 1970s forming Permabond. Other manufacturers of cyanoacrylate include LePage, the Permabond Division of National Starch and Chemical, together, Loctite, Eastman and Permabond accounted for approximately 75% of the industrial cyanoacrylate market. As of 2013 Permabond continued to manufacture the original 910 formula, in its liquid form, cyanoacrylate consists of monomers of cyanoacrylate molecules. Methyl-2-cyanoacrylate has a weight equal to 111.1, a flashpoint of 79 °C. Ethyl 2-cyanoacrylate has a weight equal to 125 and a flashpoint of >75 °C. To facilitate easy handling, an adhesive is frequently formulated with an ingredient such as fumed silica to make it more viscous or gel-like. More recently, formulations are available with additives to increase shear strength, such additives may include rubber, as in Loctites Ultra Gel, or others which are not specified. In general, cyanoacrylate is a resin that rapidly polymerises in the presence of water, forming long, strong chains. Because the presence of moisture causes the glue to set, exposure to normal levels of humidity in the air causes a thin skin to start to form within seconds, because of this cyanoacrylate is applied thinly, to ensure that the reaction proceeds rapidly for bonding
2. 1,3-Butadiene – 1, 3-Butadiene is a simple conjugated diene with the formula C4H6. It is an important industrial chemical used as a monomer in the production of synthetic rubber, the molecule can be viewed as two vinyl groups joined together. The word butadiene usually refers to 1, 3-butadiene, which has the structure H2C=CH−CH=CH2, although butadiene breaks down quickly in the atmosphere, it is nevertheless found in ambient air in urban and suburban areas as a consequence of its constant emission from motor vehicles. The name butadiene can also refer to the isomer,1, 2-butadiene, however, this allene is difficult to prepare and has no industrial significance. This diene is also not expected to act as a diene in a Diels–Alder reaction due to its structure, to effect a Diels–Alder reaction, only a conjugated diene will suffice. The rest of this article concerns only 1, 3-butadiene, in 1863, the French chemist E. Caventou isolated a previously unknown hydrocarbon from the pyrolysis of amyl alcohol. This hydrocarbon was identified as butadiene in 1886, after Henry Edward Armstrong isolated it from among the products of petroleum. In 1910, the Russian chemist Sergei Lebedev polymerized butadiene and obtained a material with rubber-like properties and this polymer was, however, found to be too soft to replace natural rubber in many applications, notably automobile tires. The butadiene industry originated in the leading up to World War II. In 1929, Eduard Tschunker and Walter Bock, working for IG Farben in Germany, worldwide production quickly ensued, with butadiene being produced from grain alcohol in the Soviet Union and the United States and from coal-derived acetylene in Germany. In the United States, western Europe, and Japan, butadiene is produced as a byproduct of the cracking process used to produce ethylene. When mixed with steam and briefly heated to high temperatures, aliphatic hydrocarbons give up hydrogen to produce a complex mixture of unsaturated hydrocarbons. The quantity of butadiene produced depends on the used as feed. Light feeds, such as ethane, give primarily ethylene when cracked, but heavier feeds favor the formation of heavier olefins, butadiene, butadiene can also be produced by the catalytic dehydrogenation of normal butane. The first such post-war commercial plant, producing 65,000 tons per year of butadiene, began operations in 1957 in Houston, today, butadiene from n-butane is commercially practiced using the Houdry catadiene process, which was developed during World War II. In other parts of the world, including South America, Eastern Europe, China, while not competitive with steam cracking for producing large volumes of butadiene, lower capital costs make production from ethanol a viable option for smaller-capacity plants. At the same time this type of manufacture was canceled in Brazil, nowadays there is no industrial production of butadiene from ethanol. Recently, Lanxess announced plans to produce butadiene from ethanol, the process remains in use today in China and India
3. Butene – Butene, also known as butylene, is a series of alkenes with the general formula C4H8. The word butene may refer to any of the individual compounds and they are colourless gases that are present in crude oil as a minor constituent in quantities that are too small for viable extraction. Butene is therefore obtained by cracking of long-chain hydrocarbons left during refining of crude oil. Cracking produces a mixture of products, and the butene is extracted from this by fractional distillation, butene can be used as the monomer for polybutene but this polymer is more expensive than alternatives with shorter carbon chains such as polypropylene. Polybutene is therefore used as a co-polymer, such as in hot-melt adhesives. Among the molecules which have the chemical formula C4H8 four isomers are alkenes, all four of these hydrocarbons have four carbon atoms and one double bond in their molecules, but have different chemical structures. Other organic compounds have the formula C4H8, namely cyclobutane and methylcyclopropane, there are also cyclic alkenes with four carbon atoms overall such as cyclobutene and two isomers of methylcyclopropene, but they do not have the formula C4H8 and are not discussed here. All four of these isomers are gases at room temperature and pressure and these gases are colourless, but do have distinct odours, and are highly flammable. Although not naturally present in petroleum in high percentages, they can be produced from petrochemicals or by catalytic cracking of petroleum, although they are stable compounds, the carbon-carbon double bonds make them more reactive than similar alkanes, which are more inert compounds in various ways. Because of the bonds, these 4-carbon alkenes can act as monomers in the formation of polymers. They are used in the production of synthetic rubber, but-1-ene is a linear or normal alpha-olefin and isobutylene is a branched alpha-olefin. In a rather low percentage, but-1-ene is used as one of the comonomers, along with other alpha-olefins, in the production of high-density polyethylene, butyl rubber is made by cationic polymerisation of isobutylene with about 2 - 7% isoprene. Isobutylene is also used for the production of methyl tert-butyl ether and isooctane, both of which improve the combustion of gasoline
4. Caprolactam – Caprolactam is an organic compound with the formula 5CNH. This colourless solid is a lactam of caproic acid, approximately 4.5 billion kilograms are produced annually. Caprolactam is the precursor to Nylon 6, a widely used synthetic polymer, caprolactam was first described in the late 1800s when it was prepared by the cyclization of ε-aminocaproic acid, the product of the hydrolysis of caprolactam. Given the commercial significance of Nylon-6, many methods have developed for the production of caprolactam. Most of the caprolactam is synthesised from cyclohexanone, which is first converted to its oxime, treatment of this oxime with acid induces the Beckmann rearrangement to give caprolactam, The immediate product of the acid-induced rearrangement is the bisulfate salt of caprolactam. This salt is neutralized with ammonia to release the free lactam, in optimizing the industrial practices, much attention is directed toward minimizing the production of ammonium salts. The other major route involves formation of the oxime from cyclohexane using nitrosyl chloride. The advantage of this method is that cyclohexane is less expensive than cyclohexanone, in earlier times, caprolactam was prepared by treatment of caprolactone with ammonia. Cyclohexanone with hydrazoic acid has also been reported and this is known as a Schmidt ring expansion. Almost all caprolactam produced goes into the manufacture of Nylon-6, the conversion entails a ring-opening polymerization, n 5CNH → n Nylon-6 is widely used in fibers and plastics. In situ anionic polymerization is employed for cast nylon production where conversion from ε-caprolactam to Nylon-6 takes place inside a mold, in conjunction with endless fiber processing the term thermoplastic resin transfer molding is often used. Caprolactam is an irritant and is toxic, with an LD50 of 1.1 g/kg. In 1991, it was included on the list of air pollutants by the U. S. Clean Air Act of 1990. It was subsequently removed from the list in 1996, in water, caprolactam hydrolyzes to aminocaproic acid, which is used medicinally. As of 2016 caprolactam had the status of being the only chemical in the International Agency for Research on Cancers lowest hazard category, Group 4. Currently, there is no official permissible exposure limit set for workers handling caprolactam in the United States, the recommended exposure limit is set at 1 mg/m3 over an eight-hour work shift for caprolactam dusts and vapors. The short-term exposure limit is set at 3 mg/m3 for caprolactam dusts and vapors
5. Diamine – A diamine is an amine with exactly two amino groups. Diamines are used as monomers to prepare polyamides, polyimides and polyureas, in terms of quantities produced,1, 6-diaminohexane, a precursor to Nylon 6-6, is most important, followed by ethylenediamine. Vicinal diamines are a motif in many biological compounds and are used as ligands in organometallic chemistry 2 carbons. Related derivatives include the N-alkylated compounds,1, 1-dimethylethylenediamine,1, 1-dimethylethylenediamine, ethambutol,3 carbons,1, 3-diaminopropane 4 carbons, putrescine 5 carbons, cadaverine 6 carbons, hexamethylenediamine Derivatives of ethylenediamine are prominent,1, 2-diaminopropane, which is chiral. Xylylenediamines are classified as alkylamines since the amine is not directly attached to an aromatic ring, o-xylylenediamine or OXD m-xylylenediamine or MXD p-xylylenediamine or PXD Three phenylenediamines are known, o-phenylenediamine or OPD m-phenylenediamine or MPD p-phenylenediamine or PPD. 2, 5-Diaminotoluene is related to PPD but contains a group on the ring. Various N-methylated derivatives of the phenylenediamines are known, dimethyl-4-phenylenediamine, a reagent
6. Ethylene – Ethylene is a hydrocarbon which has the formula C 2H4 or H2C=CH2. It is a flammable gas with a faint sweet and musky odour when pure. Ethylene is widely used in the industry, and its worldwide production exceeds that of any other organic compound. Much of this production goes toward polyethylene, a used plastic containing polymer chains of ethylene units in various chain lengths. Ethylene is also an important natural plant hormone, used in agriculture to force the ripening of fruits and this hydrocarbon has four hydrogen atoms bound to a pair of carbon atoms that are connected by a double bond. All six atoms that comprise ethylene are coplanar, the H-C-H angle is 117. 4°, close to the 120° for ideal sp² hybridized carbon. The molecule is relatively rigid, rotation about the C-C bond is a high energy process that requires breaking the π-bond. The π-bond in the molecule is responsible for its useful reactivity. The double bond is a region of high density, thus it is susceptible to attack by electrophiles. Many reactions of ethylene are catalyzed by metals, which bind transiently to the ethylene using both the π and π* orbitals. Being a simple molecule, ethylene is spectroscopically simple and its UV-vis spectrum is still used as a test of theoretical methods. In the United States and Europe, approximately 90% of ethylene is used to produce ethylene oxide, ethylene dichloride, most of the reactions with ethylene are electrophilic addition. Polyethylene consumes more than half of the worlds ethylene supply, polyethylene, also called polyethene, is the worlds most widely used plastic. It is primarily used to make films in packaging, carrier bags, linear alpha-olefins, produced by oligomerization are used as precursors, detergents, plasticisers, synthetic lubricants, additives, and also as co-monomers in the production of polyethylenes. Ethylene is oxidized to ethylene oxide, a key raw material in the production of surfactants and detergents by ethoxylation. Ethylene oxide is hydrolyzed to produce ethylene glycol, widely used as an automotive antifreeze as well as higher molecular weight glycols, glycol ethers. Ethylene undergoes oxidation by palladium to give acetaldehyde and this conversion remains a major industrial process. The process proceeds via the initial complexation of ethylene to a Pd center, major intermediates from the halogenation and hydrohalogenation of ethylene include ethylene dichloride, ethyl chloride and ethylene dibromide
7. Isoprene – Isoprene, or 2-methyl-1, 3-butadiene, is a common organic compound with the formula CH2=C−CH=CH2. In its pure form it is a volatile liquid. Isoprene is produced by plants, and its polymers are the main component of natural rubber. C. G. Williams named the compound in 1860 after obtaining it from thermal decomposition of natural rubber, isoprene is produced and emitted by many species of trees. Yearly production of emissions by vegetation is around 600 million metric tons, half from tropical broadleaf trees. This is about equivalent to methane emissions and accounts for ~1/3 of all released into the atmosphere. Isoprene is made through the methyl-erythritol 4-phosphate pathway in the chloroplasts of plants, one of the two end products of MEP pathway, dimethylallyl pyrophosphate, is catalyzed by the enzyme isoprene synthase to form isoprene. Therefore, inhibitors that block the MEP pathway, such as fosmidomycin, isoprene emission increases dramatically with temperature and maximizes at around 40 °C. This has led to the hypothesis that isoprene may protect plants against heat stress, emission of isoprene is also observed in some bacteria and this is thought to come from non-enzymatic degradations from DMAPP. Isoprene emission in plants is controlled both by the availability of substrate and by enzyme activity, isoprene is the most abundant hydrocarbon measurable in the breath of humans. The estimated production rate of isoprene in the body is 0.15 µmol/. Isoprene is common in low concentrations in many foods, isoprene emission appears to be a mechanism that trees use to combat abiotic stresses. In particular, isoprene has been shown to protect against moderate heat stress and it may also protect plants against large fluctuations in leaf temperature. Isoprene is incorporated into and helps stabilize cell membranes in response to heat stress, isoprene also confers resistance to reactive oxygen species. The amount of isoprene released from isoprene-emitting vegetation depends on mass, leaf area, light. This is thought to add resistance to harsh environments in which many Archaea are found. The isoprene skeleton can be found in naturally occurring compounds called terpenes, terpenes can be viewed as multiples of isoprene subunits, and this perspective is the cornerstone of the isoprene rule. The precursor to isoprene units in biological systems is dimethylallyl pyrophosphate, the plural “isoprenes” is sometimes used to refer to terpenes in general
8. Lactide – Lactide is the cyclic di-ester of lactic acid, i. e. 2-hydroxypropionic acid. Lactic acid cannot form a lactone as other hydroxy acids do because the group is too close to the carboxylic group. Instead, lactic acid first forms a dimer, which is similar to a 5-hydroxyacid, the dimer contains a hydroxy group at a convenient distance from the carboxylic group for the formation of a lactone. Indeed, the dimer readily forms a six-membered cyclic diester known as lactide, lactides may be prepared by heating lactic acid in the presence of an acid catalyst. In general, a lactide is the cyclic diester, i. e. the di-lactone of two molecules of any 2-hydroxycarboxylic acid, lactic acid is chiral, two enantiomeric forms, -lactic acid and -lactic acid, may exist. Thus, lactide formed from two equivalents of lactic acid consists of two stereocenters
9. Acrylamide – Acrylamide is a chemical compound with the chemical formula C3H5NO. It is a white crystalline solid, soluble in water, ethanol, ether. Acrylamide decomposes in the presence of acids, bases, oxidizing agents, iron and it decomposes non-thermally to form ammonia, and thermal decomposition produces carbon monoxide, carbon dioxide, and oxides of nitrogen. Acrylamide can be prepared by the hydrolysis of acrylonitrile by nitrile hydratase, in industry, most acrylamide is used to synthesize polyacrylamides, which find many uses as water-soluble thickeners. These include use in treatment, gel electrophoresis, papermaking, ore processing, tertiary oil recovery. Some acrylamide is used in the manufacture of dyes and the manufacture of other monomers, the discovery of acrylamide in some cooked starchy foods in 2002 prompted concerns about the carcinogenicity of those foods. As of 2016 it is not clear whether acrylamide consumption affects peoples risk of developing cancer. Acrylamide is classified as a hazardous substance in the United States as defined in Section 302 of the U. S. Emergency Planning and Community Right-to-Know Act, and is subject to reporting requirements by facilities which produce, store. Polyacrylamide was first used in a setting in the early 1950s. In 1959, the groups of Davis and Ornstein and of Raymond, the technique is widely accepted today, and remains a common protocol in molecular biology labs. Acrylamide has many uses in molecular biology laboratories, including the use of linear polyacrylamide as a carrier. Many laboratory supply companies sell LPA for this use, the majority of acrylamide is used to manufacture various polymers. In the 1970s and 1980s, the proportionately largest use of polymers was in water treatment. Polyacrylamide is also used in potting soil. Another use of polyacrylamide is as an intermediate in the production of N-methylol acrylamide and N-butoxyacrylamide. US demand for acrylamide was 253,000,000 pounds as of 2007, acrylamide is considered a potential occupational carcinogen by U. S. government agencies and classified as a Group 2A carcinogen by the IARC. The Occupational Safety and Health Administration and the National Institute for Occupational Safety, in animal models, exposure to acrylamide causes tumors in the adrenal glands, thyroid, lungs, and testes
10. Acrylonitrile – Acrylonitrile is an organic compound with the formula CH2CHCN. It is a volatile liquid, although commercial samples can be yellow due to impurities. In terms of its structure, it consists of a vinyl group linked to a nitrile. It is an important monomer for the manufacture of plastics such as polyacrylonitrile. It is reactive and toxic at low doses, Acrylonitrile was first synthesized by the French chemist Charles Moureu in 1893. Acrylonitrile is produced by ammoxidation of propylene, also known as the SOHIO process. In 2002, world production capacity was estimated at 5 million tonnes per year, acetonitrile and hydrogen cyanide are significant byproducts that are recovered for sale. In fact, the 2008–2009 acetonitrile shortage was caused by a decrease in demand for acrylonitrile. 2CH3-CH=CH2 + 2NH3 + 3O2 → 2CH2=CH-C≡N + 6H2O In the SOHIO process, propylene, ammonia, the reactants pass through the reactor only once, before being quenched in aqueous sulfuric acid. Excess propylene, carbon monoxide, carbon dioxide, and dinitrogen that do not dissolve are vented directly to the atmosphere, the aqueous solution consists of acrylonitrile, acetonitrile, hydrocyanic acid, and ammonium sulfate. A recovery column removes bulk water, and acrylonitrile and acetonitrile are separated by distillation, historically, one of the first successful catalysts was bismuth phosphomolybdate supported on silica as a heterogeneous catalyst. Further improvements have since been made, various green chemistry routes are being developed for the synthesis of acrylonitrile from renewable feedstocks, such as lignocellulosic biomass, glycerol, or glutamic acid. The lignocellulosic route involves fermentation of the biomass to propionic acid, the glycerol route begins with pyrolysis to acrolein, which undergoes ammoxidation to give acrylonitrile. The glutamic route employs oxidative decarboxylation to 3-cyanopropanoic, followed by a decarbonylation-elimination to acrylonitrile, of these the glycerol route is broadly considered to be the most viable, although current methods are still unable to compete with the SOHIO process in terms of cost. Dimerization of acrylonitrile affords adiponitrile, used in the synthesis of certain polyamides, small amounts are also used as a fumigant. Acrylonitrile and derivatives, such as 2-chloro-acrylonitrile, are dienophiles in Diels-Alder reactions, Acrylonitrile is also a precursor in the industrial manufacture of acrylamide and acrylic acid. Acrylonitrile is highly flammable and toxic at low doses, the burning material releases fumes of hydrogen cyanide and oxides of nitrogen. It evaporates quickly at room temperature to reach dangerous concentrations, skin irritation, respiratory irritation, Acrylonitrile increases cancer in high dose tests in male and female rats and mice
11. Cyclohexanone oxime – Cyclohexanone oxime is an organic compound containing the functional group oxime. This colorless solid is an important intermediate in the production of nylon 6 and this method is advantageous as cyclohexane is much cheaper than cyclohexanone. Typical of oximes, the compound can be reduced by sodium amalgam gives cyclohexylamine and it can also be hydrolyzed with acetic acid to give back cyclohexanone
12. Cyclopentene – Cyclopentene is a chemical compound with the formula C5H8. It is a liquid with a petrol-like odor. It is one of the cycloalkenes, cyclopentene is produced industrially in large amounts. It is used as a monomer for synthesis of plastics, and it can be obtained from vinylcyclopropane in the vinylcyclopropane-cyclopentene rearrangement