|
Tetramethyltin
Tetramethyltin is an organometallic compound with the formula (CH3)4Sn. This liquid, one of the simplest organotin compounds, is useful for transition-metal mediated conversion of acid chlorides to methyl ketones and aryl halides to aryl methyl ketones. It is volatile and toxic, so care should be taken when using it in the laboratory. Synthesis and structure Tetramethyltin is synthesized by reaction of the Grignard reagent methylmagnesium iodide, with tin tetrachloride, which is synthesized by reacting tin metal with chlorine gas. :4 CH3MgI + SnCl4 → (CH3)4Sn + 4 MgICl In tetramethyltin, the metal surrounded by four methyl groups in a tetrahedral structure is a heavy analogue of neopentane. Applications Precursor to methyltin compounds Tetramethyltin is a precursor to trimethyltin chloride (and related methyltin halides), which are precursors to other organotin compounds. These methyltin chlorides are prepared via the so-called Kocheshkov redistribution reaction. Thus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimethyltin Chloride
Trimethyltin chloride is an organotin compound with the formula . It is a white solid that is highly toxic and malodorous. It is susceptible to hydrolysis. Synthesis Trimethyltin chloride can be prepared by the Redistribution (chemistry), redistribution reaction of tetramethyltin with tin tetrachloride. : This is the Kocheshkov redistribution reaction. It is performed under an inert atmosphere, such as argon, typically with no solvent. A second route to involves treating the corresponding Organotin chemistry#Organotin oxides and hydroxides, hydroxide or oxide with a halogenating agent such as hydrogen chloride or thionyl chloride (): : Uses Trimethyltin chloride is used as a source of the trimethylstannyl group. For example, it is a precursor to vinyltrimethylstannane and indenyltrimethylstanane: :CH2=CHMgBr + Me3SnCl → Me3SnCH=CH2 + MgBrCl :LiC9H7 + Me3SnCl → Me3SnC9H7 + LiCl An example of an Organolithium reagent, organolithium reagent reacting with Me3SnCl to form a tin- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrabutyltin
Tetrabutyltin is the organotin compound with the molecular formula (C4H9)4Sn or SnBu4. Sometimes abbreviated TTBT, it is a colorless, lipophilic oil. Tetrabutyltin is a precursor to tributyltin and dibutyltin compounds. By the redistribution reaction with tin(IV) chloride it forms tributyltin chloride and dibutyltin chloride. These compounds are starting materials for a wide range of organotin compounds used as stabilizers for PVC and as biocides, fungicides, wood preservatives, and (historically) marine anti-biofouling Biofouling or biological fouling is the accumulation of microorganisms, plants, algae, or small animals where it is not wanted on surfaces such as ship and submarine hulls, devices such as water inlets, pipework, grates, ponds, and rivers that ... agents. References {{Reflist Organotin compounds Tin(IV) compounds Butyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neopentane
Neopentane, also called 2,2-dimethylpropane, is a double-branched-chain alkane with five carbon atoms. Neopentane is a flammable gas at room temperature and pressure which can condense into a highly volatile liquid on a cold day, in an ice bath, or when compressed to a higher pressure. Neopentane is the simplest alkane with a quaternary carbon, and has achiral tetrahedral symmetry. It is one of the three structural isomers with the molecular formula C5H12 (pentanes), the other two being ''n''-pentane and isopentane. Out of these three, it is the only one to be a gas at standard conditions; the others are liquids. Nomenclature The traditional name neopentane was still retained in the 1993 IUPAC recommendations, but is no longer recommended according to the 2013 recommendations. The preferred IUPAC name is the systematic name 2,2-dimethylpropane, but the substituent numbers are superfluous because it is the only possible “dimethylpropane”. A neopentyl substituent, often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organotin Compounds
Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin chemistry is part of the wider field of organometallic chemistry. The first organotin compound was diethyltin diiodide (), discovered by Edward Frankland in 1849. The area grew rapidly in the 1900s, especially after the discovery of the Grignard reagents, which are useful for producing Sn–C bonds. The area remains rich with many applications in industry and continuing activity in the research laboratory. Structure Organotin compounds are generally classified according to their oxidation states. Tin(IV) compounds are much more common and more useful. Organic derivatives of tin(IV) The tetraorgano derivatives are invariably tetrahedral. Compounds of the type SnRR'R''R have been resolved into individual enantiomers. Organotin halides Organotin chlorides have the formula for values of ''n'' up to 3. Bromides, iodides, and fluorides are also known but less important. These ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palladium-catalyzed Coupling Reactions
In organic chemistry, a cross-coupling reaction is a reaction where two fragments are joined together with the aid of a metal catalyst. In one important reaction type, a main group organometallic compound of the type R-M (R = organic fragment, M = main group center) reacts with an organic halide of the type R'-X with formation of a new carbon–carbon bond in the product R-R'. Cross-coupling reaction are a subset of coupling reactions. It is often used in arylations. Richard F. Heck, Ei-ichi Negishi, and Akira Suzuki were awarded the 2010 Nobel Prize in Chemistry for developing palladium-catalyzed coupling reactions. Mechanism The mechanism generally involves reductive elimination of the organic substituents R and R' on a metal complex of the type LnMR(R') (where L is some arbitrary spectator ligand). The crucial intermediate LnMR(R') is formed in a two step process from a low valence precursor Ln. The oxidative addition of an organic halide (RX) to LnM gives LnMR(X). Subseq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one of the most important branches of organic chemistry. There are several main areas of research within the general area of organic synthesis: ''total synthesis'', ''semisynthesis'', and ''methodology''. Total synthesis A total synthesis is the complete chemical synthesis of complex organic molecules from simple, commercially available petrochemical or natural precursors. Total synthesis may be accomplished either via a linear or convergent approach. In a ''linear'' synthesis—often adequate for simple structures—several steps are performed one after another until the molecule is complete; the chemical compounds made in each step are called synthetic intermediates. Most often, each step in a synthesis refers to a separate rea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeolite
Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These positive ions can be exchanged for others in a contacting electrolyte solution. exchanged zeolites are particularly useful as solid acid catalysts. The term ''zeolite'' was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that rapidly heating a material, believed to have been stilbite, produced large amounts of steam from water that had been adsorbed by the material. Based on this, he called the material ''zeolite'', from the Greek , meaning "to boil" and , meaning "stone". Zeolites occur naturally but are also produced industrially on a large scale. , 253 unique zeolite frameworks have been identified, and over 40 naturally occurring zeolite frameworks are known. Every new zeolite structure that is ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silica
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as a synthetic product. Notable examples include fused quartz, fumed silica, silica gel, opal and aerogels. It is used in structural materials, microelectronics (as an Insulator (electricity), electrical insulator), and as components in the food and pharmaceutical industries. Structure In the majority of silicates, the silicon atom shows tetrahedral coordination geometry, tetrahedral coordination, with four oxygen atoms surrounding a central Si atomsee 3-D Unit Cell. Thus, SiO2 forms 3-dimensional network solids in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. In contrast, CO2 is a linear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury(II) Chloride
Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine with the formula HgCl2. It is white crystalline solid and is a laboratory reagent and a molecular compound that is very toxic to humans. Once used as a treatment for syphilis, it is no longer used for medicinal purposes because of mercury toxicity and the availability of superior treatments. Synthesis Mercuric chloride is obtained by the action of chlorine on mercury or on mercury(I) chloride. It can also be produced by the addition of hydrochloric acid to a hot, concentrated solution of mercury(I) compounds such as the nitrate: :Hg2(NO3)2 + 4 HCl → 2 HgCl2 + 2 H2O + 2 NO2 Heating a mixture of solid mercury(II) sulfate and sodium chloride also affords volatile HgCl2, which can be separated by sublimation. Process for synthesis of Mercuric chloride first appeared in Abu Bakr al-Razi's ''De ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedral Molecular Geometry
In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1(−) = 109.4712206...° ≈ 109.5° when all four substituents are the same, as in methane () as well as its heavier analogues. Methane and other perfectly symmetrical tetrahedral molecules belong to point group Td, but most tetrahedral molecules have lower symmetry. Tetrahedral molecules can be chiral. Tetrahedral bond angle The bond angle for a symmetric tetrahedral molecule such as CH4 may be calculated using the dot product of two vectors. As shown in the diagram, the molecule can be inscribed in a cube with the tetravalent atom (e.g. carbon) at the cube centre which is the origin of coordinates, O. The four monovalent atoms (e.g. hydrogens) are at four corners of the cube (A, B, C, D) chosen so that no two atoms are at adjacent corners linked by only one cube edge. If the edge length of the cube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetraethyltin
Tetraethyltin or tetraethyl tin is a chemical compound with the formula and molecular structure (CH3CH2)4Sn, that is, a tin atom attached to four ethyl groups. It is an important example of an organotin compound, often abbreviated as TET. Tetraethyltin is a colourless flammable liquid, soluble in diethyl ether and insoluble in water, that freezes at -112 °C and boils at 181 °C.SAFC corp''tetraethyltin''catalog page. Accessed on 2011-01-18. It is used in the electronics industry. Tetraethyltin can be obtained by reacting ethylmagnesium bromide with tin(IV) chloride:G. J. M. Van Der Kerk and J. G. A. Luijten (1956)"Tetraethyltin" ''Organic Syntheses'', volume 36, page 86; Coll. Vol. 4, p.881 (1963) :SnCl4 + 4 (C2H5)MgBr → (CH3CH2)4Sn + 4 MgBrCl The same reaction can be used to obtain tetra-''n''-propyltin and tetra-''n''-butyltin. Tetraethyltin is converted in the body to the more toxic triethyltin. See also * Tetraethyllead * Tetraethylgermanium Tetraethylg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
