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Titanocene Dicarbonyl
Dicarbonylbis(cyclopentadienyl)titanium is the chemical compound with the formula (''η''5-C5H5)2Ti(CO)2, abbreviated Cp2Ti(CO)2. This maroon-coloured, air-sensitive species is soluble in aliphatic and aromatic solvents. It has been used for the deoxygenation of sulfoxides, reductive coupling of aromatic aldehydes and reduction of aldehydes. Structure and synthesis Cp2Ti(CO)2 is prepared by the reduction of titanocene dichloride with magnesium as a slurry in THT under an atmosphere of carbon monoxide. :(C5H5)2TiCl2 + Mg + 2 CO → (C5H5)2Ti(CO)2 + MgCl2 Both Cp2Ti(CO)2 and Cp2TiCl2 are tetrahedral as are related zirconium and hafnium compounds. Of historical interest, the complex was first prepared by the reduction of titanocene dichloride with sodium cyclopentadienyl under an atmosphere of carbon monoxide. Its structure has been confirmed by X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrophoric
A substance is pyrophoric (from grc-gre, πυροφόρος, , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolithium compounds and triethylborane. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air. They can be handled safely in atmospheres of argon or (with a few exceptions) nitrogen. Fire Classes#Metal, Class D fire extinguisher#Class D dry powder and other agents for metal fires, fire extinguishers are designated for use in fires involving pyrophoric materials. A related concept is hypergolic propellant, hypergolicity, in which two compounds spontaneously ignite when mixed. Uses The creation of spark (fire), sparks from metals is based on the pyrophoricity of small metal particles, and pyrophoric alloys are made for this purpose. The sparking mechanisms in lighters and various toys, using fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic table) it occurs naturally only in combination with other elements and it almost always has an oxidation state of +2. It reacts readily with air to form a thin passivation coating of magnesium oxide that inhibits further corrosion of the metal. The free metal burns with a brilliant-white light. The metal is obtained mainly by electrolysis of magnesium salts obtained from brine. It is less dense than aluminium and is used primarily as a component in strong and lightweight alloys that contain aluminium. In the cosmos, magnesium is produced in large, aging stars by the sequential addition of three helium nuclei to a carbon nucleus. When such stars explode as supernovas, much of the magnesium is expelled into the interstellar medium where it ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonyl Complexes
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a carbonyl group is often referred to as a carbonyl compound. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e.g. nickel carbonyl). The remainder of this article concerns itself with the organic chemistry definition of carbonyl, where carbon and oxygen share a double bond. Carbonyl compounds In organic chemistry, a carbonyl group characterizes the following types of compounds: Other organic carbonyls are urea and the carbamates, the derivatives of acyl chlorides chloroformates and phosgene, carbonate esters, thioesters, lactones, lactams, hydroxamates, and isocyanates. Examples of inorganic carbonyl compounds are carbon dioxide and carbonyl sulfide. A sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organotitanium Compounds
Organotitanium chemistry is the science of organotitanium compounds describing their physical properties, synthesis, and reactions. Organotitanium compounds in organometallic chemistry contain carbon-titanium chemical bonds. They are reagents in organic chemistry and are involved in major industrial processes. Brief history Although the first attempt to prepare an organotitanium compound dates back to 1861, the first example was not reported until 1954. In that year titanocene dichloride was described by Wilkinson and Birmingham. Independently, titanium-based Ziegler–Natta catalysts were described leading to major commercial applications, for which the 1963 Nobel Prize in Chemistry was awarded. This technology underscored the technical significance of organotitanium chemistry. Properties The titanium electron configuration ( rd24s2) vaguely resembles that of carbon and like carbon, the +4 oxidation state dominates. Titanium is however a much larger element than carbon, reflected ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information. Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among various mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Cyclopentadienyl
Sodium cyclopentadienide is an organosodium compound with the formula C5H5Na. The compound is often abbreviated as NaCp, where Cp− is the cyclopentadienide anion. Sodium cyclopentadienide is a colorless solid, although samples often are pink owing to traces of oxidized impurities. Preparation Sodium cyclopentadienide is commercially available as a solution in THF. It is prepared by treating cyclopentadiene with sodium: : The conversion can be conducted by heating a suspension of molten sodium in dicyclopentadiene.Tarun K. Panda, Michael T. Gamer, Peter W. Roesky "An Improved Synthesis of Sodium and Potassium Cyclopentadienide" Organometallics, 2003, 22, 877–878. In former times, the sodium was provided in the form of "sodium wire" or "sodium sand", a fine dispersion of sodium prepared by melting sodium in refluxing xylene and rapidly stirring. Sodium hydride is a convenient base: : In early work, Grignard reagents were used as bases. With a p''K''a of 15, cyclope ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopedia Of Reagents For Organic Synthesis
The ''Encyclopedia of Reagents for Organic Synthesis'' is published in print and online by John Wiley & Sons Ltd. The online version is also known as e-EROS. The encyclopedia contains a description of the use of reagents used in organic chemistry. The eight-volume print version includes 3500 alphabetically arranged articles and the online version is regularly updated to include new reagents and catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...s. References External links *Print version Encyclopedias of science Chemistry books {{encyclopedia-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Monoxide
Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest molecule of the oxocarbon family. In coordination complexes the carbon monoxide ligand is called carbonyl. It is a key ingredient in many processes in industrial chemistry. The most common source of carbon monoxide is the partial combustion of carbon-containing compounds, when insufficient oxygen or heat is present to produce carbon dioxide. There are also numerous environmental and biological sources that generate and emit a significant amount of carbon monoxide. It is important in the production of many compounds, including drugs, fragrances, and fuels. Upon emission into the atmosphere, carbon monoxide affects several processes that contribute to climate change. Carbon monoxide has important biological roles across phylogenetic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanocene Dichloride
Titanocene dichloride is the organotitanium compound with the formula ( ''η''5-C5H5)2TiCl2, commonly abbreviated as Cp2TiCl2. This metallocene is a common reagent in organometallic and organic synthesis. It exists as a bright red solid that slowly hydrolyzes in air. It shows antitumour activity and was the first non-platinum complex to undergo clinical trials as a chemotherapy drug. Preparation and structure The standard preparations of Cp2TiCl2 start with titanium tetrachloride. The original synthesis by Wilkinson and Birmingham, using sodium cyclopentadienide, is still commonly used: :2 NaC5H5 + TiCl4 → (C5H5)2TiCl2 + 2 NaCl It can also be prepared by using freshly distilled cyclopentadiene rather than its sodium derivative: :2 C5H6 + TiCl4 → (C5H5)2TiCl2 + 2 HCl Focusing on the geometry of the Ti center, Cp2TiCl2 adopts a distorted tetrahedral geometry (counting Cp as a monodentate ligand). The Ti-Cl distance is 2.37 Å and the Cl-Ti-Cl angle is 9 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon. Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. Benzene is a colorless and highly flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. It is used primarily as a precursor to the manufacture of chemicals with more complex structure, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. Although benzene is a major industrial chemical, it finds limited use in consumer items because of its toxicity. History Discovery The word "''benzene''" derives from "''gum benzoin''" (benzoin res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldehydes
In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are common and play important roles in the technology and biological spheres. Structure and bonding Aldehydes feature a carbon center that is connected by a double bond to oxygen and a single bond to hydrogen and single bond to a third substituent, which is carbon or, in the case of formaldehyde, hydrogen. The central carbon is often described as being sp2- hybridized. The aldehyde group is somewhat polar. The C=O bond length is about 120-122 picometers. Physical properties and characterization Aldehydes have properties that are diverse and that depend on the remainder of the molecule. Smaller aldehydes are more soluble in water, formaldehyde and acetaldehyde completely so. The volatile aldehydes have pungent odors. Aldehy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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