- Synthesis, characterization and theoretical calculations of model compounds of silanols catalyzed by TEMPO to elucidate the presence of Si-O-Si and Si-O-N bonds
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We report the results from the reactions of 1-phenylethanol, 2-methylpropanol, trimethylsilanol and triphenylsilanol with TEMPO, OH-TEMPO and Br-TEMPO salt at different reaction conditions to obtain model functionalized compounds. With 1-phenylethanol, the ketone compound was obtained as expected, but when using triphenylsilanol the corresponding hexaphenyldisiloxane [di(triphenylsilane)ether] was obtained in crystal form, as well as the silaneoxiamine (Si-O-N). The hexaphenyldisiloxane crystal belonged to the triclinic crystal system with a space group P1, a = 8.5829(4) ?, b = 9.4856(4) ?, c = 10.9694(5) ?, α = 95.951(4)°, β = 90.059(3)°, γ = 113.352(4)°, the asymmetric unit comprised of Z = 1. The results showed that the synthetic method to obtain silane ether is simple and can be completed in one step, as well as independently of the type of TEMPO and base used. Also, under the same reactions conditions, we prepared the corresponding TEMPO-containing silanes as triphenylsilaneoxiamine and observed formation of Si-oxide chains through an in situ polycondensation reaction. The resulting compounds were characterized by FT-IR spectroscopy, mass spectrometry (EI), and 1H-NMR. The best assignment for infrared spectroscopy characterization and the structural parameters by vibrational frequencies were determined by DFT calculations.
- Percino, Judith,Pacheco, Jos A.,Soriano-Moro, Guillermo,Cern, Margarita,Castro, M. Eugenia,Chapela, Vctor M.,Bonilla-Cruz, Jos,Lara-Ceniceros, Tania E.,Flores-Guerrero, Mildred,Saldivar-Guerra, Enrique
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- The interaction of fluoride ion with organosilicons: facile isomerizations and new reactions of silicon hydrides
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Cesium fluoride isomerization of several derivatives of 3-silabicyclooctane and 2-silabicycloheptane as well as chiral α-NpPhMeSiH are described.The effect of solvent, 18-crown-6 ether, and other salts is discussed.Associated side reactions prompted study of the conversion of Ph3SiH to Ph3SiF by CsF and the identification of the products formed from the reaction of Ph3SiH with DMF, N-methylformanilide, and benzamide in the presence of metal fluorides.
- Blankenship, Craig,Cremer, Sheldon E.
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- Silane-silanol dehydrocondensation. The microscopic reverse of hydrogen activation by an organometallic oxide complex
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Hydrogen evolution from the dehydrocondensation reaction of triphenylsilane with triphenylsilanol is catalyzed by sodium trimethylsiloxide at 90 deg C in dioxane solvent.This system is the first example of a silane hydrolysis reaction that exhibits simple first order kinetics when investigated under second order conditions, equal concentrations of silane to proton source.Further analysis of the kinetics by the method of initial rates indicates that the reaction is first order in silane and zero order in silanol, demonstrating a multistep mechanistic process and that the proton source is not involved in the rate limiting step.The microscopic reverse process, hydrogen activation, has been investigated at 200-250 deg C and 330 atm of hydrogen using hexamethyldisiloxane and sodium trimethylsiloxide to yield significant, 12percent, quantities of trimethylsilyl hydride; however, the reaction has limited application since the methyl groups are concurrently cleaved to the organic product methane under these conditions.
- Klingler, R. J.,Krause, T. R.,Rathke, J. W.
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- Cobalt-Catalyzed Selective Synthesis of Disiloxanes and Hydrodisiloxanes
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Selective syntheses of symmetrical siloxanes and cyclotetrasiloxanes are attained from reactions of silanes and dihydrosilanes, respectively, with water, and the reactions are catalyzed by a NNNHtBu cobalt(II) pincer complex. Interestingly, when phenylsilane was subjected to catalysis with water, a siloxane cage consisting 12 silicon and 18 oxygen centers was obtained and remarkably the reaction proceeded with liberation of 3 equiv of molecular hydrogen (36 H2) under mild experimental conditions. Upon reaction of silane with different silanols, highly selective and controlled syntheses of higher order monohydrosiloxanes and disiloxymonohydrosilanes were achieved by cobalt catalysis. The liberated molecular hydrogen is the only byproduct observed in all of these transformations. Mechanistic studies indicated that the reactions occur via a homogeneous pathway. Kinetic and independent experiments confirmed the catalytic oxidation of silane to silanol, and further dehydrocoupling processes are involved in syntheses of symmetrical siloxanes, cyclotetrasiloxanes, and siloxane cage compounds, whereas the unsymmetrical monohydrosiloxane syntheses from silanes and silanols proceeded via dehydrogenative coupling reactions. Overall these cobalt-catalyzed oxidative coupling reactions are based on the Si-H, Si-OH, and O-H bond activation of silane, silanol, and water, respectively. Catalytic cycles consisting of Co(II) intermediates are suggested to be operative.
- Pattanaik, Sandip,Gunanathan, Chidambaram
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p. 5552 - 5561
(2019/06/05)
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- Nickel(0) catalyzed oxidation of organosilanes to disiloxanes by air as an oxidant
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We report here an efficient non-aqueous route to symmetrical disiloxanes from their corresponding organosilanes using Ni(COD)2 with 3,4,7,8-tetramethyl-1,10-phenanthroline in air. Our methodology is very simple and high yielding. The reaction mechanism is also proposed.
- Lv, Haiping,Laishram, Ronibala Devi,Li, Jiayan,Shi, Guangrui,Sun, Weiqing,Xu, Jianbin,Yang, Yong,Luo, Yang,Fan, Baomin
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supporting information
p. 971 - 974
(2019/03/07)
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- Breaking C-O Bonds with Uranium: Uranyl Complexes as Selective Catalysts in the Hydrosilylation of Aldehydes
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We report herein the possibility to perform the hydrosilylation of carbonyls using actinide complexes as catalysts. While complexes of the uranyl ion [UO2]2+ have been poorly considered in catalysis, we show the potentialities of the Lewis acid [UO2(OTf)2] (1) in the catalytic hydrosilylation of a series of aldehydes. [UO2(OTf)2] proved to be a very active catalyst affording distinct reduction products depending on the nature of the reductant. With Et3SiH, a number of aliphatic and aromatic aldehydes are reduced into symmetric ethers, while iPr3SiH yielded silylated alcohols. Studies of the reaction mechanism led to the isolation of aldehyde/uranyl complexes, [UO2(OTf)2(4-Me2N-PhCHO)3], [UO2(μ-κ2-OTf)2(PhCHO)]n, and [UO2(μ-κ2-OTf)(κ1-OTf)(PhCHO)2]2, which have been fully characterized by NMR, IR, and single-crystal X-ray diffraction.
- Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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p. 9025 - 9033
(2019/10/02)
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- FLAME RETARDANT RESIN COMPOSITION
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A flame-retarded resin includes at least one resin for which flame retardant capability is desired and at least one triaryl silicon-containing compound (I) as flame retardant in admixture therewith and/or chemically bonded, e.g.. grafted, to the resin.
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Paragraph 00113; 00114
(2018/02/28)
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- Metal-Free Ammonium Iodide Catalyzed Oxidative Dehydrocoupling of Silanes with Alcohols
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An ammonium iodide catalyzed direct oxidative coupling of silanes with alcohols to give various alkoxysilane derivatives was discovered. tert -Butyl hydroperoxide proved to be an efficient oxidant for this transformation. Attractive features of this protocol include its transition-metal-free nature and the mild reaction conditions.
- Yuan, Yan-Qin,Kumar, Pailla Santhosh,Guo, Sheng-Rong
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p. 1620 - 1623
(2017/08/11)
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- Controlled synthesis of cyclosiloxanes by NHC-catalyzed hydrolytic oxidation of dihydrosilanes
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Hydrolytic oxidation of various hydrosilanes in acetonitrile and in the absence of organic solvents catalyzed by an N-heterocyclic carbene organocatalysis is described. The NHC organocatalyst exhibited a very high activity with only 0.1 mol% loading of the catalyst in acetonitrile for aryl-substituted dihydrosilanes to produce hydrogen gas and cyclosiloxanes almost quantitatively in several minutes. The calculated TOF (15 000 h-1) of this organocatalyst is comparable to those of precious metal-based heterogeneous catalysts and much superior to those of the existing homogeneous metal catalysts. The catalytic reaction selectively yielded cyclosiloxanes in high yield without the contamination of silanols. Furthermore, the catalytic reaction can also be furnished under solvent-free conditions at elevated temperatures with 2.5 mol% loading of the NHC in 5-12 hours.
- Qing, Guoping,Cui, Chunming
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supporting information
p. 8746 - 8750
(2017/07/22)
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- Transition-Metal-Free Catalytic Hydrodefluorination of Polyfluoroarenes by Concerted Nucleophilic Aromatic Substitution with a Hydrosilicate
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A transition-metal-free catalytic hydrodefluorination (HDF) reaction of polyfluoroarenes is described. The reaction involves direct hydride transfer from a hydrosilicate as the key intermediate, which is generated from a hydrosilane and a fluoride salt. The eliminated fluoride regenerates the hydrosilicate to complete the catalytic cycle. Dispersion-corrected DFT calculations indicated that the HDF reaction proceeds through a concerted nucleophilic aromatic substitution (CSNAr) process.
- Kikushima, Kotaro,Grellier, Mary,Ohashi, Masato,Ogoshi, Sensuke
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supporting information
p. 16191 - 16196
(2017/11/27)
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- Reactivity of a titanocene pendant Si-H group toward alcohols. Unexpected formation of siloxanes from the reaction of hydrosilanes and Ph3COH catalyzed by B(C6F5)3
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The reaction of [Cp(η5-C5H4CH 2SiMe2H)TiCl2] (1; Cp = η5- C5H5) and methanol in the presence of catalytic amounts of B(C6F5)3 afforded a complex with a pendant silyl ether group, [Cp(η5-C5H4CH 2SiMe2OMe)TiCl2] (2), in good yield. The analogous reaction of 1 and Ph3COH resulted in the unexpected formation of [CpTiCl2{μ-η5:η5- (C5H4)CH2SiMe2OSiMe 2CH2(C5H4)}TiCl2Cp] (4). The formation of siloxanes from the reaction of 2 equiv of hydrosilane with Ph3COH mediated by B(C6F5)3 has a general applicability and proceeds in two consecutive steps: (i) transfer of the hydroxyl group from the trityl moiety to the silicon atom and (ii) silylation of the silanol formed in situ with the second equivalent of hydrosilane. The different hydrosilane reactivity toward Ph3COH in comparison with other alcohols can be attributed to the easy generation of the borate salt [Ph3C]+[(C6F5)3B(μ-OH) B(C6F5)3]- (5) under catalytic conditions. The intramolecular Si-H and Ti-Cl exchange in 1 is catalyzed by B(C6F5)3 in the presence of no alcohol. This process affords presumably a transient titanocene hydrido chloride, which is either chlorinated to give [Cp(η5-C5H 4CH2SiMe2Cl)TiCl2] (3) in CD 2Cl2 or decomposes into several paramagnetic Ti(III) species in toluene-d8. Complex 3 was independently synthesized from 1 and Ph3CCl in a good yield.
- Strasak, Tomas,Sykora, Jan,Lamac, Martin,Kubista, Jiri,Horacek, Michal,Gyepes, Robert,Pinkas, Jiri
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p. 4122 - 4129
(2013/09/02)
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- An efficient method for the synthesis of symmetrical disiloxanes from alkoxysilanes using Meerwein's reagent
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We report here a new and efficient route to symmetrical disiloxanes from their corresponding alkoxysilanes using Meerwein's reagent as mediator and potassium carbonate as additive under mild reaction conditions in acetonitrile. Our methodology is very simple, economic, and high yielding. We have also proposed a reaction mechanism with the plausible silyloxonium intermediates. Georg Thieme Verlag Stuttgart · New York.
- Jorapur, Yogesh R.,Shimada, Toyoshi
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supporting information; experimental part
p. 1633 - 1638
(2012/08/07)
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- Metal-catalyzed reduction of HCONR'2, R' = Me (DMF), et (DEF), by silanes to produce R'2NMe and disiloxanes: A mechanism unraveled
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We demonstrate that using Mo(CO)6, Mo(CO)5NMe 3, and (η5-C5H5)Mn(CO) 3 as catalysts for the silane, R3SiH, reduction of N,N-dimethylformamide (DMF), and N,N-diethylformamide (DEF), we can observe, intercept, and isolate, the important siloxymethylamine intermediates, R 3SiOCH2NR'2, R' = Me, Et, for the first time. In the presence of excess DMF such intermediates thermally react with a variety of silanes to form the corresponding disiloxanes in the absence of a metal catalyst. We also show that the germanium hydrides, Et3GeH and Bu3GeH, also reduce DMF to form trimethylamine and the corresponding digermoxane but observe no intermediates R3GeOCH2NMe 2. Bu3SnH reduces DMF, but along with the low yields of Bu3SnOSnBu3 (but no Bu3SnOCH 2NMe2) significant side products are obtained including (Bu3Sn)2 and Bu4Sn. In the absence of DMF the siloxymethylamines can undergo metal-catalyzed reactions with silanes, germanes and stannanes to form disiloxanes, and R3SiOER3 E = Ge, Sn, respectively. To date, the most efficient catalyst for this latter process is (η5-C5H5)Mo(CO)3CH 3 via a photochemical reaction.
- Arias-Ugarte, Renzo,Sharma, Hemant K.,Morris, Andrew L.C.,Pannell, Keith H.
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scheme or table
p. 848 - 851
(2012/03/07)
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- An efficient and simple method for the preparation of symmetrical disiloxanes from hydrosilanes by Lewis acid-catalyzed air oxidation
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Symmetrical disiloxanes were prepared in high yields by air oxidation of mono, di, and trihydrosilanes under Lewis acid catalysis.
- Sridhar, Madabhushi,Ramanaiah, Beeram China,Narsaiah, Chinthala,Kumara Swamy, Mudam,Mahesh, Bellam,Kumar Reddy, Mallu Kishore
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experimental part
p. 7166 - 7168
(2010/02/27)
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- Supported gold nanoparticle catalyst for the selective oxidation of silanes to silanols in water
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Hydroxyapatite-supported gold nanoparticles (AuHAP) can act as highly efficient and reusable catalysts for the oxidation of diverse silanes into silanols in water; this is the first catalytic methodology for the selective synthesis of aliphatic silanols using water under organic-solvent-free conditions.
- Mitsudome, Takato,Noujima, Akifumi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information; experimental part
p. 5302 - 5304
(2010/01/31)
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- Au(I) complexes-catalyzed transfer vinylation of alcohols and carboxylic acids
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Au(I) complexes-catalyzed transfer vinylation of alcohols and carboxylic acids has been achieved. The catalyst system consists of 2 mol % AuClPPh3 and 2 mol % AgOAc. Primary alcohols and secondary alcohols were converted into corresponding vinyl ethers in good yield (64-93%); however, tertiary alcohols showed poor reactivities. Carboxylic acids were also transformed into corresponding vinyl esters in good yield (78-96%).
- Nakamura, Aki,Tokunaga, Makoto
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p. 3729 - 3732
(2008/09/20)
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- From carbon dioxide to methane: Homogeneous reduction of carbon dioxide with hydrosilanes catalyzed by zirconium-borane complexes
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A mixture of a zirconium benzyl phenoxide complex and tris(pentafluorophenyl)borane is reported that catalyzes the hydrosilation reaction of carbon dioxide to generate methane via a bis(silyl)acetal intermediate. Copyright
- Matsuo, Tsukasa,Kawaguchi, Hiroyuki
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p. 12362 - 12363
(2007/10/03)
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- On a new catalyzed silylation of alcohols by phenylhydrosilanes
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KOH-18-crown-6 ether is a valuable system for the catalyzed dehydrocoupling of alcohols with phenylhydrosilanes (Ph3SiH and PhMe2SiH).
- Bideau, Franck Le,Coradin, Thibaud,Henique, Josette,Samuel, Edmond
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p. 1408 - 1409
(2007/10/03)
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- Synthesis, structure, and reactions of a novel triarylsilanol with a bowl-type framework: A silanol extremely resistant to self-condensation
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A novel nano-scale triarylsilanol bearing a bowl-shaped framework was synthesized, the structure of which was established by X-ray crystallographic analysis. The silanol was found to be extremely resistant to self-condensation whereas it reacted easily with appropriate molecules to give the corresponding derivatives.
- Goto, Kei,Okumura, Tomoko,Kawashima, Takayuki
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p. 1258 - 1259
(2007/10/03)
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- SOLVOLYSE ALCALINE DU TRIPHENYLSILANE. II. INFLUENCE DE LA TENEUR EN EAU SUR LA CINETIQUE DANS L'ACETONITRILE
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The influence of the composition of acetonitrile-water mixtures on the kinetics of the alkaline hydrolysis of triphenylsilane is investigated, by hydrogen volumetry, at 25 deg C.Within the range of increasing molarities 1.09 (mol l-1) II = rate/) is observed.A tentative interpretation, taking into account the variation of the transfer activity coefficient of OH(1-), leads to a 4th order with respect to water, which would normally imply that four water molecules are involved in the transition state, but this conclusion could be questionable, since the structure of the mixture is deeply modified when the water content is varied.The values of the Gibbs function of transfer for the activated state in the rate determining step are close to those for OH(1-), indicating a structure with original bonds almost broken.
- Tondeur, J.-J.,Borghese, A.,Vandendunghen, G.
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p. 165 - 178
(2007/10/02)
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- Regioselective β-Addition of Sulfonyl Anions to an α,β-Epoxysilane. Use of Triphenylsilyloxirane for Synthesis of Stable Cyclopropene Derivatives
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Anions generated from primary alkyl phenyl sulfones react with triphenylsilyloxirane to yield products of addition in the β-position, which were used for synthesis of stable cyclopropene derivatives.
- Jankowski, Pawel,Wicha, Jerzy
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p. 802 - 803
(2007/10/02)
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- Electrochemical Halogenation of Trisubstituted Germanes and Silanes
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Electrochemical halogenation of trisubstituted germanes and silanes in acetonitrile occured in the cathode compartment in contrast to the well-known electrochemical halogenations which always occur in the anode compartment.
- Okano, Mitsutoshi,Mochida, Kunio
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p. 1381 - 1382
(2007/10/02)
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- Metallkomplexe in Anorganichen Matrices, 5. Katalytische Silanoxidation an einem heterogenisierten Rhodium-Komplex
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A heterogenized rhodium complex, prepared by sol-gel processing of Rh(CO)Cl2 and Si(OEt)4, is shown to catalyze the conversion of the silanes H4-nSiPhn (n = 1-3) or (HMe2Si)2O to (poly)siloxanes by air or water.Using THF as a solvent, the silanoles Ph3SiOH or Ph2Si(OH)2 are obtained instead.The reaction of phenylacetic acid or acetic acid with HSiPh3 to give silyl esters is catalyzed by the same compound.
- Egger, Christian,Schubert, Ulrich
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p. 783 - 788
(2007/10/02)
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- Les triorganosilylpotasium: nouvelle voie d'acces et quelques aspects de leur reactivite
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We report here a new procedure for the convenient and easy preparation of silylanions and especially of Me3Si-.These undergo coupling reaction with halides and α-enone in good yields.Reactions with 5-bromo-1 hexene, benzophenone and carbon dioxide provide evidence for the ability of the silylpotassium to act as monoelectron transfer reagents.The course of these reactions varies substantially with the nature of the solvent.
- Corriu, R. J. P .,Guerin, C.,Kolani, B.
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p. 973 - 979
(2007/10/02)
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- (Aminoethynyl) Metalations, 12. Reactions of Ynamines with Olefins of the (Methylene)malonic Acid Type
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The (silylethynyl)- and (stannylethynyl)amines 1 react in the same way like other ynamines 7 (H, Me and CO2Me in the β-position) with the olefins 3 of the methylenemalonic acid type to give the 1,3-butadiene derivatives 6 and 8.These products arise from the spontaneous electrocyclic ring opening of primarily formed -cycloadducts.By heating, the derivatives 6a and 6c bearing an ester group in the 1-position and a trimethylsilyl group in the 3-position formally loose methyl trimethylsilyl ether and form the methylenecyclobutenones 9 and 11.
- Himbert, Gerhard,Brunn, Wolfgang
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p. 642 - 653
(2007/10/02)
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- ADDITION 1-3 D'HYDROSILANES ET STANNANES SUR DIVERSES NITRONES : RADICAUX NITROXYDES α-METALLES R3M-C-N.-O ET O- ET C-METALLA-HYDROXYLAMINES R3M-O-N-C-H ET R3M-C-N-OH
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Free radical 1,3-addition of silanes or stannanes to various nitrones generally leads to corresponding O-organometallohydroxylamines.The α-metallonitroxide radicals =-M-C-N.-O, obtained by trapping silyl or stannyl-centred radicals with an appropriate nitrone, have been characterised by e.s.r. spectroscopy.The O-stannylhydroxylamines are generally sufficiently stable to be isolated by distillation under vacuum.The less stable O-germyl or O-silylhydroxylamines decompose readily upon heating or by photolysis by competing intra- and intermolecular processes.Under special conditions favouring the formation of silylanions (MeNO2, NEt3), a competitive 1,3-dipolar addition of phenyldichloro- or trichlorosilane with the nitrone leads to the unstable C-metallohydroxylamine =-M-C-N-OH .
- Riviere, Pierre,Richelme, Suzanne,Riviere-Baudet, Monique,Satge, Jacques,Riley, Paul I.,et al.
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p. 1663 - 1683
(2007/10/02)
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- ELECTROCHEMICAL REDUCTION OF TRIORGANOHALO-SILANES AND -GERMANES
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The electrochemical reduction of triorganohalo-silanes and -germanes in 1,2-dimethoxyethane has been investigated by polarography, cyclic voltammetry, controlled potential coulometry, and macroscale electrolysis.The reduction of the silicon compounds exhibits a single irreversible wave.The polarograms for the germanium compounds exhibit two irreversible waves.The second wave shifts to more anodic potentials with addition of phenol or acetic acid.Dimer (i.e. disilanes or digermanes) are the main product of macroscale electrolysis in aprotic solvent but the hydrides are the principal products in protic solution.The results are interpreted in terms of the coexistence of two separate processes.The first involves a one electron reduction followed by dimerization of the radical.At higher cathodic potential a two electron charge transfer step occurs to form an anion, which in aprotic solvents reacts with the starting halogeno compound to form dimer, and in protic solutions gives the hydride.
- Corriu, R. J. P.,Dabosi, G.,Martineau, M.
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Brominations of triphenylallylsilane, methylphenyl-1-naphthylallylsilane, 2(1-naphthyl)-2-allyl-1,2,3,4-tetrahydro-2-silanaphthalene and triphenylallylgermane have been studied in carbon tetrachloride, acetic acid and methanol as solvents. Either cleavage
- Carre,Corriu,Henner
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p. 589 - 598
(2007/10/05)
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