5272-18-4Relevant academic research and scientific papers
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.
Plasma synthesis of carbon nanotube-gold nanohybrids: Efficient catalysts for green oxidation of silanes in water
Liu, Ting,Yang, Fan,Li, Yongfeng,Ren, Liang,Zhang, Liqiang,Xu, Kai,Wang, Xian,Xu, Chunming,Gao, Jinsen
, p. 245 - 250 (2014)
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.
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.
Cu3(BTC)2 catalyzed oxidation of silane to silanol using TBHP or water as oxidants
Anbu, Nagaraj,Dhakshinamoorthy, Amarajothi
, p. 145 - 153 (2017)
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.
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.
Hydrogen production from hydrolytic oxidation of organosilanes using a cationic oxorhenium catalyst
Ison, Elon A.,Corbin, Rex A.,Abu-Omar, Mahdi M.
, p. 11938 - 11939 (2005)
We describe herein the novel application of a transition metal oxo complex, a cationic oxorhenium(V) oxazoline, in the production of molecular hydrogen (H2) from the catalytic hydrolytic oxidation of organosilanes. The main highlights of the reaction are quantitative hydrogen yields, low catalyst loading, ambient conditions, high selectivity for silanols, water as the only co-reagent, and no solvent requirement. The amount of hydrogen produced is proportional to the water stoichiometry. Thus, reaction mixtures of polysilyl organics such as HC(SiH3)3 and water contain potentially >6 wt % hydrogen. Kinetic and isotope labeling experiments have revealed a new mechanistic paradigm for the activation of Si-H bonds by oxometalates. Copyright
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.
Stereoselective Catalysis Achieved through in Situ Desymmetrization of an Achiral Iron Catalyst Precursor
Manna, Cesar M.,Kaur, Aman,Yablon, Lauren M.,Haeffner, Fredrik,Li, Bo,Byers, Jeffery A.
, p. 14232 - 14235 (2015)
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.
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.
A novel iron complex for highly efficient catalytic hydrogen generation from the hydrolysis of organosilanes
Liang Teo, Alan Kay,Fan, Wai Yip
, p. 7191 - 7194 (2014)
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.
