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Bromochloromethane
Bromochloromethane or methylene bromochloride and Halon 1011 is a mixed halomethane. It is a heavy low-viscosity liquid with refractive index 1.4808. Halon 1011 was invented for use in fire extinguishers in Germany during the mid-1940s, in an attempt to create a less toxic, more effective alternative to carbon tetrachloride. This was a concern in aircraft and tanks as carbon tetrachloride produced highly toxic by-products when discharged onto a fire. It was slightly less toxic, and used up until the late 1960s, being officially banned by the NFPA for use in fire extinguishers in 1969, as safer and more effective agents such as halon 1211 and 1301 were developed. Due to its ozone depletion potential its production was banned from January 1, 2002, at the ''Eleventh Meeting of the Parties for the Montreal Protocol on Substances that Deplete the Ozone Layer''. Bromochloromethane's biodegradation is catalyzed by the hydrolase enzyme alkylhalidase: :CH2BrCl + H2O → CH2O + HBr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloromethane
Chloromethane, also called methyl chloride, Refrigerant-40, R-40 or HCC 40, is an organic compound with the chemical formula . One of the haloalkanes, it is a colorless, odorless, flammable gas. Methyl chloride is a crucial reagent in industrial chemistry, although it is rarely present in consumer products, and was formerly utilized as a refrigerant. Occurrence Chloromethane is an abundant organohalogen, anthropogenic or natural, in the atmosphere. Marine Laboratory cultures of marine phytoplankton (''Phaeodactylum tricornutum'', ''Phaeocystis'' sp., ''Thalassiosira weissflogii'', ''Chaetoceros calcitrans'', ''Isochrysis'' sp., ''Porphyridium'' sp., ''Synechococcus'' sp., ''Tetraselmis'' sp., ''Prorocentrum'' sp., and ''Emiliana huxleyi'') produce CH3Cl, but in relatively insignificant amounts. An extensive study of 30 species of polar macroalgae revealed the release of significant amounts of CH3Cl in only ''Gigartina skottsbergii'' and ''Gymnogongrus antarcticus''. Biogenesis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dibromochloromethane
Dibromochloromethane is a colorless to yellow, heavy and nonflammable compound with formula . It is a trihalomethane. The substance has a sweet odour. Small quantities of dibromochloromethane are produced in ocean by algae. Applications Dibromochloromethane was formerly used as a flame retardant and as an intermediate in chemicals manufacturing. Today it is used only as a laboratory reagent. Dibromochloromethane is also a disinfection byproduct, formed by the reaction of chlorine with natural organic matter and bromide ions in the raw water supply. As a result, it is commonly found in chlorinated drinking water. Also, it is able to reduce methane production in ruminants by 79 % See also * Asparagopsis taxiformis ''Asparagopsis taxiformis'', (red sea plume or limu kohu) formerly ''A. sanfordiana'', is a species of red algae, with cosmopolitan distribution in tropical to warm temperate waters. Researchers have demonstrated that feeding ruminants a diet c ... References Ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2-Chloroethanol
2-Chloroethanol (also called ethylene chlorohydrin or glycol chlorohydrin) is an organic chemical compound with the chemical formula HOCH2CH2Cl and the ''simplest'' beta-halohydrin (chlorohydrin). This colorless liquid has a pleasant ether-like odor. It is miscible with water. The molecule is bifunctional, consisting of both an alkyl chloride and an alcohol functional group. Synthesis and applications 2-Chloroethanol is produced by treating ethylene with hypochlorous acid: : 2-Chloroethanol was once produced on a large scale as a precursor to ethylene oxide: : :HOCH2CH2Cl + NaOH → C2H4O + NaCl + H2O This application has been supplanted by the more economic direct oxidation of ethylene. Otherwise chloroethanol is still used in the production of pharmaceuticals, biocides, and plasticizers. Many of these applications entail its use in installing 2-hydroxyethyl groups. Several dyes are prepared by the alkylation of aniline derivatives with chloroethanol. It is also used for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halomethane
Halomethane compounds are derivatives of methane () with one or more of the hydrogen atoms replaced with halogen atoms ( F, Cl, Br, or I). Halomethanes are both naturally occurring, especially in marine environments, and human-made, most notably as refrigerants, solvents, propellants, and fumigants. Many, including the chlorofluorocarbons, have attracted wide attention because they become active when exposed to ultraviolet light found at high altitudes and destroy the Earth's protective ozone layer. Structure and properties Like methane itself, halomethanes are tetrahedral molecules. The halogen atoms differ greatly in size and charge from hydrogen and from each other. Consequently, most halomethanes deviate from the perfect tetrahedral symmetry of methane.Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick “Fluorine Compounds, Organic” Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. The ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halomethanes
Halomethane compounds are derivatives of methane () with one or more of the hydrogen atoms replaced with halogen atoms ( F, Cl, Br, or I). Halomethanes are both naturally occurring, especially in marine environments, and human-made, most notably as refrigerants, solvents, propellants, and fumigants. Many, including the chlorofluorocarbons, have attracted wide attention because they become active when exposed to ultraviolet light found at high altitudes and destroy the Earth's protective ozone layer. Structure and properties Like methane itself, halomethanes are tetrahedral molecules. The halogen atoms differ greatly in size and charge from hydrogen and from each other. Consequently, most halomethanes deviate from the perfect tetrahedral symmetry of methane.Günter Siegemund, Werner Schwertfeger, Andrew Feiring, Bruce Smart, Fred Behr, Herward Vogel, Blaine McKusick “Fluorine Compounds, Organic” Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. The ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroiodomethane
Chloroiodomethane is the halomethane with the formula is . It is a colorless liquid of use in organic synthesis. Together with other iodomethanes, chloroiodomethane is produced by some microorganisms. Applications Chloroiodomethane is used in cyclopropanation (''Simmon-Smith reaction''), where it often replaces diiodomethane because of higher yields and selectivity. It is also used in Mannich reaction, aminomethylation, epoxidation, ring opening and addition to terminal alkenes. It is a precursor to chloromethylenating agent Ph3P=CHCl. It reacts with organolithium compounds to give chloromethyllithium (ClCH2Li). Crystallography It crystallizes orthorhombic crystal system with space group ''Pnma'' with lattice constants A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has ...: ''a'' = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkylhalidase
In enzymology, an alkylhalidase () is an enzyme that catalyzes the chemical reaction :bromochloromethane + H2O \rightleftharpoons formaldehyde + bromide + chloride Thus, the two substrates of this enzyme are bromochloromethane and H2O, whereas its 3 products are formaldehyde, bromide, and chloride. This enzyme belongs to the family of hydrolases, specifically those acting on halide bonds in carbon-halide compounds. The systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivial ... of this enzyme class is alkyl-halide halidohydrolase. Other names in common use include halogenase, haloalkane halidohydrolase, and haloalkane dehalogenase. References * Further reading * EC 3.8.1 Enzymes of unknown structure {{hydrolase-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozone Depletion
Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events. The main causes of ozone depletion and the ozone hole are manufactured chemicals, especially manufactured halocarbon refrigerants, solvents, propellants, and foam-blowing agents (chlorofluorocarbons (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS). These compounds are transported into the stratosphere by turbulent mixing after being emitted from the surface, mixing much faster than the molecules can settle. Once in the stratosphere, they release atoms from the halogen group through photodissociation, which ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire Suppression Agents
Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames are produced. The ''flame'' is the visible portion of the fire. Flames consist primarily of carbon dioxide, water vapor, oxygen and nitrogen. If hot enough, the gases may become ionized to produce plasma. Depending on the substances alight, and any impurities outside, the color of the flame and the fire's intensity will be different. Fire in its most common form can result in conflagration, which has the potential to cause physical damage through burning. Fire is an important process that affects ecological systems around the globe. The positive effects of fire include stimulating growth and maintaining various ecological systems. Its negative effects include hazard to life and property, atmospheric pollution, and water contamination. If fire re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylene Bromide
Preparation Dibromomethane is prepared commercially from dichloromethane via bromochloromethane: :6 CH2Cl2 + 3 Br2 + 2 Al → 6 CH2BrCl + 2 AlCl3 :CH2Cl2 + HBr → CH2BrCl + HCl The latter route requires aluminium trichloride as a catalyst. The bromochloromethane product from either reaction can further react in a similar manner: :6 CH2BrCl + 3 Br2 + 2 Al → 6 CH2Br2 + 2 AlCl3 :CH2BrCl + HBr → CH2Br2 + HCl In the laboratory, it is prepared from bromoform: :CHBr3 + Na3AsO3 + NaOH → CH2Br2 + Na3AsO4 + NaBr using sodium arsenite and sodium hydroxide. Another way is to prepare it from diiodomethane and bromine. Uses Dibromomethane is used as a solvent, gauge fluid, and in organic synthesis (often as 1H-NMR internal standard). It is a convenient agent for converting catechols to their methylenedioxy derivatives. Natural occurrence It is naturally produced by marine algae and liberated to the oceans. Releasing on soil causes it to evaporate and leach into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium Trichloride
Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms hexahydrate with the formula , containing six water molecules of hydration. Both are colourless crystals, but samples are often contaminated with iron(III) chloride, giving a yellow color. The anhydrous material is important commercially. It has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large amounts are also used in other areas of the chemical industry. The compound is often cited as a Lewis acid. It is an example of an inorganic compound that reversibly changes from a polymer to a monomer at mild temperature. Structure Anhydrous adopts three structures, depending on the temperature and the state (solid, liquid, gas). Solid has a sheet-like layered structure with cubic close-packed chloride ions. In this framework, the Al centres exhibit octahedral coordination geometry. In contrast, has a more mole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichloromethane
Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible with water, it is slightly polar, and miscible with many organic solvents.Rossberg, M. ''et al.'' (2006) "Chlorinated Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. . Occurrence Natural sources of dichloromethane include oceanic sources, macroalgae, wetlands, and volcanoes. However, the majority of dichloromethane in the environment is the result of industrial emissions. Production DCM is produced by treating either chloromethane or methane with chlorine gas at 400–500 °C. At these temperatures, both methane and chloromethane undergo a series of reactions producing progressively more chlorinated products. In this way, an estimated 400,000 tons were produced in the US, Europe, and Japan in 1993. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
