- Acyl iodides in organic synthesis: IX. Cleavage of the Si-O-C and Si-O-Si moieties
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Reactions of acyl iodides RCOI (R = Me, Ph) with organosilicon compounds involve cleavage of the Si-O-C and Si-O-Si fragments. Acetyl iodide reacts with alkyl(alkoxy)silanes with evolution of heat, and cleavage of the Si-O bond results in the formation of oligo-or polysiloxanes, alkyl iodides, and alkyl acetates. 1,3-Diacetoxytetramethyldisiloxane is formed in the reaction of acetyl iodide with dimethoxy(dimethyl)silane. Acyl iodides readily react with 1-ethoxysilatrane to give 1-acyloxysilatranes as a result of cleavage of the C-O bond. The reaction of acetyl iodide with hexaethyldisiloxane yields triethylsilyl acetate and triethyliodosilane, while in the reaction with octamethyltrisiloxane iodo(trimethyl)silane and dimethyl(trimethylsiloxy)silyl acetate are obtained. Nauka/Interperiodica 2007.
- Voronkov,Trukhina,Belousova,Kuznetsova,Vlasova
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p. 501 - 506
(2008/02/02)
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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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- 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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p. 1031 - 1035
(2007/10/03)
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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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