- SYNTHESIS OF ORGANO CHLOROSILANES FROM ORGANOSILANES
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The invention relates to a process for the production of chlorosilanes by subjecting one or more hydndosilanes to the reaction with hydrogen chloride in the presence of at least one ether compound, and a process for the production of such hydndosilanes serving as starting materials.
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Page/Page column 36; 37
(2019/04/16)
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- Lewis Base Catalyzed Selective Chlorination of Monosilanes
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A preparatively facile, highly selective synthesis of bifunctional monosilanes R2SiHCl, RSiHCl2 and RSiH2Cl is reported. By chlorination of R2SiH2 and RSiH3 with concentrated HCl/ether solutions, the stepwise introduction of Si?Cl bonds is readily controlled by temperature and reaction time for a broad range of substrates. In a combined experimental and computational study, we establish a new mode of Si?H bond activation assisted by Lewis bases such as ethers, amines, phosphines, and chloride ions. Elucidation of the underlying reaction mechanisms shows that alcohol assistance through hydrogen-bond networks is equally efficient and selective. Remarkably, formation of alkoxysilanes or siloxanes is not observed under moderate reaction conditions.
- Sturm, Alexander G.,Schweizer, Julia I.,Meyer, Lioba,Santowski, Tobias,Auner, Norbert,Holthausen, Max C.
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supporting information
p. 17796 - 17801
(2018/11/23)
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- Amorphous silicon: New insights into an old material
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Amorphous silicon is synthesized by treating the tetrahalosilanes SiX4 (X=Cl, F) with molten sodium in high boiling polar and non-polar solvents such as diglyme or nonane to give a brown or a black solid showing different reactivities towards suitable reagents. With regards to their technical relevance, their stability towards oxygen, air, moisture, chlorine-containing reaction partners RCl (R=H, Cl, Me) and alcohols is investigated. In particular, reactions with methanol are a versatile tool to deliver important products. Besides tetramethoxysilane formation, methanolysis of silicon releases hydrogen gas under ambient conditions and is thus suitable for a decentralized hydrogen production; competitive insertion into the MeO-H versus the Me-OH bond either yields H- and/or methyl-substituted methoxy functional silanes. Moreover, compounds, such as MenSi(OMe)4-n (n=0-3) are simply accessible in more than 75% yield from thermolysis of, for example, tetramethoxysilane over molten sodium. Based on our systematic investigations we identified reaction conditions to produce the methoxysilanes MenSi(OMe)4-n in excellent (n=0:100%) to acceptable yields (n=1:51%; n=2:27%); the yield of HSi(OMe)3 is about 85%. Thus, the methoxysilanes formed might possibly open the door for future routes to silicon-based products. Amorphous silicon is easily synthesized from tetrahalosilanes SiX4 (X=Cl, F) and molten sodium in different solvents. Reactivity studies prove the resulting materials as versatile tools for the formation of technical important silanes, such as the silicon chloro-, alkoxy-, and methylalkoxy-substituted derivatives (see figure; bl=black, br=brown).
- Spomer, Natalie,Holl, Sven,Zherlitsyna, Larissa,Maysamy, Fariba,Frost, Andreas,Auner, Norbert
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p. 5600 - 5616
(2015/03/30)
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- Process For Preparing Si-H-Containing Silanes
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Silanes of the general formula (1) [in-line-formulae]RaSiHbX4-b-a ??(1)[/in-line-formulae] are prepared by disproportionating at least one more highly chlorinated silane in the presence of a homogeneous catalyst in an apparatus with at least one reactive distillation column and at least one additional reactor selected from among prereactors and side reactors, where R is an alkyl, aryl, alkaryl or haloalkyl radical, X is a halogen atom, a is 0 or 1, and b is 2, 3 or 4.
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Page/Page column 4-5
(2009/01/24)
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- An experimental and theoretical study of spin-spin coupling in chlorosilanes
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An experimental and theoretical study of the absolute value of the one-bond spin-spin coupling constant |1J(Si,H)| in SiH nCl4-n (n = 0-4) dissolved in THF-d8 is presented. We found |1J(Si,H)| to increase with an increasing number of chlorine substituents, and the quantitative changes were found to differ from the values previously reported for the same compounds dissolved in cyclohexane-d12. We also report on the variations in | 1J(Si,H)| as a function of temperature, which we found to be linearly temperature dependent for the chlorine-substituted silanes and temperature independent for SiH4. Furthermore, the temperature dependence of |1J(Si,H)| varied between the different chlorosilanes. Solvent-solute interactions were studied by quantum chemical DFT calculations. The variations in chloro-silane bond lengths upon adduct formation and the different adduct interaction energies may explain the temperature dependences of the coupling constants.
- Thorshaug, Knut,Swang, Ole,Dahl, Ivar M.,Olafsen, Anja
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p. 9801 - 9804
(2008/10/09)
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- Process for preparing organohydrongenosilanes
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Preparation of organylhydrogensilanes comprises comproportionating a mixture of organylhalosilanes in the presence of a catalyst, which contains at least one completely organically substituted ammonium or phosphonium unit. Preparation of organylhydrogensilanes comprises: comproportionating a mixture of organylhalosilanes by reaction of a organylhalosilane compound of formula (Z-R aSiCl 4-a) with organylhalosilane compound of formula (SiH bCl 4-b) to give a organylhalosilane compound of formula (Z-R aSiCl 3-a) and a organylhalosilane compound of formula (SiH b-yCl 4-b +y) in the presence of a catalyst which contains at least one completely organically substituted ammonium or phosphonium unit. R : alkyl, aryl, or alkaryl radical (optionally substituted with halo); a : 1-3; y, Z : 1-4; and b : 2-4.
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Page/Page column 8
(2008/06/13)
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- Alkaloids
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The present invention provides novel alkaloid compounds and collections of these compounds, and provides methods for the synthesis of these compounds using biomimetic synthetic strategies. Additionally, the present invention provides pharmaceutical compositions and methods for treating disorders such as bacterial infections, proliferative diseases, and reproductive disorders, to name a few.
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- Ion-enhanced etching of Si(100) with molecular chlorine: Neutral and ionic product yields as a function of ion kinetic energy and molecular chlorine flux
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Time-of-flight mass spectrometry (TOFMS) is used to measure neutral and ionic silicon etch products evolved during argon ion-enhanced etching of room temperature Si(100) with molecular chlorine. The yields of these neutral and ionic etch products are examined as a function of ion energy, ion flux, and molecular chlorine flux. For the neutral products, an Ar+ ion energy range of 275-975 eV is used, while the ionic product measurements are continued down to 60 eY The atomic Si, SiCl, and SiCl2 neutral etch products are measured without complications due to fragmentation by using 118-nm laser single-photon TOFMS. Atomic Si and SiCl are the major observed etch products. The ionic Si+ and SiCl+ etch products are also measured using TOFMS; however, the SiQ2+ species is not observed. The similarities between neutral and ionic Si and SiCl etch products as a function of various parameters suggest a model based on direct collisional desorption. For the observed neutral SiCl2 product, the absence of SiCl2+ suggests a different mechanism than that for Si and SiCl. For SiCl2, formation models based on thermal heating or reaction and desorption of neutral species at chemically active surface sites, which are ruled out for Si and SiCl, should be considered.
- Materer,Goodman, Rory S.,Leone, Stephen R.
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p. 3261 - 3266
(2007/10/03)
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Bu3SnH is an effective reagent for partial conversion of Si-Cl into Si-H groups. The presented hydrogenation mechanism postulates the coordination of the catalyst (Lewis bases) or the solvent to silicon, giving an intermediate with higher coordinated silicon atom in the first step, followed by the attack of tributyltin hydride by a single electron transfer. This mechanism implies that the intermediate having a hypervalent silicon atom reacts more rapidly than the starting tetracoordinated silane.
- Paetzold,Roewer,Herzog
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p. 147 - 152
(2007/10/03)
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- Surface Loss Coefficients for the Silyl Radical
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Direct loss measurements for the heterogeneous reaction of the silyl radical, SiH3, obtained in a discharge flow reactor with mass spectrometric detection, are reported.From these measurements and the calculated gas-surface collision frequency, total surface loss coefficients, β, are determined for silyl on two different surfaces, one coated with a growing silicon-containing film and the other coated with Halocarbon wax.
- Jasinski, Joseph M.
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p. 7385 - 7387
(2007/10/02)
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- Selective and sequential reduction of polyhalosilanes with alkyltin hydrides
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The reactions between alkyltin hydrides and a variety of polyhalo- and mixed halosilanes have been investigated. For SiCl4 and SiCl3H, the reductions proceed in a stepwise manner to yield the monoreduced species as the major products. The reduction of SiBr4 occurs much faster to yield a mixture of SiBr3H and SiH4, or, in the vapor phase, SiBr3H as the sole product. SiF3X (X = Br, Cl) is converted into SiF3H, with no further reduction of SiF3H observed upon addition of a second equivalent of alkyltin hydride. SiF2HX compounds (X = Br, Cl) are obtained from SiF2X2 and are converted into SiF2H2 with excess Me3SnH. Redistribution becomes competitive with reduction in reactions between Me3SnH and SiFBr3, leading to mixtures of SiH4, SiF2H2, and SiF3H. The major products in the reaction between SiCl2Br2 and Me3SnH are SiCl3H and SiH4 (no SiCl2H2 was observed). Several probable intermediates were independently synthesized and allowed to react with Me3SnH. Together with deuterium labeling experiments, these reactions shed light on the mechanisms involved in these systems. In particular, the reactions appear not to proceed via free radicals.
- D'Errico, John J.,Sharp, Kenneth G.
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p. 2177 - 2180
(2008/10/08)
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- Chemiluminescent reactions of ground and metastable states of the group IV a elements with halogens
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Earlier work on chemiluminescent beam-gas reactions of the ground states (3Pj) of Si, Ge, and Sn with F2 and of both ground and metastable states (1D, 1S) of Sn with Cl 2, Br2, and I2 is extended to include reactions of both ground and metastable states of Si, Ge, and Sn with F2, Cl2, Br2, I2, and ICl. Chemiluminescent products of metal halides and/or dihalides were observed in all of these reactions, although attempts to observe that in the similar reactions of Pb were unsuccessful. In ICl reactions with Si, Ge, and Sn, both monochloride and dichloride emission occurs, confirming the previously proposed mechanism for creating dihalide emission in Sn reactions with Br2 and I2 via a monohalide intermediate.
- Wang,Cheong,Parson
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p. 2834 - 2839
(2007/10/02)
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- Resonance-Enhanced Multiphoton Ionization Spectra of the SiCl Radical between 430 and 520 nm
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The resonance-enhanced multiphoton ionization spectra of the SiCl radical observed between 430 and 520 nm are reported.The spectral structure arises from two-photon transition to the C 2Πr, D 2Σ+, and E states.Absorption of a third laser photon formed the cation.No subsequent fragmentation of cations was observed.The spectra terminating on the C 2Pr(υ' = 3-7) levels and the Si37Cl spectrum of the C 2Πr state are reported for the first time.The Si35Cl C 2Πr state spectroscopic constants of οe = 682.7 +/- 3.8 cm-1 and ωeχe = 3.8 +/- 0.5 cm-1 are reported.
- Johnson, Russell D.,Fang, Erti,Hudgens, Jeffrey W.
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p. 3880 - 3883
(2007/10/02)
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- Reaction of Magnesium Silicide and Silicon Tetrachloride/Trichlorosilane in Presence of Hydrogen
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The formation of silane (SiH4) has been observed during the reaction of silicon tetrachloride and hydrogen (SiCl4 + H2) with magnesium silicide (Mg2Si) at 400-500 deg C.The silane formed decomposes to give silicon in the vicinity of Mg2Si charge.A mixture of trichlorosilane + H2 reacts with Mg2Si at 250 deg C to afford silane which has been separated and decomposed to high purity silicon.The reaction of SiHCl3 + H2 with Mg2Si gives optimum conversion when SiHCl3:H2 ratio is 1:4 at the reaction temperature of 250 deg C.
- Mulla, I. S.,Choube, A. C.,Dongare, M. K.,Sinha, A. P. B.
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p. 756 - 758
(2007/10/02)
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- Preparation and Characterization of Thiagerma- and Selenagermaadamantanes
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In the presence of Al2Cl6 RGeCl3 reacts with (H3Si)2E to yield (RGe)4E6(R = Et, CF3, E = S; R = CF3, E = Se).X-ray structure determinations proved for (CF3Ge)4E6(E = S, Se) an adamantane structure.
- Haas, Alois,Kutsch, H.-Juergen,Krueger, Carl
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p. 1045 - 1048
(2007/10/02)
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- KINETIC FEATURES OF THE REACTION OF SILANE WITH CHLORINE AND NITROGEN TRICHLORIDE IN RAREFIED FLAMES.
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A new, branched-chain process has been found, the reaction of silane with nitrogen trichloride. It was established that the rate of reaction of SiH//4 with NCl//3 and Cl//2, the spectral composition, and the intensity of the chemiluminescence of the flame, as well as the dependence of the nature of these quantities on the initial pressure, undergo discontinuous changes when the ratio of the concentrations of the initial reactants is varied within the autoflammability region close to a particular value. Regimes of twofold inflammation of SiH//4 with Cl//2 and NCl//3 in a closed volume have been found: the flame of the two inflammations which follow one another in this regime changes color. This indicates a change in the mechanism of combustion.
- Azatyan,Markevich
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p. 1120 - 1126
(2008/10/08)
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- Silyl isothiocyanates
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The invention concerns novel compounds of formula IIIA wherein Ra is selected from electron donating substituents consisting of alkoxy of 1-10 carbon atoms, cycloalkoxy of 4-8 carbon atoms, aralkoxy of 7-12 carbon atoms, phenoxy which may b
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- Infrared Laser Photochemistry of SiH4-HCl Mixtures
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The infrared laser photochemistry of SiH4-HCl mixtures has been studied in a pressure range of 28-60 torr and in a temperature range of 295-414 K.The gaseous products observed are H2, Si2H6, SiH3Cl, SiH2Cl2, and SiHCl3 with trace amounts of Si3H8 and Si2H5Cl.As is usual in silane decompositions, a solid product containing silicon, hydrogen, and perhaps very small amounts of chlorine was also formed.The photochemical conversion is best described by initial decomposition of SiH4 to SiH2 and H2 followed by competition of SiH4 and HCl for SiH2 molecules.The simultaneous formation of all chlorosilanes suggests that decomposition of the initial product of SiH2-HCl reaction leads in turn to SiHCl and SiCl2 molecules.Studies of the temperature dependence of the rates of the competing reactions indicate that the activation energy for insertion of SiH2 into HCl is less than 1.3 kcal/mol.
- Moore, C. B.,Biedrzycki, J.,Lampe, F. W.
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p. 7761 - 7765
(2007/10/02)
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