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Ynol
In organic chemistry, an alkynol (shortened to ynol) is an alkyne with a hydroxyl group affixed to one of the two carbon atoms composing the triple bond (). The deprotonated anions of ynols are known as ''ynolates''. An ynol with hydroxyl groups on both sides of its triple bond is known as an ynediol; only one ynediol, acetylenediol, exists. Ynolates Ynolates are chemical compounds with a negatively charged oxygen atom attached to an alkyne functionality. They were first synthesized in 1975 by Schöllkopf and Hoppe via the ''n''-butyllithium fragmentation of 3,4-diphenylisoxazole. Synthetically, they behave as ketene precursors or synthons. Ynol–ketene tautomerism Ynols can interconvert with ketenes, much like enols can with aldehydes and ketones. The ynol tautomer is usually unstable, does not survive long, and changes into the ketene. This is because oxygen is more electronegative than carbon and thus forms stronger bonds. For instance, ethynol quickly inter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ynolate
Ynolates are chemical compounds with a negatively charged oxygen attached to an alkyne functionality. They were first synthesized in 1975 by Schöllkopf and Hoppe via the ''n''-butyllithium fragmentation of 3,4-diphenylisoxazole. Synthetically, they behave as ketene precursors or synthons. See also *Enolate In organic chemistry, enolates are organic anions derived from the deprotonation of carbonyl () compounds. Rarely isolated, they are widely used as reagents in the synthesis of organic compounds. Bonding and structure Enolate anions are electr ... References Functional groups {{organic-chemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enol
In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene ( olefin) with a hydroxyl group attached to one end of the alkene double bond (). The terms ''enol'' and ''alkenol'' are portmanteaus deriving from "-ene"/"alkene" and the "-ol" suffix indicating the hydroxyl group of alcohols, dropping the terminal "-e" of the first term. Generation of enols often involves removal of a hydrogen adjacent (α-) to the carbonyl group—i.e., deprotonation, its removal as a proton, . When this proton is not returned at the end of the stepwise process, the result is an anion termed an enolate (see images at right). The enolate structures shown are schematic; a more modern representation considers the molecular orbitals that are formed and occupied by electrons in the enolate. Similarly, generation of the enol often is accompanied by "trapping" or masking of the hydroxy group as an ether, such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethynol
Ethynol (or hydroxyacetylene) is an alkyne–alcohol (ynol) with the formula C2H2O. It is the much-less-stable tautomer of ethenone. At low temperature in a solid argon matrix it is possible to tautomerise ethenone to form ethynol. See also *Ethanol (ethyl alcohol) *Ethenol (vinyl alcohol) *Acetylenediol Acetylenediol, or ethynediol, is a chemical substance with formula HO−C≡C−OH (an ynol). It is the diol of acetylene. Acetylenediol is unstable in the condensed phase, although its tautomer glyoxal (CHO)2 is well known. Detection Acetyl ... References Alkynols {{Alcohol-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethynol
Ethynol (or hydroxyacetylene) is an alkyne–alcohol (ynol) with the formula C2H2O. It is the much-less-stable tautomer of ethenone. At low temperature in a solid argon matrix it is possible to tautomerise ethenone to form ethynol. See also *Ethanol (ethyl alcohol) *Ethenol (vinyl alcohol) *Acetylenediol Acetylenediol, or ethynediol, is a chemical substance with formula HO−C≡C−OH (an ynol). It is the diol of acetylene. Acetylenediol is unstable in the condensed phase, although its tautomer glyoxal (CHO)2 is well known. Detection Acetyl ... References Alkynols {{Alcohol-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetylenediol
Acetylenediol, or ethynediol, is a chemical substance with formula HO−C≡C−OH (an ynol). It is the diol of acetylene. Acetylenediol is unstable in the condensed phase, although its tautomer glyoxal (CHO)2 is well known. Detection Acetylenediol was first observed in the gas-phase by mass spectrometry. The compound was later obtained by photolysis of squaric acid in a solid argon matrix at . Derivatives Alkoxide derivatives Like the diol, most simple ether derivatives are labile. Di-tert-butoxyacetylene is however a distillable liquid. Acetylenediolate salts Salts of the acetylenediolate (ethynediolate) dianion −O−C≡C−O− are known. They are not however prepared from ethynediol, but by the reduction of carbon monoxide. Potassium acetylenediolate (K2C2O2) was first obtained by Liebig in 1834, from the reaction of carbon monoxide with metallic potassium;Justus Liebig (1834), Annalen der Chemie und Pharmacie, volume 11, p. 182. Cited by Raymond N. Vrtis et a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ketene
In organic chemistry, a ketene is an organic compound of the form , where R and R' are two arbitrary monovalent chemical groups (or two separate substitution sites in the same molecule). The name may also refer to the specific compound ethenone , the simplest ketene. Although they are highly useful, most ketenes are unstable. When used as reagents in a chemical procedure, they are typically generated when needed, and consumed as soon as (or while) they are produced. History Ketenes were first studied as a class by Hermann Staudinger before 1905. Ketenes were systematically investigated by Hermann Staudinger in 1905 in the form of diphenylketene (conversion of \alpha-chlorodiphenyl acetyl chloride with zinc). Staudinger was inspired by the first examples of reactive organic intermediates and stable radicals discovered by Moses Gomberg in 1900 (compounds with triphenylmethyl group). Properties Ketenes are highly electrophilic at the carbon atom bonded with the heteroatom, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethenone
In organic chemistry, ethenone is the formal name for ketene, an organic compound with formula or . It is the simplest member of the ketene class. It is an important reagent for acetylations. Properties Ethenone is a highly reactive gas (at standard conditions) and has a sharp irritating odour. It is only reasonably stable at low temperatures (−80 °C). It must therefore always be prepared for each use and processed immediately, otherwise a dimerization to diketene occurs or it reacts to polymers that are difficult to handle. The polymer content formed during the preparation is reduced, for example, by adding sulfur dioxide to the ketene gas. Because of its cumulative double bonds, ethenone is highly reactive and reacts in an addition reaction H-acidic compounds to the corresponding acetic acid derivatives. It does for example react with water to acetic acid or with primary or secondary amines to the corresponding acetamides. Preparation In industrial chemistry, k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethenone
In organic chemistry, ethenone is the formal name for ketene, an organic compound with formula or . It is the simplest member of the ketene class. It is an important reagent for acetylations. Properties Ethenone is a highly reactive gas (at standard conditions) and has a sharp irritating odour. It is only reasonably stable at low temperatures (−80 °C). It must therefore always be prepared for each use and processed immediately, otherwise a dimerization to diketene occurs or it reacts to polymers that are difficult to handle. The polymer content formed during the preparation is reduced, for example, by adding sulfur dioxide to the ketene gas. Because of its cumulative double bonds, ethenone is highly reactive and reacts in an addition reaction H-acidic compounds to the corresponding acetic acid derivatives. It does for example react with water to acetic acid or with primary or secondary amines to the corresponding acetamides. Preparation In industrial chemistry, k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Covalent Bond
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding. For many molecules, the sharing of electrons allows each atom to attain the equivalent of a full valence shell, corresponding to a stable electronic configuration. In organic chemistry, covalent bonding is much more common than ionic bonding. Covalent bonding also includes many kinds of interactions, including σ-bonding, π-bonding, metal-to-metal bonding, agostic interactions, bent bonds, three-center two-electron bonds and three-center four-electron bonds. The term ''covalent bond'' dates from 1939. The prefix ''co-'' means ''jointly, associated in action, partnered to a lesser degree, '' etc.; thus a "co-valent bond", in essence, means that the atoms share " valence", such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bond Energy
In chemistry, bond energy (''BE''), also called the mean bond enthalpy or average bond enthalpy is the measure of bond strength in a chemical bond. IUPAC defines bond energy as the average value of the gas-phase bond-dissociation energy (usually at a temperature of 298.15 K) for all bonds of the same type within the same chemical species. The bond dissociation energy (enthalpy) is also referred to as bond disruption energy, bond energy, bond strength, or binding energy (abbreviation: ''BDE'', ''BE'', or ''D''). It is defined as the standard enthalpy change of the following fission: R - ''X'' → R + ''X''. The ''BDE'', denoted by Dº(R - ''X''), is usually derived by the thermochemical equation, : \begin \mathrmX) \ = \Delta H^\circ_f\mathrm + \Delta H^\circ_f(X) - \Delta H^\circ_f(\mathrmX) \end The enthalpy of formation Δ''Hf''º of a large number of atoms, free radicals, ions, clusters and compounds is available from the websites of NIST, NASA, CODATA, and IUPAC. Most aut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
