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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. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyurethanes
Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term does not refer to the single type of polymer but a group of polymers. Unlike polyethylene and polystyrene, polyurethanes can be produced from a wide range of starting materials resulting in various polymers within the same group. This chemical variety produces polyurethanes with different chemical structures leading to many List of polyurethane applications, different applications. These include rigid and flexible foams, and coatings, adhesives, Potting (electronics), electrical potting compounds, and fibers such as spandex and polyurethane laminate (PUL). Foams are the largest application accounting for 67% of all polyurethane produced in 2016. A polyurethane is typically produced by reacting a polymeric isocyanate with a polyol. Since a ... [...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. On Earth they are exclusively synthetic, but in interstellar space the parent compound HN=C=NH has been detected by its maser emissions. 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°. ... [...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 oxime-like dimers in the reaction: :4 PhNCO + 2 RCH2NO2 → 2(PhNH)2CO + 2 CO2 + (RCNO)2 Structure PhNCO is a planar molecule, according to X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isocyanic Acid
Isocyanic acid is a chemical compound with the structural formula HNCO, which is often written as . It is a colourless, volatile and poisonous gas, condensing at 23.5 °C. It is the predominant tautomer and an isomer of cyanic acid ''(aka. cyanol)'' (), and the monomer of cyanuric acid. The derived anion of isocyanic acid is the same as the derived anion of cyanic acid, and that anion is , which is called cyanate. The related functional group is isocyanate; it is distinct from cyanate (), fulminate (), and nitrile oxide (). Isocyanic acid was discovered in 1830 by Justus von Liebig and Friedrich Wöhler. Isocyanic acid is the simplest stable chemical compound that contains carbon, hydrogen, nitrogen, and oxygen, the four most commonly found elements in organic chemistry and biology. It is the only fairly stable one of the four linear isomers with molecular formula HOCN that have been synthesized, the others being cyanic acid (cyanol, ) and the elusive fulminic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanate
The cyanate ion is an anion with the chemical formula . It is a resonance of three forms: (61%) ↔ (30%) ↔ (4%). Cyanate is the derived anion of isocyanic acid, H−N=C=O, and its lesser tautomer cyanic acid (a.k.a. cyanol), H−O−C≡N. Any salt containing the ion, such as ammonium cyanate, is called a cyanate. The cyanate ion is an isomer of the much-less-stable fulminate anion, or .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. 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. Compounds that contain the cyanate functional group, −O−C≡N, are known as cyanates or cyanate esters. The cyanate functional group is distinct from the isocyanate functional ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrene
In chemistry, a nitrene or imene () is the nitrogen analogue of a carbene. The nitrogen atom is uncharged and valence (chemistry)#monovalent, monovalent, so it has only 6 electrons in its valence level—two covalent bonded and four non-bonded electrons. It is therefore considered an electrophile due to the octet rule, unsatisfied octet. A nitrene is a reactive intermediate and is involved in many chemical reactions. The simplest nitrene, HN, is called imidogen, and that term is sometimes used as a synonym for the nitrene class. Electron configuration In the simplest case, the linear N–H molecule (imidogen) has its nitrogen atom sp hybrid orbital, sp hybridized, with two of its four non-bonded electrons as a lone pair in an sp orbital and the other two occupying a degenerate orbital, degenerate pair of p orbitals. The electron configuration is consistent with Hund's rule: the low energy form is a triplet state, triplet with one electron in each of the p orbitals and the high en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palladium
Palladium is a chemical element; it has symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1802 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas (formally 2 Pallas), which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form together a group of elements referred to as the platinum group metals (PGMs). They have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. More than half the supply of palladium and its congener platinum is used in catalytic converters, which convert as much as 90% of the harmful gases in automobile exhaust (hydrocarbons, carbon monoxide, and nitrogen dioxide) into nontoxic substances (nitrogen, carbon dioxide and water vapor). Palladium is also used in electronics, dentistry, medicine, hydrogen purification ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amide
In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula , where R, R', and R″ represent any group, typically organyl functional group, groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the Polymer backbone, main chain of a protein, and an isopeptide bond when it occurs in a side chain, as in asparagine and glutamine. It can be viewed as a Derivative (chemistry), derivative of a carboxylic acid () with the hydroxyl group () replaced by an amino group (); or, equivalently, an acyl group, acyl (alkanoyl) group () joined to an amino group. Common amides are formamide (), acetamide (), benzamide (), and dimethylformamide (). Some uncommon examples of amides are ''N''-chloroacetamide () and chloroformamide (). Amides are qualified as primary (chemistry), primary, secondary (chemistry), secondary, and tertiary (chemistry), tertiary according to the number of acyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitroso
In organic chemistry, nitroso refers to a functional group in which the nitric oxide () group is attached to an organic moiety. As such, various nitroso groups can be categorized as ''C''-nitroso compounds (e.g., nitrosoalkanes; ), ''S''-nitroso compounds ( nitrosothiols; ), ''N''-nitroso compounds (e.g., nitrosamines, ), and ''O''-nitroso compounds ( alkyl nitrites; ). Synthesis Nitroso compounds can be prepared by the reduction of nitro compounds or by the oxidation of hydroxylamines. Ortho-nitrosophenols may be produced by the Baudisch reaction. In the Fischer–Hepp rearrangement, aromatic 4-nitrosoanilines are prepared from the corresponding nitrosamines. Properties Nitrosoarenes typically participate in a monomer–dimer equilibrium. The azobenzene ''N'',''N'-''dioxide (Ar(–O)N+=+N(O–)Ar) dimers, which are often pale yellow, are generally favored in the solid state, whereas the deep-green monomers are favored in dilute solution or at higher temperatures. They ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schmidt Reaction
In organic chemistry, the Schmidt reaction is an organic reaction in which an azide reacts with a carbonyl derivative, usually an aldehyde, ketone, or carboxylic acid, under acidic conditions to give an amine or amide, with expulsion of nitrogen. It is named after Karl Friedrich Schmidt (1887–1971), who first reported it in 1924 by successfully converting benzophenone and hydrazoic acid to benzanilide. The intramolecular reaction was not reported until 1991 but has become important in the synthesis of natural products. The reaction is effective with carboxylic acids to give amines (above), and with ketones to give amides (below). Reaction mechanism The reaction is closely related to the Curtius rearrangement except that in this reaction the acyl azide is produced by reaction of the carboxylic acid with hydrazoic acid via the protonated carboxylic acid, in a process akin to a Fischer esterification. An alternative, involving the formation of an acylium ion, becomes more im ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxylic Acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl group (e.g., alkyl, alkenyl, aryl), or hydrogen, or other groups. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion. Examples and nomenclature Carboxylic acids are commonly identified by their trivial names. They often have the suffix ''-ic acid''. IUPAC-recommended names also exist; in this system, carboxylic acids have an ''-oic acid'' suffix. For example, butyric acid () is butanoic acid by IUPAC guidelines. For nomenclature of complex molecules containing a carboxylic acid, the carboxyl can be considered position one of the parent chain even if there are other substituents, such as 3-chloropropanoic acid. Alternately, it can be named ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
