|
Disiloxane
Disiloxane has the chemical formula . It is the simplest known siloxane with hydrogen only R groups. The molecule contains six equivalent Si−H bonds and two equivalent Si−O bonds. Disiloxane exists as a colorless, pungent gas under standard conditions. However, it is generally safe for human use as evidence in its widespread use in cosmetics. It is also commonly known as disilyl ether, disilyl oxide, and perhydrodisiloxane Structure Disiloxane has a simple structure that consists of a siloxane bond (Si−O−Si) and hydrogen R groups. The structure of disiloxane has been studied by a variety of spectroscopic methods such as electron diffraction, X-ray crystallography, dipole moment, and nuclear magnetic resonance spectroscopy. Due to their unusual nature, the Si−O−Si bond angles are commonly studied. These bonds typically exhibit angles that are larger than average, around 130 to 160 degrees, and larger bond lengths are not uncommon. For example, in the solid state at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexamethyldisiloxane
Hexamethyldisiloxane (HMDSO or MM) is an organosilicon compound with the formula O[Si(CH3)3]2. This volatile colourless liquid is used as a solvent and as a reagent in organic synthesis. It is prepared by the hydrolysis of trimethylsilyl chloride. The molecule is the protypical disiloxane and resembles a subunit of polydimethylsiloxane. Synthesis and reactions Hexamethyldisiloxane can be produced by the addition of trimethylsilyl chloride to purified water: : 2 Me3SiCl + H2O → 2 HCl + O[Si(CH3)3]2 It also results from the hydrolysis of silyl ethers and other silyl-protected functional groups. HMDSO can be converted back to the chloride by reaction with Me2SiCl2.Röshe, L.; John, P.; Reitmeier, R. “Organic Silicon Compounds” ''Ullmann’s Encyclopedia of Industrial Chemistry''. John Wiley and Sons: San Francisco, 2003. . Hexamethyldisiloxane is mainly used as source of the trimethylsilyl functional group (-Si(CH3)3) in organic synthesis. For example, in the presence of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon–oxygen Bond
A silicon–oxygen bond ( bond) is a chemical bond between silicon and oxygen atoms that can be found in many inorganic and organic compounds. In a silicon–oxygen bond, electrons are shared unequally between the two atoms, with oxygen taking the larger share due to its greater electronegativity. This polarisation means Si–O bonds show characteristics of both covalent and ionic bonds. Compounds containing silicon–oxygen bonds include materials of major geological and industrial significance such as silica, silicate minerals and silicone polymers like polydimethylsiloxane. Bond polarity, length and strength On the Pauling electronegativity scale, silicon has an electronegativity of 1.90 and oxygen 3.44. The electronegativity difference between the elements is therefore 1.54. Because of this moderately large difference in electronegativities, the bond is polar but not fully ionic. Carbon has an electronegativity of 2.55 so carbon–oxygen bonds have an electronegativit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silanol
A silanol is a functional group in silicon chemistry with the connectivity Si–O–H. It is related to the hydroxy functional group (C–O–H) found in all alcohols. Silanols are often invoked as intermediates in organosilicon chemistry and silicate mineralogy. If a silanol contains one or more organic residues, it is an organosilanol. Preparation From alkoxysilanes The first isolated example of a silanol was , reported in 1871 by Albert Ladenburg. He prepared the “silicol” by hydrolysis of (Et = ). From silyl halides and related compounds Silanols are generally synthesized by hydrolysis of halosilanes, alkoxysilanes, or aminosilanes. Chlorosilanes are the most common reactants: :R3Si–Cl + H2O → R3Si–OH + HCl The hydrolysis of fluorosilanes requires more forcing reagents, i.e. alkali. The alkoxysilanes ( silyl ethers) of the type are slow to hydrolyze. Compared to the silyl ethers, silyl acetates are faster to hydrolyze, with th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siloxane
In organosilicon chemistry, a siloxane is an organic compound containing a functional group of two silicon atoms bound to an oxygen atom: . The parent siloxanes include the oligomeric and polymeric hydrides with the formulae and . Siloxanes also include branched compounds, the defining feature of which is that each pair of silicon centres is separated by one oxygen atom. The siloxane functional group forms the backbone of silicones , the premier example of which is polydimethylsiloxane (PDMS). The functional group (where the three Rs may be different) is called siloxy. Siloxanes are manmade and have many commercial and industrial applications because of the compounds’ hydrophobicity, low thermal conductivity, and high flexibility. Structure Siloxanes generally adopt structures expected for linked tetrahedral ("''sp''3-like") centers. The Si−O bond length is 1.64 Å (vs Si–C distance of 1.92 Å) and the Si-O-Si angle is rather open at 142.5°. By ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethyl Ether
Dimethyl ether (DME; also known as methoxymethane) is the organic compound with the formula CH3OCH3, (sometimes ambiguously simplified to C2H6O as it is an isomer of ethanol). The simplest ether, it is a colorless gas that is a useful precursor to other organic compounds and an aerosol propellant that is currently being demonstrated for use in a variety of fuel applications. Dimethyl ether was first synthesised by Jean-Baptiste Dumas and Eugene Péligot in 1835 by distillation of methanol and sulfuric acid. Production Approximately 50,000 tons were produced in 1985 in Western Europe by dehydration of methanol:Manfred Müller, Ute Hübsch, "Dimethyl Ether" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. : The required methanol is obtained from synthesis gas ( syngas). Other possible improvements call for a dual catalyst system that permits both methanol synthesis and dehydration in the same process unit, with no methanol isolation and purificatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Orbital
In quantum mechanics, an atomic orbital () is a Function (mathematics), function describing the location and Matter wave, wave-like behavior of an electron in an atom. This function describes an electron's Charge density, charge distribution around the Atomic nucleus, atom's nucleus, and can be used to calculate the probability of finding an electron in a specific region around the nucleus. Each orbital in an atom is characterized by a set of values of three quantum numbers , , and , which respectively correspond to electron's energy, its angular momentum, orbital angular momentum, and its orbital angular momentum projected along a chosen axis (magnetic quantum number). The orbitals with a well-defined magnetic quantum number are generally complex-valued. Real-valued orbitals can be formed as linear combinations of and orbitals, and are often labeled using associated Spherical harmonics#Harmonic polynomial representation, harmonic polynomials (e.g., ''xy'', ) which describe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acta Crystallographica B
''Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials'' publishes scientific articles on structural science. According to the journal: "Knowledge of the arrangements of atoms, including their temporal variations and dependencies on temperature and pressure, is often the key to understanding physical and chemical phenomena and is crucial for the design of new materials and supramolecular devices." It was formed in 1968 when the journal ''Acta Crystallographica'' was split into two parts and has been published for the International Union of Crystallography under the following titles: *''Acta Crystallographica. Section B: Structural Crystallography and Crystal Chemistry'' () from its formation until the end of 1982. It was published in Denmark by Munksgaard and accepted articles in English, French, and German. *On the launch of ''Acta Crystallographica Section C'' in 1983, the title of Section B changed to ''Acta Crystallographica Section B: Struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bent Molecular Geometry
In chemistry, molecules with a non-collinear arrangement of two adjacent bonds have bent molecular geometry, also known as angular or V-shaped. Certain atoms, such as oxygen, will almost always set their two (or more) covalent bonds in non-collinear directions due to their electron configuration. Water (H2O) is an example of a bent molecule, as well as its analogues. The bond angle between the two hydrogen atoms is approximately 104.45°. Nonlinear geometry is commonly observed for other triatomic molecules and ions containing only main group elements, prominent examples being nitrogen dioxide (NO2), sulfur dichloride (SCl2), and methylene (CH2). This geometry is almost always consistent with VSEPR theory, which usually explains non- collinearity of atoms with a presence of lone pairs. There are several variants of bending, where the most common is AX2E2 where two covalent bonds and two lone pairs of the central atom (A) form a complete 8-electron shell. They have central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Journal Of Inorganic Chemistry
The ''European Journal of Inorganic Chemistry'' is a weekly peer-reviewed scientific journal covering inorganic chemistry, inorganic, Organometallic chemistry, organometallic, Bioinorganic chemistry, bioinorganic, and solid-state chemistry. It is published by Wiley-VCH on behalf of Chemistry Europe. The journal, along with the ''European Journal of Organic Chemistry'', was established in 1998 as the result of a merger of ''Chemische Berichte, Chemische Berichte/Recueil,'' ''Bulletin de la Société Chimique de France,'' ''Bulletin des Sociétés Chimiques Belges,'' ''Gazzetta Chimica Italiana,'' ''Anales de Química,'' ''Chimika Chronika,'' ''Revista Portuguesa de Química, and'' ''ACH-Models in Chemistry.'' According to the ''Journal Citation Reports'', the journal has a 2021 impact factor of 2.551. See also *List of chemistry journals *''European Journal of Organic Chemistry'' References External links * {{DEFAULTSORT:European Journal Of Inorganic Chemistry Chemistry Eur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis Acids And Bases
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis acid to form a Lewis adduct. For example, NH3 is a Lewis base, because it can donate its lone pair of electrons. Trimethylborane CH3)3Bis a Lewis acid as it is capable of accepting a lone pair. In a Lewis adduct, the Lewis acid and base share an electron pair furnished by the Lewis base, forming a dative bond. In the context of a specific chemical reaction between NH3 and Me3B, a lone pair from NH3 will form a dative bond with the empty orbital of Me3B to form an adduct NH3•BMe3. The terminology refers to the contributions of Gilbert N. Lewis. From p. 142: "We are inclined to think of substances as po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pi Backbonding
In chemistry, pi backbonding or π backbonding is a π-bonding interaction between a filled (or half filled) orbital of a transition metal atom and a vacant orbital on an adjacent ion or molecule. In this type of interaction, electrons from the metal are used to bond to the ligand, which dissipates excess negative charge and stabilizes the metal. It is common in transition metals with low oxidation states that have ligands such as carbon monoxide, olefins, or phosphines. The ligands involved in π backbonding can be broken into three groups: carbonyls and nitrogen analogs, alkenes and alkynes, and phosphines. Compounds where π backbonding is prominent include Ni(CO)4, Zeise's salt, and molybdenum and iron dinitrogen complexes. Metal carbonyls, nitrosyls, and isocyanides The electrons are partially transferred from a d-orbital of the metal to anti-bonding molecular orbitals of CO (and its analogs). This electron-transfer strengthens the metal–C bond and weakens the C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
