5272-18-4Relevant articles and documents
Tellurorhodamine photocatalyzed aerobic oxidation of organo-silanes and phosphines by visible-light
Rettig, Irving D.,Van, Jackson,Brauer, Jacob B.,Luo, Wentai,McCormick, Theresa M.
, p. 5665 - 5673 (2019)
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.
Organosilane oxidation by water catalysed by large gold nanoparticles in a membrane reactor
Gitis, Vitaly,Beerthuis, Rolf,Shiju, N. Raveendran,Rothenberg, Gadi
, p. 2156 - 2160 (2014)
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.
Highly efficient generation of hydrogen from the hydrolysis of silanes catalyzed by [RhCl(CO)2]2
Yu, Mengmeng,Jing, Huize,Fu, Xuefeng
, p. 10741 - 10743 (2013)
Catalytic hydrolysis of silanes mediated by chlorodicarbonylrhodium(I) dimer [RhCl(CO)2]2 to produce silanols and dihydrogen efficiently under mild conditions is reported. Second-order kinetics and activation parameters are determined by monitoring the rate of dihydrogen evolution. The mixing of [RhCl(CO)2]2 and HSiCl 3 results in rapid formation of a rhodium silane σ complex.
Titanium-catalyzed heterogeneous oxidations of silanes, chiral allylic alcohols, 3-alkylcyclohexanes, and thianthrene 5-oxide: A comparison of the reactivities and selectivities for the large-pore zeolite Ti-β, the mesoporous Ti-MCM-41, and the layered alumosilicate Ti-ITQ-2
Adam, Waldemar,Corma, Avelino,Garcia, Hermenegildo,Weichold, Oliver
, p. 339 - 344 (2000)
A comparative study of silane oxidation, olefin epoxidation, and thianthrene 5-oxide sulfoxidation with the oxidants Ti-β/H2O2, Ti-MCM-41/t-BuOOH, and Ti-ITQ-2/t-BuOOH provides the catalytic reactivity order Ti-β > Ti-MCM-41 > Ti-ITQ-2. The steric constraints of the narrow channels make the Ti-β zeolite the most selective. For the more open structures of the Ti-MCM-41 and Ti-ITQ-2 hosts, such steric constraints are less pronounced and, therefore, a lower selectivity is exhibited by these heterogeneous catalysts. Both activate t-BuOOH for oxygen transfer through a transition structure analogous to the homogeneous Ti(Oi-Pr)4/t-BuOOH oxidant.
Synthesis of acetyldimethyl(phenyl)silane and its enantioselective conversion into (R)-(1-hydroxyethyl)dimethyl(phenyl)silane by plant cell suspension cultures of Symphytum officinale L. and Ruta graveolens L.
Tacke, Reinhold,Wagner, Stephan A.,Brakmann, Susanne,Wuttke, Frank,Eilert, Udo,et al.
, p. 13 - 18 (1993)
Starting from chlorodimethyl(phenyl)silane (3), acetyldimethyl(phenyl)silane (1) was prepared by a two-step synthesis in a total yield of 90percent PhMe2SiC(OMe)=CH2 (4) PhMe2SiC(O)Me (1)>.The prochiral acetylsilane 1 was transformed enantioselectively into (R)-(1-hydroxyethyl)dimethyl(phenyl)silane using plant cell suspension cultures of Symphytum officinale L. or Ruta graveolens L.Under preparative conditions (300-mg scale, not optimized), (R)-2 was isolated in 15percent (Symphytum) and 9percent yield (Ruta), respectively.The enantiomeric purities of the products were 81percent ee (Symphytum) and 60percent ee (Ruta), respectively.
Postsynthetic functionalization of a hollow silica nanoreactor with manganese oxide-immobilized metal nanocrystals inside the cavity
Kim, Soo Min,Jeon, Mina,Kim, Ki Woong,Park, Jaiwook,Lee, In Su
, p. 15714 - 15717 (2013)
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.
Metal-free hydrogen evolution cross-coupling enabled by synergistic photoredox and polarity reversal catalysis
Cao, Jilei,Lu, Kanghui,Ma, Lishuang,Yang, Xiaona,Zhou, Rong
, 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.
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.
