- Heterogeneous nickel catalyst for selective hydration of silanes to silanols
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Selective catalytic hydration of silanes to silanols is studied by Ni metal nanoparticles (NPs) on activated carbon (Ni/C) prepared by in situ H 2-reduction of NiO-loaded activated carbon (NiO/C). The catalytic activity of Ni/C increases with decrease in the average Ni particle size. Ni/C with the smallest size (7.6 nm) exhibits a high selectivity for silanols, high turnover number (TON) of 9300, and excellent reusability. Studies on the structure-activity relationship show that metallic Ni species on the surface of small Ni metal particles are catalytically active species. Based on mechanistic studies, a catalytic cycle involving the activation of Et3SiH as the rate limiting step is proposed.
- Shimizu, Ken-Ichi,Shimura, Katsuya,Imaiida, Naomichi,Satsuma, Atsushi
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Read Online
- Hydrosilane-assisted formation of metal nanoparticles on graphene oxide
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Metal nanoparticles were formed on graphene oxide by a deposition process with hydrosilane, giving thin layer metalgraphene oxide (metal/GO) composites. The particle size and catalytic activity could be controlled by varying the hydrosilane amount. Hydrosilane prevented the aggregation of GO layers by surface functionalization via silane coupling reaction. The metal/GO composites were evaluated as catalysts in hydrosilane oxidation.
- Saito, Akinori,Kinoshita, Hiroshi,Shimizu, Ken-Ichi,Nishina, Yuta
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- Copper-Catalyzed Oxidation of Hydrosilanes: A New Method for the Synthesis of Alkyl- and Siloxysilanols
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A simple method for the preparation of silanols from the corresponding hydrosilanes is reported. The method employs a commercially available oxidizing system based on CuCO 3 / t -BuOOH (aq) under relatively mild conditions (80 °C, atmospheric pressure) with acetonitrile as the solvent. Furthermore, we present a method that permits the Si-H group to be oxidized to a Si-OH group not only in triethylsilane, but also in bis(trimethylsiloxy)methylsilane, a siloxy derivative of hydrosilane. The products were isolated in gram amounts in yields of 61-73%.
- Arzumanyan, Ashot V.,Goncharova, Irina K.,Novikov, Roman A.,Milenin, Sergey A.,Muzafarov, Aziz M.
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Read Online
- 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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- Integration of Pd nanoparticles with engineered pore walls in MOFs for enhanced catalysis
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Achieving free-access metal sites with the ability to regulate interactions with substrates is highly desired yet remains a grand challenge in catalysis. Herein, naked Pd nanoparticles were encapsulated inside a metal-organic framework (MOF), giving Pd@MIL-101-NH2. Its activity and selectivity toward de/hydrogenation reactions can be greatly promoted via the MOF pore wall engineering to regulate Pd surrounding microenvironment and substrate adsorption behavior. Creating free-access active sites and regulating their interaction with substrates are crucial for efficient catalysis, yet remain a grand challenge. Herein, naked Pd nanoparticles (NPs) have been encapsulated in a metal-organic framework (MOF), MIL-101-NH2, to afford Pd@MIL-101-NH2. The hydrophobic perfluoroalkyls were post-synthetically modified onto -NH2 group to yield Pd@MIL-101-Fx (x = 3, 5, 7, 11, 15), which engineer the MOF pore walls to regulate Pd surrounding microenvironment and interaction with substrates. As a result, both the dehydrogenation coupling of organosilane and hydrogenation of halogenated nitrobenzenes show that their activity and selectivity can be greatly promoted upon hydrophobic modification due to the favorable substrate enrichment and regulated interactions between Pd and the modified MOF hosts, far surpassing the traditional supported or surfactant-protected Pd NPs. We envision metal NPs@MOF composites would be an ideal platform integrating the inherent activity of well-accessible metal sites with engineered microenvironment via readily tunable MOFs. Regulating the interaction between active sites and substrates is of great importance in catalysis. The common strategy is to modify the surface of active sites (mostly, metal nanoparticles/NPs in heterogeneous catalysts) with diverse molecules, which, unfortunately, is unfavorable to substrate accessibility and, thus, detrimental to activity. Therefore, it is highly desired to develop heterogeneous catalysts featuring naked metal NPs, which are simultaneously able to regulate interaction with substrates. This puts forward long-standing contradictory challenges on metal NP-based catalysts: (1) exposed active sites, requiring naked metal surface, for their good accessibility; (2) functional molecules around active sites, affording tunable interaction with substrates, for enhanced activity and selectivity. To meet the above challenges, we judiciously encapsulate surface-naked metal NPs into MOFs, achieving tunable interaction with substrates by engineering the MOF pore wall microenvironment.
- Li, Luyan,Li, Zhixin,Yang, Weijie,Huang, Yamin,Huang, Gang,Guan, Qiaoqiao,Dong, Yemin,Lu, Junling,Yu, Shu-Hong,Jiang, Hai-Long
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p. 686 - 698
(2021/02/27)
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- Oxidation of Triorganosilanes and Related Compounds by Chlorine Dioxide
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Abstract: Oxidation of triethylsilane, tert-butyldimethylsilane, dimethylphenylsilane, triphenylsilane, 1,1,1,2tetramethyl-2-phenyldisilane, tris(trimethylsilyl)silane, hexamethyldisilane, tetrakis(trimethylsilyl)silane, 1,1,3,3tetraisopropyldisiloxane with chlorine dioxide was carried out. The reaction products of studied triorganosilanes with chlorine dioxide in an acetonitrile solution were the corresponding silanols and siloxanes. A mechanism explaining the formation of products and the observed regularities of the oxidation of silanes with chlorine dioxide has been proposed. A thermochemical analysis of some possible pathways in the gas phase using methods G4, G3, M05, and in an acetonitrile solution by the SMD-M05 method was carried out. The oxidation process can occur both with the participation of ionic and radical intermediates, depending on the structure of the oxidized substrate and medium.
- Grabovskiy,Kabal’nova
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p. 2391 - 2402
(2022/01/22)
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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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- Catalytic CO2 hydrosilylation with [Mn(CO)5Br] under mild reaction conditions
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Carbon dioxide hydrosilylation with earth-abundant transition-metal catalysts is an attractive alternative for the design of greener and cost-effective synthetic strategies. Herein, simple [Mn(CO)5Br] is an efficient precatalyst in the hydrosilylation of carbon dioxide with Et3SiH under mild reaction conditions. Using THF as a solvent, triethylsilylformate Et3SiCH(O)O was obtained in 67% yield after 1 h at 50 °C and 4 bar of CO2 pressure. The selectivity of the reaction was tuned by changing the solvent to a mixture of THF and toluene producing bis(triethylsilyl)acetal (Et3SiO)2CH2 in 86% yield. The CO2 hydrosilylation was also effective at room temperature and atmospheric pressure using either THF or the mixture THF/toluene as the solvent resulting in high Et3SiH conversion (92%–99%) but with a decrease in the selectivity. Radical trapping experiments indicated the participation of radical species in the catalytic mechanism. To the best of our knowledge, this is the first report on CO2 hydrosilylation catalyzed by transition-metal radical intermediates.
- García, Juventino J.,González, Tania
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supporting information
(2021/06/07)
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- METHOD OF PREPARING SILANOLS WITH SELECTIVE CYTOCHROME P450 VARIANTS AND RELATED COMPOUNDS AND COMPOSITIONS
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This disclosure provides a method of preparing a silanol-functional organosilicon compound with a cytochrome P450 variant that facilitates the oxidization of a silyl hydride group to a silanol group in the presence of oxygen. The method includes combining the cytochrome P450 variant and an organosilicon compound having at least one silicon-bonded hydrogen atom to give a reaction mixture and exposing the reaction mixture to oxygen to oxidize the organosilicon compound, thereby preparing the silanol-functional organosilicon compound. Cytochrome P450 variants suitable for use in the method are also disclosed, along with methods for engineering and optimizing the same. Nucleic acids encoding the cytochrome P450 variants and compositions, expression vectors, and host cells including the same are also disclosed.
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Paragraph 00122-00123
(2021/08/27)
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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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- Selective Enzymatic Oxidation of Silanes to Silanols
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Compared to the biological world's rich chemistry for functionalizing carbon, enzymatic transformations of the heavier homologue silicon are rare. We report that a wild-type cytochrome P450 monooxygenase (P450BM3 from Bacillus megaterium, CYP102A1) has promiscuous activity for oxidation of hydrosilanes to give silanols. Directed evolution was applied to enhance this non-native activity and create a highly efficient catalyst for selective silane oxidation under mild conditions with oxygen as the terminal oxidant. The evolved enzyme leaves C?H bonds present in the silane substrates untouched, and this biotransformation does not lead to disiloxane formation, a common problem in silanol syntheses. Computational studies reveal that catalysis proceeds through hydrogen atom abstraction followed by radical rebound, as observed in the native C?H hydroxylation mechanism of the P450 enzyme. This enzymatic silane oxidation extends nature's impressive catalytic repertoire.
- Arnold, Frances H.,B?hr, Susanne,Brinkmann-Chen, Sabine,Garcia-Borràs, Marc,Houk, K. N.,Katsoulis, Dimitris E.,Roberts, John M.
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supporting information
p. 15507 - 15511
(2020/05/05)
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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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- Neutral-Eosin-Y-Photocatalyzed Silane Chlorination Using Dichloromethane
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Chlorosilanes are versatile reagents in organic synthesis and material science. A mild pathway is now reported for the quantitative conversion of hydrosilanes to silyl chlorides under visible-light irradiation using neutral eosin Y as a hydrogen-atom-transfer photocatalyst and dichloromethane as a chlorinating agent. Stepwise chlorination of di- and trihydrosilanes was achieved in a highly selective fashion assisted by continuous-flow micro-tubing reactors. The ability to access silyl radicals using photocatalytic Si?H activation promoted by eosin Y offers new perspectives for the synthesis of valuable silicon reagents in a convenient and green manner.
- Fan, Xuanzi,Xiao, Pin,Jiao, Zeqing,Yang, Tingting,Dai, Xiaojuan,Xu, Wengang,Tan, Jin Da,Cui, Ganglong,Su, Hongmei,Fang, Weihai,Wu, Jie
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supporting information
p. 12580 - 12584
(2019/08/16)
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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 0058
(2019/07/04)
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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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- Aerobic Co-/ N-Hydroxysuccinimide-Catalyzed Oxidation of p-Tolylsiloxanes to p-Carboxyphenylsiloxanes: Synthesis of Functionalized Siloxanes as Promising Building Blocks for Siloxane-Based Materials
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Synthesis of organosilicon products with a "polar" functional group within organic substituents is one of the most fundamentally and practically important challenges in today's chemistry of silicones. In our study, we suggest a solution to this problem, viz., a high-efficiency preparative method based on aerobic Co-/N-hydroxysuccinimide (NHSI) catalyzed oxidation of p-tolylsiloxanes to p-carboxyphenylsiloxanes. This approach is based on "green", commercially available, simple, and inexpensive reagents and employs mild reaction conditions: Co(OAc)2/NHSI catalytic system, O2 as the oxidant, process temperature from 40 to 60 °C, atmospheric pressure. This reaction is general and allows for synthesizing both mono- and di-, tri-, and poly(p-carboxyphenyl)siloxanes with p-carboxyphenyl groups at 1,1-, 1,3-, 1,5-, and 1,1,1-positions. All the products were obtained and isolated in gram amounts (up to 5 g) and in high yields (80-96%) and characterized by NMR, ESI-HRMS, GPC, IR, and X-ray data: p-carboxyphenylsiloxanes in crystalline state form HOF-like structures. Furthermore, it was shown that the suggested method is applicable for the oxidation of organic alkylarene derivatives (Ar-CH3, Ar-CH2-R) to the corresponding acids and ketones (Ar-C(O)OH and Ar-C(O)-R), as well as hydride silanes ([Si]-H) to silanols ([Si]-OH). The possibility of synthesizing monomeric (methyl) and polymeric (siloxane-containing PET analogue, Sila-PET) esters based on 1,3-bis(p-carboxyphenyl)disiloxane was studied. These processes occur with retention of the organosiloxane frame and allow to obtain the corresponding products in 90 and 99% yields.
- Goncharova, Irina K.,Silaeva, Kseniia P.,Arzumanyan, Ashot V.,Anisimov, Anton A.,Milenin, Sergey A.,Novikov, Roman A.,Solyev, Pavel N.,Tkachev, Yaroslav V.,Volodin, Alexander D.,Korlyukov, Alexander A.,Muzafarov, Aziz M.
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supporting information
p. 2143 - 2151
(2019/02/05)
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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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- 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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- Asymmetric Bisvinylogous Aldolation of Aldehydes via 2-Oxonia-Cope Rearrangement Enabling Total Stereochemical Control
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Highly stereoselective 2-oxonia-Cope rearrangement reactions between newly designed bisvinylogous aldolation synthons and aldehydes, which can provide ?-hydroxy-α,β,γ,δ-unsaturated esters with excellent enantioselectivities, as well as with unprecedented
- Woody, David,Padarti, Akhil,Han, Hyunsoo
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supporting information
p. 2472 - 2476
(2018/04/25)
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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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- 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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- Hydrogenation of silyl formates: sustainable production of silanol and methanol from hydrosilane and carbon dioxide
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A new process for simultaneously obtaining two chemical building blocks, methanol and silanol, was realized starting from silyl formates which can be derived from silane and carbon dioxide. Understanding the reaction mechanism enabled us to improve the reaction efficiency by the addition of a small amount of methanol.
- Koo, Jangwoo,Kim, Seung Hyo,Hong, Soon Hyeok
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p. 4995 - 4998
(2018/05/23)
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- Ruthenacyclic Carbamoyl Complexes: Highly Efficient Catalysts for Organosilane Hydrolysis
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The ruthenacyclic carbamoyl complexes [RuX{2-NHC(O)C5H3NR}(CO)2(NCMe)] (R = H and Me; X = Br and SC6H3-o,o-Me2) are excellent catalysts for the hydrolysis of organosilanes, particularly towards primary silanes, generating hydrogen under ambient conditions within seconds. These complexes are structural mimics of the [Fe]-hydrogenase active site and like the natural enzyme, a labile ligand at the sixth coordination site is essential to the catalytic activity.
- Barik, Chandan Kr,Ganguly, Rakesh,Li, Yongxin,Leong, Weng Kee
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p. 4982 - 4986
(2018/12/11)
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- Aerobic Co or Cu/NHPI-catalyzed oxidation of hydride siloxanes: Synthesis of siloxanols
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A highly efficient preparative method for the synthesis of siloxanols based on aerobic Co(OAc)2 or Cu(OAc)2/NHPI-catalyzed oxidation of hydride siloxanes using "green", commercially available, simple inexpensive reagents and mild reaction conditions has been proposed. This is a general reaction for the synthesis of mono-, oligo- and polymeric siloxanols with various structures (linear, branched and cyclic).
- Arzumanyan, Ashot V.,Goncharova, Irina K.,Novikov, Roman A.,Milenin, Sergey A.,Boldyrev, Konstantin L.,Solyev, Pavel N.,Tkachev, Yaroslav V.,Volodin, Alexander D.,Smol'Yakov, Alexander F.,Korlyukov, Alexander A.,Muzafarov, Aziz M.
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supporting information
p. 1467 - 1471
(2018/04/12)
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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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- 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 0016; 0025; 0026
(2017/07/12)
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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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- 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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- Palladium on Charcoal Catalyzed 3,4-Hydroperoxidation of α-Substituted Enals with Triethylsilane and Water
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Aldehyde α-hydroperoxides can be accessed from α-substituted acroleins with triethylsilane and water under Pd/C catalysis and aerobic conditions. The reaction is composed of a Pd/C-catalyzed conjugate reduction step and a hydroperoxidation step. The hydroperoxidation takes place via autoxidation of sufficiently stable enols formed in situ by transfer hydrogenation. Upon reduction, 2,2-disubstituted 1,2-diols are obtained directly from aldehydes.
- Tuokko, Sakari,Pihko, Petri M.
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supporting information
p. 1649 - 1652
(2016/07/06)
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- Evaluation of AgPd Nanoshells in Dual Catalysis: One-Pot Silane Oxidation and Reduction of Organic Compounds
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AgPd nanoshells (AgPd NSs) were used as dual catalysts for hydrogen production and reduction of organic compounds in a one-pot protocol. AgPd NSs were very efficient catalysts for the reduction of several functional groups, including alkenes, alkynes, imines, nitro compounds, and azides. Excellent chemoselectivities were observed for α,β-unsaturated ketones, esters, and cinnamonitrile. Also, deuterium-labeled compounds were prepared by using D2O instead of H2O. A packed-bed reactor containing the immobilized AgPd NSs in silica (AgPd/SiO2) was designed to be used in continuous-flow conditions. An optimized flow system with AgPd NSs was able to give the desired compounds in high conversions with 30–60 min residence time (tR).
- Kisukuri, Camila M.,Reis, Jo?o L. M. S.,Rodrigues, Thenner S.,Camargo, Pedro H. C.,Andrade, Leandro H.
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p. 3657 - 3662
(2016/12/14)
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- Catalytic reduction of CO2with organo-silanes using [Ru3(CO)12]
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The reaction of carbon dioxide with Et3SiH in the presence of catalytic amounts of [Ru3(CO)12] as a catalytic precursor was achieved to produce silyl formate (Et3SiOCOH) 1s with a TON of 9000. A similar reaction in the presence of KF yielded potassium formate (8s) in a one-pot protocol with high selectivity using water or MeCN as the solvent. In the current report the complete reduction of carbon dioxide to methane was achieved, with the use of a more reactive silane (phenylsilane). A catalytically relevant species was the ruthenium cluster [H4Ru4(CO)12]. This is the second report on the hydrosilylation of carbon dioxide catalyzed by highly active and readily available ruthenium clusters and this is the first report of hydrosilylation of CO2to methane.
- Jurado-Vázquez, Tamara,Ortiz-Cervantes, Carmen,García, Juventino J.
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- Synthesis of Ethers via Reaction of Carbanions and Monoperoxyacetals
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Although transfer of electrophilic alkoxyl ("RO+") from organic peroxides to organometallics offers a complement to traditional methods for etherification, application has been limited by constraints associated with peroxide reactivity and stability. We now demonstrate that readily prepared tetrahydropyranyl monoperoxyacetals react with sp3 and sp2 organolithium and organomagnesium reagents to furnish moderate to high yields of ethers. The method is successfully applied to the synthesis of alkyl, alkenyl, aryl, heteroaryl, and cyclopropyl ethers, mixed O,O-acetals, and S,S,O-orthoesters. In contrast to reactions of dialkyl and alkyl/silyl peroxides, the displacements of monoperoxyacetals provide no evidence for alkoxy radical intermediates. At the same time, the high yields observed for transfer of primary, secondary, or tertiary alkoxides, the latter involving attack on neopentyl oxygen, are inconsistent with an SN2 mechanism. Theoretical studies suggest a mechanism involving Lewis acid promoted insertion of organometallics into the O-O bond.
- Kyasa, ShivaKumar,Meier, Rebecca N.,Pardini, Ruth A.,Truttmann, Tristan K.,Kuwata, Keith T.,Dussault, Patrick H.
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p. 12100 - 12114
(2016/01/09)
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- Selective Oxidation with Aqueous Hydrogen Peroxide by [PO4{WO(O2)2}4]3- Supported on Zinc-Modified Tin Dioxide
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We prepared supported phosphorus-containing tetranuclear peroxotungstate ([PO4{WO(O2)2}4]3-, denoted by PW4) catalysts by using zinc-modified SnO2 supports with different zinc contents [PW4-Zn(x)/SnO2, in which x denotes the zinc content (wt%)]. The supported catalysts, in particular PW4-Zn(0.8)/SnO2, could act as efficient and reusable heterogeneous catalysts for selective oxidation with aqueous H2O2 as the terminal oxidant. The catalytic performance of PW4-Zn(0.8)/SnO2 was much superior to those of the corresponding homogeneous analogue THA3PW4 (THA=tetra-n-hexylammonium) and the previously reported tungstate-based heterogeneous catalysts such as our W-Zn/SnO2. In the presence of PW4-Zn(0.8)/SnO2, various types of organic substrates such as alkenes, amines, silanes, and sulfides could be converted into the corresponding oxygenated products in high to excellent yields by using near-stoichiometric amounts of H2O2 with respect to the substrates (typically 1.2 equiv.). The PW4 species interacting with highly dispersed Zn2+ species on SnO2 likely plays an important role in the present oxidation.
- Nojima, Susumu,Kamata, Keigo,Suzuki, Kosuke,Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 1097 - 1104
(2015/04/14)
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- Hydrolysis and Methanolysis of Silanes Catalyzed by Iridium(III) Bis-N-Heterocyclic Carbene Complexes: Influence of the Wingtip Groups
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New [Ir(CH3CN)2(I)2{κC,C′-bis(NHC)}]BF4 complexes featuring bis-NHC ligands with a methylene bridge and different N substitution (-CH2CH2CH2CH3 and -CH2CH2OPh) were synthesized. NMR studies and X-ray diffraction structures evidenced that the wingtip group -CH2CH2OPh presents a hemilabile behavior in solution, with the oxygen atom coordinating and dissociating at room temperature, which contrasts with the strong coordination of the ether functions in the complex [Ir(I)2{κC,C′,O,O′-bis(NHCOMe)}]BF4 (bis(NHCOMe) = methylenebis(N,N′-bis(2-methoxyethyl)imidazol-2-ylidene)), previously reported by us. These complexes proved to be efficient catalysts for the hydrolysis and methanolysis of silanes, affording molecular hydrogen and silyl alcohols or silyl ethers as the main reaction products in excellent yields. The hydrogen generation rates were very much dependent on the nature of the hydrosilane and the coordination ability of the wingtip group. The latter also played a key role in the recyclability of the catalytic system. (Chemical Equation Presented).
- Aliaga-Lavrijsen, Mélanie,Iglesias, Manuel,Cebollada, Andrea,Garcés, Karin,García, Nestor,Sanz Miguel, Pablo J.,Fernández-Alvarez, Francisco J.,Pérez-Torrente, Jesús J.,Oro, Luis A.
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p. 2378 - 2385
(2015/06/23)
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- Stereoselective Catalysis Achieved through in Situ Desymmetrization of an Achiral Iron Catalyst Precursor
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Stereoselective catalysis is described that proceeds with catalyst control but without the need to synthesize preformed chiral catalysts or ligands. Iron-based catalysts were discovered to effect the stereoselective polymerization of lactides starting from a single achiral precursor and the proper choice of an achiral silanol additive. Spectroscopic analysis of the polymer revealed that the stereoselectivity originates from an enantiomorphic site rather than a chain end stereocontrol mechanism. Iron intermediates that are stereogenic at iron are proposed to form in situ as a result of desymmetrization that occurs from a change in the metal coordination number. The proposed mechanism is supported by a combination of spectroscopic measurements, model complexes, kinetic measurements, and DFT calculations.
- Manna, Cesar M.,Kaur, Aman,Yablon, Lauren M.,Haeffner, Fredrik,Li, Bo,Byers, Jeffery A.
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supporting information
p. 14232 - 14235
(2015/11/27)
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- Iridium-catalyzed hydrogen production from hydrosilanes and water
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The iridium(III) complex [Ir(H)(CF3SO3)(NSiN)(coe)] (NSiN=fac-coordinated bis(pyridine-2-yloxy)methylsilyl, coe=cyclooctene) has been proven to be an effective catalyst precursor for hydrogen production from the hydrolysis of hydrosilanes at room temperature. The reaction performance depends both on the nature of the silane and the solvent. Interestingly, high turnover frequencies of around 105 h-1 were obtained by using Et2SiH2 or (Me2HSi)2O as hydrogen sources and THF as the solvent. Moreover a mechanistic insight into this Ir-catalyzed hydrogen generation process, based on both theoretical calculations and NMR spectroscopy, is reported. The overall catalytic cycle can be viewed as a two-stage process that involves water-promoted Si-H bond activation followed by water splitting by a proton transfer. From hydrosilanes to hydrogen: The iridium(III) complex [Ir(H)(CF3SO 3)(NSiN)(coe)] is an effective homogeneous catalyst precursor for hydrogen production from the hydrolysis of hydrosilanes (NSiN=fac-coordinated bis(pyridine-2-yloxy)methylsilyl, coe=cyclooctene).
- Garces, Karin,Fernandez-Alvarez, Francisco J.,Polo, Victor,Lalrempuia, Ralte,Perez-Torrente, Jesus J.,Oro, Luis A.
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p. 1691 - 1697
(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 × 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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- 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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- 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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- Nickel-catalyzed hydrosilylation of CO2 in the Presence of Et3B for the synthesis of formic acid and related formates
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The reaction of CO2 with Et3SiH catalyzed by the nickel complex [(dippe)Ni(μ-H)]2 (1) afforded the reduction products Et3SiOCH2OSiEt3 (12%), Et 3SiOCH3 (3%), and CO, which were characterized by standard spectroscopic methods. Part of the generated CO was found as the complex [(dippe)Ni(CO)]2 (2), which was characterized by single-crystal X-ray diffraction. When the same reaction was carried out in the presence of a Lewis acid, such as Et3B, the hydrosilylation of CO2 efficiently proceeded to give the silyl formate (Et3SiOC(O)H) in high yields (85-89%), at 80 C for 1 h. Further reactivity of the silyl formate to yield formic acid, formamides, and alkyl formates was also investigated.
- Gonzalez-Sebastian, Lucero,Flores-Alamo, Marcos,Garcia, Juventino J.
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p. 7186 - 7194
(2014/01/06)
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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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- Highly efficient and selective oxidation of various substrates under mild conditions using a lanthanum-containing polyoxometalate as catalyst
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A lanthanum-containing polyoxometalate (POM) of DA11[La(PW 11O39)2] (denoted as DA-La(PW 11)2; DA = Decyltrimethylammonium cation) is highly efficient and selective for oxidation of various substrates including alkenes, alkenols, sulfides, silane and alcohol with only one equiv. H2O 2 as oxidant at 25 °C, and the POM catalyst can be easily recovered and reused for ten times without obvious decrease of catalytic activity and the yields for catalyst recovery are all above 95%. The epoxidation of cis-cyclooctene proceeds efficiently in 98% yield with only 0.08 mol% of DA-La(PW11)2, and the turnover number (TON) can reach as high as 1200 at 25 °C.
- Zhao, Shen,Jia, Yueqing,Song, Yu-Fei
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p. 188 - 194
(2013/03/28)
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- Heterogeneously catalyzed aerobic cross-dehydrogenative coupling of terminal alkynes and monohydrosilanes by gold supported on oms-2
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Cross-dehydrogenative coupling of various terminal alkynes and monohydrosilanes efficiently proceeded in the presence of gold supported on OMS-2 (Au/OMS-2) using O2 as a terminal oxidant, affording the corresponding alkynylsilanes in moderate to high yields (see picture). The observed catalysis was truly heterogeneous, and the catalyst could be reused at least ten times without a significant loss of its high catalytic performance. Copyright
- Yamaguchi, Kazuya,Wang, Ye,Oishi, Takamichi,Kuroda, Yoshiyuki,Mizuno, Noritaka
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supporting information
p. 5627 - 5630
(2013/06/27)
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