- Interaction of organodialkoxysilanolates with carbon dioxide
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A series of organo(alkoxy)disiloxanes was obtained by the reaction of carbon dioxide with sodium alkoxy(organo)silanolates under high pressure as well as by bubbling CO2 through the reaction mixture. It has been suggested that the reaction involves the intermediate formation of carbonate derivatives of sodium alkoxy(organo)silanolates.
- Temnikov,Cherkun,Boldyrev,Zimovets,Kononova,Elmanovich,Gallyamov,Muzafarov
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p. 105161 - 105165
(2016)
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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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- 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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- Diffusion pump oil synthesis method
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The invention relates to the chemical industry field, particularly to a diffusion pump oil synthesis method, which specifically comprises: (1) carrying out a hydrolysis reaction on methyl triethoxysilane to obtain 1,3-dimethyl-1,1,3,3-tetraethoxydisiloxane (short for compound B); (2) under a strong alkali condition, carrying out balanced telomerization on the compound B and a dimethyl ring body or methylphenyl ring body to obtain a compound D; (3) carrying out a sodium condensation reaction on the compound D, chlorobenzene and sodium to obtain the diffusion pump oil. According to the present invention, the reaction order is re-combined, and the method has advantages of low energy consumption and environmentally friendly process compared to the method in the prior art.
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Paragraph 0066; 0067; 0068; 0087; 0088; 0089
(2017/03/08)
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- Br?nsted acid-promoted formation of stabilized silylium ions for catalytic friedel-crafts C-H silylation
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A counterintuitive approach to electrophilic aromatic substitution with silicon electrophiles is disclosed. A strong Br?nsted acid that would usually promote the reverse reaction, i.e., protodesilylation, was found to initiate the C-H silylation of electron-rich (hetero)arenes with hydrosilanes. Protonation of the hydrosilane followed by liberation of dihydrogen is key to success, fulfilling two purposes: to generate the stabilized silylium ion and to remove the proton released from the Wheland intermediate.
- Chen, Qing-An,Klare, Hendrik F. T.,Oestreich, Martin
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supporting information
p. 7868 - 7871
(2016/07/07)
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- Treatment of alkyltriethoxysilanes with Amberlyst 15 cation-exchange resin in the presence of hexamethyldisiloxane
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Methyltriethoxysilane and ethyltriethoxysilane were treated with Amberlyst 15 cation-exchange resin in the presence of hexamethyldisiloxane at 40 deg C.The reaction involves partial or full replacement of the ethoxyl group by trimethylsiloxyl to give RSi(OEt)n(OSiMe3)3-n (n=0, 1, 2).The degree of substitution depends mainly on the ratio in which hexamethyldisiloxane and alkyltriethoxysilane are mixed.The nature of alkyl group in an alkyltriethoxysilane had little effect on the degree of substitution at a given mixing ratio.
- Hasegawa, Isao,Sakka, Sumio
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