- Benzocyclobutene/vinylphenyl-introduced polycarbosilanes with low dielectric constant, high temperature performance and photopatternability
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With the development of microelectronic industry, low dielectric-constant insulating materials with high temperature performance and photopatternability have aroused interest. In this work, a kind of benzocyclobutene/vinylphenyl-introduced polycarbosilane
- Hu, Huan,Liu, Lili,Li, Zheng,Zhao, Cuijiao,Huang, Yawen,Chang, Guanjun,Yang, Junxiao
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- Infrared and Raman spectra, conformational stability, normal coordinate analysis, ab initio calculations, and vibrational assignment of 1-fluoro-1-methylsilacyclobutane
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The infrared (3500-40 cm-1) spectra of gaseous and solid 1-fluoro-1-methylsilacyclobutane, c-C3H6SiF(CH3), have been recorded. Additionally, the Raman spectrum (3500-30 cm-1) of the liquid has been recorded and quantitative depolarization values have been obtained. Both the axial and equatorial (with respect to the methyl group) conformers have been identified in the fluid phases. Variable temperature (-55--100 °C) studies of the infrared spectra of the sample dissolved in liquid xenon have been carried out. From these data, the enthalpy difference has been determined to be 267±10 cm-1 (3.19±0.12 kJ mol-1), with the axial conformer being the more stable form and the only conformer remaining in the polycrystalline solid. A complete vibrational assignment is proposed for the axial conformer and many of the fundamentals for the equatorial conformer have also been identified. The vibrational assignments are supported by normal coordinate calculations utilizing ab initio force constants. Complete equilibrium geometries have been determined for both rotamers by ab initio calculations employing the 6-31G* and 6-311++G** basis sets at the levels of restricted Hartree-Fock (RHF) and/or Moller-Plesset (MP) to second order. The results are discussed and compared to those obtained for some similar molecules.
- Guirgis, Gamil A.,Gounev, Todor K.,Zhen, Pengqian,Durig, James R.
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- Synthesis of sodium-polystyrenesulfonate-grafted nanoparticles by core-cross-linking of block copolymer micelles
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Sodium poly(styrenesulfonate)(polySSNa)-grafted polymer nanoparticles were synthesized by core-cross-linking of block copolymer micelles and subsequent chemical transformation. Block copolymers, poly(p-((1-methyl)silacyclobutyl) styrene-block-poly(neopent
- Matsumoto, Kozo,Hasegawa, Hirohiko,Matsuoka, Hideki
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- Rhodium-Catalyzed Intermolecular Silylation of Csp?H by Silacyclobutanes
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The signature reactivity of silacyclobutane (SCB) is their cycloaddition reactions with various π bonds. Recently, the first cases were disclosed where SCBs reacted with both Csp2?H and Csp3?H σ bonds in an intramolecular fashion. Herein, it is reported that SCB is also an efficient reagent for Csp?H bond silylation. Thus, rhodium-catalyzed intermolecular reactions between SCBs and terminal alkynes produced a series of symmetrical and unsymmetrical tetraorganosilicons bearing a Csp?Si functionality. Preliminary studies suggested that the reaction did not involve a cycloaddition pathway, but instead a direct activation of Csp?H bonds.
- He, Tao,Li, Bin,Liu, Lichuan,Ma, Wenpeng,He, Wei
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supporting information
p. 5648 - 5652
(2021/03/08)
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- SYNTHETIC PROCESS FOR CYCLIC ORGANOSILANES
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A process for preparing a cyclic organosilane using a solvent that promotes ring-closure reactions between an organosilane compound and a dihalo organic compound is disclosed. The ring-closure reactions may form a 4-, 5- or 6-member cyclic organosilane. The process involves a mixture including a dihalo organic compound, an organosilane having at least two functional groups, a solvent and magnesium (Mg). The two functional groups in the organosilane may include halogen, alkoxy or a combination thereof. In the presence of Mg, a Grignard intermediate is formed from the dihalo organic compound in the mixture. The solvent favors intra-molecular or self-coupling reactions of the Grignard intermediate. The intra-molecular or self-coupling reaction promotes ring-closure reaction of the Grignard intermediate to form the cyclic organosilane.
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Page/Page column 8-9
(2008/06/13)
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- Metallocene compounds, metallocene catalysts including the compounds and methods of polymerizing olefins with the catalysts
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There are disclosed new metallocene compounds and catalysts for olefin polymerization. The metallocene compound is a complex of transition metal and cyclopentadienyl-type ligands substituted with silacycloalkyl group. The metallocene catalyst comprises the above metallocene compound and at least one activator such as aluminoxanes, aromatic boron compounds substituted with fluoride, and modified clays. The metallocene catalyst can be used for polymerization of olefin in liquid phase, slurry phase or gas phase process.
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- Diphenylsiloxane oligomers functionalized at both terminal and method for the preparation thereof
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There is disclosed a diphenylsiloxane oligomer functionalized at both terminals, and methods for the preparation thereof, said oligomer having the following general formula G-(OSi(Ph)2)m O--G wherein Ph denotes a phenyl radical, m is 3 to 50 and G is has a formula independently selected from the group consisting of STR1 in which R1 is independently selected from the group consisting of hydrogen and a monovalent hydrocarbon group having 2 to 8 carbon atoms, said monovalent hydrocarbon group excluding phenyl, tolyl, xylyl, and ethylphenyl radicals, R is independently selected from the group consisting of R1, methyl radical and phenyl radical, Q is a divalent hydrocarbon group and n is an integer having a value of 1 to 3.
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- Chemistry of enoxysilacyclobutanes: Highly selective uncatalyzed aldol additions
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O-(Silacyclobutyl) ketene acetals derived from esters, thiol esters, and amides underwent facile aldol addition with a variety of aldehydes at room temperature without the need for catalysts. The uncatalyzed aldol addition reaction of O-(silacyclobutyl) ketene acetals displayed the following characteristics: (1) the rate of reaction was highly dependent on the spectator substituent on silicon and the geometry of the ketene acetal, (2) the O,O-ketene acetal of E configuration afforded the syn aldol products with high diastereoselectivity (93/7 to 99/1), (3) conjugated aldehydes reacted more rapidly than aliphatic aldehydes, and (4) the reaction was mildly sensitive to solvent. In addition, the aldol reaction was found to be efficiently catalyzed by metal alkoxides. Labeling experiments revealed that the thermal aldol reaction proceeds by direct intramolecular silicon group transfer, while the alkoxide-catalyzed version probably proceeds via in situ generated metal enolates. Computational modeling of the transition states suggests that the boat transition structures are preferred, supporting the observed syn selectivity of the thermal aldol reaction. Both thermal and alkoxide-catalyzed Michael additions were investigated, revealing a competition between 1,2- and 1,4-addition favoring the former.
- Denmark, Scott E.,Griedel, Brian D.,Coe, Diane M.,Schnute, Mark E.
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p. 7026 - 7043
(2007/10/02)
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- Silaethenes, XV. Pyrolysis of 1-Methyl-1-vinyl-1-silacyclobutane and 1,1-Divinyl-1-silacyclobutane - Follow-up Reactions of the Silaethenes Me(Vi)Si=CH2 and Vi2Si=CH2
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The pyrolysis of the silacyclobutanes Vi(Me)Si(CH2)3 (VMS) and Vi2Si(CH2)3 (V2S) at 700-800 deg C and 1E-1 - 1E-2 mbar leads to the intermediates Vi(Me)Si=CH2 and Vi2Si=CH2, which undergo isomerisation to siliranes followed by cleavage to give allene and the corresponding silylenes Me(H)Si: and Vi(H)Si: respectively.Copyrolyes of these silacyclobutanes with dienes (2,3-dimethyl-1,3-butadiene or isoprene) yield silacyclopentene derivatives (4, 14 and 20).The formation of these products supports the proposed mechanism.The simultaneous existence of silaethenes and silylenes in the gas phase is proven by the presence of the disilacyclobutanes 13 and 17, respectively, in the reaction mixtures.Using isoprene as the quenching reagent for Vi(Me)Si=CH2 the two isomeric silacyclohexenes 15 and 16 are formed in low yield, in addition to almost equal amounts of 13 and 14 (eq. (6)).
- Grobe, Joseph,Ziemer, Harald
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p. 1193 - 1202
(2007/10/02)
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- Silaheterocyclen II. Erzeugung und Cycloadditionsreaktionen der Neopentylsilaethene (R = H, Me)
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The monosilacyclobutanes (3) and (4) react with LiBut in pentane to yield the neopentylsilaethenes (1) and (2), respectively.Without suitable reactants, 1 and 2 undergo cyclodimerization to 2,4-dineopentyl-1,3-disilacyclobutanes; in the presence of organic dienes they form cycloaddition compounds: with cyclopentadiene only products are obtained, with cyclohexa-1,3-diene - and -cycloaddition reactions occur at comparable rates; in the reaction with norbornadiene the - is favoured over the -cycloaddition, whereas with 2,3-dimethyl-1,3-butadiene the -process together with the ene-reaction predominate.The -cycloadducts indicate a multistep-pathway, probably with participation of lithiated species, whereas the - and -cycloaddition reactions confirm that the silaethenes 1 and 2 are formed as reactive intermediates.
- Auner, N.
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- SILAETHENE I. DARSTELLUNG UND CHARAKTERISIERUNG VON MONOSILACYCLOBUTANEN
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Monosilacyclobutanes of the type RR' are prepared by ring closure reactions of 3-halopropylhalosilanes and by substitution of SiCl containing silacyclobutane rings with organometallic reagents (RMgX, LiR, NaCp).Under optimal experimental conditions yields between 50 and 95percent can be obtained by both procedures.Characterization of the compounds is accomplished by analytical (C, H, N) and NMR, IR and mass spectroscopic investigations.
- Auner, N.,Grobe, J.
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