- Synthesis of bromohydrosilanes: Reactions of hydrosilanes with CuBr2 in the presence of CuI
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Reactions of hydrosilanes, R4-nSiHn (R = alkyl or phenyl, n = 1-3), with 2 equiv of CuBr2 in the presence of a catalytic amount of CuI led to selective replacement of an H-Si bond with a Br-Si bond giving R3SiBr, R2SiHBr, or RSiH2Br, while treatment of R2SiH2 and RSiH3 with 4 equiv of the reagent produced R2SiBr2 and RSiHBr2, respectively. Similar reaction of HEt2SiSiEt2H afforded HEt2SiSiEt2Br.
- Kunai, Atsutaka,Ochi, Takahiko,Iwata, Arihiro,Ohshita, Joji
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Read Online
- Rh(iii)-Catalysed solvent-free hydrodehalogenation of alkyl halides by tertiary silanes
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Efficient catalytic reduction of CDCl3 and other alkyl halides, including persistent organic pollutants, by different tertiary silanes using the unsaturated silyl-hydrido-Rh(iii) complex {Rh(H)[SiMe2(o-C6H4SMe)](PPh3)2}[BArF4] as a pre-catalyst is accomplished. The reactions are performed in a solvent-free manner. On account of experimental evidence, a simplified catalytic cycle is suggested for the hydrodehalogenation of CDCl3.
- Almenara,Azpeitia,Garralda,Huertos
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supporting information
p. 16225 - 16231
(2018/11/30)
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- Deoxygenative reduction of carbon dioxide to methane, toluene, and diphenylmethane with [Et2Al]+ as catalyst
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The strong Lewis acid [Et2Al]+ catalyzes the reduction of carbon dioxide with hydrosilanes under mild conditions to methane. In benzene solution, the side products toluene and diphenylmethane are also obtained through Lewis acid catalyzed benzene alkylation by reaction intermediates. Copyright
- Khandelwal, Manish,Wehmschulte, Rudolf J.
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p. 7323 - 7326
(2012/09/08)
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- A new and efficient method for the synthesis of bromosilanes from hydrosilanes using Br3CCOOEt/PdCl2 as the catalyst
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Bromosilanes were prepared conveniently and efficiently via the reaction of hydrosilanes and Br3CCOOEt in the presence of a catalytic amount of PdCl2 in refluxing THF over 15 min in high yields. The developed methodology was further applied for the one-pot synthesis of silyl ethers and silyl esters in excellent yields.
- Srithanakit, Phatsupha,Chavasiri, Warinthorn
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experimental part
p. 2505 - 2507
(2011/05/09)
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- PdCl2 and NiCl2-catalyzed hydrogen-halogen exchange for the convenient preparation of bromo- and iodosilanes and germanes
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Bromination and iodination of hydrosilanes and germanes were studied. Treatment of hydrosilanes with an excess of ethyl, propyl, or allyl bromide in the presence of a catalytic amount of PdCl2 or NiCl2 gave bromosilanes in good to high yield by hydrogen-halogen exchange. By using methyl, propyl, or allyl iodide as the iodine source, similar iodination of hydrosilanes was readily performed. Halogenation of hydrogermanes also proceeded by similar treatment.
- Iwata, Arihiro,Toyoshima, Yutaka,Hayashida, Tsuyoshi,Ochi, Takahiko,Kunai, Atsutaka,Ohshita, Joji
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- Selective synthesis of halosilanes from hydrosilanes and utilization for organic synthesis
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Selective synthesis of halosilanes has been examined. Various types of halosilanes and halohydrosilanes, such as R3SiX, R2SiHX, R2SiX2, RSiH2X, RSiHX2 (X=Cl, Br, F), were obtained by the reactions of the corresponding hydrosilanes with Cu(II)-based reagents selectively in high yields. This method could be also applied to the synthesis of chlorofluorosilanes and chlorohydrogermanes. On the other hand, iodo- and bromosilanes and germanes were obtained by Pd- or Ni-catalyzed hydride-halogen exchange reactions of hydrosilanes with alkyl or allyl halides. Their synthetic applications have been demonstrated by using iodo- and bromosilanes and chlorofluorosilanes.
- Kunai, Atsutaka,Ohshita, Joji
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- Spin chemistry of organometallic compounds. 2. Interaction of N-bromohexamethyldisilazane with allyltriorganolsilanes
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Two instances have been considered demonstrating the influence of organoelement substituent on the reactivity of radicals generated from R3MCH2CH=CH2 (M = Si or Sn) in photoinduced interaction with (Me3Si)2
- Taraban, Marc B.,Kruppa, Alexander I.,Polyakov, Nikolai E.,Voronkov, Mikhail G.,Rakhlin, Vladimir I.,Grigor'ev, Stanislav V.,Volkova, Olga S.,Mirskov, Rudolph G.,Leshina, Tatyana V.
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p. 228 - 234
(2007/10/03)
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- Triorganomonohalogenosilane
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A triorganomonohalogenosilane is prepared by reacting a triorganomonohydrosilane represented by the following general formula (I): with a halogenated allyl compound represented by the following general formula (II): STR1 in the presence of metal palladium, or a salt or complex of palladium to replace the hydrogen atom directly bonded to the silicon atom of the triorganomonohydrosilane with a halogen atom. In Formula ( I ), the substituents R1 's directly bonded to the silicon atom may be identical to or different from one another and each represents a monovalent organic group. In Formula (II), the substituents R2 's may likewise be identical to or different from one another and each represents a hydrogen atom or a monovalent alkyl group and X represents a chlorine atom, a bromine atom or an iodine atom.
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- Ligand Exchange Reactions between Haloboranes and Alkylsilanes
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In a ligand exchange reaction between BHal3 (Hal = Cl, Br) and the tetraalkylsilanes Et4Si, (Me3Si)2CH2 or Ph2CHSiMe3 the alkylhaloboranes EtBBr2 or MeBHal2 and the alkylhalosilanes Et3SiBr, HalMe2Si-CH2-SiMe3, (HalMe2Si)2CH2, and Ph2CHSiMe2Br, respectively, are formed.Similarly, the methyloligosilanes (Me3Si)2 (1) and (Me3Si)2SiMe2 (2) react with BHal3 (Hal = Cl, Br, I) via methyl-halogen-transfer to give HalMe2Si-SiMe3 (Hal = Cl, Br, I), (HalMe2Si)2 (Hal = Br, I), HalMe2Si-SiMe2-SiMe3, (Me3Si)2SiMeHal, HalMe2Si-SiMeHal-SiMe3, (HalMe2Si)SiMe2 (Hal = Cl, Br) or (BrMe2Si)2SiMeBr besides MeBHal2 (Hal = Cl, Br, I) and Me2BI, respectively.
- Einholz, Wolfgang,Gollinger, Walter,Haubold, Wolfgang
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- The reaction of isosteric isobutyl(isopropoxy)silanes iBun(iPrO)3-nSiH (n = 0-3) with allyl bromide in the presence of platinum compounds
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The isosteric silanes iBun(iPrO)3-nSiH react with allyl bromide to yield the corresponding bromides iBun(iPrO)3-nSiBr.The reactivities of the silanes fall in the sequence: iBu(iPrO)2SiH iBu2(iPrO)SiH > (iPrO)3SiH > iBu3SiH which can be accounted for in terms of the anomeric effects at the silicon atom.
- Pikies, J.,Wojnowski, W.
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p. 187 - 193
(2007/10/02)
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- Radiation Induced Br-Transfer from Ethylbromide to Triethylsilane
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The radiolysis of deoxygenated triethylsilane (Et3SiH) was studied in the presence of various concentrations of ethylbromide (EtBr) as a function of the radiation dose.Chain reactions are leading to rather high yields of Br-containing final products, e.g. using 0,93 mol/dm3 EtBr we obtained: Gi(Et3SiBr) = 138, G1(HBr) = 40, G1(Br2) = 15 and Gi(Et3Si-SiEt3) = 6, in addition to small amounts of unidentified oligomers.Based on the knowledge from previous steady-state and pulse radiolysis studies of Et3SiH, a probable reaction mechanism is postulated to allow explanation of the present results. - Keywords: Radiation Induced Br-Transfer, Ethylbromide, Triethylsilane
- Lugovoi, Yu. M.,Getoff, N.
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p. 1373 - 1376
(2007/10/02)
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- Stereoselective Oxidative Addition of Silanes and Hydrogen Halides to the Iridium(I) Cis Phosphine Complexes IrX(CO)(dppe) (X = Br, CN; dppe = 1,2-Bis(diphenylphosphino)ethane)
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The oxidative addition of silanes, RnCl3-nSiH (n = 3, R = Et, Ph, OEt; n = 2, R = Me; n = 1, R = Me), to the Ir(I) cis phosphine complexes IrX(CO)(dppe) (X = Br, CN; dppe = 1,2-bis(diphenylphosphino)ethane) has been found to proceed stereoselectively under kinetic control.Of the four possible diastereomers that can form by concerted cis addition of the Si-H bond to the iridium(I) center, the one having hydride trans to CO and Si trans to P(dppe) is formed initially with >98percent stereoselectivity.For X = Br, this diastereomer is not the thermodynamically favored product.Isomerization of the initially formed silyl hydride product to the equilibrium mixture of diastereomers follows first-order kinetics for the triphenylsilyl derivative with k1 = 0.015 min-1.The rate of isomerization for the kinetic silyl hydride adducts decreases in the order Et3SiH > Ph3SiH > (OEt)3SiH > Me2ClSiH with the MeCl2SiH derivative not isomerizing even after prolonged heating.The most stable diastereomer for X = Br has hydride trans to Br and silyl trans to P(dppe).For X = CN, the kinetic isomer wiht H trans to CO and Si trans to P(dppe) is also the most stable isomer, although other isomers are observed to form after initial reaction.Secondary chemistry of the triethylsilyl hydride products for X = Br and CN is observed over longer reaction times leading to the formation of IrHX2(CO)(dppe) (X = Br), IrH2(SiEt3)(CO)(dppe), and Et3SiSiEt3.This secondary chemsitry is consistent with reductive elimination/oxidative addition sequences.The oxidative addition of HX to IrX'(CO)(dppe) also proceeds stereoselectively, giving the isomer with H trans to X' and X trans to P(dppe).This diastereomer results from cis addition in wich H-X approaches the square-planar Ir(I) complex with its axis parallel to X'-Ir-P.Thus, while R3SiH and HX both add to IrX(CO)(dppe) by a cis concerted mechanism, the diastereoselection for HX is opposite to that for R3SiH.It is proposed that this difference arises because the silane approach to the Ir(I) complex is nucleophilic while that of HX is electrophilic.
- Johnson, Curtis E.,Eisenberg, Richard
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p. 6531 - 6540
(2007/10/02)
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- Absolute Rates for Dimerization of Capto-dative Substituted Methyl Radicals in Solution: Absence of Kinetic Stabilization
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For three capto-dative substituted methyl radicals, t-butoxy(cyano)methyl radical (1), t-butylthio(cyano)methyl radical (2), and methoxy(methoxycarbonyl)methyl radical (3), absolute rates for dimerization have been measured by e.s.r. spectroscopy and substantiated by product analysis.Values for the rate constants of 1.0E8 - 1.5E9 l mol-1s-1 in the temperature range -60 to +60 deg C support the diffusion-controlled nature of the dimerization.The comparison of Arrhenius activation parameters for dimerization with those for the bulk viscosity of the solutions does not provide evidence for noticeable intrinsic barriers to recombination, indicating the absence of kinetic stabilization for capto-dative substituted methyl radicals.
- Korth, Hans-Gert,Sustmann, Reiner,Merenyi, Robert,Viehe, Heinz Guenther
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- The Mechanism of the Reaction of Molecular Bromine with Organosilicon Hydrides
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The kinetics of the bromination of 7 triarylsilanes and 14 other organosilicon hydrides by molecular bromine in CCl4 have been determined by the stopped flow method.For triethylsilane, Arrhenius parameters have been measured in octane and CCl4, and solvent effects determined in other solvents of different polarity.The results accord with a molecular mechanism involving one molecule of bromine and one of the organosilicon hydride, with partial positive charge build-up on silicon in the transition state.
- El-Durini, Nabil M. K.,Jackson, Richard A.
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p. 1275 - 1278
(2007/10/02)
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- Silyl Halides from (Phenylseleno)silanes. Reaction with Oxiranes and Alcohols To Give Hydrolytically Stable Silyl Ethers.
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The preparation of (phenylseleno)silanes and their reactions with halogens (Cl2, Br2, I2) to give silyl halides and diphenyl diselenide are described.Highly hindered tert-butyldimethyl and tert-butyl diphenylsilyl halides were easily prepared.The reaction of silyl bromides and iodides with oxiranes followed by diazabicyclononane treatment gave allylic alcohol silyl ethers.Tertiary alcohols reacted rapidly with silyliodides to give hydrolytically stable silyl ethers.Treatment of the silyl ethers with tetra-n-butylammonium fluoride gave the free alcohols withoutrearrangement or isomerization.
- Detty, Michael R.,Seidler, Mark D.
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p. 1283 - 1292
(2007/10/02)
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