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Isocyanates
In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyanates are manufactured for the production of polyurethanes, a class of polymers. Isocyanates should not be confused with cyanate esters and isocyanides, very different families of compounds. The cyanate (cyanate ester) functional group () is arranged differently from the isocyanate group (). Isocyanides have the connectivity , lacking the oxygen of the cyanate groups. Structure and bonding In terms of bonding, isocyanates are closely related to carbon dioxide (CO2) and carbodiimides (C(NR)2). The C−N=C=O unit that defines isocyanates is planar, and the N=C=O linkage is nearly linear. In phenyl isocyanate, the C=N and C=O distances are respectively 1.195 and 1.173 Å. The C-N=C angle is 134.9° and the N=C=O angle is 173.1°. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isocyanate Group
In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyanates are manufactured for the production of polyurethanes, a class of polymers. Isocyanates should not be confused with cyanate esters and isocyanides, very different families of compounds. The cyanate (cyanate ester) functional group () is arranged differently from the isocyanate group (). Isocyanides have the connectivity , lacking the oxygen of the cyanate groups. Structure and bonding In terms of bonding, isocyanates are closely related to carbon dioxide (CO2) and carbodiimides (C(NR)2). The C−N=C=O unit that defines isocyanates is planar, and the N=C=O linkage is nearly linear. In phenyl isocyanate, the C=N and C=O distances are respectively 1.195 and 1.173 Å. The C-N=C angle is 134.9° and the N=C=O angle is 173.1°. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyurethanes
Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from a wide range of starting materials. This chemical variety produces polyurethanes with different chemical structures leading to many different applications. These include rigid and flexible foams, varnishes and coatings, adhesives, electrical potting compounds, and fibers such as spandex and PUL. Foams are the largest application accounting for 67% of all polyurethane produced in 2016. A polyurethane is typically produced by reacting an isocyanate with a polyol. Since a polyurethane contains two types of monomers, which polymerize one after the other, they are classed as alternating copolymers. Both the isocyanates and polyols used to make a polyurethane contain two or more functional groups per molecule. Global production in 2019 wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosgene
Phosgene is the organic chemical compound with the formula COCl2. It is a toxic, colorless gas; in low concentrations, its musty odor resembles that of freshly cut hay or grass. Phosgene is a valued and important industrial building block, especially for the production of precursors of polyurethanes and polycarbonate plastics. Phosgene is extremely poisonous and was used as a chemical weapon during World War I, where it was responsible for 85,000 deaths. It was a highly potent pulmonary irritant and quickly filled enemy trenches due to it being a heavy gas. It is classified as a Schedule 3 substance under the Chemical Weapons Convention. In addition to its industrial production, small amounts occur from the breakdown and the combustion of organochlorine compounds, such as chloroform. Structure and basic properties Phosgene is a planar molecule as predicted by VSEPR theory. The C=O distance is 1.18 Å, the C−Cl distance is 1.74 Å and the Cl−C−Cl angle is 111 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosgenation
Phosgene is the organic chemical compound with the formula COCl2. It is a toxic, colorless gas; in low concentrations, its musty odor resembles that of freshly cut hay or grass. Phosgene is a valued and important industrial building block, especially for the production of precursors of polyurethanes and polycarbonate plastics. Phosgene is extremely poisonous and was used as a chemical weapon during World War I, where it was responsible for 85,000 deaths. It was a highly potent pulmonary irritant and quickly filled enemy trenches due to it being a heavy gas. It is classified as a Schedule 3 substance under the Chemical Weapons Convention. In addition to its industrial production, small amounts occur from the breakdown and the combustion of organochlorine compounds, such as chloroform. Structure and basic properties Phosgene is a planar molecule as predicted by VSEPR theory. The C=O distance is 1.18 Å, the C−Cl distance is 1.74 Å and the Cl−C−Cl angle is 111 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbodiimide
In organic chemistry, a carbodiimide (systematic IUPAC name: methanediimine) is a functional group with the formula RN=C=NR. They are exclusively synthetic. A well known carbodiimide is dicyclohexylcarbodiimide, which is used in peptide synthesis. Dialkylcarbodiimides are stable. Some diaryl derivatives tend to convert to dimers and polymers upon standing at room temperature, though this mostly occurs with low melting point carbodiimides that are liquids at room temperature. Solid diaryl carbodiimides are more stable, but can slowly undergo hydrolysis in the presence of water over time. Structure and bonding From the perspective of bonding, carbodiimides are isoelectronic with carbon dioxide. Three principal resonance structures describe carbodiimides: :RN=C=NR ↔ RN+≡C-N−R ↔ RN−-C≡N+R The N=C=N core is relatively linear and the C-N=C angles approach 120°. In the case of C(NCHPh2)2, the central N=C=N angle is 170° and the C-N=C angles are within 1° of 126°. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanate
Cyanate is an anion with the structural formula , usually written . It also refers to any salt containing it, such as ammonium cyanate. It is an isomer of the much less stable fulminate anion .William R. Martin and David W. Ball (2019): "Small organic fulminates as high energy materials. Fulminates of acetylene, ethylene, and allene". ''Journal of Energetic Materials'', volume 31, issue 7, pages 70-79. A cyanate ester is an organic compound containing the cyanate group. The cyanate ion is an ambidentate ligand, forming complexes with a metal ion in which either the nitrogen or oxygen atom may be the electron-pair donor. It can also act as a bridging ligand. Cyanate ion The three atoms in a cyanate ion lie on a straight line, giving the ion a linear structure. The electronic structure is described most simply as : :Ö̤−C≡N: with a single C−O bond and a triple C≡N bond. The infrared spectrum of a cyanate salt has a band at ca. 2096 cm−1; such a high frequen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenyl Isocyanate
Phenyl isocyanate is an organic compound typically abbreviated PhNCO. The molecule consists of a phenyl ring attached to the isocyanate functional group. It is a colourless liquid that reacts with water. Phenyl isocyanate has a strong odor and tearing vapours, therefore it has to be handled with care. Characteristic of other isocyanates, it reacts with amines to give ureas. Similarly, reacts with alcohols to form carbamates. It is used in addition with triethylamine to activate nitro groups to undergo (C,O) 1,3-dipolar cycloaddition (as opposed to O,O). The nitro group (RCH2NO2) is converted to RCNO in the reaction, with CO2 as one of the by products. Structure PhNCO is a planar molecule, according to X-ray crystallography. The N=C=O linkage is nearly linear. The C=N and C=O distances are respectively 1.195 and 1.173 Å. References {{Reflist External links Phenyl Isocyanate Data Sheet Isocyanates Phenyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acyl Azide
Acyl azides are carboxylic acid derivatives with the general formula RCON3. These compounds, which are a subclass of organic azides, are generally colorless. Preparation Typically acyl azides are generated under conditions where they rearrange to the isocyanate. Alkyl or aryl acyl chlorides react with sodium azide to give acyl azides. : The second major route to azides is from the acyl hydrazides with nitrous acid. Acyl azides have also been synthesized from various carboxylic acids and sodium azide in presence of triphenylphosphine and trichloroacetonitrile catalysts in excellent yields at mild conditions. Another route starts with aliphatic and aromatic aldehydes reacting with iodine azide which is formed from sodium azide and iodine monochloride in acetonitrile. Uses On Curtius rearrangement, acyl azides yield isocyanate In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen Gas
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colorless and odorless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids ( DNA and RNA) and in the energy transfer molecule adenosine triphosphate. The human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes the movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere. Many industrially importa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lossen Rearrangement
The Lossen rearrangement is the conversion of a hydroxamate ester to an isocyanate. Typically O-acyl, sulfonyl, or phosphoryl O-derivative are employed. The isocyanate can be used further to generate ureas in the presence of amines or generate amines in the presence of H2O. Reaction mechanism The mechanism below begins with an O-acylated hydroxamic acid derivative that is treated with base to form an isocyanate that generates an amine and CO2 gas in the presence of H2O. The hydroxamic acid derivative is first converted to its conjugate base by abstraction of a hydrogen by a base. Spontaneous rearrangement releases a carboxylate anion to produce the isocyanate intermediate. The isocyanate is then hydrolyzed in the presence of H2O. Finally, the respective amine and CO2 are generated by abstraction of a proton with a base and decarboxylation. Hydroxamic acids are commonly synthesized from their corresponding esters. Historical references * * * See also *Curtius rearrangemen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxamic Acid
A hydroxamic acid is a class of organic compounds bearing the functional group RC(O)N(OH)R', with R and R' as organic residues and CO as a carbonyl group. They are amides (RC(O)NHR') wherein the NH center has an OH substitution. They are often used as metal chelators. Synthesis and reactions Hydroxamic acids are usually prepared from either esters or acid chlorides by a reaction with hydroxylamine salts. For the synthesis of benzohydroxamic acid, the overall equation is: :C6H5CO2Me + NH2OH → C6H5C(O)NHOH + MeOH Hydroxamic acids can also be synthesized from aldehydes and ''N''-sulfonylhydroxylamine via the Angeli-Rimini reaction. A well-known reaction of hydroxamic acid esters is the Lossen rearrangement. Coordination chemistry and biochemistry File:Ferrichrome.svg, Ferrichrome File:Deferoxamine-2D-skeletal.png , Deferoxamine File:Rhodotorulic acid.svg, Rhodotorulic acid File:Fe(hydroxamate)3.svg, Fe(III) complex of triacetylfusarinine Many hydroxamates have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrazoic Acid
Hydrazoic acid, also known as hydrogen azide or azoimide, This also contains a detailed description of the contemporaneous production process. is a compound with the chemical formula . It is a colorless, volatile, and explosive liquid at room temperature and pressure. It is a compound of nitrogen and hydrogen, and is therefore a pnictogen hydride. It was first isolated in 1890 by Theodor Curtius. The acid has few applications, but its conjugate acid, conjugate base, the azide ion, is useful in specialized processes. Hydrazoic acid, like its fellow mineral acids, is soluble in water. Undiluted hydrazoic acid is dangerously explosive with a standard enthalpy of formation ΔfHo (l, 298K) = +264 kJ/mol. When dilute, the gas and aqueous solutions (<10%) can be safely prepared but should be used immediately; because of its low boiling point, hydrazoic acid is enriched upon evaporation and condensation such that dilute solutions incapable of explosion can form droplets in the headspace o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
