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Acetolactone
Acetolactone (α-acetolactone) is an organic compound with formula . It is the smallest member of the lactone family but can also be described as the epoxide of ethenone. The compound was described in 1997 as a transient species in mass spectrometry experiments. Related compounds Although acetolactone itself has not been isolated in bulk, the related species bis(trifluoromethyl)acetolactone ((), which has increased electronic stabilisation due to its two trifluoromethyl groups, is known and has a half-life of 8 hours at 25 °C. This compound is prepared by photolysis Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons wi ... of bis(trifluoromethyl)malonyl peroxide. Other alpha lactones have been prepared. See also * α-Propiolactone * Oxalic anhydride References Alpha-lactones Su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactone
Lactones are cyclic carboxylic esters. They are derived from the corresponding hydroxycarboxylic acids by esterification. They can be saturated or unsaturated. Lactones are formed by lactonization, the intramolecular esterification of the corresponding hydroxycarboxylic acids. Nomenclature Greek alphabet#Letters, Greek prefixes in alphabetical order indicate ring size. Lactones are usually named according to the precursor acid molecule (''aceto'' = 2 carbon atoms, ''propio'' = 3, ''butyro'' = 4, ''valero'' = 5, ''capro'' = 6, etc.), with a ''-lactone'' suffix and a Greek letter prefix that specifies the number of carbon atoms in the heterocycle — that is, the distance between the relevant -OH and the -COOH groups along said backbone. The first carbon atom after the carbon in the -COOH group on the parent compound is labelled α, the second will be labeled β, and so forth. Therefore, the prefixes also indicate the size of the lactone ring: α-lactone = 3-membered ring, β-lac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
α-Propiolactone
Methyloxiranone or α-propiolactone is a chemical compound of the lactone family, with a three-membered ring. It is a stable product which can be obtained from the 2-bromopropionate anion. It is an intermediate in the decomposition of 2-chloropropionic acid in the gas phase.Vicent S. Safont, Vicente Moliner, Juan Andrés, Luís R. Domingo (1997)''Theoretical Study of the Elimination Kinetics of Carboxylic Acid Derivatives in the Gas Phase. Decomposition of 2-Chloropropionic Acid'' J. Physical Chemistry series A, volume 101, issue 10, pp. 1859–1865. See also * β-Propiolactone * Acetolactone Acetolactone (α-acetolactone) is an organic compound with formula . It is the smallest member of the lactone family but can also be described as the epoxide of ethenone. The compound was described in 1997 as a transient species in mass spectromet ... References Alpha-lactones {{heterocyclic-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-containing compounds such as alkanes (e.g. methane ) and its derivatives are universally considered organic, but many others are sometimes considered inorganic, such as certain compounds of carbon with nitrogen and oxygen (e.g. cyanide ion , hydrogen cyanide , chloroformic acid , carbon dioxide , and carbonate ion ). Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, and even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethenone
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 temperature and pressure, 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 amine, primary or secondary amines to the corresponding acetamides. Preparation Et ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mass Spectrometry
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures. A mass spectrum is a type of plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds. In a typical MS procedure, a sample, which may be solid, liquid, or gaseous, is ionization, ionized, for example by bombarding it with a Electron ionization, beam of electrons. This may cause some of the sample's molecules to break up into positively charged fragments or simply become positively charged without fragmenting. These ions (fragmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helmut Schwarz
Helmut Schwarz (born 6 August 1943) is a German organic chemist. He has been a professor of chemistry at the Technische Universität Berlin since 1978. In 2018, he was elected a foreign associate of the U.S. National Academy of Sciences. Career Helmut Schwarz first learned to be a chemical technician and then went on to study chemistry at the TU Berlin. He completed his studies in 1971 and obtained his PhD in 1972 and his Habilitation in 1974 under Ferdinand Bohlmann. He pursued post-doctoral work at the Massachusetts Institute of Technology (MIT) and in the UK, after which he became a professor at the TU Berlin in 1978. Schwarz studies chemical reactions, specifically gas phase chemistry of ionic and radical organic species. He is furthermore working on advancing the analytical capabilities of mass spectrometry. He was president of the Alexander von Humboldt Foundation from 2008 to 2018. From 2010 to 2015 he was president of the German Academy of Researchers Leopoldina and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trifluoromethyl
The trifluoromethyl group is a functional group that has the formula . The naming of is group is derived from the methyl group (which has the formula ), by replacing each hydrogen atom by a fluorine atom. Some common examples are trifluoromethane , 1,1,1-trifluoroethane , and hexafluoroacetone . Compounds with this group are a subclass of the organofluorines. Properties The trifluoromethyl group has a significant electronegativity that is often described as being intermediate between the electronegativities of fluorine and chlorine. For this reason, trifluoromethyl-substituted compounds are often strong acids, such as trifluoromethanesulfonic acid and trifluoroacetic acid. Conversely, the trifluoromethyl group lowers the basicity of compounds like trifluoroethanol. Uses The trifluoromethyl group occurs in certain pharmaceuticals, drugs, and abiotically synthesized natural fluorocarbon based compounds. The medicinal use of the trifloromethyl group dates from 1928, although re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photodissociation
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons with one target molecule that dissociates into two fragments. Here, “light” is broadly defined as radiation spanning the vacuum ultraviolet (VUV), ultraviolet (UV), visible, and infrared (IR) regions of the electromagnetic spectrum. To break covalent bonds, photon energies corresponding to visible, UV, or VUV light are typically required, whereas IR photons may be sufficiently energetic to detach ligands from coordination complexes or to fragment supramolecular complexes. Photolysis in photosynthesis Photolysis is part of the light-dependent reaction, light phase, photochemical phase, or Hill reaction of photosynthesis. The general reaction of photosynthetic photolysis can be given in terms of photons as: :\ce + 2 \text \longrigh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxalic Anhydride
Oxalic anhydride or ethanedioic anhydride, also called oxiranedione, is a hypothetical organic compound, one of several isomers having the formula C2O3 that have been studied computationally. It can be viewed as the anhydride of oxalic acid or the two-fold ketone of ethylene oxide. It is an oxide of carbon (an oxocarbon). The simple compound apparently has yet to be observed (as of 2009). In 1998, however, Paolo Strazzolini and others have claimed the synthesis of dioxane tetraketone (C4O6), which can be viewed as the cyclic dimer of oxalic anhydride. It has been conjectured to be a fleeting intermediate in the thermal decomposition of certain oxalate Oxalate (systematic IUPAC name: ethanedioate) is an anion with the chemical formula . This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (), and several esters such as ...s and certain chemoluminescent reactions of oxalyl chloride. See also * 1,2- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
