- Synthesis and Properties of Ethyl, Propyl, and Butyl Hexa-alkyldisilanes and Tetrakis(tri-alkylsilyl)silanes
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The preparation of (R 3Si)4Si (R = ethyl, n-propyl, iso-propyl, n-butyl, and iso-butyl) was attempted using the procedure reported for [(CH3)3Si)]4Si.1 The type of alkyl group affected the resulting materials significantly. For R = ethyl, [(C2H5)3Si]2 [hexaethyldisilane (1)] was obtained phase pure if careful fractional distillation (under vacuum) was used, otherwise a mixture of 1, [(C2H5)2Si]4 (octaethyltetra-cyclo-silane), and other unidentified product(s) was obtained. For R = n-propyl a mixture of [(CH3CH2CH)3Si]2 (hexa-n-propyldisilane), [(CH3CH2CH2)2Si]4, (octa-n-propyltetra-cyclo-silane), [(CH3CH2CH2)3Si]4Si {tetrakis(tri-n-propylsilyl)silane} (2)], and other unidentified product(s) was obtained. From this mixture only 2, a new and previously unreported compound, was purified. 2 is the second compound of this type to be reported and is characterized by mass spectrometry (MS), elemental analysis (EA), and thermogravimetry (TG). The crystal structure of 2 is also reported [space group R βar{3}$ (no.148), a = 17.9249(10) ?, c = 12.2752(7) ?, at 100 K]. For R = iso-propyl pure [{(CH3)2CH2}3Si]2 [hexa-iso-propyldisilane (3)] was obtained in a good yield. For R = n-butyl or iso-butyl no phase pure compounds were synthesized. The pure compounds prepared have potential as precursors for the currently problematic atomic layer deposition of silicon, as demonstrated by their complete sublimation under thermal analysis. The sublimation temperature is dependent on the size of the molecule.
- Ahmed, Mohammed A. K.,Wragg, David S.,Nilsen, Ola,Fjellv?g, Helmer
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- Cp2TiPh2-Catalyzed Dehydrogenative Coupling of Polyhydromonosilanes
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The Cp2TiPh2-catalyzed reaction of dihydrosilanes afforded dehydrogenative coupling products, disilanes and/or trisilanes.The reaction using phenylsilane produced hydride-terminated poly(phenylsilylene) polymers with Mn=730 and Mw=960, which exhibited the longest UV absorption maximum at 245 nm (ε, 5.7x104).
- Nakano, Taichi,Nakamura, Hidehisa,Nagai, Yoichiro
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- Redox reactions of GeII and SnII dihalides with triethylsilane and triethylgermane
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Dihalogermylenes, dihalostannylenes, and their complexes (EI2, ECl2?dioxane, and (CO)5W=ECl2?THF, where E = Ge or Sn), unlike organylgermylenes, are not inserted at the Si-H (Ge-H) bond of triethylsilane (triethylgermane). The reactions of SnI 2, ECl2?dioxane, and (CO)5W=ECl 2?THF (E = Ge or Sn) with Et3E′H (E′ = Si or Ge) occur as redox processes. Depending on the nature of the reagents, the reactions afford products of oxidative coupling (Et3SiSiEt 3) and/or haloiodination (Et3SiX and Et3GeX) of triethylsilane (triethylgermane). The proposed mechanism of these reactions involves the electron transfer to form radical-ion pairs.
- Nosov,Koroteev,Egorov
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- An Electroreductive Approach to Radical Silylation via the Activation of Strong Si-Cl Bond
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The construction of C(sp3)-Si bonds is important in synthetic, medicinal, and materials chemistry. In this context, reactions mediated by silyl radicals have become increasingly attractive but methods for accessing these intermediates remain limited. We present a new strategy for silyl radical generation via electroreduction of readily available chlorosilanes. At highly biased potentials, electrochemistry grants access to silyl radicals through energetically uphill reductive cleavage of strong Si-Cl bonds. This strategy proved to be general in various alkene silylation reactions including disilylation, hydrosilylation, and allylic silylation under simple and transition-metal-free conditions.
- Lu, Lingxiang,Siu, Juno C.,Lai, Yihuan,Lin, Song
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supporting information
p. 21272 - 21278
(2020/12/21)
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- Disilane and preparation method thereof
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The invention discloses disilane and a preparation method thereof. The preparation method of disilane includes: subjecting a uniformly mixed reaction system containing tertiary hydrosilane and a catalyst to dehydrogenation reaction at a temperature ranging from -10DEG C to 120DEG C to obtain disilane, wherein the catalyst comprises a silver salt. The invention also discloses the disilane preparedby the method. The method for preparation of the disilane by catalyzing tertiary silane dehydrogenation with the silver salt adopts the silver salt to activate the Si-H bond in the silane so as to realize construction of disilane. Therefore, the invention provides an efficient and simple method for preparation of the compound, and the application prospect is wide.
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Paragraph 0058-0061
(2020/01/25)
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- Method for continuously preparing disilane compounds by micro-reaction device
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The invention discloses a method for continuously preparing disilane compounds by a micro-reaction device. The method comprises the following steps: (1) a solution A is prepared from organosilane by dissolving in a first organic solvent, or is organosilane; (2) a solution B is prepared from an oxidant by dissolving in a second organic solvent, or is an oxidant; (3) the solution A and the solutionB are pumped into a micro-mixer of the micro-reaction device simultaneously for mixing, a product then flows into a microreactor of the micro-reaction device for reaction, and the disilane compounds are prepared, wherein the microreactor is filled with a catalyst. Raw materials required in the method are easily available and have better stability, metal copper compounds are used as a catalyst forcoupling reaction on trisubstituted silanes, and the coupling effect on trisubstituted silanes is better than that of alkali metal catalysts and transition metal catalysts; a micro-channel reactor issuitable for an exothermic coupling reaction due to good mixing and heat transfer performance.
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Paragraph 0025; 0026; 0035; 0036
(2018/05/16)
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- Nucleophilic displacement versus electron transfer in the reactions of alkyl chlorosilanes with electrogenerated aromatic anion radicals
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Anion radicals of a series of aromatic compounds (C6H5CN, C6H5COOEt, anthracene, 9,10-dimethyl-, 9,10-diphenyl-and 9-phenylanthracene, pyrene and naphthalene) react with trialkyl chlorosilanes R1R2R3SiCl (R1-3 = Me, Et; R1,2 = Me, R3 = t-Bu) in multiple ways, following classical bimolecular schemes. The ratio of one-electron transfer (ET) to a two-electron process (SN2-like nucleophilic attack of the reduced form of mediator on the chlorosilane, with k2 ? 102-108 M-1 s-1) is inversely related to the steric availability of Si for nucleophilic displacement reactions. The nucleophilic substitution pathway mainly results in mono-and disilylated aromatic products. Paralleling the electrochemical data with DFT calculations, the role of silicophilic solvent (DMF) in SN process was shown to be quite complex because of its involvement into coordination extension at silicon, dynamically modifying energetics of the process along the reaction coordinate. Although 2,2'-bipyridine also forms delocalized persistent anion radicals, they do not induce neither ET nor SN reactions in the same manner as aromatic mediators. Silicophilicity of 2,2'-bipyridine being superior to that of DMF, a R3SiCl·bipy complex of hypercoordinated silicon with electroactive ligand was formed instead, whose reduction requires about 1 V less negative potentials than bipyridine itself.
- Soualmi, Saida,Dieng, Mamadou,Ourari, Ali,Gningue-Sall, Diariatou,Jouikov, Viatcheslav
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p. 457 - 469
(2015/03/04)
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- Gold nanoparticles-catalyzed activation of 1,2-disilanes: Hydrolysis, silyl protection of alcohols and reduction of tert-benzylic alcohols
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Gold nanoparticles supported on TiO2 catalyze under mild conditions the activation of a series of 1,2-disilanes towards hydrolysis and alcoholysis, with concomitant evolution of H2 gas. For the case of tert-benzyl alcohols, the main or only pathway is reduction to the corresponding alkanes.
- Gryparis, Charis,Stratakis, Manolis
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supporting information
p. 10751 - 10753,3
(2020/09/02)
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- PREPARATION OF SI-SI BOND-BEARING COMPOUNDS
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Si—Si bond-bearing compounds are effectively prepared by irradiating with radiation or heating Si—H group-bearing silicon compounds in organic solvents in the presence of iron complex catalysts. The Si—Si bond-bearing compounds are useful as a base material in photoresist compositions, ceramic precursor compositions, and conductive compositions.
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Page/Page column 3
(2009/05/28)
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- Electrolytic Behavior of Iodo- and Chlorosilanes. The Formation of Si-Si and Si-sp-C Bonds
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Electrolysis of iodosilanes with Al/Pt electrodes in pivalonitrile results in the formation of the Si-Si bonds to give the corresponding disilanes.On the other hand, the electrolysis of various halosilanes such iodo-, chloro-, and fluorosilanes with Pt/Pt electrodes in the presence of phenylacetylene leads to the formation of the Si-sp-carbon bonds to give phenylethynylated products.
- Kunai, Atsutaka,Ohnishi, Osamu,Sakurai, Tomohiro,Ishikawa, Mitsuo
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p. 1051 - 1052
(2007/10/03)
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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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- Photochemical dimerization and functionalization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and silanes
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The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and primary, secondary and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.
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- Making Mercury-Ptotosensitized Dehydrodimerization into an Organic Synthetic Method: Vapor Pressure Selectivity and the Behavior of Functionalized Substrates
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Mercury-photosensitized dehydrodimerization in the vapor phase can be made synthetically useful by taking advantage of a simple reflux apparatus (Figure 1), in which the products promptly condense and are protected from further conversion.This vapor pressure selectivity gives high chemical selectivity even at high conversion and on a multigram scale.Mercury absorbs 254-nm light to give the 3P1 excited state (Hg*), which homolyses a C-H bond of the substrate with a 3o>2o>1o selectivity.Quantitative prediction of product mixtures in alkane dimerization and in alkane-alkane cross-dimerizations is discussed.Radical disproportionation gives alkene, but this intermediate is recycled back into the radical pool via H atom attack, which is beneficial both for yield and selectivity.The method is very efficient at constructing C-C bonds between highly substituted carbon atoms, yet the method fails if a dimer has four sets of obligatory 1,3-syn methyl-methyl steric repulsions, as in the unknown 2,3,4,4,5,5,6,7-octamethyloctane.We have extended the range of substrates susceptible to the reaction, for example to higher alcohols, ethers, silanes, partially fluorinated alcohols, and partially fluorinated ethers.We see selectivity for dimers involving C-H bonds α to O or N and for S-H over C-H.An important advantage of our experimental conditions in the case of alcohols is that the aldehyde or ketone disproportionation product (which is not subject to H. attack) is swept out of the system by the stream of H2 also produced, so it does not remain and inhibit the rate and lower the selectivity. kdis/krec is estimated for a number of radicals studied.The very hindered 3o 1,4-dimethylcyclohex-1-yl radical is notable in having a kdis/krec as high as 7.1.
- Brown, Stephen H.,Crabtree, Robert H.
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p. 2935 - 2946
(2007/10/02)
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- Alkane Functionalization on a Preparative Scale by Mercury-Photosensitized Cross-Dehydrodimerization
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Alkanes can be functionalized with high conversions and in high chemical and quantum yields on a multigram scale by mercury-photosensitized reaction between an alkane and alcohols, ethers, or silanes to give homodimers and cross-dehydrodimers.The separation of the product mixtures is often particulary easy because of a great difference in polarity of the homodimers and cross-dimers.It is also possible to bias the product composition when the ratio of the components in the vapor phase is adjusted by altering the liquid composition.This is useful either to maximize chemical yield or to ease separation by favoring the formation of the most easily separated pair of compounds.The mechanistic basis of the reaction is discussed and a number of specific types of syntheses, for example of 2,2-disubstituted carbinols, are described in detail.The selectivity of cross-dimerization is shown to exceed that for homodimerization and reasons are discussed.Relative reactivities of different compounds and classes of compound are MeOHp-dioxanecyclohexane1,3,5-trioxacyclohexaneethanolisobutaneTHFEt3SiH.The observed selectivities generally parallel those for homodimerization, reported in the preceding paper, but certain differences are noted, and reasons for the differences are proposed.The bond-dissociation energy of Et3SiH is estimated from the reactivity data to be 90 kcal/mol.Eleven new carbinols are synthesized.
- Brown, Stephen H.,Crabtree, Robert H.
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p. 2946 - 2953
(2007/10/02)
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- Photochemical dimerization and functionalization of alkanes, ethers, primary alcohols and silanes
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The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary alcohols and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.
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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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- ORGANIC SONOCHEMISTRY. ULTRASOUND PROMOTED COUPLING OF CHLOROSILANES IN THE PRESENCE OF LITHIUM WIRE
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Triorganometal chlorides, R3MCl (R=alkyl, aryl; M=Si, Sn) are readily coupled to form bimetallics in 42-95percent yields using Li wire and ultrasound.Dihalosilanes give good yields of cyclic polysilanes.
- Boudjouk, Philip,Han, Byung Hee
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p. 3813 - 3814
(2007/10/02)
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