- Synthesis of nitrogen and sulfur co-doped hierarchical porous carbons and metal-free oxidative coupling of silanes with alcohols
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Hierarchically porous N and S co-doped carbon was prepared by using 2,5-dihydroxy-1,4-benzoquinone as the carbon source, thiourea as the N and S source, and SiO2 particles as the template. Using the material as the catalyst, oxidative coupling of silanes with alcohols was conducted for the first time under metal-free conditions.
- Chen, Bingfeng,Li, Fengbo,Mei, Qingqing,Yang, Youdi,Liu, Huizhen,Yuan, Guoqing,Han, Buxing
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- Mechanistic Studies on the Hexadecafluorophthalocyanine–Iron-Catalyzed Wacker-Type Oxidation of Olefins to Ketones**
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The hexadecafluorophthalocyanine–iron complex FePcF16 was recently shown to convert olefins into ketones in the presence of stoichiometric amounts of triethylsilane in ethanol at room temperature under an oxygen atmosphere. Herein, we describe an extensive mechanistic investigation for the conversion of 2-vinylnaphthalene into 2-acetylnaphthalene as model reaction. A variety of studies including deuterium- and 18O2-labeling experiments, ESI-MS, and 57Fe M?ssbauer spectroscopy were performed to identify the intermediates involved in the catalytic cycle of the oxidation process. Finally, a detailed and well-supported reaction mechanism for the FePcF16-catalyzed Wacker-type oxidation is proposed.
- Grinenko, Vadim,Klau?, Hans-Henning,Kn?lker, Hans-Joachim,Puls, Florian,Seewald, Felix
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supporting information
p. 16776 - 16787
(2021/11/04)
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- Metal-free hydrogen evolution cross-coupling enabled by synergistic photoredox and polarity reversal catalysis
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A synergistic combination of photoredox and polarity reversal catalysis enabled a hydrogen evolution cross-coupling of silanes with H2O, alcohols, phenols, and silanols, which afforded the corresponding silanols, monosilyl ethers, and disilyl ethers, respectively, in moderate to excellent yields. The dehydrogenative cross-coupling of Si-H and O-H proceeded smoothly with broad substrate scope and good functional group compatibility in the presence of only an organophotocatalyst 4-CzIPN and a thiol HAT catalyst, without the requirement of any metals, external oxidants and proton reductants, which is distinct from the previously reported photocatalytic hydrogen evolution cross-coupling reactions where a proton reduction cocatalyst such as a cobalt complex is generally required. Mechanistically, a silyl cation intermediate is generated to facilitate the cross-coupling reaction, which therefore represents an unprecedented approach for the generation of silyl cationviavisible-light photoredox catalysis.
- Cao, Jilei,Lu, Kanghui,Ma, Lishuang,Yang, Xiaona,Zhou, Rong
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supporting information
p. 8988 - 8994
(2021/11/23)
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- Highly Selective Hydroxylation and Alkoxylation of Silanes: One-Pot Silane Oxidation and Reduction of Aldehydes/Ketones
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An efficient chemoselective iridium-catalyzed method for the hydroxylation and alkoxylation of organosilanes to generate hydrogen gas and silanols or silyl ethers was developed. A variety of sterically hindered silanes with alkyl, aryl, and ether groups were tolerated. Furthermore, this atom-economical catalytic protocol can be used for the synthesis of silanediols and silanetriols. A one-pot silane oxidation and chemoselective reduction of aldehydes/ketones was also realized.
- Luo, Nianhua,Liao, Jianhua,Ouyang, Lu,Wen, Huiling,Zhong, Yuhong,Liu, Jitian,Tang, Weiping,Luo, Renshi
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p. 165 - 171
(2020/01/21)
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- N-Heterocyclic Olefin Catalyzed Silylation and Hydrosilylation Reactions of Hydroxyl and Carbonyl Compounds
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N-Heterocyclic olefins (NHOs), the alkylidene derivatives of N-heterocyclic carbenes (NHCs), have recently emerged as a new family of promising organocatalysts with strong nucleophilicity and Br?nsted basicity. The development of a novel method is shown using NHOs as efficient promoters for the direct dehydrogenative silylation of alcohols or hydrosilylation of carbonyl compounds. Preliminary results of the first NHO-promoted asymmetric synthesis are also discussed.
- Kaya, U?ur,Tran, Uyen P.N.,Enders, Dieter,Ho, Junming,Nguyen, Thanh V.
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supporting information
p. 1398 - 1401
(2017/03/23)
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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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- Metal-Free Ammonium Iodide Catalyzed Oxidative Dehydrocoupling of Silanes with Alcohols
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An ammonium iodide catalyzed direct oxidative coupling of silanes with alcohols to give various alkoxysilane derivatives was discovered. tert -Butyl hydroperoxide proved to be an efficient oxidant for this transformation. Attractive features of this protocol include its transition-metal-free nature and the mild reaction conditions.
- Yuan, Yan-Qin,Kumar, Pailla Santhosh,Guo, Sheng-Rong
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supporting information
p. 1620 - 1623
(2017/08/11)
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- Catalytic Dehydrogenative Coupling of Hydrosilanes with Alcohols for the Production of Hydrogen On-demand: Application of a Silane/Alcohol Pair as a Liquid Organic Hydrogen Carrier
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The compound [Ru(p-cym)(Cl)2(NHC)] is an effective catalyst for the room-temperature coupling of silanes and alcohols with the concomitant formation of molecular hydrogen. High catalyst activity is observed for a variety of substrates affording quantitative yields in minutes at room temperature and with a catalyst loading as low as 0.1 mol %. The coupling reaction is thermodynamically and, in the presence of a Ru complex, kinetically favourable and allows rapid molecular hydrogen generation on-demand at room temperature, under air, and without any additive. The pair silane/alcohol is a potential liquid organic hydrogen carrier (LOHC) for energy storage over long periods in a safe and secure way. Silanes and alcohols are non-toxic compounds and do not require special handling precautions such as high pressure or an inert atmosphere. These properties enhance the practical applications of the pair silane/alcohol as a good LOHC in the automotive industry. The variety and availability of silanes and alcohols permits a pair combination that fulfils the requirements for developing an efficient LOHC.
- Ventura-Espinosa, David,Carretero-Cerdán, Alba,Baya, Miguel,García, Hermenegildo,Mata, Jose A.
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supporting information
p. 10815 - 10821
(2017/08/18)
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- Zinc Bis(triphenylsilyl) Stabilized by N-Heterocyclic Carbene
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Triphenylsilylzinc compounds stabilized by an N-heterocyclic carbene, [Zn(SiPh3)2(IMes)] (2) and [ZnX(SiPh3)(IMes)] [X = Cl (3a), Br (3b), I (3c)] [IMes = 1,3-Bis(2,4,6-trimethylphenyl)imidazole-2-ylidene], were synthesized by transmetalation from [ZnX2(IMes)(THF)0–1] [X = Cl (1a), Br (1b), I (1c)] and [LiSiPh3(THF)3]. According to single-crystal X-ray diffraction, [Zn(SiPh3)2(IMes)] (2) shows a trigonal-planar coordinated central zinc atom, whereas [ZnCl(SiPh3)(IMes)(THF)] (3a-THF) shows a distorted tetrahedral coordination.
- Lemmerz, Lara E.,Spaniol, Thomas P.,Okuda, Jun
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p. 1269 - 1274
(2016/11/23)
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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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- An efficient method for the synthesis of symmetrical disiloxanes from alkoxysilanes using Meerwein's reagent
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We report here a new and efficient route to symmetrical disiloxanes from their corresponding alkoxysilanes using Meerwein's reagent as mediator and potassium carbonate as additive under mild reaction conditions in acetonitrile. Our methodology is very simple, economic, and high yielding. We have also proposed a reaction mechanism with the plausible silyloxonium intermediates. Georg Thieme Verlag Stuttgart · New York.
- Jorapur, Yogesh R.,Shimada, Toyoshi
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supporting information; experimental part
p. 1633 - 1638
(2012/08/07)
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- Using the nonaqueous electrolytic solution and secondary battery
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PROBLEM TO BE SOLVED: To provide nonaqueous electrolyte solution capable of improving at least either large-current charge/discharge characteristics or charge/discharge capacity, and a nonaqueous electrolyte solution secondary battery using it. SOLUTION: Electrolyte solution that is liquid electrolyte is immersed in a separator 23. The electrolyte solution contains a liquid solvent, for instance, a nonaqueous solvent such as an organic solvent, and electrolyte salt dissolved in the nonaqueous solvent. Further, as additives, it contains at least one type selected from tris (penta-fluorophenyl) borane (TPFPB) and tris-borate (2H-hexafluoro isopropyl) (THFPB), and at least one type selected from vinylene carbonate (VC) and vinyl ethylene carbonate (VEC). COPYRIGHT: (C)2008,JPO&INPIT
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- Ruthenium carbonyl-catalysed Si-heteroatom X coupling (X = S, O, N)
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Ru3(CO)12 has been shown to catalyse the coupling of silanes with thiols, alcohols and amines with turnover number (TON) and turnover frequency (TOF) of up to 200 and 50 h-1 at 80 °C. IR, NMR and mass spectroscopic studies have identified a ruthenium dimer complex, [Ru(CO)4(SiEt3)]2 as a likely resting state of the catalyst. A mechanism involving this complex has been proposed for the silicon-thiol coupling process.
- Toh, Chun Keong,Poh, Hwa Tiong,Lim, Ching Si,Fan, Wai Yip
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- Unsuccessful attempts to add alcohols to transient 2-amino-2-siloxy- silenes-leading to a new benign route for base-free alcohol protection
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Thermolytic formation of transient 1,1-bis(trimethylsilyl)-2-dimethylamino- 2-trimethylsiloxysilene (2) from N,N-dimethyl(tris(trimethylsilyl)silyl) methaneamide (1) in presence of a series of alcohols was investigated. The products are, however, not the expected alcohol-silene addition adducts but silylethers formed in nearly quantitative yields. Thermolysis of 1 in the presence of both alcohols (MeOH or iPrOH) and 1,3-dienes (1,3-butadiene or 2,3-dimethyl-1,3-butadiene) gives alkyl-tris(trimethylsilyl)silylethers and the [4+2] cycloadducts between the silene and diene, which confirms the presence of 2 and that it is unreactive towards alcohols. The observed silylethers are substitution adducts where the amide group of the silylamide is replaced by an alkoxy group, and the reaction time is reflected in the steric bulk of the alcohol. Indeed, the formation of silylethers from the reaction of alcohols with silylamide represents a new base-free method for protection of alcohols. The protection reactions using 1 progresses at elevated temperatures, or alternatively, under acid catalysis at ambient temperature, and similar protections can be carried out with N-cyclohexyl(triphenylsilyl)methaneamide and N,N-dimethyl(trimethylsilyl)methaneamide. The latter silylamide can be used under neutral conditions at room temperature. The only by-products are formamides (N,N-dimethylformamide (DMF) or N-cyclohexylformamide), and the reactions can be performed without solvent. In addition to alcohols we also examined the method for protection of diols, thiols and carboxylic acids, and also these reactions proceeded in high yields and with good selectivities. The Royal Society of Chemistry.
- Guliashvili, Tamaz,Tibbelin, Julius,Ryu, Jiyeon,Ottosson, Henrik
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supporting information; experimental part
p. 9379 - 9385
(2011/01/07)
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- Toward selective functionalisation of oligosilanes: Borane-catalysed dehydrogenative coupling of silanes with thiols
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Among established methods for transforming Si-H bonds, carbonyl hydrosilylation and heterodehydrogenative coupling with alcohols catalysed by B(C6F5)3 are shown to provide exceptionally clean routes to the derivatisation of tetra-substituted disilanes such as [Ph2SiH]2, giving no products resulting from Si-Si bond cleavage. Even higher activity is observed for the borane-catalysed dehydrogenative coupling of silanes with alkyl- and arylthiols, the first examples of such Si-S bond formation in the absence of a transition metal catalyst. Clean, quantitative syntheses of a range of thiosilanes are reported, and the lability of the Si-S linkage toward subsequent alcoholysis is investigated. The crystal structure of 2,3-disila-2,2,3,3-tetramethyl-1,4- benzodioxane is presented.
- Harrison, Daniel J.,Edwards, David R.,McDonald, Robert,Rosenberg, Lisa
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p. 3401 - 3411
(2008/12/20)
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- Reactions of organolanthanide compounds RLnI (Ln = Yb, Eu, Sm) with organic derivatives of silicon, tin, lead, and antimony
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Reactions of compounds RLnI (R = Alk, Ar; Ln = Yb, Eu, Sm) with hexaalkyl(aryl)-distannanes, trimethylsilyltriphenyltin, and lead and antimony acetates were studied. The reactions with Sn-Sn and Si-Sn organic derivatives result in cleavage of Sn-Sn amd Sn-Si bonds with formation of tetrasubstituted stannanes and reactive organometallic derivatives with an Sn-Ln or Si-Ln bond. The reactions of RYbI with lead and antimony acetates and with tetraethoxysilane cause cleavage of the Pb-O, Sb-O, or Si-O bond with formation of tetrasubstituted derivatives of lead and silicon or trisubstituted antimony derivatives.
- Rybakova,Syutkina,Petrov
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p. 244 - 246
(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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- An Efficient Catalyst for the Conversion of Hydrosilanes to Alkoxysilanes
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The copper(I) hydride 6 is an efficient catalyst for the alcoholysis of primary and secondary silanes.The reactions proceed at room temperature within a few hours and give the alkoxysilanes in high yields.Only with bulky alcohols or silanes are longer reaction times and/or increased temperatures required.The presence of air accelarates the reactions and gives rise to higher yields of alkoxysilanes, particularly with bulky alcohols.Diols react with PhRSiH2 (R = Me, Ph) to afford 1,3-dioxo-2-silacycloalkanes and with tertiary silanes to furnish the bissilylated diols.When unsaturated alcohols (2-propen-1-ol or 2-propyn-1-ol) are employed, the double or triple bond is retained. - Keywords: Catalytic silane alcoholysis; Alkoxysilanes
- Lorenz, Catrin,Schubert, Ulrich
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p. 1267 - 1270
(2007/10/03)
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- Convenient route to di- and triorganosilyl ethyl ethers and the corresponding di- and triorganosilanes
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Tetraethoxysilane was treated with alkyl- and aryllithium reagents for the reparation of organosilyl ethyl ethers of the type R3SiOEt, R2R'SiOEt, and R2Si(OEt)2, that can be reduced to the organosilanes R3SiH, R2R'SiH, and R2SiH2, respectively, Compounds of the type RR'R''SiOEt cannot be cleanly formed.The reduction procedure involves treatment of the silyl alkoxy ethers with diisobutylaluminium hydride (DIBALH) and hydrolysis of the remaining alkylaluminium compounds with Na2SO4*10H2O.This hydrolysis provides a convenient method for the isolation of R3SiH, R2R'SiH, and R2SiH2 compounds without hydrolysis of the Si-H moiety that often occurs in standard aqueous work-up procedures of unhindered silanes.
- Tour, James M.,John, Jens A.,Stephens, Eric B.
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p. 301 - 310
(2007/10/02)
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- Mechanism of Thermal Eliminations. Part 29. The Effect of Different Silyl groups upon Thermal Elimination of Ketene from Ethyl Silylacetates
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A series of ethyl silylacetates, R3SiCH2CO2Et where R3 = Me3, Me2Ph, MePh2, Ph3, have been prepared and their rates of gas-phase thermal elimination to ketene and the corresponding ethyl silyl ether measured, each over 50 deg C temperature range.Activation energies are in the range of 136-144 kJ mol-1, and log(A/s-1) values 10.1-10.8.Increase in the electrophilicity of silicon through replacement of one methyl group by phenyl produces a minor increase in reactivity, but further similar replacements eventually produce a rate decrease, which is attributed to steric hinderance.Overall the kinetic data indicate that the strength of the silicon-oxygen bond formed is sufficiently important that alteration in the ester structure is incapable of producing substantial variation in the rate of ketene formation.
- Chapman, Sara E.,Taylor, Roger
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p. 1119 - 1120
(2007/10/02)
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- PHENYLAZOTRIORGANOSILANES AS SILYLATED PHENYLDIAZENES; A CONVENIENT PRECURSOR FOR PHENYLDIAZENE
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Phenylazotriphenyl- (Ia) and phenylazotrimethyl-silane (Ib) react with alcohols to give the corresponding alkoxytriorganosilane and benzene as the major products.Spectroscopic investigations (UV) suggested that phenyldiazene was formed as an intermediate which afforded the final reaction products.Chemical evidence for the formation of phenyldiazene was obtained by the reaction of Ia with methanol-d in nonane.Phenylazotriorganosilanes are convenient precursors for phenyldiazene.
- Watanabe, Hamao,Awano, Ken-Ichi,Ohmori, Manabu,Kodama, Nobuhiro,Sakamoto, Jun-Ichi,et al.
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