- Investigation of reaction rate of bis(triethoxysilylpropyl)tetrasulphide in silica-filled compound using pyrolysis-gas chromatography/mass spectrometry
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Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was used to examine the reaction rate of bis(triethoxysilylpropyl) tetrasulphide in silica-filled rubber. The major pyrolysis product of bis(triethoxysilylpropyl) tetrasulphide, which is used as a silane coupling agent, was found to be an allyltriethoxysilane. Allyltriethoxysilane was also detected in the uncured silica-filled styrenebutadiene rubber compound with bis(triethoxysilylpropyl) tetrasulphide. To investigate the silica/silane reaction rate, the allytriethoxysilane content was used as an indicator and quantified by the relative peak area ratio of allytriethoxysilane/styrene. Styrene is a pyrolysis product of styrene-butadiene rubber. The results revealed an increase in reaction rate with increasing allytriethoxysilane content. Overall, pyrolysisgas chromatography/mass spectrometry can be used to estimate the reaction rate of the silica/silane system.
- Ha, Sung-Ho,Kim, Sung-Woo,Jeong, Ho-Kyun
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- Sustainable Catalytic Synthesis of Diethyl Carbonate
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New sustainable approaches should be developed to overcome equilibrium limitation of dialkyl carbonate synthesis from CO2 and alcohols. Using tetraethyl orthosilicate (TEOS) and CO2 with Zr catalysts, we report the first example of sustainable catalytic synthesis of diethyl carbonate (DEC). The disiloxane byproduct can be reverted to TEOS. Under the same conditions, DEC can be synthesized using a wide range of alkoxysilane substrates by investigating the effects of the number of ethoxy substituent in alkoxysilane substrates, alkyl chain, and unsaturated moiety on the fundamental property of this reaction. Mechanistic insights obtained by kinetic studies, labeling experiments, and spectroscopic investigations reveal that DEC is generated via nucleophilic ethoxylation of a CO2-inserted Zr catalyst and catalyst regeneration by TEOS. The unprecedented transformation offers a new approach toward a cleaner route for DEC synthesis using recyclable alkoxysilane.
- Putro, Wahyu S.,Ikeda, Akira,Shigeyasu, Shinji,Hamura, Satoshi,Matsumoto, Seiji,Lee, Vladimir Ya.,Choi, Jun-Chul,Fukaya, Norihisa
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p. 842 - 846
(2020/12/07)
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- Fe and Co Complexes of Rigidly Planar Phosphino-Quinoline-Pyridine Ligands for Catalytic Hydrosilylation and Dehydrogenative Silylation
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Co and Fe dihalide complexes of a new rigidly planar PNN ligand platform are prepared and examined as precatalysts for hydrosilylation of alkenes. Lithiation of Thummel's 8-bromo-2-(pyrid-2′-yl)quinoline followed by treatment with (i-Pr)2PCl and (C6F5)2PCl afforded the phosphine-quinoline-pyridine ligands, abbreviated RPQpy for R = i-Pr and C6F5, respectively. These ligands form 1:1 adducts with the dichlorides and dibromides of iron and cobalt. Crystallographic characterization of FeBr2(iPrPQpy), FeBr2(ArFPQpy), CoCl2(iPrPQpy), CoBr2(iPrPQpy), and CoCl2(ArFPQpy) confirmed that the M-P-C-C-N-C-C-N portion of these complexes is planar within 0.078 ? unlike previous generations of PNN complexes where deviations from planarity were ~0.35 ?. Bond distances as well as magnetism indicate that the Fe complexes are high spin and the cobalt complexes are high spin or participate in spin equilibria. Also investigated were the NNN analogues of the RPQpy ligands, wherein the phosphine group was replaced by the mesityl ketimine. The complexes FeBr2(MesNQpy) and CoCl2(MesNQpy) were characterized crystallographically. Reduction of MX2(RPQpy) complexes with NaBHEt3 generates catalysts active for anti-Markovnikov silylation of simple and complex 1-alkenes with a variety of hydrosilanes. Catalysts derived from MesNQpy exhibited low activity. Fe-RPQpy derived catalysts favor hydrosilylation, whereas Co-RPQpy based catalysts favor dehydrogenative silylation. Catalysts derived from CoX2(iPrPQpy) convert hydrosilanes and ethylene to vinylsilanes. Related experiments were conducted on propylene to give propenylsilanes.
- Basu, Debashis,Gilbert-Wilson, Ryan,Gray, Danielle L.,Rauchfuss, Thomas B.,Dash, Aswini K.
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p. 2760 - 2768
(2018/09/10)
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- NOVEL SILICON COMPOUND AND POLYMER
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PROBLEM TO BE SOLVED: To provide novel silicon compounds and polymers. SOLUTION: This invention provides a compound represented by the following chemical formula (1), where Z is an allyl group, Ar is an aromatic hydrocarbon group, all or part of hydrogen atoms on an aromatic ring of the aromatic hydrocarbon group may be replaced by a halogen atom or an alkyl group having 1-8 carbon atoms, m is an integer of 1-4, n is an integer of 0-3, m+n=4, and if n is 2-3, a plurality of Ars may be the same or different. COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0048-0050
(2016/10/07)
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- Dehydrogenative Silylation and Crosslinking Using Cobalt Catalysts
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Disclosed herein are cobalt complexes containing terdentate pyridine di-imine ligands and their use as efficient and selective dehydrogenative silylation and crosslinking catalysts.
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Paragraph 0145
(2014/03/24)
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- Use of an organometallic compound to protect and/or strengthen a keratin material, and treatment process
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The use of a composition comprising at least one organometallic compound which may be obtained by partial or total hydrolysis, and partial or total condensation, of at least one metallic precursor, to at least one of protect and strengthen a keratin material.
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- Evaluation of β- and γ-Effects of Group 14 Elements Using Intramolecular Competition
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To evaluate β-effects and γ-effects of group 14 elements, we have devised a system in which the intramolecular competition between γ-elimination of tin and β-elimination of silicon, germanium, and tin can be examined. Thus, the reactions of α-acetoxy(arylmethyl)stannanes with allylmetals (metal = Si, Ge, Sn) in the presence of BF3·OEt2 were carried out. The reactions seem to proceed by the initial formation of an α-stannyl-substituted carbocation, which adds to an allylmetal to give the carbocation that is β to the metal and γ to tin. The β-elimination of the metal gives the corresponding allylated product, and the γ-elimination of tin gives the cyclopropane derivative. In the case of allylsilane, the cyclopropane derivative was formed as a major product, whereas in the case of allylgermane the allylated product was formed predominantly. In the case of the allystannane the allylated product was formed exclusively. These results indicate that the y-elimination of tin is faster than the β-elimination of silicon, but slower than the β-elimination of germanium and tin. The theoretical studies using ab initio molecular orbital calculations of the carbocation intermediates are consistent with the experimental results. The effect of substituents on silicon was also studied. The introduction of sterically demanding substituents on silicon disfavored the β-elimination of silicon probably because of the retardation of nucleophilic attack on silicon to cleave the carbon-silicon bond.
- Sugawara, Masanobu,Yoshida, Jun-Ichi
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p. 3135 - 3142
(2007/10/03)
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