- 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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- METHOD OF MAKING A TRIHALOSILANE
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A method of making a trihalosilane comprising contacting an organotrihalosilane according to the formula RS1X3 (I), wherein R is C1-C10 hydrocarbyl and each X independently is halo, with hydrogen, wherein the mole ratio of the organotrihalosilane to hydrogen is from 0.009:1 to 1:2300, in the presence of a catalyst comprising a metal selected from (i) Re, (ii) a mixture comprising Re and at least one element selected from Pd, Ru, Mn, Cu, and Rh, (iii) a mixture comprising Ir and at least one element selected from Pd and Rh, (iv) Mn, (v) a mixture comprising Mn and Rh, (vi) Ag, (vii) Mg, and (viii) Rh at from 300 to 800 °C to form a trihalosilane.
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Page/Page column 24
(2012/06/30)
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- ORGANIC CHLOROHYDROSILANE AND METHOD FOR PREPARING THEM
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Provided is an organic chlorohydrosilane, a useful starting material for preparing silicon polymers and a method for preparing the same. More particularly, the present invention enables the synthesis of various novel organic chlorohydrosilanes in high yield by an exchange reaction between an Si—H bond of a chlorosilane which can be obtained in an inexpensive and easy manner and an Si—Cl bond of an another organic chlorosilane using a quaternary organic phosphonium salt compound as a catalyst. Since the catalyst can be recovered after its use and reused, the present invention is very economical and thus effective for mass-producing silicon raw materials.
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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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- Reactivity of intermetallic compounds: A solid state approach to direct reactions of silicon
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The present work is focused on a new approach to describe, quantify, and compare the reactivity of various transition metal silicide phases toward hydrogen chloride. Thermodynamic and kinetic parameters are obtained from isothermal calorimetric studies of these reactions. The reactivity of the silicide phases is discussed in terms of reaction start temperatures, rate constants, and apparent activation energies. Negative apparent activation energies are observed at low temperatures and are attributed to an initial stage of reaction where chlorine is chemisorbed and then incorporated into the silicide lattice near the surface. At a later time, a chlorine-containing reaction layer is formed having a composition and reactivity remarkably different from that of the bulk phase. On the basis of solid-state investigations, a diffusion model of the microscopic structure of these layers is presented, where a displacement of nickel atoms occurs followed by the occupation of nickel sites by chlorine. A model is suggested in which the electron level of the reaction layer is adjusted by the chlorine content of this layer, resulting in a electronic stabilization of silylenoide species at the surface. The model is applied to explain product distribution in the induction period during the direct reaction of silicon and methyl chloride.
- Acker, Joì?rg,Bohmhammel, Klaus
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p. 5105 - 5117
(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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- Method for redistribution of trichlorosilane
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A method for the redistribution of trichlorosilane in the presence of N,N,N',N'-tetraethylethylenediamine (TEEDA) to form a complex comprising dichlorosilane and TEEDA. The dichlorosilane can be disassociated from the TEEDA by a means such as heating and then used in standard processes requiring dichlorosilane. Alternatively, the complex comprising the dichlorosilane and TEEDA can be used as a reactant for hydrosilation of α,β-unsaturated olefinic nitriles or reacted with Grignard type reagents to make organosilanes.
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- Process for the preparation of aryldimethyl(3-aryl-propyl)silanes
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The present invention relates to a process for the preparation of compounds of the formula I STR1 where X is CH=CH, N=CH, CH=N or S, R1 and R2 independently of one another are H, halogen, alkyl, alkoxy, alkylthio, haloalkyl, haloalkoxy, haloalkylthio or the bivalent methylenedioxy group, R3 is a radical of the formulae (A), (B) or (C) STR2 where R4 and R5 independently of one another are H, halogen, alkyl, alkoxy or a radical of the formula (D) STR3 in which R6 is H or halogen and Y is CH2, O or S, and m, n, o, p and q are 0, 1, or 2, which comprises reacting a compound of the formula II where R3 is as defined in formula I, with dichloromethylsilane in the presence of a catalyst suitable for hydrosilylation reactions, and reacting the resulting intermediate of the formula III STR4 where R3 is as defined in formula I, in succession and without isolation of the resulting intermediate, with a methylmagnesium halide and an arylmagnesium halide of the general formula IV STR5 where R1, R2, m, n and X are as defined in formula I and Hal is halogen. The invention furthermore relates to the compounds of the formula III.
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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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- 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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- 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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- Process for the preparation of chlorosilane
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Dichlorosilane and phenyltrichlorosilane are prepared in good yields by reacting trichlorosilane and diphenyldichlorosilane in the presence of aluminium chloride, as catalyst, and a small proportion of a co-catalyst which is selected from hydrochloric acid and alumina and mixtures thereof, isolating the dichlorosilane from the reaction medium as it is formed and isolating the phenyltrichlorosilane obtained at the end of the reaction.
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