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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 oxalates and certain chemoluminescent reactions of oxalyl chloride Oxalyl chloride is an organic chemical compound with the formula (COCl)2. This colorless, sharp-smelling liquid, the diacyl chloride of oxalic acid, is a useful reagent in organic synthesis. Preparation Oxalyl chloride was first prepared in 1892 .... See also * 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. 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, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Liv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimer (chemistry)
A dimer () ('' di-'', "two" + ''-mer'', "parts") is an oligomer consisting of two monomers joined by bonds that can be either strong or weak, covalent or intermolecular. Dimers also have significant implications in polymer chemistry, inorganic chemistry, and biochemistry. The term ''homodimer'' is used when the two molecules are identical (e.g. A–A) and ''heterodimer'' when they are not (e.g. A–B). The reverse of dimerization is often called dissociation. When two oppositely charged ions associate into dimers, they are referred to as ''Bjerrum pairs'', after Niels Bjerrum. Noncovalent dimers Anhydrous carboxylic acids form dimers by hydrogen bonding of the acidic hydrogen and the carbonyl oxygen. For example, acetic acid forms a dimer in the gas phase, where the monomer units are held together by hydrogen bonds. Under special conditions, most OH-containing molecules form dimers, e.g. the water dimer. Excimers and exciplexes are excited structures with a short lif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxocarbons
In chemistry, an oxocarbon or oxide of carbon is a chemical compound consisting only of carbon and oxygen. The simplest and most common oxocarbons are carbon monoxide (CO) and carbon dioxide (). Many other stable (practically if not thermodynamically) or metastable oxides of carbon are known, but they are rarely encountered, such as carbon suboxide ( or ) and mellitic anhydride (). Many other oxides are known today, most of them synthesized since the 1960s. Some of these new oxides are stable at room temperature. Some are metastable or stable only at very low temperatures, but decompose to simpler oxocarbons when warmed. Many are inherently unstable and can be observed only momentarily as intermediates in chemical reactions or are so reactive that they exist only in gas phase or have only been detected by matrix isolation. Graphene oxide and other stable polymeric carbon oxides with unbounded molecular structures exist. Overview Carbon dioxide (CO2) occurs widely in nature, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothetical Chemical Compounds
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous observations that cannot satisfactorily be explained with the available scientific theories. Even though the words "hypothesis" and "theory" are often used interchangeably, a scientific hypothesis is not the same as a scientific theory. A working hypothesis is a provisionally accepted hypothesis proposed for further research in a process beginning with an educated guess or thought. A different meaning of the term ''hypothesis'' is used in formal logic, to denote the antecedent of a proposition; thus in the proposition "If ''P'', then ''Q''", ''P'' denotes the hypothesis (or antecedent); ''Q'' can be called a consequent. ''P'' is the assumption in a (possibly counterfactual) ''What If'' question. The adjective ''hypothetical'', meaning "hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxylic Anhydrides
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. 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 at oftentimes have the suffix ''-ic acid''. IUPAC-recommended names also exist; in this system, carboxylic acids have an ''-oic acid'' suffix. For example, butyric acid (C3H7CO2H) 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 as a "carboxy" or "carboxylic acid" substituent on another ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha-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. 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 of bis(trifluoromethyl)malonyl peroxide.Waldemar Adam, Ju-Chao Liu, Oswaldo Rodriguez (1973), ''Bis(trifluoromethyl)acetolactone, a Stable α-Lactone''. J. Org. Chem., volume 38, pages 2269–2270 See also * α-Propiolactone *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 computati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxalyl Chloride
Oxalyl chloride is an organic chemical compound with the formula (COCl)2. This colorless, sharp-smelling liquid, the diacyl chloride of oxalic acid, is a useful reagent in organic synthesis. Preparation Oxalyl chloride was first prepared in 1892 by the French chemist Adrien Fauconnier, who reacted diethyl oxalate with phosphorus pentachloride. It can also be prepared by treating oxalic acid with phosphorus pentachloride. Oxalyl chloride is produced commercially from ethylene carbonate. Photochlorination gives the tetrachloride, which is subsequently degraded: :C2H4O2CO + 4 Cl2 → C2Cl4O2CO + 4 HCl :C2Cl4O2CO → C2O2Cl2 + COCl2 Reactions Oxalyl chloride reacts with water giving off gaseous products only: hydrogen chloride (HCl), carbon dioxide (CO2), and carbon monoxide (CO). : In this, it is quite different from other acyl chlorides which hydrolyze with formation of hydrogen chloride and the original carboxylic acid. Applications in organic synthesis Oxidation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemoluminescent
Chemiluminescence (also chemoluminescence) is the emission of light (luminescence) as the result of a chemical reaction. There may also be limited emission of heat. Given reactants A and B, with an excited intermediate ◊, : + -> lozenge -> roducts+ light For example, if is luminol and is hydrogen peroxide in the presence of a suitable catalyst we have: :\underset + \underset -> 3-APAlozenge-> + light where: * 3-APA is 3-aminophthalate * 3-APA ''◊is the vibronic excited state fluorescing as it decays to a lower energy level. General description The decay of this excited state ''◊to a lower energy level causes light emission. In theory, one photon of light should be given off for each molecule of reactant. This is equivalent to the Avogadro number of photons per mole of reactant. In actual practice, non-enzymatic reactions seldom exceed 1% QC, quantum efficiency. In a chemical reaction, reactants collide to form a transition state, the enthalpic maximum in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxalate
Oxalate (IUPAC: ethanedioate) is an anion with the formula C2O42−. This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (Na2C2O4), and several esters such as dimethyl oxalate (C2O4(CH3)2). It is a conjugate base of oxalic acid. At neutral pH in aqueous solution, oxalic acid converts completely to oxalate. Relationship to oxalic acid The dissociation of protons from oxalic acid proceeds in a stepwise manner; as for other polyprotic acids, loss of a single proton results in the monovalent hydrogenoxalate anion . A salt with this anion is sometimes called an acid oxalate, monobasic oxalate, or hydrogen oxalate. The equilibrium constant ( ''K''a) for loss of the first proton is (p''K''a = 1.27). The loss of the second proton, which yields the oxalate ion, has an equilibrium constant of (p''K''a = 4.28). These values imply, in solutions with neutral pH, no oxalic acid and only trace ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Decomposition
Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion or other chemical reaction. Decomposition temperature definition A simple substance (like water) may exist in equilibrium with its thermal decomposition products, effectively halting the decomposition. The equilibrium fraction of decomposed molecules increases with the temperature. Examples * Calcium carbonate (limestone or chalk) decomposes into calcium oxide and carbon dioxide when heated. The chemical reaction is as follows: ::CaCO3 → CaO + CO2 :The reaction is used to make quick lime, which is an industrially important product. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioxane Tetraketone
Dioxane tetraketone (or 1,4-dioxane-2,3,5,6-tetrone) is an organic compound with the formula C4O6. It is an oxide of carbon (an oxocarbon), which can be viewed as the fourfold ketone of dioxane. It can also be viewed as the cyclic dimer of oxiranedione (C2O3), the hypothetical anhydride of oxalic acid. In 1998, Paolo Strazzolini and others synthesized this compound by reacting oxalyl chloride (COCl)2 or the bromide (COBr)2 with a suspension of silver oxalate (Ag2C2O4) in diethyl ether at −15 °C, followed by evaporation of the solvent at low temperature and pressure. The substance is stable when dissolved in ether and trichloromethane at −30 °C, but decomposes into a 1:1 mixture of carbon monoxide (CO) and carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
