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Dehydrofluorination
In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications. Dehydrohalogenation from alkyl halides Traditionally, alkyl halides are substrates for dehydrohalogenations. The alkyl halide must be able to form an alkene, thus halides having no C–H bond on an adjacent carbon are not suitable substrates. Aryl halides are also unsuitable. Upon treatment with strong base, chlorobenzene dehydrohalogenates to give phenol via a benzyne intermediate. Base-promoted reactions to alkenes When treated with a strong base many alkyl chlorides convert to corresponding alkene. It is also called a β-elimination reaction and is a type of elimination reaction. Some prototypes are shown below: :\begin \ce\ &\ce \\ \ce\ &\ce \\ \ce\ &\ce \end Here ethyl chloride reacts with potassium hydroxide, typically in a solvent such as ethanol, giving ethylene. Li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1,2,3,3,3-Pentafluoropropene
1,2,3,3,3-Pentafluoropropene is the unsaturated fluorocarbon with the formula HFC=C(F)CF. This colorless gas is of interest as a precursor to hydrofluoroolefins (HFOs), which are used as refrigerants in air conditioners. Of the methods reported for its synthesis, one route involves dehydrofluorination In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes, but it has wider applications. Dehydrohalogenation from alkyl hali ... of 1,1,2,3,3,3-hexafluoropropane.Nappa, Mario Joseph; Rao, Velliyur Nott Mallikarjuna "Dehydrofluorination and hydrogenation process and catalysts for the manufacture of 1,1,1,2,3-pentafluoropropane from 1,1,1,2,3,3-hexafluoropropane" PCT Int. Appl. (1994), WO 9427940 A1 19941208. The compound exists as a mixture of E- and Z-isomers. References {{DEFAULTSORT:Pentafluoropropene, 1, 2, 3, 3, 3- Haloalkenes Refrigerants Trifluorom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthesis Of Alkenes - Dehydrohalogenation
Synthesis or synthesize may refer to: Science Chemistry and biochemistry * Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of organic compounds ***Total synthesis, the complete organic synthesis of complex organic compounds, usually without the aid of biological processes *** Convergent synthesis or linear synthesis, a strategy to improve the efficiency of multi-step chemical syntheses **Dehydration synthesis, a chemical synthesis resulting in the loss of a water molecule *Biosynthesis, the creation of an organic compound in a living organism, usually aided by enzymes **Photosynthesis, a biochemical reaction using a carbon molecule to produce an organic molecule, using sunlight as a catalyst **Chemosynthesis, the synthesis of biological compounds into organic waste, using methane or an oxidized molecule as a catalyst ** Amino acid synthesis, the synthesis of an amino a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Regioselectivity
In chemistry, regioselectivity is the preference of chemical bonding or breaking in one direction over all other possible directions. It can often apply to which of many possible positions a reagent will affect, such as which proton a strong base will abstract from an organic molecule, or where on a substituted benzene ring a further substituent will be added. A specific example is a halohydrin formation reaction with 2-propenylbenzene: : Because of the preference for the formation of one product over another, the reaction is selective. This reaction is regioselective because it selectively generates one constitutional isomer rather than the other. Various examples of regioselectivity have been formulated as rules for certain classes of compounds under certain conditions, many of which are named. Among the first introduced to chemistry students are Markovnikov's rule for the addition of protic acids to alkenes, and the Fürst-Plattner rule for the addition of nucleophiles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propylene Oxide
Propylene oxide is an acutely toxic and carcinogenic organic compound with the molecular formula CH3CHCH2O. This colourless volatile liquid with an odour similar to ether, is produced on a large scale industrially. Its major application is its use for the production of polyether polyols for use in making polyurethane plastics. It is a chiral epoxide, although it is commonly used as a racemic mixture. This compound is sometimes called 1,2-propylene oxide to distinguish it from its isomer 1,3-propylene oxide, better known as oxetane. Production Industrial production of propylene oxide starts from propylene. Two general approaches are employed, one involving hydrochlorination and the other involving oxidation. In 2005, about half of the world production was through chlorohydrin technology and one half via oxidation routes. The latter approach is growing in importance. Hydrochlorination route The traditional route proceeds via the conversion of propene to propylene chlorohy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorohydrin
In organic chemistry a halohydrin (also a haloalcohol or β-halo alcohol) is a functional group in which a halogen and a hydroxyl are bonded to adjacent carbon atoms, which otherwise bear only hydrogen or hydrocarbyl groups (e.g. 2-chloroethanol, 3-chloropropane-1,2-diol). The term only applies to saturated motifs, as such compounds like 2-chlorophenol would not normally be considered halohydrins. Megatons of some chlorohydrins, e.g. propylene chlorohydrin, are produced annually as precursors to polymers. Halohydrins may be categorized as chlorohydrins, bromohydrins, fluorohydrins or iodohydrins depending on the halogen present. Synthesis From alkenes Halohydrins are usually prepared by treatment of an alkene with a halogen, in the presence of water. The reaction is a form of electrophilic addition, similar to the halogen addition reaction and proceeds with anti addition, leaving the newly added X and OH groups in a trans configuration. The chemical equation for the conve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrofluoroolefin
Hydrofluoroolefins (HFOs) are unsaturated organic compounds composed of hydrogen, fluorine and carbon. These organofluorine compound are of interest as refrigerants. Unlike traditional hydrofluorocarbons (HFCs) and chlorofluorocarbons (CFCs), which are saturated, HFOs are olefins, otherwise known as alkenes. HFO refrigerants are categorized as having zero ozone depletion potential (ODP) and low global warming potential (GWP) and so offer a more environmentally friendly alternative to CFC, HCFC, and HFC refrigerants. Compared to HCFCs and HFCs, HFOs have shorter tropospheric lifetimes due to the reactivity of the C=C bond with hydroxyl radicals and chlorine radicals. This quick reactivity prevents them from reaching the stratosphere and participating in the depletion of good ozone, leading to strong interest in the development and characterization of new HFO blends for use as refrigerants. Many refrigerants in the HFO class are inherently stable chemically and inert, non toxic, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxychlorination
In organic chemistry, oxychlorination is a process for making C-Cl bonds. In contrast with direct use of Cl2, oxychlorination uses hydrogen chloride in combination with oxygen.{{Ullmann, author=M. Rossberg , display-authors=et al., title=Chlorinated Hydrocarbons, year=2006, doi=10.1002/14356007.a06_233.pub2 This process is attractive industrially because hydrogen chloride is less expensive than chlorine. Mechanism The reaction is usually initiated by copper(II) chloride (CuCl2), which is the most common catalyst in the production of 1,2-dichloroethane. In some cases, CuCl2 is supported on silica in presence of KCl, LaCl3, or AlCl3 as cocatalysts. Aside from silica, a variety of supports have also been used including various types of alumina, diatomaceous earth, or pumice. Because this reaction is highly exothermic (238 kJ/mol), the temperature is monitored, to guard against thermal degradation of the catalyst. The reaction is as follows: :CH2=CH2 + 2 CuCl2 → 2 CuCl + ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1,2-Dichloroethane
The chemical compound 1,2-dichloroethane, commonly known as ethylene dichloride (EDC), is a chlorinated hydrocarbon. It is a colourless liquid with a chloroform-like odour. The most common use of 1,2-dichloroethane is in the production of vinyl chloride, which is used to make polyvinyl chloride (PVC) pipes, furniture and automobile upholstery, wall coverings, housewares, and automobile parts. 1,2-Dichloroethane is also used generally as an intermediate for other organic chemical compounds, and as a solvent. It forms azeotropes with many other solvents, including water (at a boiling point of ) and other chlorocarbons. History In 1794, physician Jan Rudolph Deiman, merchant Adriaan Paets van Troostwijk, chemist Anthoni Lauwerenburg, and botanist Nicolaas Bondt, under the name of Society of Dutch Chemists ( nl, Gezelschap der Hollandsche Scheikundigen), were the first to produce 1,2-dichloroethane from olefiant gas (oil-making gas, ethylene) and chlorine gas. Although ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vinyl Chloride
Vinyl chloride is an organochloride with the formula H2C=CHCl. It is also called vinyl chloride monomer (VCM) or chloroethene. This colorless compound is an important industrial chemical chiefly used to produce the polymer polyvinyl chloride (PVC). About 13 million metric tonne are produced annually. VCM is among the top twenty largest petrochemicals (petroleum-derived chemicals) in world production. The United States currently remains the largest VCM manufacturing region because of its low-production-cost position in chlorine and ethylene raw materials. China is also a large manufacturer and one of the largest consumers of VCM. Vinyl chloride is a gas with a sweet odor. It is highly toxic, flammable, and carcinogenic. It can be formed in the environment when soil organisms break down chlorinated solvents. Vinyl chloride that is released by industries or formed by the breakdown of other chlorinated chemicals can enter the air and drinking water supplies. Vinyl chloride is a common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihalide
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluoride, chloride, bromide, iodide, astatide, or theoretically tennesside compound. The alkali metals combine directly with halogens under appropriate conditions forming halides of the general formula, MX (X = F, Cl, Br or I). Many salts are halides; the ''hal-'' syllable in ''halide'' and ''halite'' reflects this correlation. All Group 1 metals form halides that are white solids at room temperature. A halide ion is a halogen atom bearing a negative charge. The halide anions are fluoride (), chloride (), bromide (), iodide () and astatide (). Such ions are present in all ionic halide salts. Halide minerals contain halides. All these halides are colourless, high melting crystalline solids having high negative enthalpies of formation. Te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vicinal (chemistry)
In chemistry the descriptor vicinal (from Latin ''vicinus'' = neighbor), abbreviated ''vic'', describes any two functional groups bonded to two adjacent carbon atoms (i.e., in a 1,2-relationship). Relation of atoms in a molecule For example, the molecule 2,3-dibromobutane carries two vicinal bromine atoms and 1,3-dibromobutane does not. Mostly, the use of the term vicinal is restricted to two ''identical'' functional groups. Likewise in a ''gem-''dibromide the prefix ''gem'', an abbreviation of geminal, signals that both bromine atoms are bonded to the ''same'' atom (i.e., in a 1,1-relationship). For example, 1,1-dibromobutane is geminal. While comparatively less common, the term hominal has been suggested as a descriptor for groups in a 1,3-relationship. Like other such descriptors as syn, anti, exo or endo, the description ''vicinal'' helps explain how different parts of a molecule are related to each other either structurally or spatially. The vicinal adjective is somet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Tert-butoxide
Potassium ''tert''-butoxide is the chemical compound with the formula K+(CH3)3CO−. This colourless solid is a strong base (pKa of conjugate acid around 17), which is useful in organic synthesis. It exists as a tetrameric cubane-type cluster. It is often seen written in chemical literature as potassium ''t''-butoxide. The compound is often depicted as a salt, and it often behaves as such, but it is not ionized in solution. Preparation Potassium ''t''-butoxide is commercially available as a solution and as a solid, but it is often generated ''in situ'' for laboratory use because samples are so sensitive and older samples are often of poor quality. It is prepared by the reaction of dry ''tert''-butyl alcohol with potassium metal. The solid is obtained by evaporating these solutions followed by heating the solid. The solid can be purified by sublimation at 220 °C and 1 mmHg. Sublimation can also take place at 140 °C and 0.01 hPa. It is advisable to cover the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
