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Organogermanium Compounds
Organogermanium compounds are organometallic compounds containing a carbon to germanium or hydrogen to germanium chemical bond. Organogermanium chemistry is the corresponding chemical science. Germanium shares group 14 in the periodic table with silicon, tin and lead, and not surprisingly the chemistry of organogermanium is in between that of organosilicon compounds and organotin compounds. One reason that limited synthetic value of organogermanium compound is costs of germanium compounds. On the other hand, germanium is advocated as a non-toxic alternative to many toxic organotin reagents. Compounds like tetramethylgermanium and tetraethylgermanium are used in the microelectronics industry as precursors for germanium dioxide chemical vapor deposition. The first organogermanium compound, tetraethylgermane, was synthesised by Winkler in 1887, by the reaction of germanium tetrachloride with diethylzinc. The organogermanium compound ''bis (2-Carboxyethylgermanium)sesquioxide'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2-carboxyethylgermasesquioxane
Propagermanium (INN), also known by a variety of other names including bis(2-carboxyethylgermanium) sesquioxide and 2-carboxyethylgermasesquioxane, is an organometallic compound of germanium that is sold as an alternative medicine. It is a polymeric compound with the formula ((HOOCCH2CH2Ge)2O3)''n''. The compound was first synthesized in 1967 at the Asai Germanium Research Institute in Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north .... It is a water-soluble organogermanium compound used as raw material in health foods. The compound displays low toxicity in studies with rats. References Organogermanium compounds Germanium(IV) compounds Inorganic polymers Propionic acids Polyelectrolytes {{Alt-med-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germane
Germane is the chemical compound with the formula Ge H4, and the germanium analogue of methane. It is the simplest germanium hydride and one of the most useful compounds of germanium. Like the related compounds silane and methane, germane is tetrahedral. It burns in air to produce GeO2 and water. Germane is a group 14 hydride. Occurrence Germane has been detected in the atmosphere of Jupiter. Synthesis Germane is typically prepared by reduction of germanium oxides, notably germanates, with hydride reagents such as sodium borohydride, potassium borohydride, lithium borohydride, lithium aluminium hydride, sodium aluminium hydride. The reaction with borohydrides is catalyzed by various acids and can be carried out in either aqueous or organic solvent. On laboratory scale, germane can be prepared by the reaction of Ge(IV) compounds with these hydride reagents. A typical synthesis involved the reaction of potassium germanate with sodium borohydride. :NaHGeO3 + KBH4 + H2O → ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MOVPE
Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD), is a chemical vapour deposition method used to produce single- or polycrystalline thin films. It is a process for growing crystalline layers to create complex semiconductor multilayer structures. In contrast to molecular-beam epitaxy (MBE), the growth of crystals is by chemical reaction and not physical deposition. This takes place not in vacuum, but from the gas phase at moderate pressures (10 to 760 Torr). As such, this technique is preferred for the formation of devices incorporating thermodynamically metastable alloys, and it has become a major process in the manufacture of optoelectronics, such as Light-emitting diodes. It was invented in 1968 at North American Aviation (later Rockwell International) Science Center by Harold M. Manasevit. Basic principles In MOCVD ultrapure precursor gases are injected into a reactor, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isobutylgermane
Isobutylgermane (IBGe, Chemical formula: (CH3)2CHCH2GeH3, is an organogermanium compound. It is a colourless, volatile liquid that is used in MOVPE (Metalorganic Vapor Phase Epitaxy) as an alternative to germane. IBGe is used in the deposition of Ge films and Ge-containing thin semiconductor films such as SiGe in strained silicon application, and GeSbTe in NAND Flash applications. Properties IBGe is a non-pyrophoric liquid source for chemical vapor deposition ( CVD) and atomic layer deposition (ALD) of semiconductors. It possesses very high vapor pressure and is considerably less hazardous than germane gas. IBGe also offers lower decomposition temperature (the onset of decomposition at ca. 325-350 °C).,Safer alternativ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boron Trifluoride
Boron trifluoride is the inorganic compound with the formula BF3. This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds. Structure and bonding The geometry of a molecule of BF3 is trigonal planar. Its D3h symmetry conforms with the prediction of VSEPR theory. The molecule has no dipole moment by virtue of its high symmetry. The molecule is isoelectronic with the carbonate anion, . BF3 is commonly referred to as " electron deficient," a description that is reinforced by its exothermic reactivity toward Lewis bases. In the boron trihalides, BX3, the length of the B–X bonds (1.30 Å) is shorter than would be expected for single bonds, and this shortness may indicate stronger B–X π-bonding in the fluoride. A facile explanation invokes the symmetry-allowed overlap of a p orbital on the boron atom with the in-phase combination of the three similarly oriented p orbitals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonyl
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. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sakurai Reaction
The Sakurai reaction (also known as the Hosomi–Sakurai reaction) is the chemical reaction of carbon electrophiles (such as a ketone shown here) with allyltrimethylsilane catalyzed by strong Lewis acids. Lewis acid activation is essential for complete reaction. Strong Lewis acids such as titanium tetrachloride, boron trifluoride, tin tetrachloride, and AlCl(Et)2 are all effective in promoting the Hosomi reaction. The reaction is a type of electrophilic allyl shift with formation of an intermediate beta-silyl carbocation. Driving force is the stabilization of said carbocation by the beta-silicon effect. The Hosomi-Sakurai reaction can be performed on a number of functional groups. An electrophilic carbon, activated by a Lewis acid, is required. Below is a list of different functional groups that can be used in the Hosomi–Sakurai reaction. The reaction achieves results similar to the addition of an allyl Grignard reagent A Grignard reagent or Grignard compound is a chemical c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allyl
In organic chemistry, an allyl group is a substituent with the structural formula , where R is the rest of the molecule. It consists of a methylene bridge () attached to a vinyl group (). The name is derived from the scientific name for garlic, . In 1844, Theodor Wertheim isolated an allyl derivative from garlic oil and named it "". The term allyl applies to many compounds related to , some of which are of practical or of everyday importance, for example, allyl chloride. Allylation is any chemical reaction that adds an allyl group to a substrate. Nomenclature A site adjacent to the unsaturated carbon atom is called the allylic position or allylic site. A group attached at this site is sometimes described as allylic. Thus, "has an allylic hydroxyl group". Allylic C−H bonds are about 15% weaker than the C−H bonds in ordinary sp3 carbon centers and are thus more reactive. Benzylic and allylic are related in terms of structure, bond strength, and reactivity. Other re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronegativity
Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus. The higher the associated electronegativity, the more an atom or a substituent group attracts electrons. Electronegativity serves as a simple way to quantitatively estimate the bond energy, and the sign and magnitude of a bond's chemical polarity, which characterizes a bond along the continuous scale from covalent to ionic bonding. The loosely defined term electropositivity is the opposite of electronegativity: it characterizes an element's tendency to donate valence electrons. On the most basic level, electronegativity is determined by factors like the nuclear charge (the more protons an atom has, the more "pull" it will have on electrons) and the number and location ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta-silicon Effect
The beta-silicon effect also called silicon hyperconjugation in organosilicon chemistry is a special type of hyperconjugation that describes the stabilizing influence of a silicon atom on the development of positive charge at a carbon atom one position removed (β) from the silicon atom. The C-Si σ orbital is said to partially overlap with the σ* anti-bonding orbital of the C-leaving group, lowering the energy of the transition state leading to the formation of a carbocation. A prerequisite for the hyperconjugation to occur is an antiperiplanar relationship between the Si group and the leaving group.''Silicon in Organic Synthesis'' Colvin, E. Butterworth: London 1981 This allows for the maximum overlap between the C-Si σ orbital and the σ* anti-bonding orbital of the leaving group. Silicon hyperconjugation explains specific observations regarding chemical kinetics and stereochemistry of organic reactions with reactants containing silicon. The picture below shows the partial ov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
