|
Cyclobutanone
Cyclobutanone is an organic compound with molecular formula (CH2)3CO. It is a four-membered cyclic ketone (cycloalkanone). It is a colorless volatile liquid at room temperature. Since cyclopropanone is highly sensitive, cyclobutanone is the smallest easily handled cyclic ketone. Preparation The Russian chemist Nikolai Kischner first prepared cyclobutanone in a low yield from cyclobutanecarboxylic acid. Kischner's process, involving several steps, is cumbersome and inefficient; more efficient, high-yielding syntheses have since been developed. One strategy involves degradation of five-carbon building blocks. For example, the oxidative decarboxylation of cyclobutanecarboxylic acid was improved by the use of other reagents and methods. A newer, more efficient preparation of cyclobutanone was found by P. Lipp and R. Köster in which a solution of diazomethane in diethyl ether is reacted with ketene. This reaction is based on a ring expansion of the cyclopropanone intermediate ini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclobutanone Decomposition V
Cyclobutanone is an organic compound with molecular formula (CH2)3CO. It is a four-membered cyclic ketone (cycloalkanone). It is a colorless volatile liquid at room temperature. Since cyclopropanone is highly sensitive, cyclobutanone is the smallest easily handled cyclic ketone. Preparation The Russian chemist Nikolai Kischner first prepared cyclobutanone in a low yield from cyclobutanecarboxylic acid. Kischner's process, involving several steps, is cumbersome and inefficient; more efficient, high-yielding syntheses have since been developed. One strategy involves degradation of five-carbon building blocks. For example, the oxidative decarboxylation of cyclobutanecarboxylic acid was improved by the use of other reagents and methods. A newer, more efficient preparation of cyclobutanone was found by P. Lipp and R. Köster in which a solution of diazomethane in diethyl ether is reacted with ketene. This reaction is based on a ring expansion of the cyclopropanone intermediate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homo-Favorskii Rearrangement
The homo Favorskii rearrangement is the rearrangement of β-halo ketones and cyclobutanones, which in ring systems may yield ring contraction. This rearrangement takes place in the presence of a base, yielding a carboxylic acid derivative corresponding to the nucleophile (most often the base itself). E1cb will occur if α-carbon adjacent to the halogen atom has hydrogens on it. Reaction mechanism The reaction proceeds in an analogous manner to that of the Favorskii rearrangement. The major difference is that the cyclopropanone intermediate is replaced by a cyclobutanone intermediate, and therefore the intermediate's formation cannot be viewed as a 2-electron electrocyclization reaction. The selectivity is similar to the Favorskii rearrangement in that the most stable carbanion is formed. Examples The homo-Favorskii rearrangement is a key step in the synthesis of Kelsoene, constructing its four-membered ring. In this particular example, the nucleophile is absent and the b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopropanone
Cyclopropanone is an organic compound with molecular formula (CH2)2CO consisting of a cyclopropane carbon framework with a ketone functional group. The parent compound is labile, being highly sensitive toward even weak nucleophiles. Surrogates of cyclopropanone include the ketals. Preparation Cyclopropanone has been prepared by reaction of ethenone, ketene with diazomethane in an unreactive solvent such as dichloromethane. These solutions are stable at −78 °C. In the presence of protic reagents such as carboxylic acids, primary and secondary amines, and alcohols, cyclopropanone converts to adducts, which are often isolatable at room temperature: :(CH2)2CO + X-H → (CH2)2C(X)(OH) (X-H = R2N-H, HO-H, RO-H) Structure The C3O atoms are coplanar. As deduced from the Microwave spectroscopy, microwave spectrum, the H2C-CH2 bond length of 157.5 picometer, pm is unusually long. By contrast, the C-C bond lengths in cyclopropane are 151 pm. The C=O bond le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclic Ketone
In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone (where R and R' are methyl), with the formula . Many ketones are of great importance in biology and industry. Examples include many sugars (ketoses), many steroids, ''e.g.'', testosterone, and the solvent acetone. Nomenclature and etymology The word ''ketone'' is derived from ''Aketon'', an old German word for ''acetone''. According to the rules of IUPAC nomenclature, ketone names are derived by changing the suffix ''-ane'' of the parent alkane to ''-anone''. Typically, the position of the carbonyl group is denoted by a number, but traditional nonsystematic names are still generally used for the most important ketones, for example acetone and benzophenone. These nonsystematic names are considered retained IUPAC names, although some introdu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopropanone
Cyclopropanone is an organic compound with molecular formula (CH2)2CO consisting of a cyclopropane carbon framework with a ketone functional group. The parent compound is labile, being highly sensitive toward even weak nucleophiles. Surrogates of cyclopropanone include the ketals. Preparation Cyclopropanone has been prepared by reaction of ethenone, ketene with diazomethane in an unreactive solvent such as dichloromethane. These solutions are stable at −78 °C. In the presence of protic reagents such as carboxylic acids, primary and secondary amines, and alcohols, cyclopropanone converts to adducts, which are often isolatable at room temperature: :(CH2)2CO + X-H → (CH2)2C(X)(OH) (X-H = R2N-H, HO-H, RO-H) Structure The C3O atoms are coplanar. As deduced from the Microwave spectroscopy, microwave spectrum, the H2C-CH2 bond length of 157.5 picometer, pm is unusually long. By contrast, the C-C bond lengths in cyclopropane are 151 pm. The C=O bond le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Activation Energy
In the Arrhenius model of reaction rates, activation energy is the minimum amount of energy that must be available to reactants for a chemical reaction to occur. The activation energy (''E''a) of a reaction is measured in kilojoules per mole (kJ/mol) or kilocalories per mole (kcal/mol). Activation energy can be thought of as a magnitude of the potential barrier (sometimes called the energy barrier) separating minima of the potential energy surface pertaining to the initial and final thermodynamic state. For a chemical reaction to proceed at a reasonable rate, the temperature of the system should be high enough such that there exists an appreciable number of molecules with translational energy equal to or greater than the activation energy. The term "activation energy" was introduced in 1889 by the Swedish scientist Svante Arrhenius. Other uses Although less commonly used, activation energy also applies to nuclear reactions and various other physical phenomena. Temperature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon bond, carbon–carbon double bonds). Ethylene is widely used in the chemical industry, and its worldwide production (over 150 million tonnes in 2016) exceeds that of any other organic compound. Much of this production goes toward creating polyethylene, which is a widely used plastic containing polymer chains of ethylene units in various chain lengths. Production greenhouse gas emissions, emits greenhouse gases, including methane from feedstock production and carbon dioxide from any non-sustainable energy used. Ethylene is also an important natural plant hormone and is used in agriculture to induce ripening of fruits. The hydrate of ethylene is ethanol. Structure and properties This hydrocarbon has four hydrogen atoms bound to a pair of carbon atoms that are con ... [...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] |
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] |
Cycloaddition
In organic chemistry, a cycloaddition is a chemical reaction in which "two or more Unsaturated hydrocarbon, unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the Multiplicity (chemistry)#Molecules, bond multiplicity". The resulting reaction is a cyclization reaction. Many but not all cycloadditions are Concerted reaction, concerted and thus pericyclic. Nonconcerted cycloadditions are not pericyclic. As a class of addition reaction, cycloadditions permit carbon–carbon bond formation without the use of a nucleophile or electrophile. Cycloadditions can be described using two systems of notation. An older but still common notation is based on the size of linear arrangements of atoms in the reactants. It uses parentheses: where the variables are the numbers of linear atoms in each reactant. The product is a cycle of size . In this system, the standard Diels-Alder reaction is a (4 + 2)-cyc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
