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Diiodomethane
Diiodomethane or methylene iodide, commonly abbreviated "MI", is an organoiodine compound. Diiodomethane is a colorless liquid; however, it decomposes upon exposure to light liberating iodine, which colours samples brownish. It is slightly soluble in water, but soluble in organic solvents. It has a relatively high refractive index of 1.741, and a surface tension of 0.0508 N·m−1.Website of Krüss'' (8.10.2009) Uses Because of its high density, diiodomethane is used in the determination of the density of mineral and other solid samples. It can also be used as an optical contact liquid, in conjunction with the gemmological refractometer, for determining the refractive index of certain gemstones. Diiodomethane is a reagent for installing the CH2 group. In the Simmons–Smith reaction, it is a source of methylene. In fact the Simmons–Smith reaction does not produce free carbene but proceeds via Zn-CH2I intermediates. Diiodomethane is also a source of the equivalent of CH22+. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Simmons–Smith Reaction
The Simmons–Smith reaction is an organic cheletropic reaction involving an organozinc carbenoid that reacts with an alkene (or alkyne) to form a cyclopropane. It is named after Howard Ensign Simmons, Jr. and Ronald D. Smith. It uses a methylene free radical intermediate that is delivered to both carbons of the alkene simultaneously, therefore the configuration of the double bond is preserved in the product and the reaction is stereospecific. : Thus, cyclohexene, diiodomethane, and a zinc-copper couple (as iodomethylzinc iodide, ICH2ZnI) yield norcarane (bicyclo .1.0eptane). : The Simmons–Smith reaction is generally preferred over other methods of cyclopropanation, however it can be expensive due to the high cost of diiodomethane. Modifications involving cheaper alternatives have been developed, such as dibromomethane or diazomethane and zinc iodide. The reactivity of the system can also be increased by using the Furukawa modification, exchanging the zinc‑copper cou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodoform
Iodoform (also known as triiodomethane and, inaccurately, as carbon triiodide) is the organoiodine compound with the chemical formula C H I3. A pale yellow, crystalline, volatile substance, it has a penetrating and distinctive odor (in older chemistry texts, the smell is sometimes referred to as that of hospitals, where the compound is still commonly used) and, analogous to chloroform, sweetish taste. It is occasionally used as a disinfectant. Structure The molecule adopts tetrahedral molecular geometry with C3v symmetry. Synthesis and reactions The synthesis of iodoform was first described by Georges-Simon Serullas in 1822, by reactions of iodine vapour with steam over red-hot coals, and also by reaction of potassium with ethanolic iodine in the presence of water; and at much the same time independently by John Thomas Cooper. It is synthesized in the haloform reaction by the reaction of iodine and sodium hydroxide with any one of these four kinds of organic compounds: a methyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Tetraiodide
Carbon tetraiodide is a tetrahalomethane with the molecular formula CI4. Being bright red, it is a relatively rare example of a highly colored methane derivative. It is only 2.3% by weight carbon, although other methane derivatives are known with still less carbon. Structure The tetrahedral molecule features C-I distances of 2.12 ± 0.02 Å. The molecule is slightly crowded with short contacts between iodine atoms of 3.459 ± 0.03 Å, and possibly for this reason, it is thermally and photochemically unstable. Carbon tetraiodide crystallizes in tetragonal crystal structure (''a'' 6.409, ''c'' 9.558 (.10−1 nm)). It has zero dipole moment due to its symmetrically substituted tetrahedral geometry. Properties, synthesis, uses Carbon tetraiodide is slightly reactive towards water, giving iodoform and I2. It is soluble in nonpolar organic solvents. It decomposes thermally and photochemically to tetraiodoethylene, C2I4. Its synthesis entails AlCl3-catalyzed halide exchange, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethane
Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining. Its chief use is as feedstock for ethylene production. Related compounds may be formed by replacing a hydrogen atom with another functional group; the ethane moiety is called an ethyl group. For example, an ethyl group linked to a hydroxyl group yields ethanol, the alcohol in beverages. History Ethane was first synthesised in 1834 by Michael Faraday, applying electrolysis of a potassium acetate solution. He mistook the hydrocarbon product of this reaction for methane and did not investigate it further. During the period 1847–1849, in an effort to vindicate the radical theory of organic chemistry, Hermann Kolbe and Edward Frankland produced ethane by the reductions of propionitrile (ethyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethyl Iodide
Ethyl iodide (also iodoethane) is a colorless flammable chemical compound. It has the chemical formula C2H5I and is prepared by heating ethanol with iodine and phosphorus.''Merck Index of Chemicals and Drugs'', 9th ed., monograph 3753 On contact with air, especially on the effect of light, it decomposes and turns yellow or reddish from dissolved iodine. It may also be prepared by reaction between hydroiodic acid and ethanol distilling off the ethyl iodide. Ethyl iodide should be stored in the presence of copper powder to avoid rapid decomposition, though even with this method samples do not last more than 1 year. Because iodide is a good leaving group, ethyl iodide is an excellent ethylating agent. It is also used as the hydrogen radical promoter. Production Ethyl iodide is prepared by using red phosphorus, absolute ethanol and iodine. The iodine dissolves in the ethanol, where it reacts with the solid phosphorus to form phosphorus triiodide Phosphorus triiodide (PI3) is an i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodoform
Iodoform (also known as triiodomethane and, inaccurately, as carbon triiodide) is the organoiodine compound with the chemical formula C H I3. A pale yellow, crystalline, volatile substance, it has a penetrating and distinctive odor (in older chemistry texts, the smell is sometimes referred to as that of hospitals, where the compound is still commonly used) and, analogous to chloroform, sweetish taste. It is occasionally used as a disinfectant. Structure The molecule adopts tetrahedral molecular geometry with C3v symmetry. Synthesis and reactions The synthesis of iodoform was first described by Georges-Simon Serullas in 1822, by reactions of iodine vapour with steam over red-hot coals, and also by reaction of potassium with ethanolic iodine in the presence of water; and at much the same time independently by John Thomas Cooper. It is synthesized in the haloform reaction by the reaction of iodine and sodium hydroxide with any one of these four kinds of organic compounds: a methyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density
Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematically, density is defined as mass divided by volume: : \rho = \frac where ''ρ'' is the density, ''m'' is the mass, and ''V'' is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight. For a pure substance the density has the same numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure. To simplify comparisons of density across different s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl Iodide
Iodomethane, also called methyl iodide, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one hydrogen atom by an atom of iodine. It is naturally emitted by rice plantations in small amounts. It is also produced in vast quantities estimated to be greater than 214,000 tons annually by algae and kelp in the world's temperate oceans, and in lesser amounts on land by terrestrial fungi and bacteria. It is used in organic synthesis as a source of methyl groups. Preparation and handling Iodomethane is formed via the exothermic reaction that occurs when iodine is added to a mixture of methanol with red phosphorus. The iodinating reagent is phosphorus triiodide that is formed ''in situ:'' :3 CH3OH + PI3 → 3 CH3I + H2PO3H Alternatively, it is prepared from the reaction of dimethyl sulfate with potassium iodide in the presence of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methane
Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it poses technical challenges due to its gaseous state under normal conditions for temperature and pressure. Naturally occurring methane is found both below ground and under the seafloor and is formed by both geological and biological processes. The largest reservoir of methane is under the seafloor in the form of methane clathrates. When methane reaches the surface and the atmosphere, it is known as atmospheric methane. The Earth's atmospheric methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. It has also been detected on other plane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Iodide
Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I−) in a crystal lattice. It is used mainly as a nutritional supplement and in organic chemistry. It is produced industrially as the salt formed when acidic iodides react with sodium hydroxide. It is a chaotropic salt. Uses Food supplement Sodium iodide, as well as potassium iodide, is commonly used to treat and prevent iodine deficiency. Iodized table salt contains 10 ppm iodide. Organic synthesis Sodium iodide is used for conversion of alkyl chlorides into alkyl iodides. This method, the Finkelstein reaction, relies on the insolubility of sodium chloride in acetone to drive the reaction: ::R–Cl + NaI → R–I + NaCl Nuclear medicine Some radioactive iodide salts of sodium, including Na 125I and Na 131I, have radioph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodoalkanes
Organoiodine compounds are organic compounds that contain one or more carbon–iodine bonds. They occur widely in organic chemistry, but are relatively rare in nature. The thyroxine hormones are organoiodine compounds that are required for health and the reason for government-mandated iodization of salt. Structure, bonding, general properties Almost all organoiodine compounds feature iodide connected to one carbon center. These are usually classified as derivatives of I−. Some organoiodine compounds feature iodine in higher oxidation states. The C–I bond is the weakest of the carbon–halogen bonds. These bond strengths correlate with the electronegativity of the halogen, decreasing in the order F > Cl > Br > I. This periodic order also follows the atomic radius of halogens and the length of the carbon-halogen bond. For example, in the molecules represented by CH3X, where X is a halide, the carbon-X bonds have strengths, or bond dissociation energies, of 115, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkylating Agent
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting alkylation. Alkyl groups can also be removed in a process known as dealkylation. Alkylating agents are often classified according to their nucleophilic or electrophilic character. In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. For upgrading of petroleum, alkylation produces a premium blending stock for gasoline. In medicine, alkylation of DNA is used in chemotherapy to damage the DNA of cancer cells. Alkylation is accomplished with the class of drugs called alkylating antineoplastic agents. Nucleophilic alkylating agents Nucleophilic alkylating agents deliver the equivalent of an alkyl anion (carbanion). The formal "alkyl anion" attacks an electrophile, forming a new covalent bond be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
