- Chemistry of Silicon-Nitrogen Compounds, CLXVI: Organylamino Substitutions on Hexachlorodisiloxane
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Reaction of hexachlorodisiloxane with primary and secondary amines leads - in dependence of stoichiometry - to numerous partially and totally organylamino substituted disiloxanes.Partially aminosubstituted chlorodisiloxanes are very sensitive to moisture and can be converted into disiloxanes with different organylamino groups.Exhaustive alkanolysis substitutes amino as well as chloro groups giving hexaalkoxydisiloxanes, but partial alkanolysis may substitute amino in preference to chloro groups.Mass spectra can be interpreted by abstraction of RR'N., RR'N+, RR'NH and (RR'N minus H) units.Most of the compounds are colourless liquids but hexakis(piperidino)-disiloxane melts at 270 deg C.
- Wannagat, Ulrich,Bogedain, Gabriele,Hajibegli, Hamid,Moretto, Hans-Heinrich
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- Direct synthesis of tetraalkoxysilanes from silica and alcohols
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A new simple and efficient process for synthesizing tetraalkoxysilanes (TROS) directly from silica and alcohols was developed using molecular sieves as dehydrating agents. Using this method, a variety of TROS (R = ethoxy, n-propoxy, or n-butoxy) were obtained over 70% yields within 6 h. We also employed various natural silica sources in this process for practical applications.
- Fukaya, Norihisa,Choi, Seong Jib,Horikoshi, Toshio,Kataoka, Sho,Endo, Akira,Kumai, Hiroshi,Hasegawa, Minoru,Sato, Kazuhiko,Choi, Jun-Chul
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- A new route to silicon alkoxides from silica
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A novel route to tetraethoxysilane and other silicon alkoxides is described, from amorphous silica (SiO2·H2O) as the raw material. The reaction of amorphous silica with triethanolamine is enhanced by using an alkali metal hydroxide catalyst, to form a range of triethanolamine-substituted silatrane species. These can undergo alkoxide exchange in acidic alcohols to form alkoxysilatranes, tetraalkoxysilanes, hexaalkoxydisiloxanes and higher siloxanes. Reaction of triethanolamine-substituted silatranes with acetic anhydride produces acetoxysilatrane. Products were identified by multinuclear (1H, 13C and 29Si) magnetic resonance spectroscopy, electrospray mass spectrometry or high-resolution gas chromatography electron impact mass spectrometry.
- Kemmitt, Tim,Henderson, William
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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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- BRANCHED ORGANOSILOXANES USED AS HEAT TRANSFER FLUID
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The invention relates to a method for operating a system at an operating temperature of between 300° C. and 500° C., using a heat transfer fluid comprising branched siloxanes of general formula (I) (R3SiO1/2), (SiO4/2) in which w represents integral values of between 4 and 20, z represents integral values of between 1 and 15, and R represents a methyl group, the sum of the fractions of all siloxanes of general formula (1) being at least 95 mass %, in relation to the whole heat transfer fluid.
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Paragraph 0036; 0037; 0050; 0051; 0052
(2018/02/06)
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- Reaction of silicon with alcohols in autoclave
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A reaction of activated silicon with alcohols in an autoclave at 240—270 °C was studied. It was found that primary alcohols form tetraalkoxysilanes Si(OR)4 with high selectivity (up to 97%), while the secondary PriOH gave a mixture of compounds HSi(OPri)3, Si(OPri)4, HSi(OPri)2OSi(OPri)2H, HSi(OPri)2OSi(OPri)3, and Si(OPri)3OSi(OPri)3 with the predominance of trialkoxysilane (up to 67%). Carrying out the reaction under the indicated conditions has the advantage of experimental simplicity, reagent availability, high conversion of silicon, good isolated yields of products.
- Krylova,Egorov,Nefedov
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p. 260 - 266
(2017/07/11)
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- Bis(acetylacetonato)Ni(II)/NaBHEt3-catalyzed hydrosilylation of 1,3-dienes, alkenes and alkynes
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The utility of commercially available Ni(II) salts, Ni(acac)2 (acac = acetylacetonato) (1a) and its derivatives bis(hexafluoroacetylacetonato)nickel(II) (1b) and bis(2,2,6,6-tetramethyl-3,5-heptanedionato)nickel(II) (1c) as versatile hydrosilylation catalyst precursors is described. Complexes 1a-c catalyze 1,4-selective hydrosilylation of 1,3-dienes in the presence of NaBHEt3 at ambient temperature. The reactions exhibit good regioselectivity to give the branched isomers as major products. The catalytic system also catalyzes hydrosilylation of alkenes including industriary important siloxy-, amino-, and epoxy-substituted ones as well as both terminal and internal alkynes.
- Srinivas, Venu,Nakajima, Yumiko,Ando, Wataru,Sato, Kazuhiko,Shimada, Shigeru
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- Mononuclear Heteroscorpionate Zwitterionic Zinc Terminal Hydride: Synthesis, Reactivity, and Catalysis for Hydrosilylation of Aldehydes
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Treatment of heteroscorpionate zinc benzyloxy complex LZnOBn (1, L = (MePz)2CP(Ph)2NPh, MePz = 3,5-dimethylpyrazolyl) with phenylsilane (PhSiH3) gave a zinc hydride complex LZnH (2) containing a rare terminal hydride fragment. X-ray diffraction analysis and the DFT calculation confirm the zwitterionic structure of complex 2. The stoichiometric reaction of 2 with CS2 readily afforded a dithioformate complex LZnSCH(S) (3) of the C = S insertion into the Zn-H product. Moreover, complex 2 was an efficient catalyst for the hydrosilylation reaction of a series of silanes and aldehydes under mild conditions, featuring excellent functional group tolerance. The preliminary mechanistic study revealed that both zinc benzyloxy complex 1 and zinc hydride complex 2 were involved in the hydrosilylation process as the reaction intermediates. (Chemical Equation Presented).
- Mou, Zehuai,Xie, Hongyan,Wang, Meiyan,Liu, Na,Yao, Changguang,Li, Lei,Liu, Jingyao,Li, Shihui,Cui, Dongmei
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p. 3944 - 3949
(2015/09/01)
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- Copper-catalyzed formic acid synthesis from CO2 with hydrosilanes and H2O
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A copper-catalyzed formic acid synthesis from CO2 with hydrosilanes has been accomplished. The Cu(OAc)2?H 2O-1,2-bis(diphenylphosphino)benzene system is highly effective for the formic acid synthesis under 1 atm of CO2. The TON value approached 8100 in 6 h. The reaction pathway was revealed by in situ NMR analysis and isotopic experiments.
- Motokura, Ken,Kashiwame, Daiki,Miyaji, Akimitsu,Baba, Toshihide
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experimental part
p. 2642 - 2645
(2012/08/13)
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- PROCESS FOR PRODUCTION OF TRIALKOXYHALOSILANES, PROCESS FOR PRODUCTION OF ALKOXY(DIALKYLAMINO)SILANES, CATALYSTS FOR (CO)POLYMERIZATION OF ALPHA-OLEFINS, CATALYST COMPONENTS THEREFOR, AND PROCESS ES FOR POLYMERIZATION OF ALPHA-OLEFINS WITH THE CATALYSTS
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A process for the production of trialkoxyhalosilanes which comprises reacting a tetrahalosilane [37] with a tetra- alkoxysilane [38] in the presence of an alcohol whose alkoxy group is the same as those of the tetraalkoxysilane to thereby obtain a trialkoxyhalosilane [39], characterized in that the alcohol is used in an amount of 5 to 50 % by mole based on the total amount of Si of the tetrahalosilane and the tetraalkoxysilane: SiX4 [37] (wherein X is halogeno) Si(OR1)4 [38] (wherein R1 is a hydrocarbon group having 1 to 6 carbon atoms) XSi(OR1)3 [39] (wherein X and R1 are each as defined above).
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Page/Page column 17-18
(2010/11/08)
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- Hydrosilylation of cyclohexene and allyl chloride with trichloro-, dichloro(methyl)-, and chlorodimethylsilanes in the presence of Pt(0) complexes
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Hydrosilylation of cyclohexene and allyl chloride in the presence of Pt(0) complexes with tetramethyldivinyldisiloxane (Karstedt catalyst) and hexavinyldisiloxane was studied. It was shown that these catalysts are much more active in the hydrosilylation of cyclohexene with trichloro-, dichloro(methyl)-, and chlorodimethylsilane than the Pt(II)-containing Speier catalyst. In the hydrosilylation of allyl chloride in the presence of Pt(0) complexes, the ratio of the fraction of addition products to the fraction of reduction products increases from 5.7 (Speier catalyst) to 10-16. Quantum-chemical calculations showed that Pt(0) complexes are more active than Pt(II) complexes on the stage of formation of platinum silicon hydride complexes. Pleiades Publishing, Inc., 2006.
- Belyakova,Chernyshev,Storozhenko,Knyazev,Turkel'taub,Parshina,Kisin
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p. 925 - 930
(2008/02/03)
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- Triethoxysilane, tetraethoxysilane and hexaethoxydisiloxane - Three complementary reagents for the synthesis of hydrogen-rich silylarenes
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Triethoxysilane HSi(OEt)3, tetraethoxysilane Si(OEt) 4 and hexaethoxydisiloxane Si2O(OEt)6 have been probed as reagents for the synthesis of hydrogen-rich silyl-arenes Ar(SiH3)n. A large set of new silyl-arenes, varying in their substitution patterns and grades, have been prepared. The results establish the two new silylating agents HSi(OEt)3 and Si 2O(OEt)6 as particularly useful alternatives to Si(OEt)4. The products, which include trihydrosilyl-substituted methylbenzenes, naphthalenes and ferrocenes, have been characterized by NMR and IR spectroscopy, mass spectrometry and single crystal X-ray diffraction.
- Minge, Oliver,Nogai, Stefan,Schmidbaur, Hubert
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p. 153 - 160
(2007/10/03)
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- Syntheses and properties of isocyanatodisiloxanes and their alkoxy- substituted derivatives
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Isocyanatooligosiloxanes and their alkoxy derivatives were synthesized. The hydrolysis of triisocyanato(methyl)silane followed by distillation provided 1,1,3,3-tetraisocyanato-1,3-dimethyldisiloxane in good yield. The reaction of 1,1, 3,3-tetraisocyanato-1,3-dimethyldisiloxane with ethanol, isopropyl alcohol, and t-butyl alcohol proceeded selectively to afford partially alkoxy substituted isocyanatodimethyldisiloxanes, (RO)n(NCO)(4- n)Me2Si2O (R = Et, n = 1 - 4; R = Pr(i), n = 1 - 4; and R = Bu(t), n = 1 - 2). On the other hand, the hydrolysis of tetraisocyanatosilane provided a mixture of isocyanatooligosiloxanes. Hexaisocyanatodisiloxane was isolated by distillation from the reaction mixture with some impurities produced by the disproportionation of hexaisocyanatodisiloxane on heating. The reaction of hexaisocyanatodisiloxane with alcohols provided partially alkoxy-substituted isocyanatodisiloxanes, [(RO)(n)(NCO)(3-n)Si]2O (R = Et, n = 2-3; R = Pr(i), n = 1 - 3; and R = Bu(t), n = 1 - 2), selectively and in high yield.
- Gunji,Setogawa,Asakura,Abe
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p. 2967 - 2972
(2007/10/03)
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- Synthesis and reactivity of bis(triethoxysilyl)methane, tris(triethoxysilyl)methane and some derivatives
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Syntheses of new poly(trifunctional-silyl)alkanes, which are potent coupling agents of hybrid organic-inorganic materials have been thoroughly examined. Optimization of the Benkeser reaction using chloroform, trichlorosilane and tri-n-butylamine (respective ratios 1:4.5:3) afforded bis(trichlorosilyl)methane isolated as bis(triethoxysilyl)methane after ethanolysis (overall yield 60%). With nine equivalents of trichlorosilane, tris(trichlorosilyl)methane is preferentially formed, isolated as tris(triethoxysilyl)methane (30% yield). C-Substituted bis(triethoxysilyl) methanes were obtained after metallation of the α-carbon and trapping experiments with the corresponding alkyl halides. In the case of tris(triethoxysilyl)carbanion, only MeI and Br2 were able to give the anticipated products. Unexpectedly, CO2 insertion afforded the stable ketene, [(EtO)3Si]2C=C=O.
- Corriu, Robert J.P.,Granier, Michel,Lanneau, Gerard F.
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- The Reaction of with Triethoxysilane in the Presence of PPh3: a New Method for Synthesis of
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The reaction of with triethoxysilane in the presence of PPh3 is examined under oxygen-free conditions, permitting isolation of 1 formed by elimination of one acac ligand (as protonated and hydrosilylated product) from the nickel complex with its simultaneous silylation which is followed by C-O bond cleavage in triethoxysilyl ligand via a mechanism involving transfer of an ethyl group to Ni with elimination of pentaethoxyhydrodisiloxane in the excess of triethoxysilane.
- Marciniec, Bogdan,Maciejewski, Hieronim,Gulinski, Jacek
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p. 717 - 718
(2007/10/02)
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- A new route to alkoxysilanes and alkoxysiloxanes of use for the preparation of ceramics by the sol-gel technique
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The preparation of (EtO)4Si from Ca3(SiO4)O, Ca2SiO4, and portland cement, (EtO)3SiOSi(OEt)3 from Ca2Zn(SiO3)2O, (n-PrO)3SiOSi(O-n-Pr)2OSi(O-n-Pr)3 from Ca3(SiO3)3, [(EtO)2SiO]4 from Ca8(SiO3)4Cl8, and the bicyclic [5.5.1]- and [5.3.3]-isomers of (EtO)10Si6O7 from Cu6(SiO3)6·6H2O and Na4Ca4(SiO3)6 is described. The route employed in these preparations has two variations. Both can be described in terms of three steps. In one, the synthesized silicate variation, the first step is the conversion of silica or an available silicate to a silicate having an ion with a framework that is the same as that of the product or similar to it. The second is either the conversion of this silicate to a silicic acid that is solvated by an alcohol and has a framework that is the same as or similar to that of the product or the conversion of this silicate to one or more corresponding partially alkoxylated silicic acids. The third is the conversion of the silicic acid or acids to the product. In the second, or the available silicate variation, the first step entails the acquisition of a silicate with the needed framework from natural or other sources and the last two steps involve conversions that are the same as those in the synthesized silicate variation. The procedures and conditions used in the route are discussed.
- Goodwin, George B.,Kenney, Malcolm E.
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p. 1216 - 1220
(2008/10/08)
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- Transesterification Reaction of Tetraethoxysilane and Butyl Alcohols
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Tetraethoxysilane was treated with Amberlyst 15 cation-exchange resin in the presence of butyl alcohol.On treating the mixture of tetraethoxysilane and 1-butanol, the transesterification took place in which butoxyl groups were substituted for ethoxyl groups in tetraethoxysilane.The degree of the transesterification depended on the molar ratio of tetraethoxysilane to 1-butanol of a mixture.The distribution of alkoxysilane species present in the tetraethoxysilane-1-butanol solution was compared with the tetrabutoxysilane-ethanol solution, and it was found that the degree of the transesterification depended on the ratio of numbers of alkyl groups in tetraalkoxysilane and alcohol used.The time required for equilibrium in the distribution of alkoxysilane species in the solution was different with the variety of butyl alcohol used, suggesting the presence of steric effect of butyl alcohols on this reaction.
- Hasegawa, Isao,Sakka, Sumio
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p. 4087 - 4092
(2007/10/02)
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- KINETICS AND MECHANISM OF PYROLYSIS OF TETRAETHOXYSILANE (TEOS).
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In view of the contradictory nature of experimental data on the kinetic parameters of high-temperature decomposition of TEOS, and also of the need to elucidate the course of the chemical reactions at the first stage of plasma-chemical production of SiO//2, the authors undertook a detailed study of the kinetics and mechanism of TEOS pyrolysis. It is shown that the experiments showed that decomposition of TEOS in a current of argon ends at 973 K. The main products of pyrolysis in the 773-973 K range are ethanol and ethylene. The degree of conversion of TEOS into ethanol decreases with rise of temperature.
- Ivanov,Kupryashkina,Kompaniets,Kopteva,Konoplev
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p. 1691 - 1695
(2007/10/02)
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- CATALYSIS OF HYDROSILYLATION. VII. CATALYSIS OF HYDROSILYLATION OF C=C BONDS BY RUTHENIUM PHOSPHINE COMPLEXES
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A full account of the catalysis of hydrosilylation of the C=C bond in olefins, their derivatives with functional groups as well as in vinyl-trisubstituted silanes by ruthenium(II) and ruthenium(III) phosphine precursors is given.The ruthenium complexes are far more efficient catalysts for the hydrosilylation of 1-alkenes and vinyl-substituted silanes than for the substituted olefins and unsaturated esters.General features characterizing all hydrosilylation reactions catalyzed by the above catalysts are as follows: the reaction proceeds with alkoxy-substituted silanes(also with vinylsilanes) in the absence of solvent, and is enhanced (for RuII and olefins occurs exclusively) in the presence of molecular oxygen.Two general mechanisms are proposed for hydrosilylation of olefins and of vinylsilanes, respectively, which account for most of the experimental observations.
- Marciniec, Bogdan,Gulinski, Jacek
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p. 349 - 362
(2007/10/02)
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