597-52-4Relevant articles and documents
Heterogeneous nickel catalyst for selective hydration of silanes to silanols
Shimizu, Ken-Ichi,Shimura, Katsuya,Imaiida, Naomichi,Satsuma, Atsushi
, p. 50 - 54 (2012)
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.
Hydrosilane-assisted formation of metal nanoparticles on graphene oxide
Saito, Akinori,Kinoshita, Hiroshi,Shimizu, Ken-Ichi,Nishina, Yuta
, p. 67 - 73 (2016)
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.
Copper-Catalyzed Oxidation of Hydrosilanes: A New Method for the Synthesis of Alkyl- and Siloxysilanols
Arzumanyan, Ashot V.,Goncharova, Irina K.,Novikov, Roman A.,Milenin, Sergey A.,Muzafarov, Aziz M.
, p. 489 - 492 (2018)
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%.
METHOD OF PREPARING SILANOLS WITH SELECTIVE CYTOCHROME P450 VARIANTS AND RELATED COMPOUNDS AND COMPOSITIONS
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Paragraph 00122-00123, (2021/08/27)
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.
Cobalt single atoms anchored on nitrogen-doped porous carbon as an efficient catalyst for oxidation of silanes
Yang, Fan,Liu, Zhihui,Liu, Xiaodong,Feng, Andong,Zhang, Bing,Yang, Wang,Li, Yongfeng
, p. 1026 - 1035 (2021/02/09)
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.
Metal-free hydrogen evolution cross-coupling enabled by synergistic photoredox and polarity reversal catalysis
Cao, Jilei,Lu, Kanghui,Ma, Lishuang,Yang, Xiaona,Zhou, Rong
supporting information, p. 8988 - 8994 (2021/11/23)
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.
Integration of Pd nanoparticles with engineered pore walls in MOFs for enhanced catalysis
Li, Luyan,Li, Zhixin,Yang, Weijie,Huang, Yamin,Huang, Gang,Guan, Qiaoqiao,Dong, Yemin,Lu, Junling,Yu, Shu-Hong,Jiang, Hai-Long
, p. 686 - 698 (2021/02/27)
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.
Oxidation of Triorganosilanes and Related Compounds by Chlorine Dioxide
Grabovskiy,Kabal’nova
, p. 2391 - 2402 (2022/01/22)
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.
Visible-light photoredox-catalyzed selective carboxylation of C(sp3)?F bonds with CO2
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
supporting information, p. 3099 - 3113 (2021/11/16)
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.
Catalytic CO2 hydrosilylation with [Mn(CO)5Br] under mild reaction conditions
García, Juventino J.,González, Tania
supporting information, (2021/06/07)
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.
