16068-37-4Relevant academic research and scientific papers
Cyclization phenomena in the Sol-Gel polymerization of α,ω-bis(triethoxysilyl)alkanes and incorporation of the cyclic structures into network silsesquioxane polymers
Loy, Douglas A.,Carpenter, Joseph P.,Alam, Todd M.,Shaltout, Raef,Dorhout, Peter K.,Greaves, John,Small, James H.,Shea, Kenneth J.
, p. 5413 - 5425 (1999)
Intramolecular cyclizations during acid-catalyzed sol-gel polymerizations of α,ω-bis(triethoxysilyl)-alkanes substantially lengthen gel times for monomers with ethylene (1), propylene (2), and butylene (3) bridging groups. These cyclization reactions were found, using mass spectrometry and 29Si NMR spectroscopy, to lead preferentially to monomeric and dimeric products based on six- and seven-membered disilsesquioxane rings. 1,2-Bis(triethoxysilyl)ethane (1) reacts under acidic conditions to give a bicyclic dimer (5) that is composed of two annelated seven-membered rings. Under the same conditions, 1,3-bis(triethoxysilyl)propane (2), 1,4-bis(triethoxysilyl)butane (3), and Z-1,4-bis(triethoxysilyl)but-2-ene (10) undergo an intramolecular condensation reaction to give the six- and seven-membered cyclic disilsesquioxanes 6, 7, and 11. Subsequently, these cyclic monomers slowly react to form the tricyclic dimers 8, 9, and 12. With NaOH as polymerization catalyst, these cyclic silsesquioxanes readily reacted to afford gels that were shown by CP MAS 29Si NMR and infrared spectroscopies to retain some cyclic structures. Comparison of the porosity and microstructure of xerogels prepared from the cyclic monomers 6 and 7 with those of gels prepared directly from their acyclic precursors 2 and 3 indicates that the final pore structure of the xerogels is markedly dependent on the nature of the precursor. In addition, despite the fact that the monomeric cyclic disilsesquioxane species cannot be isolated from 1-3 under basic conditions due to their rapid rate of gelation, spectroscopic techniques also detected the presence of the cyclic structures in the resulting polymeric gels.
Sulfur-modified SBA-15 supported amorphous palladium with superior catalytic performance for aerobic oxidation of alcohols
Liu, Kun,Chen, Zhaoxiang,Hou, Zhiqiang,Wang, Yuanyuan,Dai, Liyi
, p. 935 - 942 (2014)
A series of sulfur-modified SBA-15 supported amorphous palladium catalysts are prepared, and the effects of preparation parameters on the aerobic oxidation of benzyl alcohol are systematically investigated. The optimal catalyst exhibits remarkably enhanced catalytic activity (conversion 100 % and selectivity 99 %) and could be separated conveniently. The catalysts are characterized by X-ray diffraction patterns, BET, ICP, X-ray photoelectron spectroscopy, CO chemisorption and transmitting electron microscopy, and the results show that disulfur bond framework in the optimal catalyst act as both a stable linker and a good chelator for Pd species. Pd2+ is reduced to Pd0 with the increasement of the carbon chain lengths between sulfur bonds, which is the cause of deactivation. The mechanism is that a base abstracts a proton from the coordinated alcohol to form a Pd alcoholate species that subsequently undergo b-hydride elimination to give benzyl aldehyde, which is confirmed by the catalytic and characteristic results. Springer Science+Business Media New York 2014.
SILICIUMORGANISCHE VERBINDUNGEN LXXXVIII. DISILATRANYLALKANE
Birkofer, Leonhard,Grafen, Klaus
, p. 143 - 148 (1986)
By hydrosilation of triethoxyvinylsilane (1), 1,5-hexadiene (10) and 3,3-dimethyl-3-sila-1,4-pentadiene (14) with triethoxysilane (2) we obtained 1,2-bis(triethoxysilyl)ethane (3), 1,6-bis(triethoxysilyl)hexane (11) and 1,5-bis(triethoxysilyl)-3,3-dimethyl-3-silapentane (15).The reaction of 3 with triethanolamine (4), triisopropanolamine (6) and tris(1-t-butyl-ethanol)amine (8) leads to the 1,2-disilatranylethanes 5, 7 and 9.The 1,6-disilatranylhexanes 12 and 13 are formed from 11, 4 and 6 respectively, and 15 with 4 gives 3,3-dimethyl-1,5-disilatranyl-3-silapentane (16).
Alkoxylation of 1,2-bis(methylchlorosilyl)ethylenes and -acetylenes
Lakhtin,Nosova,Kisin,Ivanov,Chernyshev
, p. 1252 - 1254 (2001)
Reactions of a series of 1,2-bis(methylchlorosilyl)ethylenes and -acetylenes MenCl3-nSi-Z-SiCl3-nMen (Z = CH=CH, C=C; n = 0-2) with ethanol and acetoxime were studied. Novel alkoxy-and isopropylideneaminooxysilanes were obtained and characterized. A relation was found between the activity of Si-Cl bonds in the reactions studied and the structure of the carbon-carbon bridge.
AN ACTIVE AND STABLE HYDROSILYLATION CATALYST: A SILICA SUPPORTED POLY-γ-MERCAPTOPROPYLSILOXANE-PLATINUM COMPLEX
Wang, Lin-Zhi,Jiang, Ying-Yan
, p. 39 - 44 (1983)
A silica-supported poly-γ-mercaptopropylsiloxane-platinum complex was prepared and used as hydrosilylation catalyst with 1-hexene and acetylene.When it was used as the catalyst for addition of triethoxysilane to 1-hexene at 80 deg C or room temperature, the product was n-hexyltriethoxysilane only, and the catalyst could be reused over twenty times (turnover numbers achieved were about 10.000) without any appreciable loss in the catalytic activity.The addition of triethoxysilane to acetylene by this catalyst at 80 deg C or room temperature under an atmospheric pressure gave vinyltriethoxysilane and bis(triethoxysilyl)ethane in good yields.
Catalysis of hydrosilylation. Part XXV. Effect of nickel(0) and nickel(II) complex catalysts on dehydrogenative silylation, hydrosilylation and dimerization of vinyltriethoxysilane
Marciniec, Bogdan,Maciejewski, Hieronim,Rosenthal, Uwe
, p. 147 - 152 (1994)
General catalysis by Ni(O) and Ni(II) phosphine and non-phosphine complexes of the competitive-consecutive reaction of vinyltriethoxysilane with triethoxysilane has been observed to give mainly products of dehydrogenative silylation and hydrogenative dimerization accompanied by products of regular hydrosilylation, disproportionation of substrates and secondary reactions of the product-bis(silyl)ethene.In an excess of vinylsilane, side reactions can be practically eliminated.Tertiary phosphine and phosphite ligands of nickel acetylacetonate (Ni(acac)2*2PR3) stop the consecutive reactions of bis(silyl)ethene but in the presence of ?-basic and bulky tricyclohexylphosphine the system catalyzes selectively the regular hydrosilylation of bis(silyl)ethene.Keywords: Nickel; Silicon; Hydrosilylation; Silane; Catalysis
Efficient magnetically separable heterogeneous platinum catalyst bearing imidazolyl schiff base ligands for hydrosilylation
Huo, Yingpeng,Hu, Jiwen,Tu, Yuanyuan,Huang, Zhenzhu,Lin, Shudong,Luo, Xiaojiong,Feng, Chao
, (2021/02/06)
Reported herein is a magnetically separable heterogeneous nano catalyst Fe3O4@SiO2-biIMI- PtCl2, which is prepared by firstly applying a SiO2 coating onto readily synthesized magnetite nanoparticles via the hydrolysis condensation of tetraethyl orthosilicate (TEOS) under basic conditions, then modifying it using aminopropyl triethoxysilane and bis(imidazole) aldehyde, and finally incorporating a PtCl2 complex via coordination chemistry. The chemical structure and morphology of the nanocatalyst as well as the valence state and content of platinum within this catalyst were carefully characterized. This catalyst can mediate the hydrosilylation between 1-octene and hydrosilane, with the conversion of 1-octene reaching up to 99%, and it shows good regioselectivity as only β-adducts are identified. In addition, this catalyst can be reused for at least 5 cycles. The hydrosilylation reaction between different olefins and hydrosilanes can also be efficiently mediated by Fe3O4@SiO2-biIMI-PtCl2.
Platinum-Pyridine Schiff base complexes immobilized onto silica gel as efficient and low cost catalyst for hydrosilylation
Huo, Yingpeng,Hu, Jiwen,Liu, Feng,Wu, Jiapei,Zhang, Yikun,Zhang, Yalan,Wang, Qianyi
, p. 812 - 818 (2021/07/25)
A heterogeneous platinum catalyst with tridentate pyridine Schiff base ligands supported on silica gel is reported. The catalyst was fully characterized via FTIR, solid-state 13C NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The catalyst showed potential application in mediating hydrosilylation reactions between olefins and hydrosilanes, and it can be reused for at least five cycles.
Platinum-Imidazolyl Schiff Base Complexes Immobilized in Periodic Mesoporous Organosilica Frameworks as Catalysts for Hydrosilylation
Huo, Yingpeng,Hu, Jiwen,Tu, Yuanyuan,Huang, Zhenzhu,Lin, Shudong,Hu, Yangfei,Feng, Chao
, (2020/05/18)
An imidazolyl Schiff base-containing periodic mesoporous organosilica (PMO) was synthesized via co-condensation reactions between a newly prepared bis (imidazolyl)imine-bridged bis silane and tetraethyl orthosilicate in the presence of cetyltrimethyl ammonium bromide as a soft template. The resultant as-synthesized PMO was then employed as a solid support for platinum catalysts. This complex was fully characterized via various techniques including FTIR, solid-state13C NMR, and 29Si-NMR spectroscopy, as well as N2 adsorption/desorption analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. In addition, the catalyst was proven to efficiently mediate hydrosilylation reactions between olefins and hydrosilanes, and it can be reused for at least five cycles without significant loss of activity.
Platinum(II) complexes bearing bulky Schiff base ligands anchored onto mesoporous SBA-15 supports as efficient catalysts for hydrosilylation
Huo, Yingpeng,Hu, Jiwen,Lin, Shudong,Ju, Xingming,Wei, Yanlong,Huang, Zhenzhu,Hu, Yangfei,Tu, Yuanyuan
, (2019/04/26)
Reported herein is an easy-to-prepare novel heterogeneous catalyst of platinum complexes bearing binary ligands of bidentate naphthalenolimine and cyclo-1,5-octadiene that are anchored onto mesoporous silica SBA-15. The presence of the binary ligands not only stabilized the platinum, but also enabled the platinum atoms to form nanoclusters with diameters of ca 1?nm, and led to high platinum loading (8.69?wt%). Moreover, the platinum catalyst exhibited high catalytic activity towards hydrosilylation of terminal alkenes and styrene with silanes under mild and solvent-free conditions, with excellent regioselectivity.
