- Novel fluoride ion mediated synthesis of unsymmetrical siloxanes under phase transfer catalysis conditions
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Unsymmetrical siloxanes have been prepared from silanols or hydrosilanes using phase transfer catalytic (PTC) systems Me3 SiN3-CsF-18-crown-6-toluene or Me3SiN 3-CsF-18-crown-6-H2O-toluene, correspond
- Abele, Ramona,Abele, Edgars,Fleisher, Mendel,Grinberga, Solveiga,Lukevics, Edmunds
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- Platinum-catalyzed aromatic C-H silylation of arenes with 1,1,1,3,5,5,5-heptamethyltrisiloxane
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The intermolecular dehydrogenative coupling of 1,1,1,3, 5,5,5-heptamethyltrisiloxane with arenes proceeded in the presence of a catalytic amount of platinum complexes prepared in situ from PtCl2 and hydrotris(pyrazolyl)borate derivatives. Copyr
- Murata, Miki,Fukuyama, Naoaki,Wada, Jun-Ichi,Watanabe, Shinji,Masuda, Yuzuru
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- Synthesis of siloxanes. XVII. Increment system for prediction of 17O NMR shifts of siloxanes
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17O NMR data have been obtained for a series of siloxanes and an incremental system derived for predicting the 17O shift of variously-substituted siloxanes.
- Scheim, U.,Ruehlmann, K.,Kelly, J. W.,Evans, S. A.
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- Preparation method and application of trimethyl silicon alkoxide
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The invention discloses a preparation method and an application of trimethyl silicon alkoxide. The preparation method includes the preparation steps: placing hexamethyldisiloxane and potassium hydroxide into a 10L three-mouth flask; adding 10ml of alcohol preparations; performing heating reflux for 48 hours; dividing water by a water knockout trap; cooling, filtering and drying materials to obtain white solid potassium trimethylsilanolate. Inexpensive trimethyl silicon alkoxide (MM) in industrial production serves as a raw material, and the trimethyl silicon alkoxide and the potassium hydroxide are subjected to heating reflux reaction under various catalysts to prepare potassium trimethylsilanolate with high content. All the catalysts are beneficial to dissolution of the potassium hydroxide, and reaction is facilitated.
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Paragraph 0023; 0024
(2017/10/22)
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- DMF-activated chlorosilane chemistry: Molybdenum-catalyzed reactions of R3SiH, DMF and R′3SiCl to initially form R′3SiOSiR′3 and R3SiCl
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The room temperature reactions between R3SiH (R3?=?Et3, PhMe2, Ph2Me) and R′3SiCl (R′3?=?Me3, PhMe2, Ph2Me), with an excess of dimethylformamide (DMF) in the presence of (Me3N)Mo(CO)5 as a catalyst, result in the initial formation of R3SiCl, R′3SiOSiR′3 and Me3N as detected by 29Si, 13C, 1H NMR spectroscopy and GC/MS. As the reaction proceeds, the more so if the reaction temperature is raised, mixed disiloxanes R3SiOSiR′3 and ultimately lesser amounts of R3SiOSiR3 may be detected. A mechanism involving the activation of chlorosilanes by the nucleophilic DMF is proposed to produce transient imminium siloxy ion pairs, [Me2N[dbnd]CHCl]+[R′3SiO]? ? [Me2N[dbnd]CH(OSiR′3)]+Cl? which react with R3SiH to form Me2NCH2OSiR′3 and R3SiCl. A secondary reaction of Me2NCH2OSiR′3 with R′3SiCl produces the symmetrical disiloxane R′3SiOSiR′3 and ClCH2NMe2. The final stage of the reaction is the reduction of ClCH2NMe2 by R3SiH, a reaction which is reported for the first time. The newly created chlorosilane R3SiCl can become involved in the initial DMF activation chemistry thereby forming the other disiloxanes observed as the reaction proceeds.
- Gonzalez, Paulina E.,Sharma, Hemant K.,Pannell, Keith H.
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supporting information
p. 376 - 381
(2017/06/30)
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- Pd/C-catalyzed cross-coupling reaction of benzyloxysilanes with halosilanes for selective synthesis of unsymmetrical siloxanes
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A new protocol for the nonhydrolytic synthesis of unsymmetrical siloxanes has been developed. The cross-coupling reaction of benzyloxysilanes with halosilanes catalyzed by Pd/C afforded various unsymmetrical siloxanes with co-production of benzyl halides. the Partner Organisations 2014.
- Igarashi, Masayasu,Kubo, Keiko,Matsumoto, Tomohiro,Sato, Kazuhiko,Ando, Wataru,Shimada, Shigeru
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p. 19099 - 19102
(2014/05/20)
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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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supporting information; experimental part
p. 848 - 851
(2012/03/07)
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- Silylation of silanols with vinylsilanes catalyzed by a ruthenium complex
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A new ruthenium complex-catalyzed O-silylation of silanols with vinylsilanes leading to siloxane bond formation with the evolution of ethylene is described. A maximum conversion of silanol is reached using an excess of vinylsilane to also yield the product of the homo-coupling of the latter. Under the optimum conditions, when vinylsilane with at least one ethoxy substituent is used, the reaction gives exclusively unsymmetrical siloxanes.
- Marciniec, Bogdan,Pawlu?, Piotr,Hreczycho, Grzegorz,Macina, Anna,Madalska, Martyna
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p. 1310 - 1313
(2008/09/18)
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- Rh(I)-catalyzed O-silylation of alcohol with vinylsilane
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Silyl ethers can be produced from alcohols and vinylsilanes under a rhodium(I) catalyst. The reaction is believed to proceed through an O-H bond cleavage of alcohol by rhodium(I) complex and a subsequent hydride insertion into vinylsilane followed by β-silyl elimination of the resulting β-silylethyl rhodium(III) complex. Georg Thieme Verlag Stuttgart.
- Park, Jung-Woo,Chang, Hoon-Jo,Jun, Chul-Ho
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p. 771 - 775
(2007/10/03)
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- Novel carbon-carbon bond formation through Mizoroki-Heck type reaction of silanols and organotin compounds
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The reaction of dimethyl(phenyl)silanol with butyl acrylate in the presence of a stoichiometric amount of Pd(OAc)2 or by a combined use of 0.1 molar amount of Pd(OAc)2 and Cu(OAc)2/LiOAc (molar ratio 3/2) gave butyl cinnamate in 76% or 57% yield, respectively. The similar reaction with tributyl(phenyl)tin also proceeded in 77% yield. The organotin compound was shown to react faster than the sitanol, although the tin reagent sometimes induced undesirable homocoupling, while the reaction with silanol did not give such by-product.
- Hirabayashi, Kazunori,Ando, Jun-Ichi,Kawashima, Jun,Nishihara, Yasushi,Mori, Atsunori,Hiyama, Tamejiro
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p. 1409 - 1417
(2007/10/03)
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- Influence of macroscopic factors on the composition of the products of cohydrolysis of triorganochlorosilanes
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The composition of the products of heterogeneous cohydrolysis of trimethyl- and dimethylphenylchlorosilanes by excess aqueous ammonia (4-5% solution) is determined by the regime of heterofunctional condensation of the initial chlorosilanes with the products of their hydrolysis, triorganosilanols. In a diffusion regime, hexaorganodisiloxanes are formed because of the limited possibility of removing silanols from the reaction zone, while silanols are predominantly formed in a kinetic regime. The influence of the nature of the solvent and surfactant and the intensity of stirring of the reaction mixture on the composition of the final products of hydrolytic cocondensation of triorganochlorosilanes is considered.
- Ivanov,Mlakhovskaya,Chernyshev,Kostikova,Mozzhukhin,Buzyreva
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p. 719 - 725
(2007/10/03)
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