- Unexpected silicon group transfer in difunctional alkoxy silanes
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During the hydrosilylation reaction of a difunctional silane with allyl glycidyl ether (AGE), two scrambled hydrosilylation products were produced in significant amounts. This scrambling is reaction condition dependent and has been observed in a few other examples. It appears to be the first such alkoxysilane transformation to occur under these conditions, although similar siloxane transformations have been documented. This also introduces a method of preparing certain organofunctional alkyldialkoxysilanes in high purities via hydrosilylation, where the close boiling rearrangement by-products are minimized.
- Filipkowski, Michelle A.,Petty, Herbert E.,Westmeyer, Mark D.,Schilling Jr., Curtis L.
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- N,N-Dimethylformamide-protected Fe2O3 Combined with Pt Nanoparticles: Characterization and Catalysis in Alkene Hydrosilylation
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We report a combination of N,N-dimethylformamide (DMF)-protected Fe2O3 nanoparticles (NPs) and Pt NPs for the hydrosilylation of various industrially relevant alkenes and tertiary silanes. The DMF-protected Fe2O3 and Pt NPs catalysts were characterized by transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. The catalyst of DMF-protected Fe2O3 NPs combined with Pt NPs can be recycled for five cycles by a simple extraction using hexane/DMF. The developed combination Fe2O3/Pt NPs catalyst is effective up to the 1-kilogram scale.
- Nagata, Tatsuki,Tanaka, Tatsuya,Lin, Xianjin,Kondo, Ryota,Suzuki, Takeyuki,Kanda, Yasuharu,Toyao, Takashi,Shimizu, Ken-ichi,Obora, Yasushi
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- Accelerated Anti-Markovnikov Alkene Hydrosilylation with Humic-Acid-Supported Electron-Deficient Platinum Single Atoms
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The hydrosilylation reaction is one of the largest-scale applications of homogeneous catalysis, and Pt homogeneous catalysts have been widely used in this reaction for the commercial manufacture of silicon products. However, homogeneous Pt catalysts result in considerable problems, such as undesired side reactions, unacceptable catalyst residues and disposable platinum consumption. Here, we synthesized electron-deficient Pt single atoms supported on humic matter (Pt1@AHA_U_400), and the catalyst was used in hydrosilylation reactions, which showed super activity (turnover frequency as high as 3.0×107 h?1) and selectivity (>99 %). Density functional theory calculations reveal that the high performance of the catalyst results from the atomic dispersion of Pt and the electron deficiency of the Pt1 atoms, which is different from conventional Pt nanoscale catalysts. Excellent performance is maintained during recycle experiments, indicating the high stability of the catalyst.
- Antonietti, Markus,Badamdorj, Bolortuya,Janik, Michael J.,Liu, Kairui,Yang, Fan
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supporting information
p. 24220 - 24226
(2021/10/07)
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- Cobalt bis(2-ethylhexanoate) and terpyridine derivatives as catalysts for the hydrosilylation of olefins
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A simple method for the hydrosilylation of olefins by using air-stable cobalt catalysts is developed. The catalyst system is composed of simple, cheap, and readily available cobalt(II) salts and well-defined terpyridine derivatives as cocatalysts or ligands, and the hydrosilylation processes can be processed smoothly under mild conditions without either Grignard reagents or NaHBEt3 as activator.
- Dai, Zinan,Yu, Zehao,Bai, Ying,Li, Jiayun,Peng, Jiajian
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- Highly-active, graphene-supported platinum catalyst for the solventless hydrosilylation of olefins
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Herein we report the development of the first graphene-supported platinum catalyst that has demonstrated exceptional catalytic activity and stability for hydrosilylation reactions of olefins (TOF 4.8 × 106 h-1, TON = 9.4 × 106). The catalyst also exhibited functional group tolerance over a broad range of industrially relevant substrates with minimal metal leaching. In addition, the catalyst system was successfully translated into a packed bed platform for continuous hydrosilylation reactions.
- Kong, Caleb J.,Gilliland, Stanley E.,Clark, Brian R.,Gupton, B. Frank
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supporting information
p. 13343 - 13346
(2018/12/13)
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- Manganese-Catalyzed Hydrofunctionalization of Alkenes
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The manganese-catalyzed hydrosilylation and hydroboration of alkenes has been developed using a single manganese(II) precatalyst and reaction protocol. Both reactions proceed with excellent control of regioselectivity and in high yields across a variety of sterically and electronically differentiated substrates (25 examples). Alkoxide activation, using NaOtBu, was key to precatalyst activation and reactivity. Catalysis was achieved across various functional groups and on gram-scale for both the developed methodologies with catalysts loadings as low as 0.5 mol %.
- Carney, Jonathan R.,Dillon, Barry R.,Campbell, Leonie,Thomas, Stephen P.
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supporting information
p. 10620 - 10624
(2018/07/31)
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- Mode of activation of cobalt(II) amides for catalytic hydrosilylation of alkenes with tertiary silanes
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Cobalt(II) complexes capable of catalyzing alkene hydrosilylation in the absence of external activators are rarely known, and their activation mode has remained poorly understood. We present here that cobalt(II) amide complexes, [Co(N(SiMe3)2)2] and its NHC adducts [(NHC)Co(N(SiMe3)2)2] (NHC = N-heterocyclic carbene), are effective catalysts for the hydrosilylation of alkenes with tertiary silanes. Mechanistic studies revealed that cobalt(II) amides can react with hydrosilane to form cobalt(I) species, silylamide, and hydrogen, which serves as the entry to the genuine catalytically active species, presumably cobalt(I) species, for the cobalt-catalyzed hydrosilylation reaction.
- Liu, Yang,Deng, Liang
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supporting information
p. 1798 - 1801
(2017/02/15)
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- Bench-Stable, Substrate-Activated Cobalt Carboxylate Pre-Catalysts for Alkene Hydrosilylation with Tertiary Silanes
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High-spin pyridine diimine cobalt(II) bis(carboxylate) complexes have been synthesized and exhibit high activity for the hydrosilylation of a range of commercially relevant alkenes and tertiary silanes. Previously observed dehydrogenative silylation is suppressed with the use of sterically unencumbered ligands, affording exclusive hydrosilylation with up to 4000 TON. The cobalt precatalysts were readily prepared and handled on the benchtop and underwent substrate activation, obviating the need for external reductants. The cobalt catalysts are tolerant of epoxide, amino, carbonyl, and alkyl halide functional groups, broadening the scope of alkene hydrosilylation with earth-abundant metal catalysts.
- Schuster, Christopher H.,Diao, Tianning,Pappas, Iraklis,Chirik, Paul J.
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p. 2632 - 2636
(2016/04/26)
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- Alkene Hydrosilylation Using Tertiary Silanes with α-Diimine Nickel Catalysts. Redox-Active Ligands Promote a Distinct Mechanistic Pathway from Platinum Catalysts
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Combination of the readily available α-diimine ligand, ((ArN=C(Me))2 Ar = 2,6-iPr2-C6H3), (iPrDI) with air-stable nickel(II) bis(carboxylates) generated a highly active catalyst exhibiting anti-Markovnikov selectivity for the hydrosilylation of alkenes with a variety of industrially relevant tertiary alkoxy- and siloxy-substituted silanes. A combination of the method of continuous variations with stoichiometric studies identified the formally Ni(I) hydride dimer, [(iPrDI)NiH]2 as the nickel compound formed following reduction of the carboxylate ligands. For the hydrosilylation of 1-octene with (EtO)3SiH, a rate law of [Ni]1/2[1-octene][(EtO)3SiH] in combination with deuterium-labeling studies establish dissociation of the nickel hydride dimer followed by fast and reversible alkene insertion into (iPrDI)NiH, consistent with turnover-limiting C-Si bond formation. The hydrosilylation of 1-octene with triethoxysilane, a reaction performed commercially in the silicones industry on a scale of >5000000 kg/year, was conducted on a 10 g scale with 96% yield and >98% selectivity for the desired product. Silicone cross-linking, another major industrial application of homogeneous hydrosilylation, was also demonstrated using the air-stable nickel and ligand precursors.
- Pappas, Iraklis,Treacy, Sean,Chirik, Paul J.
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p. 4105 - 4109
(2016/07/12)
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- Hydrosilylation of alkenes catalyzed by rhodium with polyethylene glycol-based ionic liquids as ligands
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A series of polyethylene glycol-functionalized imidazolium ionic liquids has been prepared and characterized. These ionic liquids have been successfully applied in the hydrosilylation of alkenes catalyzed by rhodium complexes. The effects of the length of the polyether chain, the amount of ionic liquid, and the reaction temperature on the catalytic performance of hydrosilylation have been investigated. Furthermore, the catalytic system has been tested for the hydrosilylation of different alkenes with triethoxysilane. The new catalytic system exhibits both excellent catalytic activity and selectivity under low-temperature conditions. The catalyst system could be recycled five times with slightly deactivation.
- Xu, Yisong,Bai, Ying,Peng, Jiajian,Li, Jiayun,Xiao, Wenjun,Lai, Guoqiao
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- RHODIUM(II) COMPLEXES AS HYDROSILYLATION AND HYDROGENATION CATALYSTS
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Two phosphine-rhodium(II) complexes, bis(tris-o-tolylphosphine)dichlororhodium(II) and bis(tricyclohexylphosphine)dichlororhodium(II), have been found to be active catalysts for the hydrosilylation of a variety of organic substrates, and, in conjunction with triethylaluminum, to be hydrogenation catalysts.
- Howe, J.P.,Lung, K.,Nile, Terence A.
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p. 401 - 406
(2007/10/02)
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