998-30-1Relevant articles and documents
How a Thermally Unstable Metal Hydrido Complex Can Yield High Catalytic Activity Even at Elevated Temperatures
Ehm, Christian,Krüger, Juliane,Lentz, Dieter
, p. 9305 - 9310 (2016)
Despite their instability in ethereal solvents, organotitanium hydride catalysts are successfully employed in catalysis at moderate to high temperatures (110 °C), even in the presence of alcohols. It is shown computationally (bond dissociation energy (BDE) analysis and energetic profile for regeneration) and experimentally (EPR studies and kinetic studies), with the specific example of hydrodefluorination (HDF), that despite the long standing belief, regeneration of Ti?H bonds from Ti?F bonds using silanes is endergonic. The resulting low concentration of Ti?H species is crucial for the catalytic stability of those systems. The resting state in the catalysis is a Ti?F species. The most promising silanes for regeneration are not the ones that have the strongest Si?F bond, but the ones that show the largest difference in Si?F and Si?H BDEs.
Sustainable Catalytic Synthesis of Diethyl Carbonate
Putro, Wahyu S.,Ikeda, Akira,Shigeyasu, Shinji,Hamura, Satoshi,Matsumoto, Seiji,Lee, Vladimir Ya.,Choi, Jun-Chul,Fukaya, Norihisa
, p. 842 - 846 (2020/12/07)
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.
Mechanochemical method of producing triethoxysilane
Temnikov,Anisimov,Chistovalov,Zhemchugov,Kholodkov,Zimovets,Vysochinskaya, Yu. S.,Muzafarova
, p. 270 - 274 (2019/04/27)
A mechanochemical method for synthesis of triethoxysilane from silicon-copper contact mass and ethyl alcohol in the developed vibration reactor is presented. It is shown that the process of a direct alkoxysilane synthesis in the vibro-boiling layer is affected by a series of control parameters such as the ratio between the contact mass and the mass of grinding bodies, the grinding body sizes and their ratios in a polydisperse mixture, power density. Optimization of these parameters allowed us to obtain HSi(OEt)3 with a selectivity of 50% at a silicon conversion of 90% without the use of promoters.
Calyciphylline B-Type Alkaloids: Total Syntheses of (-)-Daphlongamine H and (-)-Isodaphlongamine H
Hugelshofer, Cedric L.,Palani, Vignesh,Sarpong, Richmond
supporting information, p. 8431 - 8435 (2019/06/13)
The first total synthesis of the complex hexacylic Daphniphyllum alkaloid (-)-daphlongamine H has been accomplished. Key to the success of the strategy are a complexity-building Mannich reaction, efficient cyclizations, and a highly diastereoselective hydrogenation to assemble multigram quantities of the tricyclic core bearing four contiguous stereocenters. Following construction of the hydro-indene substructure by means of a Pauson-Khand reaction, endgame redox manipulations delivered the natural product. Importantly, the synthetic studies have also given access to (-)-isodaphlongamine H and led to a revision of the reported structure of deoxyisocalyciphylline B.
Mechanochemistry-a new powerful green approach to the direct synthesis of alkoxysilanes
Temnikov, Maxim N.,Anisimov, Anton A.,Zhemchugov, Pavel V.,Kholodkov, Dmitry N.,Goloveshkin, Alexander S.,Naumkin, Alexander V.,Chistovalov, Sergey M.,Katsoulis, Dimitris,Muzafarov, Aziz M.
supporting information, p. 1962 - 1969 (2018/05/23)
The present work shows a new one-stage mechanochemical method for the direct synthesis of alkoxysilanes by silicon mechanoactivation followed by a reaction with an alcohol. Alkoxysilanes were obtained with nearly complete silicon and alcohol conversion. This method allows for a considerable simplification of the traditional multistage process by eliminating three stages that include silicon and catalyst preparation, and adapts it to green chemistry requirements. Vibration milling removed the oxide film, and the mechanoactivation of the large silicon fraction (1000-2000 μm) occurs in the reactor working space. Abrasion of the reactor walls and grinding bodies made of brass results in a developed catalytic surface on silicon, as it has been proven by a set of physical analytical methods such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (PXRD), and X-ray photoelectron spectroscopy (XPS).
METHOD FOR PRODUCING HYDROSILANE
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Paragraph 0026, (2019/01/06)
PROBLEM TO BE SOLVED: To provide a method for producing hydrosilane capable of efficiently producing hydrosilane under mild conditions. SOLUTION: Provided is a method for producing hydrosilane where hydrosilane can be efficiently produced by reacting alkoxysilane having a structure represented by formula (a) with hydroborane and/or hydrogen under the presence of a complex with at least one kind of atom selected from the group consisting of a yttrium atom (Y), a zirconium atom (zr) and a hafnium atom (Hf) as a central metal(s)(in the formula (a), R denotes a 1 to 20C hydrocarbon group). SELECTED DRAWING: None COPYRIGHT: (C)2018,JPO&INPIT
New vinyl alkoxy silane preparation process
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Paragraph 0041; 0042, (2016/10/08)
The present invention discloses a new vinyl alkoxy silane preparation process, which is characterized in that hydrogen chloride produced during a preparation process is adopted as a reactant to synthesize an initial raw material trichlorosilane, the hydrogen chloride is recycled, and the byproduct bis(trialkoxy)silyl ethane is adopted as a reaction solvent during a hydrogen silicon addition process, such that the byproduct emission is reduced, the new impurity introduction is avoided, and the product purity is improved. According to the present invention, the new process has characteristics of stable production, simple preparation process, and mild reaction conditions, and the yield of the product vinyl alkoxy silane is high, and the product purity is more than 99%.
Amorphous silicon: New insights into an old material
Spomer, Natalie,Holl, Sven,Zherlitsyna, Larissa,Maysamy, Fariba,Frost, Andreas,Auner, Norbert
, p. 5600 - 5616 (2015/03/30)
Amorphous silicon is synthesized by treating the tetrahalosilanes SiX4 (X=Cl, F) with molten sodium in high boiling polar and non-polar solvents such as diglyme or nonane to give a brown or a black solid showing different reactivities towards suitable reagents. With regards to their technical relevance, their stability towards oxygen, air, moisture, chlorine-containing reaction partners RCl (R=H, Cl, Me) and alcohols is investigated. In particular, reactions with methanol are a versatile tool to deliver important products. Besides tetramethoxysilane formation, methanolysis of silicon releases hydrogen gas under ambient conditions and is thus suitable for a decentralized hydrogen production; competitive insertion into the MeO-H versus the Me-OH bond either yields H- and/or methyl-substituted methoxy functional silanes. Moreover, compounds, such as MenSi(OMe)4-n (n=0-3) are simply accessible in more than 75% yield from thermolysis of, for example, tetramethoxysilane over molten sodium. Based on our systematic investigations we identified reaction conditions to produce the methoxysilanes MenSi(OMe)4-n in excellent (n=0:100%) to acceptable yields (n=1:51%; n=2:27%); the yield of HSi(OMe)3 is about 85%. Thus, the methoxysilanes formed might possibly open the door for future routes to silicon-based products. Amorphous silicon is easily synthesized from tetrahalosilanes SiX4 (X=Cl, F) and molten sodium in different solvents. Reactivity studies prove the resulting materials as versatile tools for the formation of technical important silanes, such as the silicon chloro-, alkoxy-, and methylalkoxy-substituted derivatives (see figure; bl=black, br=brown).
METHOD FOR HYDROGENATING SILANE COMPOUND
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Paragraph 0086 - 0095, (2016/12/12)
In the present invention, provided is a method for hydrogenating silane compounds, comprising the steps of supplying hydrogen to a low-temperature plasma reaction apparatus and accordingly generating low-temperature plasmas including hydrogen ions, electrons and hydrogen atom radicals; supplying raw materials including the silane compound to the low-temperature plasma reaction apparatus; and making the silane compound, the hydrogen ion, the electrons and the hydrogen atom radical have the hydrogenating reaction.
METHOD FOR PREPARING TRIALKOXYSILANE
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Paragraph 0062, (2014/07/23)
The present invention relates to a method for preparing SiH(OR3)-type trialkoxysilane (wherein, R is a C1-C3 methyl, ethyl, propyl or isopropyl group), and more specifically, the method comprises the steps of: preventing the oxidation of a silicon surface by pulverizing raw silicon material in a solvent environment without contact with the air so that the initial induction period of the direct synthesis of trialkoxysilane is dramatically reduced; and removing impurities from a reaction environment by continuously selecting a part of the solvent through a membrane filter provided in a reactor body.
