- 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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- Charge Modified Porous Organic Polymer Stabilized Ultrasmall Platinum Nanoparticles for the Catalytic Dehydrogenative Coupling of Silanes with Alcohols
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Developing an ideal stabilizer to prevent the aggregation of nanoparticles is still a big challenge for the practical application of noble metal nanocatalysts. Herein, we develop a charge (NTf2?) modified porous organic polymer (POP-NTf2) to stabilize ultrasmall platinum nanoparticles. The catalyst is characterized and applied in the catalytic dehydrogenative coupling of silanes with alcohols. The catalyst exhibits excellent catalytic performance with highly dispersed ultrasmall platinum nanoparticles (ca. 2.22?nm). Moreover, the catalyst can be reused at least five times without any performance significant loss and Pt NPs aggregation. Graphic Abstract: [Figure not available: see fulltext.]
- Chen, Chao,Cheng, Dan,Ding, Shunmin,Liang, Sanqi,Liu, Senqun,Ma, Xiaohua,Su, Tongtong,Wu, Shaohua,Zeng, Rong
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- Rhodium(III)-Catalyzed Direct C-H Arylation of Various Acyclic Enamides with Arylsilanes
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The stereoselective β-C(sp2)-H arylation of various acyclic enamides with arylsilanes via Rh(III)-catalyzed cross-coupling reaction was illustrated. The methodology was characterized by extraordinary efficacy and stereoselectivity, a wide scope of substrates, good functional group tolerance, and the adoption of environmentally friendly arylsilanes. The utility of this present method was evidenced by the gram-scale synthesis and further elaboration of the product. In addition, Rh(III)-catalyzed C-H activation is considered to be the critical step in the reaction mechanism.
- Li, Xiaolan,Sun, Kai,Shen, Wenjuan,Zhang, Yong,Lu, Ming-Zhu,Luo, Xuzhong,Luo, Haiqing
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supporting information
p. 31 - 36
(2021/01/09)
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- Silylation of Aryl Chlorides by Bimetallic Catalysis of Palladium and Gold on Alloy Nanoparticles
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Supported palladium-gold alloy-catalyzed cross-coupling of aryl chlorides and hydrosilanes enabled the selective formation of aryl-silicon bonds. Whereas a monometallic palladium catalyst predominantly promoted the hydrodechlorination of aryl chlorides and gold nanoparticles showed no catalytic activity, gold-rich palladium-gold alloy nanoparticles efficiently catalyzed the title reaction to give arylsilanes with high selectivity. A wide array of aryl chlorides and hydrosilanes participated in the heterogeneously-catalyzed reaction to furnish the corresponding arylsilanes in 34–80% yields. A detailed mechanistic investigation revealed that palladium and gold atoms on the surface of alloy nanoparticles independently functioned as active sites for the formation of aryl nucleophiles and silyl electrophiles, respectively, which indicates that palladium and gold atoms on alloy nanoparticles work together to enable the selective formation of aryl-silicon bonds. (Figure presented.).
- Miura, Hiroki,Masaki, Yosuke,Fukuta, Yohei,Shishido, Tetsuya
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p. 2642 - 2650
(2020/04/22)
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- Dimethylformamide-stabilised palladium nanoclusters catalysed coupling reactions of aryl halides with hydrosilanes/disilanes
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N,N-Dimethylformamide-stabilised Pd nanocluster (NC) catalysed cross-coupling reactions of hydrosilane/disilane have been investigated. In this reaction, the coupling reaction proceeds without ligands with low catalyst loading. N,N-Dimethylacetamide is a crucial solvent in these reactions. The solvent effect was considered by various techniques, such as transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The Pd NCs can be recycled five times under both hydrosilane and disilane reaction conditions.
- Nagata, Tatsuki,Inoue, Takeru,Lin, Xianjin,Ishimoto, Shinya,Nakamichi, Seiya,Oka, Hideo,Kondo, Ryota,Suzuki, Takeyuki,Obora, Yasushi
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p. 17425 - 17431
(2019/06/24)
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- Bench-Stable Cobalt Pre-Catalysts for Mild Hydrosilative Reduction of Tertiary Amides to Amines and Beyond
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The readily synthesized and bench-stable cobalt dichloride complex (dpephos)CoCl2 is employed as a pre-catalyst for a diversity of silane additions to unsaturated organic molecules, including the normally challenging reduction of amides to amines. With regard to hydrosilative reduction of amides even more effective and activator free catalytic systems can be generated from the bench-stable, commercially available Co(acac)2 and Co(OAc)2 with dpephos and PPh3 ligands. These systems operate under mild conditions (100 °C), with many examples of room temperature transformations, presenting a first example of mild cobalt-catalyzed hydrosilylation of amides.
- Nurseiit, Alibek,Janabel, Jaysan,Gudun, Kristina A.,Kassymbek, Aishabibi,Segizbayev, Medet,Seilkhanov, Tulegen M.,Khalimon, Andrey Y.
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p. 790 - 798
(2019/01/09)
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- Environment-friendly preparation method of diphenyldimethoxysilane
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The invention relates to a preparation method of phenyl alkoxysilane, which includes: dissolving phenyl chlorosilane in an organic solvent, adding alcohol-alkoxide solution and performing a reaction in an inert atmosphere; when the reaction is carried out to a certain degree, adding a sodium alkoxide solution, continuously carrying out the reaction; when the reaction is finished, distilling the reaction product to form the phenyl alkoxysilane.
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Paragraph 0042; 0043; 0060; 0061
(2019/01/08)
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- Pollution-free method for preparing diphenyldiethoxysilane
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The invention relates to a synthetic method of phenyl alkoxysilane, which includes: dissolving phenyl chlorosilane in an organic solvent, and adding an alcohol-alkoxide solution, performing a reactionin an inert atmosphere; when the reaction is carried out to a certain degree, adding a sodium alkoxide solution, continuously carrying out the reaction; when the reaction is finished, distilling thereaction product to form the phenyl alkoxysilane.
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Paragraph 0043; 0045; 0046-0047; 0049; 0051; 0053; 0055
(2019/01/08)
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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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- Hydrosilylation of Aldehydes and Formates Using a Dimeric Manganese Precatalyst
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The formally zero-valent Mn dimer [(Ph2PEtPDI)Mn]2 has been synthesized upon reducing (Ph2PEtPDI)MnCl2 with excess Na/Hg. Single crystal X-ray diffraction analysis has revealed that [(Ph2PEtPDI)Mn]2 possesses a η4-PDI chelate about each Mn center, as well as η2-imine coordination across the dimer. The chelate metrical parameters suggest single electron PDI reduction and EPR spectroscopic analysis afforded a signal consistent with two weakly interacting S = 1/2 Mn centers. At ambient temperature in the absence of solvent, [(Ph2PEtPDI)Mn]2 has been found to catalyze the hydrosilylation of aldehydes at loadings as low as 0.005 mol % (0.01 mol % relative to Mn) with a maximum turnover frequency of 9,900 min-1 (4,950 min-1 per Mn). Moreover, the [(Ph2PEtPDI)Mn]2-catalyzed dihydrosilylation of formates has been found to proceed with turnover frequencies of up to 330 min-1 (165 min-1 relative to Mn). These metrics are comparable to those described for the leading Mn catalyst for this transformation, the propylene-bridged variant (Ph2PPrPDI)Mn; however, [(Ph2PEtPDI)Mn]2 is more easily inhibited by donor functionalities. Carbonyl and carboxylate hydrosilylation is believed to proceed through a modified Ojima mechanism following dimer dissociation.
- Mukhopadhyay, Tufan K.,Ghosh, Chandrani,Flores, Marco,Groy, Thomas L.,Trovitch, Ryan J.
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supporting information
p. 3477 - 3483
(2017/10/03)
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- Dehydrogenative Coupling of Hydrosilanes and Alcohols by Alkali Metal Catalysts for Facile Synthesis of Silyl Ethers
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Cross-dehydrogenative coupling (CDC) of hydrosilanes with hydroxyl groups, using alkali metal hexamethyldisilazide as a single-component catalyst for the formation of Si-O bonds under mild condition, is reported. The potassium salt [KN(SiMe3)2] is highly efficient and chemoselective for a wide range of functionalized alcohols (99% conversion) under solvent-free conditions. The CDC reaction of alcohols with silanes exhibits first-order kinetics with respect to both catalyst and substrate concentrations. The most plausible mechanism for this reaction suggests that the initial step most likely involves the formation of an alkoxide followed by the formation of metal hydride as active species.
- Harinath, Adimulam,Bhattacharjee, Jayeeta,Anga, Srinivas,Panda, Tarun K.
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p. 724 - 730
(2017/05/31)
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- Nucleophilic attack of R-lithium at tetrahedral silicon in alkoxysilanes. An alternate mechanism
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The currently accepted mechanism for nucleophilic attack at silicon in tetraalkoxysilanes, e.g. Si(OEt)4 is suggested to involve formation of penta- and then hexacoordinated intermediates as supported by the apparent exclusive formation of R3SiOR′ and R4Si from nucleophilic attack by RLi and RMgX. Our recent discovery of a direct route from biogenic silica to tetraalkoxyspirosiloxanes prompted us to revisit this reaction as a potential route to diverse silicon-containing species with single SiC bonds as early studies demonstrate that spirosiloxanes form quite stable pentacoordinated alkoxysilane compounds. As anticipated, Si(2-methyl-2,4-pentanediolato)2 (SP) reacts with RLi (R = Ph, anthracene, phenylacetylene, etc.) at -78 °C to form pentacoordinated Si, e.g. LiPhSP equilibrates with the starting reagents even at 3:1 ratios of PhLi:SP with no evidence for formation of hexacoordinated species by mass spectral, NMR and quenching studies. Thus, quenching with MeI or Me3SiCl allows isolation of monosubstituted products from RLi:SP; RSi(OR′)3 including some ring-opened oligomers. Comparative studies of reactions of PhLi with Si(OEt)4 allows isolation of mono- and disubstituted products again even at 1:1 ratios of PhLi:Si(OEt)4. However, on standing at -78 °C for long periods of time or on warming to 0 °C, the primary product for both reactions is Ph4Si even with 0.5 equivalents of PhLi. At reaction temperatures ≥0 °C the primary product is again Ph4Si. These results suggest that hexacoordinated intermediates are not part of the substitution mechanism and may suggest that the higher-substituted compounds arise from disproportionation processes. We also briefly describe the conversion of anthracenylSP and 9,9-dimethylfluoreneSP to silsesquioxanes.
- Furgal, Joseph C.,Laine, Richard M.
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p. 705 - 725
(2016/07/14)
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- Synthesis of dimethylmanganese(II) complexes bearing N-heterocyclic carbenes and nucleophilic substitution reaction of tetraalkoxysilanes by diorganomanganese(II) complexes
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Reactions of manganese(II) dichlorides bearing a N-heterocyclic carbene ligand (L), [MnCl(μ-Cl)(L)]2(1a, L?=?1,3-diisopropyl-4,5-dimethylimidazole-2-ylidene (IiPr); 1b, L?=?1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene (IMes); 1c, L?=?1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene (IPr)) with MeLi afford the dinuclear dimethylmanganese(II) complexes, [MnMe(μ-Me)(L)]2(2a, L?=?IiPr; 2b, L?=?IMes; 2c, L?=?IPr). Complexes 2a-c achieve nucleophilic substitution of Si(OEt)4to selectively form MeSi(OEt)3. Related arylmanganese(II) complexes analogously react with Si(OEt)4to afford ArSi(OEt)3and Ar2Si(OEt)2(Ar?= Ph, 2,6-Me2(C6H3)). Kinetic studies support an associative mechanism for the observed transformation of Si(OEt)4, in which both the manganese species and Si(OEt)4are involved in the rate-limiting step.
- Hashimoto, Takayoshi,Kawato, Yuko,Nakajima, Yumiko,Ohki, Yasuhiro,Tatsumi, Kazuyuki,Ando, Wataru,Sato, Kazuhiko,Shimada, Shigeru
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- Alkyl silane compound (or arylsilanes compd.) manufacturing method (by machine translation)
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PROBLEM TO BE SOLVED: alkyl silane compound (or arylsilanes compd.) in order to obtain an effective compd. perfluoroalkylated (or aryl-) is found, novel alkyl silane compound (or aryl compound) and to provide a method of manufacturing. SOLUTION: the following eq. (A-1), (A-2), (A-3), or (A-4) alkylalkoxysilane compd. represented by, alkyl (or aryl demanganese compd.) demanganese compd. reacting and, by perfluoroalkylated (or aryl-), alkyl silane compound (or arylsilanes compd.) can be efficiently manufactured. ( Eq. (A-1), (A-2), (A-3), during and (A-4), R 1 to 1-20 hydrocarbon groups, R 2 silicon atoms and oxygen atoms are each independently selected from the group consisting of at least 1 may also include a kind of carbon number 1-20 hydrocarbon group. ) Selected drawing: no (by machine translation)
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Paragraph 0028
(2016/10/08)
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- Hydrosilylation of Aldehydes and Ketones Catalyzed by a Terminal Zinc Hydride Complex, [κ3-Tptm]ZnH
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Tris(2-pyridylthio)methyl zinc hydride, [κ3-Tptm]ZnH, is an effective catalyst for multiple insertions of carbonyl groups into the Si-H bonds of PhxSiH4-x (x = 1, 2). Specifically, [κ3-Tptm]ZnH catalyzes the insertion of a variety of aldehydes and ketones into the Si-H bonds of PhSiH3 and Ph2SiH2 to afford PhSi[OCH(R)R′]3 and Ph2Si[OCH(R)R′]2, respectively. The mechanism for hydrosilylation is proposed to involve insertion of the carbonyl group into the Zn-H bond to afford an alkoxy species, followed by metathesis with the silane to release the alkoxysilane and regenerate the zinc hydride catalyst. Multiple insertion of prochiral ketones results in the formation of diastereomeric mixtures of alkoxysilanes that can be identified by NMR spectroscopy.
- Sattler, Wesley,Ruccolo, Serge,Rostami Chaijan, Mahnaz,Nasr Allah, Tawfiq,Parkin, Gerard
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p. 4717 - 4731
(2015/10/28)
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- Dehydrogenative silylation of alcohols catalysed by half-sandwich iron N-heterocyclic carbene complexes
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A new series of tetramethylcyclopentadienyl-functionalised N-heterocyclic carbene complexes of iron bearing different wingtips of general type (Cp?-NHCR)Fe(CO)I (R = nBu, iBu, Et, CH2CH2OMe, CH2Ph) were prepared by direct reaction of Fe3(CO)12 and the corresponding imidazolium proligands. These new iron-NHC complexes have been found to be efficient catalysts for the dehydrogenative silylation of alcohols with silanes. Iron metal complexes bearing iso-butyl and n-butyl wingtips displayed slightly better catalytic performances than the related complexes (Cp?-NHCR)Fe(CO)I (R = Et, CH2CH2OMe, CH2Ph), affording quantitative yields of the corresponding silylethers in 8 h at 70 °C in acetonitrile.
- Cardoso, Jo?o M.S.,Lopes, Rita,Royo, Beatriz
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p. 173 - 177
(2015/02/19)
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- COSMETIC TREATMENT METHOD COMPRISING THE APPLICATION OF A COATING BASED ON AN AEROGEL COMPOSITION OF LOW BULK DENSITY
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The present invention relates to a cosmetic treatment method comprising the formation of a coating on keratin fibres characterized in that it comprises: 1) the preparation of an aerogel precursor composition comprising:—at least one organic solvent chosen from acetone, C1-C4 alcohols, C1-C6 alkanes, C1-C4 ethers, which may or may not be perfluorinated, and mixtures thereof and at least one precursor compound that contains:—at least one atom chosen from silicon, titanium, aluminium and zirconium,—at least one hydroxyl or alkoxy function directly attached to the atom chosen from silicon, titanium, aluminium and zirconium by an oxygen atom, and,—optionally an organic group directly attached to the atom chosen from silicon, titanium, aluminium and zirconium by a carbon atom, 2) the removal of the solvent or solvents resulting in the formation of an aerogel composition having a bulk density less than or equal to 0.35 g/cm3, 3) the application to the keratin fibres of the aerogel composition resulting from step 2) or of the aerogel precursor composition resulting from step 1). Advantageously, the molar ratio between the precursor compounds and the solvent is at most 1/20.
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Paragraph 0067
(2014/02/15)
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- FIRST-ROW TRANSITION METAL HYDROGENATION AND HYDROSILYLATION CATALYSTS
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Transition metal compounds, and specifically transition metal compounds having a tetradentate and/or pentadentate supporting ligand are described, together with methods for the preparation thereof and the use of such compounds as hydrogenation and/or hydrosilylation catalysts.
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Paragraph 00235-00236
(2015/01/09)
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- A highly active manganese precatalyst for the hydrosilylation of ketones and esters
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The reduction of (Ph2 PPrPDI)MnCl2 allowed the preparation of the formally zerovalent complex, (Ph2 PPrPDI)Mn, which features a pentadentate bis(imino)pyridine chelate. This complex is a highly active precatalyst for the hydrosilylation of ketones, exhibiting TOFs of up to 76,800 h-1 in the absence of solvent. Loadings as low as 0.01 mol % were employed, and (Ph2 PPrPDI)Mn was found to mediate the atom-efficient utilization of Si-H bonds to form quaternary silane products. (Ph2PPrPDI)Mn was also shown to catalyze the dihydrosilylation of esters following cleavage of the substrate acyl C-O bond. Electronic structure investigation of (Ph 2PPrPDI)Mn revealed that this complex possesses an unpaired electron on the metal center, rendering it likely that catalysis takes place following electron transfer to the incoming carbonyl substituent.
- Mukhopadhyay, Tufan K.,Flores, Marco,Groy, Thomas L.,Trovitch, Ryan J.
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supporting information
p. 882 - 885
(2014/02/14)
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- Nanoporous palladium catalyzed silicon-based one-pot cross-coupling reaction of aryl iodides with organosilanes
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One-pot cross-coupling of aryl iodides with organosilanes is realized in excellent yield by utilizing dealloyed nanoporous palladium as a sustainable and heterogeneous catalyst. The reaction is completed under mild conditions and the catalyst can be reused several times without evident loss of its catalytic activity. This journal is the Partner Organisations 2014.
- Li, Zhiwen,Lin, Sha,Ji, Lisha,Zhang, Zhonghua,Zhang, Xiaomei,Ding, Yi
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p. 1734 - 1737
(2014/06/09)
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- Highly selective oxidation of organosilanes with a reusable nanoporous silver catalyst
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Room temperature highly selective oxidation of organosilanes to organosilanols and organosilyl ethers is achieved in liquid-phase with dealloyed nanoporous silver catalysts. In both cases, aromatic and aliphatic silanes can be effectively converted into the corresponding silanols and silyl ethers by using water and alcohols as oxidant, respectively. Moreover, hydrogen gas is the only by-product and the catalyst can be recycled for several times without evident loss of activity and selectivity.
- Li, Zhiwen,Zhang, Congcong,Tian, Jing,Zhang, Zhonghua,Zhang, Xiaomei,Ding, Yi
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- Copper nanoparticles supported on doped graphenes as catalyst for the dehydrogenative coupling of silanes and alcohols
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Copper nanoparticles (NPs) supported on a series of undoped and doped graphene materials (Gs) have been obtained by pyrolysis of alginate or chitosan biopolymers, modified or not with boric acid, containing Cu2+ ions at 900 °C under inert atmosphere. The resulting Cu-G materials containing about 17 wt% Cu NPs (from 10 to 200 nm) exhibit high catalytic activity for the dehydrogenative coupling of silanes with alcohols. The optimal material consisting on Cu-(B)G is more efficient than Cu NPs on other carbon supports.
- Blez, Juan F.,Primo, Ana,Asiri, Abdullah M.,lvaro, Mercedes,Garc, Hermenegildo
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supporting information
p. 12581 - 12586
(2015/04/16)
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- One-pot synthesis and structural characterization of poly(alkoxysilane)s catalyzed by silver-gold complexes
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Combinative one-pot Si-Si/Si-O dehydrocoupling of hydrosilanes with alcohols (1:1.5 mole ratio), mediated by a mixture of AgNO3-AuCl 3 (100/1 mole ratio) rapidly produced poly(alkoxysilane)s in reasonably high yield. The addition of small amount of gold complex to the reaction mixture effectively accelerated the coupling reaction compared to the reaction rate with AgNO3 alone. The hydrosilanes include p-X-C 6H4SiH3 (X = H, CH3, OCH 3, F), PhCH2SiH3, and (PhSiH2) 2. The alcohols include MeOH, EtOH, iPrOH, PhOH, and CF 3(CF2)2CH2OH. The weight average molecular weight and polydispersity of the poly(alkoxysilane)s were in the range of 1,600~8,000 Dalton and 1.4~3.5, respectively. The dehydrocoupling reactions of phenylsilane with ethanol (1:3 mole ratio) in the presence of the Ag-Au complexes gave only triethoxyphenylsilane. Copyright
- Cheong, Hyeonsook,Roh, Sung-Hee,Cho, Myong-Shik,Kim, Myoung-Hee,Woo, Hee-Gweon,Yang, Kap-Seung,Kim, Bo-Hye,Jun, Jin,Sohn, Honglae
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p. 702 - 705
(2013/06/26)
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- N-heterocyclic carbene organocatalysts for dehydrogenative coupling of silanes and hydroxyl compounds
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Go organic! N-Heterocyclic carbene (NHC) 1,3-diisopropyl-4,5- dimethylimidazol-2-ylidene (IiPr) has been found to be an efficient and selective catalyst for the dehydrogenative coupling of a wide range of silanes and hydroxyl groups to form Si-O bonds under mild and solvent-free conditions (see scheme). Mechanistic studies indicated that the activation of hydroxyl groups by the NHC is the most plausible initial step for the process. Copyright
- Gao, Dongjing,Cui, Chunming
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supporting information
p. 11143 - 11147
(2013/09/02)
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- METHOD OF PRODUCING A HYDROLYZABLE SILICON-CONTAINING COMPOUND
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The present invention provides a safe, inexpensive, and high yield means of producing a hydrolyzable silicon-containing compound, e.g., an organooxysilane and the like. A compound (A) represented by the general formula R1-O-R2 wherein R1 represents a C4-30, substituted or unsubstituted, tertiary alkyl group or aralkyl group and R2 represents a C1-30, substituted or unsubstituted, monovalent hydrocarbyl group or acyl group, is reacted in the presence of a Lewis acid catalyst with a halosilane (B) represented by the general formula R3mSiX4-m wherein R3 represents the hydrogen atom or a C1-30 substituted or unsubstituted monovalent hydrocarbyl group, X is independently bromine or chlorine, and m represents an integer from 0 to 3.
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Page/Page column 17; 20
(2012/07/14)
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- Preparation of monodispersed spherical titania-octadecylamine particles containing silane-coupling reagents
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Well-defined spherical titania-octadecylamine (titania-ODA) (titania: titanium dioxide) hybrid particles containing silane-coupling reagents including aminopropyl, sulfanylpropyl, octadecyl, and phenyl groups (molar Ti:silane-coupling reagent ratio of 50:1) were prepared by sol-gel reaction of titanium tetraisopropoxide with the aid of a flow reactor. Average particle sizes were 520, 380, 540, and 510 nm for aminopropyl, sulfanylpropyl, octadecyl, and phenyl group containing particles, respectively. ODA was removed by washing the as-synthesized products with acidic EtOH, resulting in the formation of organosilyl group containing nanoporous titania. The porosity was investigated by the nitrogen adsorption/desorption isotherms (BET surface area of 250 to 400 m2g-1) and the surface hydrophilicity/hydrophobicity is discussed based on the water and benzene vapor adsorption/desorption isotherms. Crystallization of anatase within the spherical particles is possible by postsynthetic hot water or hydrothermal treatment.
- Shiba, Kota,Sato, Soh,Ogawa, Makoto
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p. 1040 - 1047,8
(2020/08/24)
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- Practical conversion of chlorosilanes into alkoxysilanes without generating HCl
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Alcohol-free: A versatile, efficient, and practical synthesis of alkoxysilanes without generation of HCl involves the reaction of chlorosilanes with unsymmetrical ethers in the presence of a Lewis acid (see scheme). The reaction proceeds through selective cleavage of C-O bonds and is superior to conventional processes. Industrially feasible reagents are used and only one by-product results. Copyright
- Wakabayashi, Ryutaro,Sugiura, Yasushi,Shibue, Toshimichi,Kuroda, Kazuyuki
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supporting information; experimental part
p. 10708 - 10711
(2011/12/05)
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- Rhodium(I)-catalyzed synthesis of aryltriethoxysilanes from arenediazonium tosylate salts with triethoxysilane
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An efficient method for the preparation of aryltriethoxy-silanes from arenediazonium tosylate salts has been developed, which expands the substrates of rhodium-catalyzed silylation from iodides, bromides, and triflates to diazonium salts. A new method for hydrodediazoniation has also been explored.
- Tang, Zhi Yong,Zhang, Yuan,Wang, Tao,Wang, Wei
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supporting information; experimental part
p. 804 - 808
(2010/06/14)
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- Indium-catalyzed radical reductions of organic halides with hydrosilanes
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(Equation Presented) The In(OAc)3-catalyzed reaction of bromo- and iodoalkanes with PhSiH3 in THF at 70°C gave dehalogenated alkanes in good to high yields. In the presence of Et3B and air, the reduction proceeded smoothly at 30°C. When 2,6-lutidine and air were used as additives, the In(OAc)3-catalyzed system enabled an efficient reduction of simple and functionalized iodoalkanes in EtOH. Catalytic use of GaCl3 was found to be effective in the reduction of haloalkanes with poly(methylhydrosiloxane) (PMHS). These catalytic reductions probably involve a radical chain mechanism in which indium or gallium hydride species work as the actual reductants.
- Miura, Katsukiyo,Tomita, Mitsuru,Yamada, Yusuke,Hosomi, Akira
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p. 787 - 792
(2007/10/03)
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- Synthesis of aryltriethoxysilanes via rhodium(I)-catalyzed cross-coupling of aryl electrophiles with triethoxysilane
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The general and efficient silylation of aryl halides has been developed utilizing triethoxysilane and a rhodium catalyst. The substrate scope is broad and includes ortho-, meta-, and para-substituted electron-rich and -deficient aryl iodides. In addition, the silylation of aryl bromides and fluoroalkanesulfonates proceeded in the presence of tetra-n-butylammonium iodide.
- Murata, Miki,Yamasaki, Hiyoruki,Ueta, Tsukasa,Nagata, Masayuki,Ishikura, Masanori,Watanabe, Shinji,Masuda, Yuzuru
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p. 4087 - 4094
(2008/01/03)
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- Continuous process for preparing SiOC containing compounds
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Continuous preparation of organosilicon compounds (A) containing (SiOC) groups, comprises: partially reacting chlorosilanes (I) with alcohol and optionally with water to produce a partial reaction mixture (II); reacting (II) with alcohol and water (optional) to provide a crude product mixture (III) containing volatile constituents (IV); additionally adding alcohol to (III) to remove (IV); and removing (A). Continuous preparation of organosilicon compounds (A) containing (SiOC) groups, comprises: partially reacting one or more chlorosilanes (I) with alcohol and optionally with water in a prereactor (Ia) to produce a partial reaction mixture (II); introducing (II) into a first reaction column unit (Ib) and reacting with alcohol and optionally with water to provide a crude product mixture (III) containing volatile constituents (IV); transferring (III) to a second reaction column unit (Ic), into which the alcohol is additionally introduced to remove (IV), and optionally feeding the unreactive organic solvent into (Ic); and removing (A) from the lower end of (Ic).
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Page/Page column 8
(2008/06/13)
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- A facile and efficient synthesis of aryltriethoxysilanes via sonochemical Barbier-type reaction
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A series of aryltriethoxysilanes was synthesized from the reaction mixture of aryl bromide, Mg powder, 1,2-dibromoethane and tetraethyl orthosilicate in THF under ultrasound. This sonochemical Barbier-type reaction provides a simple and efficient method for preparation of aryltriethoxysilanes. The Hiyama cross-coupling reaction of phenyltriethoxysilane with bromobenzene was investigated under different palladium catalysts and Pd(PhCN)2Cl2 was found to be the best choice.
- Lee, Adam Shih-Yuan,Chang, Yu-Ting,Chu, Shu-Fang,Tsao, Kuo-Wei
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p. 7085 - 7087
(2007/10/03)
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- Convenient synthesis of alkoxyhalosilanes from hydrosilanes
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Selective dehydrogenative coupling of di- and trihydrosilanes with alcohols catalyzed by PdCl2 or NiCl2 afforded alkoxyhydro- and dialkoxyhydrosilanes in good yield. Further treatment of the resulting alkoxyhydrosilanes with carbon tetrachloride or allyl bromide in the presence of the same catalyst led to the formation of alkoxychloro- and alkoxybromosilanes, respectively. Similar reactions of dialkoxyhydrosilanes with carbon tetrachloride afforded dialkoxychlorosilanes in good yield, although contamination of small amounts of trialkoxysilanes and alkoxydichlorosilanes was detected in the products. Selective substitution of the alkoxyhalosilanes with nucleophiles is also reported.
- Ohshita, Joji,Taketsugu, Ryosuke,Nakahara, Yuki,Kunai, Atsutaka
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p. 3258 - 3264
(2007/10/03)
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- Improved synthesis of aryltrialkoxysilanes via treatment of aryl Grignard or lithium reagents with tetraalkyl orthosilicates
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General reaction conditions for the synthesis of aryl(trialkoxy)silanes from aryl Grignard and lithium reagents and tetraalkyl orthosilicates (Si(OR)4) have been developed. Ortho-, meta-, and para-substituted bromoarenes underwent efficient metalation and silylation at low temperature to provide aryl siloxanes. Mixed results were obtained with heteroaromatic substrates: 3-bromothiophene, 3-bromo-4-methoxypyridine, 5-bromoindole, and N-methyl-5-bromoindole underwent silylation in good yield, whereas a low yield of siloxane was obtained from 2-bromofuran, and 2-bromopyridine failed to give silylated product. The synthesis of siloxanes via organolithium and magnesium reagents was limited by the formation of di- and triarylated silanes (Ar 2Si(OR)2 and Ar3SiOR, respectively) and dehalogenated (Ar-H) byproducts. Silylation at low temperature gave predominantly monoaryl siloxanes, without requiring a large excess of the electrophile. Optimal reaction conditions for the synthesis of siloxanes from aryl Grignard reagents entailed addition of arylmagnesium reagents to 3 equiv of tetraethyl- or tetramethyl orthosilicate at -30 °C in THF. Aryllithium species were silylated using 1.5 equiv of tetraethyl- or tetramethyl orthosilicate at -78 °C in ether.
- Manoso, Amy S.,Ahn, Chuljin,Soheili, Arash,Handy, Christopher J.,Correia, Reuben,Seganish, W. Michael,DeShong, Philip
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p. 8305 - 8314
(2007/10/03)
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- One-pot synthesis of poly(alkoxysilane)s by Si-Si/Si-O dehydrocoupling of silanes with alcohols using Group IV and VIII metallocene complexes
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Si-Si/Si-O dehydrocoupling reactions of silanes with alcohols (1:1.5 mole ratio), catalyzed by Cp2MCl2/Red-Al (M=Ti, Zr) and Cp2M′ (M′=Co, Ni), produced poly(alkoxysilane)s in one-pot in high yield. The silanes included p-X-C6H4SiH3 (X=H, CH3, OCH3, F), PhCH2SiH3, and (PhSiH2)2. The alcohols were MeOH, EtOH, iPrOH, PhOH, and CF3(CF2) 2CH2OH. The weight average molecular weight of the poly(alkoxysilane)s ranged from 600 to 8000. The dehydrocoupling reactions of phenylsilane with ethanol (1:1.5 mole ratio) using Cp2HfCl2/Red-Al and phenylsilane with ethanol (1:3 mole ratio) using Cp2TiCl2/Red-Al gave only triethoxyphenylsilane as product.
- Kim, Bo-Hye,Cho, Myong-Shik,Kim, Mi-Ae,Woo, Gee-Gweon
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- Rhodium(I)-Catalyzed Silylation of Aryl Halides with Triethoxysilane: Practical Synthetic Route to Aryltriethoxysilanes
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(Equation Presented) The specific silylation of aryl iodides and bromides with triethoxysilane (EtO)3SiH in the presence of NEt3 and a catalytic amount of [Rh-(cod)(MeCN)2]BF4 provides the corresponding aryltriethoxysilanes in high yield.
- Murata, Miki,Ishikura, Masanori,Nagata, Masayuki,Watanabe, Shinji,Masuda, Yuzuru
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p. 1843 - 1845
(2007/10/03)
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- Improved synthesis of aryltriethoxysilanes via palladium(O)-catalyzed silylation of aryl iodides and bromides with triethoxysilane
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The scope of the palladium-catalyzed silylation of aryl halides with triethoxysilane has been expanded to include aryl bromides. A more general Pd(0) catalyst/ligand system has been developed that activates bromides and iodides: palladium(O) dibenzylideneacetone (Pd(dba)2) is activated with 2-(di-tert-butylphosphino)biphenyl (Buchwald's ligand) (1:2 mol ratio of Pd/phosphine). Electronrich para- and meta-substituted aryl halides (including unprotected aniline and phenol derivatives) undergo silylation to form the corresponding aryltriethoxysilane in fair to excellent yield; however, ortho-substituted aryl halides failed to be silylated.
- Manoso,DeShong
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p. 7449 - 7455
(2007/10/03)
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- Palladium-catalyzed cross-coupling reaction of aryltriethoxysilanes with aryl bromides under basic aqueous conditions
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Aryltriethoxysilanes were cross-coupled with aryl bromides in high yield in the presence of a palladium catalyst and aqueous sodium hydroxide.
- Murata,Shimazaki,Watanabe,Masuda
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p. 2231 - 2233
(2007/10/03)
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- Hydrolytic Etherification of Phenyltrichlorosilane and Structure of Reaction Products
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Hydrolytic etherification of phenyltrichlorosilane by C1-C4 primary alcohols was studied. The effect of the concentration and nature of alcohol on the structure and properties of oligomeric polyphenyl-alkoxysilanes were examined.
- Kuz'menko, N. Ya.
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p. 516 - 522
(2007/10/03)
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- Utilization of bottoms of the direct synthesis of methylchlorosilanes in production of the crude mixtures of phenylethoxysilanes by continuous organomagnesium Procedure
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Utilization of the bottoms after distillation of methylchlorosilanes in continuous organomagnesium synthesis of organosilicon raw materials for production of polyphenylsiloxane resins and lacquers and enamels based on them was analyzed.
- Klokov
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p. 476 - 478
(2007/10/03)
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- Reaction of Tetraalkoxysilanes with Alkyl(aryl)chlorosilanes
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Alkyl(aryl)trichloro- or dialkyl(diaryl)dichlorosilanes react with tetraalkoxysilanes Si(OMe)4, Si(OEt)4, and Si(OBu)4 to give partially etherfied alkyl(aryl)chlorosilanes RSiCl2(OAlk), RSiCl(OAlk)2, and R2SiCl(OAlk).
- Chernyshev, E. A.,Komalenkova, N. G.,Tagachenkov, A. A.,Bykovchenko, V. G.
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p. 241 - 243
(2007/10/03)
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- ESTERIFICATION OF CHLOROSILANES IN CYCLOHEXENE SOLUTION.
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The authors have developed a method for production of organoalkoxysilanes by interaction of organochlorosilanes with alcohols in cyclohexene solutions in presence of catalytic amounts of tin tetrachloride. As the result of the synthesis, formation of alkoxysilanes (yield 59-91%) is accompanied by formation of cyclohexyl chloride in 73-90% yield. This compound is an intermediate for production of tricyclohexylhydroxystannane, the principal component of Plictrin. The annual demand for cyclohexyl chloride for this purpose is 250-300 tons. At the same time, cyclohexene obtained as a waste product during manufacture of Kapron is destroyed by burning. Its use as a hydrogen chloride acceptor in esterification of chlorosilanes makes it possible to obtain, virtually without additional cost, a second valuable product, cyclohexyl chloride, in a yield of 1-2 parts by weight per 1 part of organoalkoxysilane.
- Pomerantseva,Belyakova,Shryaev,Efimova,Sheludyakov
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p. 1314 - 1315
(2007/10/02)
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- CARBON-SILICON BOND CLEAVAGE OF ORGANOTRIALKOXYSILANES AND ORGANOSILATRANES WITH m-CHLOROPERBENZOIC ACID AND N-BROMOSUCCINIMIDE. NEW ROUTE TO PHENOLS, PRIMARY ALCOHOLS AND BROMIDES
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Alkyl- and aryltriethoxysilanes undergo oxidative carbon-silicon bond cleavage smoothly with m-chloroperbenzoic acid (MCPBA) to afford the corresponding alcohols.Silatranes similarly gave alcohols and bromides with MCPBA and N-bromosuccinimide, respectively.
- Hosomi, Akira,Iijima, Susumu,Sakurai, Hideki
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p. 243 - 246
(2007/10/02)
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- Preparation of organically modified silicon dioxides
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Process for the preparation of modified, porous silicon dioxides by the hydrolytic polycondensation of tetraalkoxysilanes or polyalkoxysiloxanes in the heterogenous phase in the presence of an organoalkoxysilane.
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