- Reactions of carboxamides with vinylsilanes under oxidative conditions
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The reactions of acetamide, benzamide and trifluoroacetamide with trimethyl(vinyl)-, triphenyl(vinyl)-, dimethyl(divinyl)- and diphenyl(divinyl)silanes in the presence of oxidants (t-BuOCl + NaI) or N-bromosuccinimide (NBS) in acetonitrile have been studied. Generally, all unsaturated silanes react with trifluoroacetamide to give the products of haloamidation, whereas with acetamide or benzamide the reaction affords mainly the products of halogenation. The formation of bromoamination product containing the MeCONH moiety in the NBS-induced reaction of trimethylvinylsilane with all studied amides clearly indicates that the reaction proceeds with the solvent (MeCN) interception rather than by the attack of the amide nucleophile. The product of bromoamidation from the NBS-promoted reaction undergoes a base-induced cyclization to the corresponding 1,3-oxazoline in quantitative yield.
- Astakhova, Vera V.,Moskalik, Mikhail Yu.,Shainyan, Bagrat A.
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- Cobalt single atoms anchored on nitrogen-doped porous carbon as an efficient catalyst for oxidation of silanes
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The oxidation reactions of organic compounds are important transformations for the fine and bulk chemical industry. However, they usually involve the use of noble metal catalysts and suffer from toxic or environmental issues. Here, an efficient, environmentally friendly, and atomically dispersed Co catalyst (Co-N-C) was preparedviaa simple, porous MgO template and etching method using 1,10-phenanthroline as C and N sources, and CoCl2·6H2O as the metal source. The obtained Co-N-C catalyst exhibits excellent catalytic performance for the oxidation of silanes with 97% isolated yield of organosilanol under mild conditions (room temperature, H2O as an oxidant, 1.8 h), and good stability with 95% isolated yield after nine consecutive reactions. The turnover frequency (TOF) is as high as 381 h?1, exceeding those of most non-noble metal catalysts and some noble metal catalysts. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), extended X-ray absorption fine structure (EXAFS), and wavelet transform (WT) spectroscopy corroborate the existence of atomically dispersed Co. The coordination numbers of Co affected by the pyrolysis temperature in Co-N-C-700, Co-N-C-800, and Co-N-C-900 are 4.1, 3.6, and 2.2, respectively. Owing to a higher Co-N3content, Co-N-C-800 shows more outstanding catalytic performance than Co-N-C-700 and Co-N-C-800. Moreover, density functional theory (DFT) calculations reveal that the Co-N3structure exhibits more activity compared with Co-N4and Co-N2, which is because the Co atom in Co-N3was bound with both H atom and Si atom, and it induced the longest Si-H bond.
- Yang, Fan,Liu, Zhihui,Liu, Xiaodong,Feng, Andong,Zhang, Bing,Yang, Wang,Li, Yongfeng
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p. 1026 - 1035
(2021/02/09)
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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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- Selective Electrochemical Hydrolysis of Hydrosilanes to Silanols via Anodically Generated Silyl Cations
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The first electrochemical hydrolysis of hydrosilanes to silanols under mild and neutral reaction conditions is reported. The practical protocol employs commercially available and cheap NHPI as a hydrogen-atom transfer (HAT) mediator and operates at room temperature with high selectivity, leading to various valuable silanols in moderate to good yields. Notably, this electrochemical method exhibits a broad substrate scope and high functional-group compatibility, and it is applicable to late-stage functionalization of complex molecules. Preliminary mechanistic studies suggest that the reaction appears to proceed through a nucleophilic substitution reaction of an electrogenerated silyl cation with H2O.
- Liang, Hao,Wang, Lu-Jun,Ji, Yun-Xing,Wang, Han,Zhang, Bo
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supporting information
p. 1839 - 1844
(2020/12/01)
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- HCl-Catalyzed Aerobic Oxidation of Alkylarenes to Carbonyls
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The construction of C?O bonds through C?H bond functionalization remains fundamentally challenging. Here, a practical chlorine radical-mediated aerobic oxidation of alkylarenes to carbonyls was developed. This protocol employed commercially available HCl as a hydrogen atom transfer (HAT) reagent and air as a sustainable oxidant. In addition, this process exhibited excellent functional group tolerance and a broad substrate scope without the requirement for external metal and oxidants. The mechanistic hypothesis was supported by radical trapping, 18O labeling, and control experiments.
- Ding, Ling,Liu, Yuxiu,Niu, Kaikai,Shi, Xiaodi,Song, Hongjian,Wang, Qingmin
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- Organic photoredox catalyzed C-H silylation of quinoxalinones or electron-deficient heteroarenes under ambient air conditions
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Direct C-H silylation of quinoxalinones was achieved by the combination of organic photoredox catalysis and hydrogen atom transfer (HAT) under ambient air conditions. Transition metal- and external oxidant-free conditions were the major features of this protocol. A series of silylated quinoxalinones with broad functional groups had been synthesized in moderate to high yields. This methodology was also applicable for the C-H silylation of some electron-deficient heteroarenes.
- Dai, Changhui,Zhan, Yanling,Liu, Ping,Sun, Peipei
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supporting information
p. 314 - 319
(2021/01/28)
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- Photocatalyzed cross-dehydrogenative coupling of silanes with alcohols and water
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An efficient method for the dehydrogenative coupling of silanes with alcohols under photocatalysis was developed. The reaction proceeded in the presence of Ru(bpy)3Cl2(0.5 mol%) under visible light irradiation in acetonitrile at room temperature. The developed methodology was also applicable for the synthesis of silanols using water as a coupling partner.
- Lv, Haiping,Laishram, Ronibala Devi,Chen, Jingchao,Khan, Ruhima,Zhu, Yuanbin,Wu, Shiyuan,Zhang, Jianqiang,Liu, Xingyuan,Fan, Baomin
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supporting information
p. 3660 - 3663
(2021/04/16)
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- Visible-light photoredox-catalyzed selective carboxylation of C(sp3)?F bonds with CO2
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It is highly attractive and challenging to utilize carbon dioxide (CO2), because of its inertness, as a nontoxic and sustainable C1 source in the synthesis of valuable compounds. Here, we report a novel selective carboxylation of C(sp3)?F bonds with CO2 via visible-light photoredox catalysis. A variety of mono-, di-, and trifluoroalkylarenes as well as α,α-difluorocarboxylic esters and amides undergo such reactions to give important aryl acetic acids and α-fluorocarboxylic acids, including several drugs and analogs, under mild conditions. Notably, mechanistic studies and DFT calculations demonstrate the dual role of CO2 as an electron carrier and electrophile during this transformation. The fluorinated substrates would undergo single-electron reduction by electron-rich CO2 radical anions, which are generated in situ from CO2 via sequential hydride-transfer reduction and hydrogen-atom-transfer processes. We anticipate our finding to be a starting point for more challenging CO2 utilization with inert substrates, including lignin and other biomass.
- Bo, Zhi-Yu,Chen, Lin,Gao, Tian-Yu,Jing, Ke,Lan, Yu,Liu, Shi-Han,Luo, Shu-Ping,Yan, Si-Shun,Yu, Bo,Yu, Da-Gang
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supporting information
p. 3099 - 3113
(2021/11/16)
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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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- Silacyclization through palladium-catalyzed intermolecular silicon-based C(sp2)-C(sp3) cross-coupling
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Silicon-based cross-coupling has been recognized as one of the most reliable alternatives for constructing carbon-carbon bonds. However, the employment of such reaction as an efficient ring expansion strategy for silacycle synthesis is comparatively little known. Herein, we develop the first intermolecular silacyclization strategy involving Pd-catalyzed silicon-based C(sp2)-C(sp3) cross-coupling. This method allows the modular assembly of a vast array of structurally novel and interesting sila-benzo[b]oxepines with good functional group tolerance. The key to success for this reaction is that silicon atoms have a stronger affinity for oxygen nucleophiles than carbon nucleophiles, and silacyclobutanes (SCBs) have inherent ring-strain-release Lewis acidity.
- Li, Kailong,Li, Lianghui,Liang, Jin-Yuan,Qin, Ying,Zhao, Dongbing
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p. 14224 - 14229
(2021/11/12)
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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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- Synthesis of a Gold–Metal Oxide Core–Satellite Nanostructure for In Situ SERS Study of CuO-Catalyzed Photooxidation
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This work reports on an assembling–calcining method for preparing gold–metal oxide core–satellite nanostructures, which enable surface-enhanced Raman spectroscopic detection of chemical reactions on metal oxide nanoparticles. By using the nanostructure, we study the photooxidation of Si?H catalyzed by CuO nanoparticles. As evidenced by the in situ spectroscopic results, oxygen vacancies of CuO are found to be very active sites for oxygen activation, and hydroxide radicals (*OH) adsorbed at the catalytic sites are likely to be the reactive intermediates that trigger the conversion from silanes into the corresponding silanols. According to our finding, oxygen vacancy-rich CuO catalysts are confirmed to be of both high activity and selectivity in photooxidation of various silanes.
- Bai, Lu,Fan, Chenghao,Hu, Yanfang,Li, Yonglong,Liu, Jun,Shi, Faxing,Xie, Wei,Yang, Ling,Zhang, Kaifu,Zhao, Yaran
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p. 18003 - 18009
(2020/08/21)
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- "canopy Catalysts" for Alkyne Metathesis: Molybdenum Alkylidyne Complexes with a Tripodal Ligand Framework
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A new family of structurally well-defined molybdenum alkylidyne catalysts for alkyne metathesis, which is distinguished by a tripodal trisilanolate ligand architecture, is presented. Complexes of type 1 combine the virtues of previous generations of silanolate-based catalysts with a significantly improved functional group tolerance. They are easy to prepare on scale; the modularity of the ligand synthesis allows the steric and electronic properties to be fine-tuned and hence the application profile of the catalysts to be optimized. This opportunity is manifested in the development of catalyst 1f, which is as reactive as the best ancestors but exhibits an unrivaled scope. The new catalysts work well in the presence of unprotected alcohols and various other protic groups. The chelate effect entails even a certain stability toward water, which marks a big leap forward in metal alkylidyne chemistry in general. At the same time, they tolerate many donor sites, including basic nitrogen and numerous heterocycles. This aspect is substantiated by applications to polyfunctional (natural) products. A combined spectroscopic, crystallographic, and computational study provides insights into structure and electronic character of complexes of type 1. Particularly informative are a density functional theory (DFT)-based chemical shift tensor analysis of the alkylidyne carbon atom and 95Mo NMR spectroscopy; this analytical tool had been rarely used in organometallic chemistry before but turns out to be a sensitive probe that deserves more attention. The data show that the podand ligands render a Mo-alkylidyne a priori more electrophilic than analogous monodentate triarylsilanols; proper ligand tuning, however, allows the Lewis acidity as well as the steric demand about the central atom to be adjusted to the point that excellent performance of the catalyst is ensured.
- Copéret, Christophe,Fürstner, Alois,Gordon, Christopher P.,Hillenbrand, Julius,Leutzsch, Markus,N?thling, Nils,Wille, Christian,Yiannakas, Ektoras
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supporting information
p. 11279 - 11294
(2020/07/13)
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- Selective Manganese-Catalyzed Oxidation of Hydrosilanes to Silanols under Neutral Reaction Conditions
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The first manganese-catalyzed oxidation of organosilanes to silanols with H2O2 under neutral reaction conditions has been accomplished. A variety of organosilanes with alkyl, aryl, alknyl, and heterocyclic substituents were tolerated, as well as sterically hindered organosilanes. The oxidation appears to proceed by a concerted process involving a manganese hydroperoxide species. Featuring mild reaction conditions, fast oxidation, and no waste byproducts, the protocol allows a low-cost, eco-benign synthesis of both silanols and silanediols.
- Wang, Kaikai,Zhou, Jimei,Jiang, Yuting,Zhang, Miaomiao,Wang, Chao,Xue, Dong,Tang, Weijun,Sun, Huamin,Xiao, Jianliang,Li, Chaoqun
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supporting information
p. 6380 - 6384
(2019/05/06)
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- Silanol organic compound and preparation method thereof
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The invention belongs to the technical field of chemical industry, and discloses a silanol organic compound and a preparation method thereof. The preparation method of the silanol organic compound takes silane and water as reaction raw materials and sulfoxide as a catalyst, and carries out reaction by heating under an argon atmosphere to prepare a corresponding silanol product. The product prepared by the method has the advantages of high yield, good selectivity, mild reaction, cheap catalyst, no metal participation, environmental protection, good atom economy, and wide application range, andthe use of the water as an oxygen source accords with the development concept of green chemistry.
- -
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Paragraph 0056
(2019/07/04)
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- Tellurorhodamine photocatalyzed aerobic oxidation of organo-silanes and phosphines by visible-light
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Tellurorhodamine, 9-mesityl-3,6-bis(dimethylamino)telluroxanthylium hexafluorophosphate (1), photocatalytically oxidizes aromatic and aliphatic silanes and triphenyl phosphine under mild aerobic conditions. Under irradiation with visible light, 1 can react with self-sensitized 1O2 to generate the active telluroxide oxidant (2). Silanes are oxidized to silanols and triphenyl phosphine is oxidized to triphenyl phoshine oxide either using 2, or 1 with aerobic irradiation. Kinetic experiments coupled with a computational study elucidate possible mechanisms of oxidation for both silane and phosphine substrates. First-order rates were observed in the oxidation of triphenyl phosphine and methyldiphenyl silane, indicating a substitution like mechanism for substrate binding to the oxidized tellurium(iv). Additionally, these reactions exhibited a rate-dependence on water. Oxidations were typically run in 50:50 water/methanol, however, the absence of water decreased the rates of silane oxidation to a greater degree than triphenyl phosphine oxidation. Parallel results were observed in solvent kinetic isotope experiments using D2O in the solvent mixture. The rates of oxidation were slowed to a greater degree in silane oxidation by 2 (kH/kD = 17.30) than for phosphine (kH/kD = 6.20). Various silanes and triphenyl phosphine were photocatalytically oxidized with 1 (5%) under irradiation with warm white LEDs using atmospheric oxygen as the terminal oxidant.
- Rettig, Irving D.,Van, Jackson,Brauer, Jacob B.,Luo, Wentai,McCormick, Theresa M.
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supporting information
p. 5665 - 5673
(2019/05/10)
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- Single-Site AuI Catalyst for Silane Oxidation with Water
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Single-site Au anchored on mpg-C3N4 (519 ppm Au loading) is developed as a highly active, selective, and stable catalyst for the oxidation of silanes with water with a turnover frequency as high as 50 200 h?1, far exceeding most known catalysts based on total gold content. Other hydrosilanes bearing unsaturated functional groups also lead to corresponding silanols under mild reaction conditions without formation of any side products in good or excellent yields. The spherical aberration correction electron microscopy and extended X-ray absorption fine structure measurements both confirm the atomic dispersion of Au atoms stabilized by mpg-C3N4. The coordination of the catalytically active AuI by three nitrogen or carbon atoms in the tri-s-triazine repeating units not only prevents the Au atoms from aggregation, but also renders the surface AuI highly active, which is completely different than homogeneous AuI species.
- Chen, Zheng,Zhang, Qi,Chen, Wenxing,Dong, Juncai,Yao, Hurong,Zhang, Xiangbo,Tong, Xuanjue,Wang, Dingsheng,Peng, Qing,Chen, Chen,He, Wei,Li, Yadong
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- Metal-free visible-light-mediated aerobic oxidation of silanes to silanols
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Oxidation of silanes into silanols using water/air has attracted considerable attention. The known methods with no exception required a metal catalyst. Herein we report the first metal-free method: 2 mol% Rose Bengal as the catalyst, air (O2) as the oxidant, water as the additive and under visible light irradiation. While this method produces various silanols in a simple, cost-effective, efficient (92%–99% yields) and scalable fashion, its reaction mechanism is very different than the reported ones associated with metal catalysis.
- Wang, Jing,Li, Bin,Liu, Li-Chuan,Jiang, Chenran,He, Tao,He, Wei
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p. 1594 - 1599
(2018/08/22)
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- Synthesis, characterization and catalytic oxidation of organosilanes with a novel multilayer polyoxomolybdate containing mixed-valence antimony
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Oxidation of organosilanes is one of the pivotal reactions in organic synthesis and the corresponding products of silanols are widely as raw materials in industrial processes. In this paper, a new type of polyoxomolybdate containing mixed-valence antimony, [SbVSbIII4Mo18O66]7? (1a), has been isolated as tetramethyl ammonium salt in aqueous solution. The compound was structurally characterized by FT-IR, XPRD, TG, XPS, ESI–MS etc. It is the first time that the containing mixed-valence antimony polyoxomolybdate was used as a heterogeneous catalyst to efficaciously catalyze the oxidation of organosilanes to silanols under mild reaction conditions. Furthermore, the catalyst was stable and maintained its catalytic activity after three reaction cycles.
- Wang, Yaping,Lu, Jingkun,Ma, Xinyi,Niu, Yanjun,Singh, Vikram,Ma, Pengtao,Zhang, Chao,Niu, Jingyang,Wang, Jingping
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p. 167 - 174
(2018/04/24)
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- Photoinduced Multicomponent Synthesis of α-Silyloxy Acrylamides, an Unexplored Class of Silyl Enol Ethers
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The photoinduced, multicomponent reaction of α-diazoketones, silanols, and isocyanides affords α-silyloxy acrylamides, formally derived from α-keto amides. The presence of a secondary amido group makes classic preparative methods for silyl enol ethers unfeasible in this case, while the mild conditions required by this photochemical approach allow their synthesis in good yields; moreover, the general structure can be easily modified by varying each component of the multicomponent reaction. Fine-tuning of the reaction conditions (i.e., solvents, radiation, additives) can be exploited to obtain complete Z selectivity. The reactivity of this overlooked class of silyl enol ethers has been investigated, and features that could pave the way to new applications have been found.
- Ibba, Francesco,Capurro, Pietro,Garbarino, Silvia,Anselmo, Manuel,Moni, Lisa,Basso, Andrea
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supporting information
p. 1098 - 1101
(2018/02/23)
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- A method for catalytic synthesis of silanol
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The invention discloses a method for catalytically synthesizing silanol and relates to the fields of organic chemicals and fine chemicals. The method is essentially a transition metal catalyzed organic synthesis reaction. In the method, the raw materials comprise organosilane and a clean oxidant, a used catalyst is inexpensive copper salt, the raw material is heated and stirred to react without a solvent so as to rapidly produce silanol at a moderate temperature. By adopting the method, the reaction time is 3-12 hours. The mole ratio of the organosilane to the clean oxidant is 1:(1-5), the copper salt as the catalyst accounts for 1-10mol% of the mole number of the organosilane, the raw materials react at a temperature of 50-80 DEG C, and then the silanol can be greatly yielded after simple posttreatment. The oxidant used in the method is safe and nontoxic, and the catalyst used in the method is cheap and easily available. The method disclosed by the invention is a very simple and practical method for synthesizing silanol.
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Paragraph 0017; 0039; 0040
(2017/07/12)
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- Wettability-Driven Palladium Catalysis for Enhanced Dehydrogenative Coupling of Organosilanes
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Direct coupling of Si-H bonds has emerged as a promising strategy for designing chemically and biologically useful organosilicon compounds. Heterogeneous catalytic systems sufficiently active, selective, and durable for dehydrosilylation reactions under mild conditions have been lacking to date. Herein, we report that the hydrophobic characteristics of the underlying supports can be advantageously utilized to enhance the efficiency of palladium nanoparticles (Pd NPs) for the dehydrogenative coupling of organosilanes. As a result of this prominent surface wettability control, the modulated catalyst showed a significantly higher level of efficiency and durability characteristics toward the dehydrogenative condensation of organosilanes with water, alcohols, or amines in comparison to existing catalysts. In a broader context, this work illustrates a powerful approach to maximize the performance of supported metals through surface wettability modulation under catalytically relevant conditions.
- Lin, Jian-Dong,Bi, Qing-Yuan,Tao, Lei,Jiang, Tao,Liu, Yong-Mei,He, He-Yong,Cao, Yong,Wang, Yang-Dong
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p. 1720 - 1727
(2017/08/15)
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- Organosilane oxidation with a half million turnover number using fibrous nanosilica supported ultrasmall nanoparticles and pseudo-single atoms of gold
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The combination of ultrasmall nanoparticles and pseudo-single atoms of gold (Au) and fibrous nanosilica (KCC-1) functionalized with 3-aminopropyltriethoxysilane (APTS) enabled the design of KCC-1-APTS/Au nanocatalysts with very high turnover numbers (TONs). KCC-1-APTS/Au catalysed the oxidation of organosilanes to silanols, with a TON of approximately half a million (591000 for dimethylphenyl silane as a model substrate). Additionally, the figure-of-merit (FOM), which provides an integrated view of the rate of the reaction, the energy required, the reaction scale and the recyclability of the catalysts, was 633 mmol h-1 K-1. KCC-1-APTS/Au also catalysed two additional challenging reactions, the alcoholysis of silane and the hydrosilylation of aldehydes, with very high TONs. These characteristics make KCC-1-APTS/Au a versatile nanocatalyst.
- Dhiman, Mahak,Chalke, Bhagyashree,Polshettiwar, Vivek
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supporting information
p. 1935 - 1940
(2017/02/10)
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- Reaction Progress Kinetics Analysis of 1,3-Disiloxanediols as Hydrogen-Bonding Catalysts
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1,3-Disiloxanediols are effective hydrogen-bonding catalysts that exhibit enhanced activity relative to silanediols and triarylsilanols. The catalytic activity for a series of 1,3-disiloxanediols, including naphthyl-substituted and unsymmetrical siloxanes, has been quantified and compared relative to other silanol and thiourea catalysts using the Friedel Crafts addition of indole to trans-β-nitrostyrene. An in-depth kinetic study using reaction progress kinetic analysis (RPKA) has been performed to probe the catalyst behavior of 1,3-disiloxanediols. The data confirm that the disiloxanediol-catalyzed addition reaction is first order in catalyst over all concentrations studied with no evidence of catalyst self-association. 1,3-Disiloxanediols proved to be robust and recoverable catalysts with no deactivation under reaction conditions. No product inhibition is observed, and competitive binding studies with nitro-containing additives suggest that 1,3-disiloxanediols bind weakly to nitro groups but are strongly activating for catalysis.
- Diemoz, Kayla M.,Hein, Jason E.,Wilson, Sean O.,Fettinger, James C.,Franz, Annaliese K.
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p. 6738 - 6747
(2017/07/15)
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- Plasma-Assisted Synthesis of Monodispersed and Robust Ruthenium Ultrafine Nanocatalysts for Organosilane Oxidation and Oxygen Evolution Reactions
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We report a facile and general approach for preparing ultrafine ruthenium nanocatalysts by using a plasma-assisted synthesis at 2 supports. This gives robust catalysts with excellent activities in both organosilane oxidation and the oxygen evolution reaction.
- Gnanakumar, Edwin S.,Ng, Wesley,Co?kuner Filiz, Bilge,Rothenberg, Gadi,Wang, Sheng,Xu, Hualong,Pastor-Pérez, Laura,Pastor-Blas, M. Mercedes,Sepúlveda-Escribano, Antonio,Yan, Ning,Shiju, N. Raveendran
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p. 4159 - 4163
(2017/10/23)
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- Cu3(BTC)2 catalyzed oxidation of silane to silanol using TBHP or water as oxidants
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In the present work, a series of metal organic frameworks are examined for the conversion of Si-H to Si-OH using either t-butylhydroperoxide (TBHP) or water as oxidants. The reaction is optimized using dimethylphenylsilane (1) as a model substrate. It is observed that Cu3(BTC)2 (BTC: 1,3,5-benzenetricarboxylate) exhibits a comparable activity with Zr(BDC) (BDC: 1,4-benzenedicarboxylate) while the activity of Fe(BTC) is lower than Cu3(BTC)2 using TBHP as oxidant. On the other hand, the reaction of 1 with water in the presence of Cu3(BTC)2 as a catalyst showed complete conversion of 1 with 99% selectivity to the corresponding silanol, but other MOFs like Fe(BTC) and Zr(BDC) are inactive under identical reaction conditions. A series of control experiments indicate that Cu2+ is essential to convert 1 to 2 under the present experimental conditions. Further, Cu2+ in Cu3(BTC)2 acts as redox centre with TBHP whereas it behaves as a Lewis acid using water as oxidant. High conversion and selectivity is observed for all the silanes studied under the present experimental conditions. The catalyst stability is assessed by powder XRD, FT-IR and SEM images and observing no structural deterioration of Cu3(BTC)2 either in TBHP or water as oxidants. Furthermore, hot filtration test indicated the absence of copper under the present reaction conditions, thus confirming the stability of Cu3(BTC)2.
- Anbu, Nagaraj,Dhakshinamoorthy, Amarajothi
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p. 145 - 153
(2017/07/26)
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- Method for synthesizing silanol from silane through catalytic oxidation by bipyridine manganese catalyst
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The invention discloses a method for synthesizing silanol from silane through catalytic oxidation by a bipyridine manganese catalyst. The method employs a bipyridine manganese complex formed by coordination of a manganese salt and a dipyridine compound as a catalyst and clean environment-friendly hydrogen peroxide as an oxidizing agent for catalytic oxidation of silane into silanol. Compared with conventional methods, the method provided by the invention has the advantages that the catalyst is low in price; the preparation method is simple; raw materials are easily available; and the method is low in the usage amount of the catalyst, wide in the range of usable substrates, mild in reaction conditions, simple to operate, friendly to environment, short in reaction time, high in yield, good in selectivity, low in industrialization cost, etc.
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Paragraph 0014; 0015; 0016; 0017-0043; 0050; 0051; 0052
(2018/01/11)
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- Silanol Compound, Composition, and Method for Producing Silanol Compound
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The purpose of the present invention is to provide silanol compounds that can be used as raw materials of siloxane compounds and the like, and a composition of the silanol compounds, as well as to provide a production method that makes it possible to produce silanol compounds at excellent yield. A composition comprising 5 mass % to 100 mass % of a silanol compound represented by Formulas (A) to (C) can be prepared by devising to produce silanol compounds under water-free conditions, to produce silanol compounds in a solvent having the effect of suppressing the condensation of silanol compounds, and to perform other such processes, the composition being able to be used as a raw material or the like of siloxane compounds because the silanol compounds can be stably present in the resulting composition.
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- Synthesis of borasiloxanes by oxidative hydrolysis of silanes and pinacolborane using Cu3(BTC)2 as a solid catalyst
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A convenient method for the synthesis of borasiloxanes from silanes and pinacolboranes using Cu3(BTC)2 as a heterogeneous catalyst in acetonitrile at 70 °C is reported. This procedure is more convenient than Ru and Pd based homogeneous catalysts because it avoids the use of noble metals, easy handling of starting materials and the catalyst can be reused.
- Dhakshinamoorthy, Amarajothi,Asiri, Abdullah M.,Concepcion, Patricia,Garcia, Hermenegildo
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supporting information
p. 9998 - 10001
(2017/09/12)
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- Controlled synthesis of cyclosiloxanes by NHC-catalyzed hydrolytic oxidation of dihydrosilanes
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Hydrolytic oxidation of various hydrosilanes in acetonitrile and in the absence of organic solvents catalyzed by an N-heterocyclic carbene organocatalysis is described. The NHC organocatalyst exhibited a very high activity with only 0.1 mol% loading of the catalyst in acetonitrile for aryl-substituted dihydrosilanes to produce hydrogen gas and cyclosiloxanes almost quantitatively in several minutes. The calculated TOF (15 000 h-1) of this organocatalyst is comparable to those of precious metal-based heterogeneous catalysts and much superior to those of the existing homogeneous metal catalysts. The catalytic reaction selectively yielded cyclosiloxanes in high yield without the contamination of silanols. Furthermore, the catalytic reaction can also be furnished under solvent-free conditions at elevated temperatures with 2.5 mol% loading of the NHC in 5-12 hours.
- Qing, Guoping,Cui, Chunming
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supporting information
p. 8746 - 8750
(2017/07/22)
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- Disiloxane Synthesis Based on Silicon-Hydrogen Bond Activation using Gold and Platinum on Carbon in Water or Heavy Water
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Disiloxanes possessing a silicon-oxygen linkage are important as frameworks for functional materials and coupling partners for Hiyama-type cross coupling. We found that disiloxanes were effectively constructed of hydrosilanes catalyzed by gold on carbon in water as the solvent and oxidant in association with the emission of hydrogen gas at room temperature. The present oxidation could proceed via various reaction pathways, such as the hydration of hydrosilane into silanol, dehydrogenative coupling of hydrosilane into disilane, and the subsequent corresponding reactions to disiloxane. Additionally, the platinum on carbon catalyzed hydrogen-deuterium exchange reaction of arylhydrosilanes as substrates in heavy water proceeded on the aromatic nuclei at 80 °C with high deuterium efficiency and high regioselectivity at the only meta and para positions of the aromatic-silicon bond to give the deuterium-labeled disiloxanes.
- Sawama, Yoshinari,Masuda, Masahiro,Yasukawa, Naoki,Nakatani, Ryosuke,Nishimura, Shumma,Shibata, Kyoshiro,Yamada, Tsuyoshi,Monguchi, Yasunari,Suzuka, Hiroyasu,Takagi, Yukio,Sajiki, Hironao
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p. 4190 - 4195
(2016/06/09)
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- A bentonite-gold nanohybrid as a heterogeneous green catalyst for selective oxidation of silanes
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A highly efficient, environmentally benign and reusable heterogeneous bentonite-gold nanohybrid catalyst was designed and synthesized. This heterogeneous catalyst could efficaciously catalyse the oxidation of organosilanes to silanols. The reaction is 98.7% atom economical and the products were obtained in excellent yield without the formation of disiloxanes as byproducts. The catalyst was also well applicable for the gram scale preparation of silanols.
- Maya,John, Jubi,Varma, R. Luxmi
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supporting information
p. 10625 - 10628
(2016/09/02)
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- Organocatalytic Enantioselective Allylic Etherification of Morita-Baylis-Hillman Carbonates and Silanols
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The organocatalytic asymmetric allylic etherification reaction of Morita-Baylis-Hillman carbonates and silanols was reported for the first time. With modified cinchona alkaloid (DHQD)2PYR as the catalyst, a series of aromatic, heterocyclic, or aliphatic Morita-Baylis-Hillman carbonates (25 examples) worked well with triphenylsilanol, affording the corresponding products in moderate to good yields (up to 98%), high regioselectivities (>20:1), and good enantioselectivities (up to 92%). When dimethylphenylsilanol was used as the nucleophile, the product was obtained in 60% yield and 87% ee.
- Liu, Hui-Li,Xie, Ming-Sheng,Qu, Gui-Rong,Guo, Hai-Ming
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supporting information
p. 10035 - 10042
(2016/11/02)
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- Nickel nanoparticles supported on graphene as catalysts for aldehyde hydrosilylation
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Nickel nanoparticles (NPs) supported on different undoped or doped with N or B graphenes (Gs) have been tested as catalyst for the hydrosilylation of aldehydes to obtain the corresponding siloxanes with high conversion and good selectivity in short reaction time. The different Gs employed were obtained by pyrolysis under inert atmosphere of alginate or chitosan, modified or not with boric acid. Then the metal NPs obtained by polyol reduction method using ethylene glycol were adsorbed on Gs. The Ni-containing G catalysts were characterized by electron microscopy, XPS and Raman spectroscopy. The scope of the Ni/G catalyst includes aliphatic and aromatic aldehydes as well as a variety of hydrosilanes.
- Blandez, Juan F.,Esteve-Adell, Iván,Primo, Ana,Alvaro, Mercedes,García, Hermenegildo
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- Metal-free catalytic hydrogen production from a polymethylhydrosilane-water mixture
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Hydrogen gas is the most promising carbon-free energy carrier although its on-demand generation remains a formidable challenge. One of the potential pathways for generating hydrogen is through hydrolytic oxidation of organosilanes. Here, we demonstrate that the hydroxide ion OH- serves as a potent room-temperature metal-free catalyst in the hydrolytic oxidation of polymethylhydrosilane, PMHS to hydrogen gas and the corresponding silanol with a turnover number and turnover frequency in excess of 200 and 8 min-1 respectively. Kinetic studies suggest the hydrogen generation rate is first order with respect to PMHS and OH- but zero order with respect to water. The first step of the reaction, where the Si center of PMHS is attacked by the OH- ion, is believed to be the rate-determining step.
- Yap, Chew Pheng,Poh, Hwa Tiong,Fan, Wai Yip
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p. 5903 - 5906
(2016/02/05)
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- O2-enhanced catalytic activity of gold nanoparticles in selective oxidation of hydrosilanes to silanols
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O2 acts as a nonconsumed activator for gold nanoparticles (AuNPs) in the oxidation of hydrosilanes to silanols with water under O2 atmosphere, providing an acceleration of more than 200 times relative to the reaction rate under Ar atmosphere. The AuNP catalyst under aerobic conditions exhibits high activity in the oxidation with high turnover numbers (1230000). Various hydrosilanes including less-reactive bulky ones can be converted to the corresponding silanols in excellent yields. Moreover, the present AuNP catalyst is reusable while maintaining the high performance.
- Urayama, Teppei,Mitsudome, Takato,Maeno, Zen,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 1062 - 1064
(2015/09/02)
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- Mild and selective catalytic oxidation of organic substrates by a carbon nanotube-rhodium nanohybrid
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A heterogeneous catalyst was assembled by stabilization of rhodium nanoparticles on carbon nanotubes. The nanohybrid was used for the catalytic aerobic oxidation of diverse substrates such as hydroquinones, hydroxylamines, silanes, hydrazines and thiols, at room temperature. The system proved very efficient on the investigated substrates and demonstrated high selectivity.
- Donck, Simon,Gravel, Edmond,Li, Alex,Prakash, Praveen,Shah, Nimesh,Leroy, Jocelyne,Li, Haiyan,Namboothiri, Irishi N. N.,Doris, Eric
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p. 4542 - 4546
(2015/09/01)
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- Catalytic hydrogen evolution from hydrolytic oxidation of organosilanes with silver nitrate catalyst
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In the light of uncertainty over the amount of recoverable fossil fuel reserves, hydrogen is touted to be a promising energy carrier in the future. Nevertheless, hydrogen storage remains a daunting challenge but a potential reaction for the generation of hydrogen on demand is the hydrolytic oxidation of organosilanes. Here, we demonstrate that silver nitrate, a readily available ionic salt, can catalyze the hydrolysis of organosilanes to produce hydrogen and organosilanols. In particular, turnover numbers and turnover frequencies in excess of 5 × 103 and 102 min-1 respectively are obtainable for the hydrolysis of triethylsilane at room temperature. This proposed silver nitrate mediated system is, by far, the simplest and cheapest catalytic hydrolysis of organosilanes. Results from the kinetic studies suggested a mechanistic scenario in which the hydrolysis of organosilanes is third order overall and first order in organosilane, water, and catalyst. The high hydrogen yield observed makes the silver nitrate catalyst an attractive material for hydrogen evolution. the Partner Organisations 2014.
- Teo, Alan Kay Liang,Fan, Wai Yip
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p. 37645 - 37648
(2014/11/27)
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- Plasma synthesis of carbon nanotube-gold nanohybrids: Efficient catalysts for green oxidation of silanes in water
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We report the green synthesis of silanols from hydrosilanes in high yields by using oleylamine (OA) stabilized gold nanoparticles (AuNPs) supported on oxidized multi-walled carbon nanotubes (o-CNTs) as catalysts in H2O. The Au catalyst can be easily synthesized by a one-pot gas-liquid interfacial plasma method, and the catalyst exhibited much more remarkable catalytic activity in the oxidation of various organosilanes by using water as the solvent compared with other organic solvents (for example THF, ethyl acetate, and acetone), which is very important for organic synthesis from both the standpoint of practical reasons and an economic perspective. The Au catalyst can be readily recovered and reused without any loss of catalytic activity. In addition, our findings indicate that o-CNTs and OA are the key components of the catalyst in which the o-CNT support makes the hybrid materials hydrophilic, and the OA stabilizer makes the hybrid materials lipophilic, resulting in the high activity of the catalyst in H2O. The Royal Society of Chemistry.
- Liu, Ting,Yang, Fan,Li, Yongfeng,Ren, Liang,Zhang, Liqiang,Xu, Kai,Wang, Xian,Xu, Chunming,Gao, Jinsen
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p. 245 - 250
(2014/01/06)
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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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- 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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- Gold nanoparticles supported on the periodic mesoporous organosilica SBA-15 as an efficient and reusable catalyst for selective oxidation of silanes to silanols
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Gold nanoparticles are confined and stabilized within the channels of SBA-15 through the poly(ionic liquid) brushes that are anchored onto the pore walls of SBA-15. The supported gold catalyst exhibited remarkably high catalytic activities for selective oxidation of silanes into silanols using water as an oxidant without the use of organic solvents.
- Ma, Lina,Leng, Wenguang,Zhao, Yaopeng,Gao, Yanan,Duan, Hongdong
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p. 6807 - 6810
(2014/02/14)
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- A novel iron complex for highly efficient catalytic hydrogen generation from the hydrolysis of organosilanes
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Hydrolytic oxidation of organosilanes based on an iron catalyst is described for the first time. The novel iron complex, [Fe(C6H 5N2O)(CO)(MeCN)3][PF6], exhibits excellent mediating power in the catalytic hydrolysis of organosilanes to produce dihydrogen and organosilanols with turnover numbers approaching 10 4 and turnover frequencies in excess of 102 min -1 under ambient conditions.
- Liang Teo, Alan Kay,Fan, Wai Yip
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supporting information
p. 7191 - 7194
(2014/07/07)
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- Organosilane oxidation by water catalysed by large gold nanoparticles in a membrane reactor
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We show that gold nanoparticles catalyse the oxidation of organosilanes using water as oxidant at ambient conditions. Remarkably, monodispersions of small gold particles (3.5 nm diameter) and large ones (6-18 nm diameter) give equally good conversion rates. This is important because separating large nanoparticles is much easier, and can be done using ultrafiltration instead of nanofiltration. We introduce a simple setup, constructed in-house, where the reaction products are extracted through a ceramic membrane under pressure, leaving the gold nanoparticles intact in the vessel. The nominal substrate/catalyst ratios are ca. 1800:1, with typical TONs of 1500-1600, and TOFs around 800 h-1. But the actual activity of the large nanoparticles is much higher, because most of their gold atoms are "inside", and therefore unavailable. Control experiments confirm that no gold escapes to the membrane permeate. The role of surface oxygen as a possible co-catalyst is discussed. Considering the ease of product separation and the robustness of the ceramic membrane, this approach opens opportunities for actual applications of gold catalysts in water oxidation reactions. The Royal Society of Chemistry 2014.
- Gitis, Vitaly,Beerthuis, Rolf,Shiju, N. Raveendran,Rothenberg, Gadi
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p. 2156 - 2160
(2014/06/24)
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- Catalytic hydrogen evolution from hydrolytic oxidation of organosilanes with silver nitrate catalyst
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In the light of uncertainty over the amount of recoverable fossil fuel reserves, hydrogen is touted to be a promising energy carrier in the future. Nevertheless, hydrogen storage remains a daunting challenge but a potential reaction for the generation of hydrogen on demand is the hydrolytic oxidation of organosilanes. Here, we demonstrate that silver nitrate, a readily available ionic salt, can catalyze the hydrolysis of organosilanes to produce hydrogen and organosilanols. In particular, turnover numbers and turnover frequencies in excess of 5 × 103and 102min-1respectively are obtainable for the hydrolysis of triethylsilane at room temperature. This proposed silver nitrate mediated system is, by far, the simplest and cheapest catalytic hydrolysis of organosilanes. Results from the kinetic studies suggested a mechanistic scenario in which the hydrolysis of organosilanes is third order overall and first order in organosilane, water, and catalyst. The high hydrogen yield observed makes the silver nitrate catalyst an attractive material for hydrogen evolution. This journal is
- Teo, Alan Kay Liang,Fan, Wai Yip
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p. 37645 - 37648
(2015/02/19)
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- Nonhydrolytic synthesis of silanols by the hydrogenolysis of benzyloxysilanes
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The hydrogenolysis of benzyloxysilanes was smoothly catalyzed by Pd/C in THF to give corresponding silanols under nonhydrolytic conditions. The reaction proved to be applicable to various benzyloxysilanes giving silanemonools, diol, and triol.
- Igarashi, Masayasu,Matsumoto, Tomohiro,Sato, Kazuhiko,Ando, Wataru,Shimada, Shigeru
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p. 429 - 431
(2014/04/17)
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- Organocatalytic oxidation of organosilanes to silanols
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The oxidation of organosilanes to silanols constitutes an attractive transformation for both industry and academia. Bypassing the need for stoichiometric oxidants or precious metal catalytic complexes, the first organocatalytic oxidation of silanes has been accomplished. Catalytic amounts of 2,2,2-trifluoroacetophenone, in combination with the green oxidant H 2O2, lead to excellent to quantitative yields in a short reaction time. A variety of alkyl, aryl, alkenyl, and alkynyl substituents can be tolerated, providing an easy, cheap, efficient, and practical solution to a highly desirable transformation.
- Limnios, Dimitris,Kokotos, Christoforos G.
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p. 2239 - 2243
(2013/10/22)
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- A discrete octahedrally shaped [Ag6]4+ cluster encapsulated within silicotungstate ligands
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By the reaction of TBA4H4[γ-SiW 10O36] (TBA = tetra-n-butylammonium) with AgOAc (OAc = acetate) using dimethylphenylsilane as a reductant in acetone, a unique polyoxometalate containing a discrete octahedrally shaped [Ag6] 4+ cluster, TBA8[Ag6(γ-H 2SiW10O36)2]·5H2O, could be synthesized, and the molecular structure was determined.
- Kikukawa, Yuji,Kuroda, Yoshiyuki,Suzuki, Kosuke,Hibino, Mitsuhiro,Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 376 - 378
(2013/03/13)
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- Postsynthetic functionalization of a hollow silica nanoreactor with manganese oxide-immobilized metal nanocrystals inside the cavity
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A postsynthetic protocol of functionalizing the preformed hollow nanoparticles with metal nanocrystals was developed based on galvanic replacement reaction on the Mn3O4 surface inside the cavity. The developed protocol produced hollow nanoreactor systems, in which a high density of ultrafine catalytic nanocrystals of a range of noble metals, such as Pd, Pt, Rh, and Ir and their alloys, are dispersively immobilized on an interior surface enclosed by a selectively permeable silica shell. The fabricated hollow nanoreactor exhibited highly enhanced activity, selectivity, and recyclability in catalyzing the oxidation of hydrosilanes, which are attributable to the synergistic combination of the porous silica nanoshell and the oxide-immobilized catalyst system.
- Kim, Soo Min,Jeon, Mina,Kim, Ki Woong,Park, Jaiwook,Lee, In Su
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supporting information
p. 15714 - 15717
(2013/11/06)
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- Diamond-shaped [Ag4]4+ cluster encapsulated by silicotungstate ligands: Synthesis and catalysis of hydrolytic oxidation of silanes
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An Ag4 diamond is encapsulated by silicotungstate ligands in TBA8[Ag4(DMSO)2(γ-H2SiW 10O36)2]·2 DMSO·2 H2O (Ag4; DMSO=dimethyl sulfoxide, TBA=tetra-n-butylammonium), which was obtained by reaction of TBA4H4[γ-SiW10O 36] with AgOAc in an organic medium. Polyoxometalate Ag4 (see picture) selectively catalyzes hydrolytic oxidation of various silanes to the corresponding silanols in high yields (72-96 %). Copyright
- Kikukawa, Yuji,Kuroda, Yoshiyuki,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information; experimental part
p. 2434 - 2437
(2012/05/05)
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