- Impact of reaction products on the Grignard reaction with silanes and ketones
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Grignard reactions with alkoxysilanes or carbonyl compounds produce alkoxymagnesium halides as by-products. Kinetic measurements for reactions of silanes and of a ketone were performed with Grignard reagents, enriched in alkoxymagnesium halides and taken in a great excess. The alkoxide-type reaction products complex tightly with Grignard reagents and enhance in this way their nucleophilicity, thus accelerating the reaction. However, alkoxides branched at α-C atom exert an unfavorable steric hindrance to reaction resulting in a decrease in the reaction rate.
- Panov, Dmitri,Tuulmets, Ants,Nguyen, Binh T.
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- Steric parameters for substituents bound to atoms of silicon and some other elements of the third period
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The kinetics of a tetraethoxysilane reaction with n-butylmagnesium chloride, stoichiometrically monosolvated with isopropyl ether or with methyl tert-butyl ether, was studied in toluene. The pseudo-first-order rate constants determined at a great excess of Grignard reagent were used for separation of the appropriate equilibrium and rate constants. Equilibrium constants for five alkyl ether ligands at the magnesium center are in an excellent correlation with isosteric ES(Si) parameters. It was concluded that these constants should be applicable to all elements of the third period of the periodic table. Taylor & Francis Group, LLC.
- Ploom, Anu,Tuulmets, Ants,Jaerv, Jaak
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- Synthetic method of linear dihydric alcohol
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The invention discloses a synthetic method of linear dihydric alcohol. The synthetic method comprises the following steps: (1) carrying out hydrosilylation reaction on alpha-olefin and siloxane to obtain alkyl siloxane; (2) carrying out hydroxymethylation reaction on alkyl siloxane, organic metal alkali and a hydrogen acceptor to obtain silyl alcohol; and (3) carrying out oxidation reaction on the silyl alcohol, fluorine-containing metal salt and peroxide to obtain the linear dihydric alcohol. The method has the advantages of mild process, easily available raw material sources, no need of post-treatment after the reaction is completed, capability of being directly used for the next reaction, simplification of the process flow, high conversion rate, high selectivity, low cost and suitability for large-scale production.
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Paragraph 0111-0113; 0131-0133
(2021/09/01)
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- High Production of Hydrogen on Demand from Silanes Catalyzed by Iridium Complexes as a Versatile Hydrogen Storage System
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The catalytic dehydrogenative coupling of silanes and alcohols represents a convenient process to produce hydrogen on demand. The catalyst, an iridium complex of the formula [IrCp?(Cl)2(NHC)] containing an N-heterocyclic carbene (NHC) ligand functionalized with a pyrene tag, catalyzes efficiently the reaction at room temperature producing H2 quantitatively within a few minutes. As a result, the dehydrogenative coupling of 1,4-disilabutane and methanol enables an effective hydrogen storage capacity of 4.3 wt % that is as high as the hydrogen contained in the dehydrogenation of formic acid, positioning the silane/alcohol pair as a potential liquid organic hydrogen carrier for energy storage. In addition, the heterogenization of the iridium complex on graphene presents a recyclable catalyst that retains its activity for at least 10 additional runs. The homogeneous distribution of catalytic active sites on the basal plane of graphene prevents diffusion problems, and the reaction kinetics are maintained after immobilization.
- Ventura-Espinosa, David,Sabater, Sara,Carretero-Cerdán, Alba,Baya, Miguel,Mata, Jose A.
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p. 2558 - 2566
(2018/03/13)
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- On the mechanism derived from kinetic solvent effects of Grignard reactions with silanes
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In this communication we present the results of initial kinetic studies in which we have established that alkoxysilanes and chlorosilanes react with Grignard reagents in entirely different ways. The Grignard reaction with alkoxysilanes consists of replacement of a donor molecule at the magnesium centre by silane, followed by a subsequent rearrangement of the complex to the products. Chlorosilanes react without solvent molecule replacement.
- Tuulmets, Ants,Sassian, Meeri
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p. 3942 - 3946
(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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