- Selective Electrochemical Hydrolysis of Hydrosilanes to Silanols via Anodically Generated Silyl Cations
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The first electrochemical hydrolysis of hydrosilanes to silanols under mild and neutral reaction conditions is reported. The practical protocol employs commercially available and cheap NHPI as a hydrogen-atom transfer (HAT) mediator and operates at room temperature with high selectivity, leading to various valuable silanols in moderate to good yields. Notably, this electrochemical method exhibits a broad substrate scope and high functional-group compatibility, and it is applicable to late-stage functionalization of complex molecules. Preliminary mechanistic studies suggest that the reaction appears to proceed through a nucleophilic substitution reaction of an electrogenerated silyl cation with H2O.
- Liang, Hao,Wang, Lu-Jun,Ji, Yun-Xing,Wang, Han,Zhang, Bo
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supporting information
p. 1839 - 1844
(2020/12/01)
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- Metal-free hydrogen evolution cross-coupling enabled by synergistic photoredox and polarity reversal catalysis
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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.
- Cao, Jilei,Lu, Kanghui,Ma, Lishuang,Yang, Xiaona,Zhou, Rong
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supporting information
p. 8988 - 8994
(2021/11/23)
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- METHOD FOR PRODUCING SILANOLS AND NOVEL SILANOLS
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PROBLEM TO BE SOLVED: To provide a method for efficiently producing silanols useful as functional chemicals, and to provide novel silanols. SOLUTION: There is provided a method for producing silanols including a reaction step of reacting alkoxysilanes having Si-OR bonds (R represents a hydrocarbon group having 1 to 6 carbon atoms) with water or heavy water in the presence of a catalyst, wherein a method for producing silanols having an Si-OR' bond (R' represents a hydrogen atom or a deuterium atom) is characterized in that the catalyst is an inorganic solid acid catalyst having a regular pore structure. There is also provided novel silanols obtained thereby. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0053-0054; 0059; 0081-0082
(2021/08/13)
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- Synthesis of a Gold–Metal Oxide Core–Satellite Nanostructure for In Situ SERS Study of CuO-Catalyzed Photooxidation
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This work reports on an assembling–calcining method for preparing gold–metal oxide core–satellite nanostructures, which enable surface-enhanced Raman spectroscopic detection of chemical reactions on metal oxide nanoparticles. By using the nanostructure, we study the photooxidation of Si?H catalyzed by CuO nanoparticles. As evidenced by the in situ spectroscopic results, oxygen vacancies of CuO are found to be very active sites for oxygen activation, and hydroxide radicals (*OH) adsorbed at the catalytic sites are likely to be the reactive intermediates that trigger the conversion from silanes into the corresponding silanols. According to our finding, oxygen vacancy-rich CuO catalysts are confirmed to be of both high activity and selectivity in photooxidation of various silanes.
- Bai, Lu,Fan, Chenghao,Hu, Yanfang,Li, Yonglong,Liu, Jun,Shi, Faxing,Xie, Wei,Yang, Ling,Zhang, Kaifu,Zhao, Yaran
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p. 18003 - 18009
(2020/08/21)
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- Highly Selective Hydroxylation and Alkoxylation of Silanes: One-Pot Silane Oxidation and Reduction of Aldehydes/Ketones
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An efficient chemoselective iridium-catalyzed method for the hydroxylation and alkoxylation of organosilanes to generate hydrogen gas and silanols or silyl ethers was developed. A variety of sterically hindered silanes with alkyl, aryl, and ether groups were tolerated. Furthermore, this atom-economical catalytic protocol can be used for the synthesis of silanediols and silanetriols. A one-pot silane oxidation and chemoselective reduction of aldehydes/ketones was also realized.
- Luo, Nianhua,Liao, Jianhua,Ouyang, Lu,Wen, Huiling,Zhong, Yuhong,Liu, Jitian,Tang, Weiping,Luo, Renshi
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p. 165 - 171
(2020/01/21)
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- Selective Manganese-Catalyzed Oxidation of Hydrosilanes to Silanols under Neutral Reaction Conditions
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The first manganese-catalyzed oxidation of organosilanes to silanols with H2O2 under neutral reaction conditions has been accomplished. A variety of organosilanes with alkyl, aryl, alknyl, and heterocyclic substituents were tolerated, as well as sterically hindered organosilanes. The oxidation appears to proceed by a concerted process involving a manganese hydroperoxide species. Featuring mild reaction conditions, fast oxidation, and no waste byproducts, the protocol allows a low-cost, eco-benign synthesis of both silanols and silanediols.
- Wang, Kaikai,Zhou, Jimei,Jiang, Yuting,Zhang, Miaomiao,Wang, Chao,Xue, Dong,Tang, Weijun,Sun, Huamin,Xiao, Jianliang,Li, Chaoqun
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supporting information
p. 6380 - 6384
(2019/05/06)
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- Metal-free visible-light-mediated aerobic oxidation of silanes to silanols
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Oxidation of silanes into silanols using water/air has attracted considerable attention. The known methods with no exception required a metal catalyst. Herein we report the first metal-free method: 2 mol% Rose Bengal as the catalyst, air (O2) as the oxidant, water as the additive and under visible light irradiation. While this method produces various silanols in a simple, cost-effective, efficient (92%–99% yields) and scalable fashion, its reaction mechanism is very different than the reported ones associated with metal catalysis.
- Wang, Jing,Li, Bin,Liu, Li-Chuan,Jiang, Chenran,He, Tao,He, Wei
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p. 1594 - 1599
(2018/08/22)
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- Ruthenacyclic Carbamoyl Complexes: Highly Efficient Catalysts for Organosilane Hydrolysis
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The ruthenacyclic carbamoyl complexes [RuX{2-NHC(O)C5H3NR}(CO)2(NCMe)] (R = H and Me; X = Br and SC6H3-o,o-Me2) are excellent catalysts for the hydrolysis of organosilanes, particularly towards primary silanes, generating hydrogen under ambient conditions within seconds. These complexes are structural mimics of the [Fe]-hydrogenase active site and like the natural enzyme, a labile ligand at the sixth coordination site is essential to the catalytic activity.
- Barik, Chandan Kr,Ganguly, Rakesh,Li, Yongxin,Leong, Weng Kee
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p. 4982 - 4986
(2018/12/11)
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- Renewable Isohexide-Based, Hydrolytically Degradable Poly(silyl ether)s with High Thermal Stability
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Several degradable poly(silyl ether)s (PSEs) have been synthesized by dehydrogenative cross-coupling between bio-based 1,4:3,6-dianhydrohexitols (isosorbide and isomannide) and commercially available hydrosilanes. An air-stable manganese salen nitrido complex [MnVN(salen-3,5-tBu2)] was employed as the catalyst. High-molecular-weight polymer was obtained from isosorbide and diphenylsilane (Mn up to 17000 g mol?1). Thermal analysis showed that these PSEs possessed high thermal stability with thermal decomposition temperatures (T?5 %) of 347–446 °C and glass transition temperatures of 42–120 °C. Structure–property analysis suggested that steric bulk and molecular weight have a significant influence to determine the thermal properties of synthesized polymers. Importantly, these polymers were degraded effectively to small molecules under acidic and basic hydrolysis conditions.
- Vijjamarri, Srikanth,Hull, Marianne,Kolodka, Edward,Du, Guodong
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p. 2881 - 2888
(2018/09/18)
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- Single-Site AuI Catalyst for Silane Oxidation with Water
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Single-site Au anchored on mpg-C3N4 (519 ppm Au loading) is developed as a highly active, selective, and stable catalyst for the oxidation of silanes with water with a turnover frequency as high as 50 200 h?1, far exceeding most known catalysts based on total gold content. Other hydrosilanes bearing unsaturated functional groups also lead to corresponding silanols under mild reaction conditions without formation of any side products in good or excellent yields. The spherical aberration correction electron microscopy and extended X-ray absorption fine structure measurements both confirm the atomic dispersion of Au atoms stabilized by mpg-C3N4. The coordination of the catalytically active AuI by three nitrogen or carbon atoms in the tri-s-triazine repeating units not only prevents the Au atoms from aggregation, but also renders the surface AuI highly active, which is completely different than homogeneous AuI species.
- Chen, Zheng,Zhang, Qi,Chen, Wenxing,Dong, Juncai,Yao, Hurong,Zhang, Xiangbo,Tong, Xuanjue,Wang, Dingsheng,Peng, Qing,Chen, Chen,He, Wei,Li, Yadong
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- Silanol Compound, Composition, and Method for Producing Silanol Compound
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The purpose of the present invention is to provide silanol compounds that can be used as raw materials of siloxane compounds and the like, and a composition of the silanol compounds, as well as to provide a production method that makes it possible to produce silanol compounds at excellent yield. A composition comprising 5 mass % to 100 mass % of a silanol compound represented by Formulas (A) to (C) can be prepared by devising to produce silanol compounds under water-free conditions, to produce silanol compounds in a solvent having the effect of suppressing the condensation of silanol compounds, and to perform other such processes, the composition being able to be used as a raw material or the like of siloxane compounds because the silanol compounds can be stably present in the resulting composition.
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Paragraph 0175; 0176; 0177
(2017/07/14)
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- A bentonite-gold nanohybrid as a heterogeneous green catalyst for selective oxidation of silanes
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A highly efficient, environmentally benign and reusable heterogeneous bentonite-gold nanohybrid catalyst was designed and synthesized. This heterogeneous catalyst could efficaciously catalyse the oxidation of organosilanes to silanols. The reaction is 98.7% atom economical and the products were obtained in excellent yield without the formation of disiloxanes as byproducts. The catalyst was also well applicable for the gram scale preparation of silanols.
- Maya,John, Jubi,Varma, R. Luxmi
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supporting information
p. 10625 - 10628
(2016/09/02)
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- In a method of manufacturing a condition anhyride silanolated
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PROBLEM TO BE SOLVED: To provide a method capable of synthesizing silanol under an anhydrous condition and a mild condition, adapting to substrates having various substituents, and producing siloxanes freely at an excellent yield, while having high structure controllability.SOLUTION: By a hydrogen addition reaction in which benzyloxy-substituted silanes are used as a silanol precursor, and a metal in the group 9 or 10 on the periodic table or a metal compound is used as a catalyst, corresponding silanols can be produced safely and easily at a high yield under an anhydrous condition and a mild condition, and especially object silanols can be isolated easily by using a carbon-carrying catalyst.
- -
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Paragraph 0031
(2018/03/24)
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- O2-enhanced catalytic activity of gold nanoparticles in selective oxidation of hydrosilanes to silanols
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O2 acts as a nonconsumed activator for gold nanoparticles (AuNPs) in the oxidation of hydrosilanes to silanols with water under O2 atmosphere, providing an acceleration of more than 200 times relative to the reaction rate under Ar atmosphere. The AuNP catalyst under aerobic conditions exhibits high activity in the oxidation with high turnover numbers (1230000). Various hydrosilanes including less-reactive bulky ones can be converted to the corresponding silanols in excellent yields. Moreover, the present AuNP catalyst is reusable while maintaining the high performance.
- Urayama, Teppei,Mitsudome, Takato,Maeno, Zen,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 1062 - 1064
(2015/09/02)
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- Mild and selective catalytic oxidation of organic substrates by a carbon nanotube-rhodium nanohybrid
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A heterogeneous catalyst was assembled by stabilization of rhodium nanoparticles on carbon nanotubes. The nanohybrid was used for the catalytic aerobic oxidation of diverse substrates such as hydroquinones, hydroxylamines, silanes, hydrazines and thiols, at room temperature. The system proved very efficient on the investigated substrates and demonstrated high selectivity.
- Donck, Simon,Gravel, Edmond,Li, Alex,Prakash, Praveen,Shah, Nimesh,Leroy, Jocelyne,Li, Haiyan,Namboothiri, Irishi N. N.,Doris, Eric
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p. 4542 - 4546
(2015/09/01)
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- Nonhydrolytic synthesis of silanols by the hydrogenolysis of benzyloxysilanes
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The hydrogenolysis of benzyloxysilanes was smoothly catalyzed by Pd/C in THF to give corresponding silanols under nonhydrolytic conditions. The reaction proved to be applicable to various benzyloxysilanes giving silanemonools, diol, and triol.
- Igarashi, Masayasu,Matsumoto, Tomohiro,Sato, Kazuhiko,Ando, Wataru,Shimada, Shigeru
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supporting information
p. 429 - 431
(2014/04/17)
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- Plasma synthesis of carbon nanotube-gold nanohybrids: Efficient catalysts for green oxidation of silanes in water
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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.
- Liu, Ting,Yang, Fan,Li, Yongfeng,Ren, Liang,Zhang, Liqiang,Xu, Kai,Wang, Xian,Xu, Chunming,Gao, Jinsen
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p. 245 - 250
(2014/01/06)
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- Highly selective oxidation of organosilanes with a reusable nanoporous silver catalyst
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Room temperature highly selective oxidation of organosilanes to organosilanols and organosilyl ethers is achieved in liquid-phase with dealloyed nanoporous silver catalysts. In both cases, aromatic and aliphatic silanes can be effectively converted into the corresponding silanols and silyl ethers by using water and alcohols as oxidant, respectively. Moreover, hydrogen gas is the only by-product and the catalyst can be recycled for several times without evident loss of activity and selectivity.
- Li, Zhiwen,Zhang, Congcong,Tian, Jing,Zhang, Zhonghua,Zhang, Xiaomei,Ding, Yi
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- Nanoporous palladium catalyzed silicon-based one-pot cross-coupling reaction of aryl iodides with organosilanes
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One-pot cross-coupling of aryl iodides with organosilanes is realized in excellent yield by utilizing dealloyed nanoporous palladium as a sustainable and heterogeneous catalyst. The reaction is completed under mild conditions and the catalyst can be reused several times without evident loss of its catalytic activity. This journal is the Partner Organisations 2014.
- Li, Zhiwen,Lin, Sha,Ji, Lisha,Zhang, Zhonghua,Zhang, Xiaomei,Ding, Yi
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p. 1734 - 1737
(2014/06/09)
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- Gold nanoparticles supported on the periodic mesoporous organosilica SBA-15 as an efficient and reusable catalyst for selective oxidation of silanes to silanols
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Gold nanoparticles are confined and stabilized within the channels of SBA-15 through the poly(ionic liquid) brushes that are anchored onto the pore walls of SBA-15. The supported gold catalyst exhibited remarkably high catalytic activities for selective oxidation of silanes into silanols using water as an oxidant without the use of organic solvents.
- Ma, Lina,Leng, Wenguang,Zhao, Yaopeng,Gao, Yanan,Duan, Hongdong
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p. 6807 - 6810
(2014/02/14)
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- Catalytic hydrogen evolution from hydrolytic oxidation of organosilanes with silver nitrate catalyst
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In the light of uncertainty over the amount of recoverable fossil fuel reserves, hydrogen is touted to be a promising energy carrier in the future. Nevertheless, hydrogen storage remains a daunting challenge but a potential reaction for the generation of hydrogen on demand is the hydrolytic oxidation of organosilanes. Here, we demonstrate that silver nitrate, a readily available ionic salt, can catalyze the hydrolysis of organosilanes to produce hydrogen and organosilanols. In particular, turnover numbers and turnover frequencies in excess of 5 × 103and 102min-1respectively are obtainable for the hydrolysis of triethylsilane at room temperature. This proposed silver nitrate mediated system is, by far, the simplest and cheapest catalytic hydrolysis of organosilanes. Results from the kinetic studies suggested a mechanistic scenario in which the hydrolysis of organosilanes is third order overall and first order in organosilane, water, and catalyst. The high hydrogen yield observed makes the silver nitrate catalyst an attractive material for hydrogen evolution. This journal is
- Teo, Alan Kay Liang,Fan, Wai Yip
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p. 37645 - 37648
(2015/02/19)
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- Catalytic hydrogen evolution from hydrolytic oxidation of organosilanes with silver nitrate catalyst
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In the light of uncertainty over the amount of recoverable fossil fuel reserves, hydrogen is touted to be a promising energy carrier in the future. Nevertheless, hydrogen storage remains a daunting challenge but a potential reaction for the generation of hydrogen on demand is the hydrolytic oxidation of organosilanes. Here, we demonstrate that silver nitrate, a readily available ionic salt, can catalyze the hydrolysis of organosilanes to produce hydrogen and organosilanols. In particular, turnover numbers and turnover frequencies in excess of 5 × 103 and 102 min-1 respectively are obtainable for the hydrolysis of triethylsilane at room temperature. This proposed silver nitrate mediated system is, by far, the simplest and cheapest catalytic hydrolysis of organosilanes. Results from the kinetic studies suggested a mechanistic scenario in which the hydrolysis of organosilanes is third order overall and first order in organosilane, water, and catalyst. The high hydrogen yield observed makes the silver nitrate catalyst an attractive material for hydrogen evolution. the Partner Organisations 2014.
- Teo, Alan Kay Liang,Fan, Wai Yip
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p. 37645 - 37648
(2014/11/27)
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- Organocatalytic oxidation of organosilanes to silanols
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The oxidation of organosilanes to silanols constitutes an attractive transformation for both industry and academia. Bypassing the need for stoichiometric oxidants or precious metal catalytic complexes, the first organocatalytic oxidation of silanes has been accomplished. Catalytic amounts of 2,2,2-trifluoroacetophenone, in combination with the green oxidant H 2O2, lead to excellent to quantitative yields in a short reaction time. A variety of alkyl, aryl, alkenyl, and alkynyl substituents can be tolerated, providing an easy, cheap, efficient, and practical solution to a highly desirable transformation.
- Limnios, Dimitris,Kokotos, Christoforos G.
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p. 2239 - 2243
(2013/10/22)
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- Highly efficient generation of hydrogen from the hydrolysis of silanes catalyzed by [RhCl(CO)2]2
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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.
- Yu, Mengmeng,Jing, Huize,Fu, Xuefeng
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supporting information
p. 10741 - 10743
(2013/10/22)
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- Catalytic oxidation of silanes by carbon nanotube-gold nanohybrids
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Turning over silanes: The first nanotube-based catalytic system for silane oxidation is reported (see scheme). The reusable gold-nanotube hybrid cleanly oxidizes both alkyl and aryl silanes in high yields, under mild reaction conditions, and compares most favorably to any other catalytic system in terms of overall efficacy and turnover values. Copyright
- John, Jubi,Gravel, Edmond,Hagege, Agnes,Li, Haiyan,Gacoin, Thierry,Doris, Eric
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supporting information; experimental part
p. 7533 - 7536
(2011/10/04)
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- Catalytic hydrogen generation from the hydrolysis of silanes by ruthenium complexes
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Dimeric Ru(II) complexes Ru2(CO)4L2X 4 (L = CO or PPh3; X = Cl or Br) have been found to catalyze the hydrolysis of silanes to produce hydrogen gas and silanols with turnover numbers in excess of 104 at room temperature. Deuteration and mass spectrometric studies have established that the hydrogen gas originates from one hydrogen atom from water and the other from silane. Ruthenium hydride intermediates have been detected in the NMR spectrum during the early stage of the reaction, while the FTIR spectra of more stable complexes such as Ru(CO)2(PPh3)(THF)Br2 and Ru(CO) 2(PPh3)2(H)Br have been recorded upon completion of catalysis. A mechanism has been proposed to account for the ruthenium-catalyzed silane hydrolysis based on the experimental data.
- Tan, Sze Tat,Kee, Jun Wei,Fan, Wai Yip
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experimental part
p. 4008 - 4013
(2011/10/03)
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- Nanostructured materials as catalysts: Nanoporous-gold-catalyzed oxidation of organosilanes with water
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Pores to the fore: Nanoporous gold shows a remarkable catalytic activity for the oxidation of organosilane compounds with water. The catalyst is easily recoverable and can be reused several times without leaching and loss of activity. Copyright
- Asao, Naoki,Ishikawa, Yoshifumi,Hatakeyama, Naoya,Menggenbateer,Yamamoto, Yoshinori,Chen, Mingwei,Zhang, Wei,Inoue, Akihisa
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experimental part
p. 10093 - 10095
(2011/03/16)
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- Supported gold nanoparticle catalyst for the selective oxidation of silanes to silanols in water
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Hydroxyapatite-supported gold nanoparticles (AuHAP) can act as highly efficient and reusable catalysts for the oxidation of diverse silanes into silanols in water; this is the first catalytic methodology for the selective synthesis of aliphatic silanols using water under organic-solvent-free conditions.
- Mitsudome, Takato,Noujima, Akifumi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information; experimental part
p. 5302 - 5304
(2010/01/31)
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- A simple synthesis of octaphenylcyclotetra(siloxane)
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An essential industrial monomer octaphenylcyclotetra(siloxane) or (Ph2SiO)4 was obtained by very simple procedures, The product was confirmed by NMR, IR, MS, elemental analysis, and X-ray crystallography.
- Luo, Mei,Yan, Bing
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experimental part
p. 5208 - 5209
(2009/12/06)
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- Catalysis by cationic oxorhenium(v): Hydrolysis and alcoholysis of organic silanes
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The cationic [2-(2′-hydroxyphenyl)-2-oxazolinato(-2)]oxorhenium(v) complex 1 promotes oxidative dehydrogenation of organosilanes with water and alcohols in a catalytic manner to give excellent yields of silanols and silyl ethers, respectively. The reactions proceed conveniently under ambient and open-flask conditions with low catalyst loading (≤1 mol%). The scope of the reaction with water is quite broad and includes aliphatic, aromatic, tertiary, secondary and primary silanes. The rate of reaction depends on the catalyst and silane concentrations and kinetic isotope effect measurements demonstrate involvement of the Si-H bond in the activated complex. The most influential factor on the silane affecting reactivity is steric hindrance and a quantitative correlation with the Taft steric parameter (E) is presented. A combination of kinetic data and isotope labelling results are used to discuss plausible mechanisms for the oxidative dehydrogenation reaction pathway.
- Corbin, Rex A.,Ison, Elon A.,Abu-Omar, Mahdi M.
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experimental part
p. 2850 - 2855
(2009/06/27)
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- Supported silver-nanoparticle-catalyzed highly efficient aqueous oxidation of phenylsilanes to silanols
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Bon Apatite! Hydroxyapatite-supported silver nanoparticles act as a highly efficient heterogeneous catalyst for the oxidation of diverse phenylsilanes into silanols in water (see picture; C orange, H red, O blue, R purple, Si green), while suppressing significant condensation to the disiloxanes. The solid silver catalyst is readily reusable without any loss of activity or selectivity. (Figure Presented)
- Mitsudome, Takato,Arita, Shusuke,Mori, Haruhiko,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information; experimental part
p. 7938 - 7940
(2009/04/18)
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- Bis(2-thienyl)silanes: new, versatile precursors to arylsilanediols
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Silanediols have been shown to be effective bioisosteres for the hydrated carbonyl group. Current methods for the formation of silanediols place a number of constraints on how and where this functionality may be used. A range of arylsilanes that would allow both the formation of arylsilanediols and that are also compatible with multi-step synthetic routes, have been investigated as possible precursors to silanediols. Through this study bis(2-furyl)silanes and, in particular, bis(2-thienyl)silanes have been identified as practical precursors to arylsilanediols.
- Anderson, Thomas F.,Statham, Matthew A.J.,Carroll, Michael A.
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p. 3353 - 3355
(2007/10/03)
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- Hydrogen production from hydrolytic oxidation of organosilanes using a cationic oxorhenium catalyst
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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
- Ison, Elon A.,Corbin, Rex A.,Abu-Omar, Mahdi M.
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p. 11938 - 11939
(2007/10/03)
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- Highly Efficient Iridium-Catalyzed Oxidation of Organosilanes to Silanols
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Hydrolytic oxidation of organosilanes to the corresponding silanols can be performed highly efficiently with a catalyst system of [IrCl(C8H 12)]2 under essentially neutral and mild conditions, and various types of silanols are produced in good to excellent yields.
- Lee, Youngjun,Seomoon, Dong,Kim, Sundae,Han, Hoon,Chang, Sukbok,Lee, Phil Ho
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p. 1741 - 1743
(2007/10/03)
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- Efficient heterogeneous oxidation of organosilanes to silanols catalysed by a hydroxyapatite-bound Ru complex in the presence of water and molecular oxygen
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RuHAP is a highly selective and reusable catalyst for the oxidation of a wide variety of organosilanes to the corresponding silanols in the presence of water and molecular oxygen.
- Mori, Kohsuke,Tano, Makoto,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 1536 - 1538
(2007/10/03)
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- Synthesis of poly(dimethyldiphenylsiloxane) α,ω-diol copolymers by acid-catalyzed polycondensation
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Polycondensation of diphenylsilanediol (DFSD) and 1,3-bis(hydroxy)-tetramethyldisiloxane (D2) was carried out in solution in order to obtain low-molecular weight poly(dimethyldiphenylsiloxane)s with OH terminal groups. A cation-exchanger, Vionit CS-34C, with SO3H groups was used as catalyst for polycondensation. The copolymers obtained from two different feed ratios were analyzed by IR, 1H-NMR, DSC and POM.
- Vlad, Angelica,Cazacu, Maria,Marcu, Mihai,Racles, Carmen
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p. 919 - 924
(2007/10/03)
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- Product-Specific Methods of Syntheses of Hexaphenylcyclotrisiloxane and Octaphenylcyclotetrasiloxane - Monomers of Phenylsilicones
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Pure hexaphenylcyclotrisiloxane (P3) and octaphenylcyclotetrasiloxane (P4) were synthesized with high yields via proper choice of preparation conditions, such as catalysts, solvents and reaction temperatures, from diphenylsilanediol.Up to 98percent yield of this pure starting material can be obtained from diphenyldichlorosilane through modifying a known procedure on carefully adjusting the temperature of hydrolysis and washing procedure.This method produced pure P3 exclusively with high yield (approximately 90percent) in ethanol in the presence of concentrated sulfuric acid as the catalyst at various reaction temperatures.P4 was produced exclusively in high yield (approximately 90percent) in alcohols in the presence of sodium hydroxide.A method applying HPLC was used to analyze the reaction products quantitatively. - Key words: Hexaphenylcyclotrisiloxane; Octaphenylcyclotetrasiloxane; Diphenylsilanediol.
- Yang, Mei-Hui,Chou, Chyuan,Lin, Chih-Hwa
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p. 923 - 928
(2007/10/03)
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- Oxyfunctionalization reactions by perfluoro cis-2,3-dialkyloxaziridines. Enantioselective conversion of silanes into silanols
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Perfluoro cis-2,3-dialkyloxaziridine 2 is shown to perform the oxyfunctionalization of silanes 1 under very mild conditions to give silanols and silanediols 3 in high chemical yields and complete enantioselectivity.
- Cavicchioli, Marcello,Montanari, Vittorio,Resnati, Giuseppe
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p. 6329 - 6330
(2007/10/02)
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- Procedures for the preparation of silanols
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Two procedures are described for the preparation of silanols and silanediols from the corresponding chlorosilanes.The first procedure, a two-phase hydrolysis-extraction process, is- particularly convenient and suited to the preparation of a wide range of mono-silanols.Hydrolysis of dichlorosilanes by this procedure gives varied results depending on the structure of the dichlorosilane and specific reaction conditions.The second procedure, a modification of a published procedure, is especially beneficial for the preparation of silanols and silanediols prone to undergo self-condensation. Key words: Silicon; Hydrolysis; Self-condensation; Silanols
- Cella, James A.,Carpenter, John C.
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- The structure of 1,1,3,3,5,5-hexaphenyl-1,3,5-trisiloxane-1,5-diol
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1,1,3,3,5,5-Hexaphenyl-1,3,5-trisiloxane-1,5-diol has an approximately planar, eight-membered Si3O4H ring structure, in which cyclization is achieved through an O-H...O hydrogen bond.In addition, adjacent molecules dimerize through an eight-membered H4O4 ring to yield a stepped tricyclic array.
- Behbehani, H.,Brisdon, B. J.,Mahon, M. F.,Molloy, K. C.,Mazhar, M.
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- Metallkomplexe in Anorganichen Matrices, 5. Katalytische Silanoxidation an einem heterogenisierten Rhodium-Komplex
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A heterogenized rhodium complex, prepared by sol-gel processing of Rh(CO)Cl2 and Si(OEt)4, is shown to catalyze the conversion of the silanes H4-nSiPhn (n = 1-3) or (HMe2Si)2O to (poly)siloxanes by air or water.Using THF as a solvent, the silanoles Ph3SiOH or Ph2Si(OH)2 are obtained instead.The reaction of phenylacetic acid or acetic acid with HSiPh3 to give silyl esters is catalyzed by the same compound.
- Egger, Christian,Schubert, Ulrich
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p. 783 - 788
(2007/10/02)
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- Formation of μ-silylene μ-hydrido manganese-platinum heterobimetallics via oxidative addition of (OC)5MnSiR2H to zerovalent platinum compounds and the structure of (OC)4Mn(μ-PPh2)(μ-H)PtPh(PPh3), a product of a solvolysis of a silylene bridge
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The complexes (OC)5MnSiR2H (R = Me, Ph, Cl) react with Pt(C2H4)(PPh3)2 or Pt(PPh3)4 via oxidative addition of the Si-H bond across Pt to give the μ-silylene μ-hydrido complexes (OC)4Mn(μ-SiR2)(μ-H)-Pt(PPh3) 2. These complexes react with PEt3 to give (OC)4Mn(μ-SiR2)(μ-H)Pt(PEt3)2, react reversibly with CO to give (OC)4Mn(μ-SiR2)(μ-H)Pt(PPh3)(CO), and react with MeOH or H2O to give (OC)4Mn(μ-PPh2)(μ-H)PtPh(PPh3) (8) (a product of P-Ph bond cleavage). The structure of 8 has been determined by single-crystal X-ray diffraction. Complex 8 is monoclinic, space group P21/c, with a = 12.929 (2) A?, b = 26.382 (5) A?, c = 11.245 (2) A?, β = 110.52 (1)°, V = 3592 A?3, and Dcalcd = 1.63 g cm-3 for 7 = 4. The structure was refined to R = 0.0348 and wR = 0.0460 for the 4763 reflections with I > 3σ(I). The structure of 8 consists of distorted pseudo-square-planar Pt and pseudooctahedral Mn centers with trans phenyl and hydride ligands on Pt. The Mn and Pt atoms are separated by 2.864 (1) A? and bridged by μ-PPh2 and μ-H ligands. The position of the μ-H was located and refined. Associated bond lengths are Pt-H = 1.64 (8) A? and Mn-H = 1.80 (8) A?; 〈PtHMn = 113 (4)°.
- Powell, John,Sawyer, Jeffery F.,Shiralian, Mahmoud
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p. 577 - 583
(2008/10/08)
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- Novel n[meth)allyloxy(meth)allylphenyl]maleimides and thermosetting imido copolymers prepared therefrom
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Novel N-[(meth)allyloxy-mono-/di(meth)allylphenyl]maleimides, in admixture with at least one N-[(meth)allyloxyphenyl]maleimide, are reacted with at least one bismaleimide, and optionally a hydroxylated organosilicon compound, in the presence of an imidazole compound, to obtain mechanically improved thermosetting imido copolymerizates well adapted for the production of, e.g., coatings, adhesive bondings, laminates and composites.
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- New mechanisms for the base-catalyzed cleavage of Si-Si bonds in organopolysilanes: the base-catalyzed solvolysis of pentaphenyldisilanecarboxylic acid and pentaphenyldisilanol in ethanol/water media
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A kinetic investigation of the base-catalyzed decomposition of pentaphenyldisilanecarboxylic acid (1) and pentaphenyldisilanol (2) in ethanol/water media is reported.The solvolysis of the Si-Si bond in 2, which also is formed on the base-catalyzed decarbonylation of 1, proceeds by concurrent first-order and second-order processes.At low base concentrations where the first-order process predominates, the intermediate, triphenylsilane (3), has been isolated.Solvent isotope effects and activation parameters have been determined.Mechanisms are proposed for the two kinetically distinguishable processes for Si-Si bond cleavage in which the pentaphenyldisilanolate ion undergoes either an internal nucleophilic displacement reaction or nucleophilic attack at Si by base in the rate-determining step.A general mechanistic approach for the cleavage of Si-Si bonds in polysilanes by aqueous-alcoholic base is proposed in which polysilonate ions are formed by nucleophilic attack by base at Si which undergo internal nucleophilic attack resulting in cleavage of the Si-Si bond adjacent to the anionic termini.Subsequently, polysilanolate ions are regenerated in which the number of Si atoms is reduced by one.
- Steward, Omar W.,Williams, James L.
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p. 199 - 212
(2007/10/02)
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- Process for preparing polyisocyanato/polyisocyanurates by catalytic cyclotrimerization of polyisocyanates
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Polyisocyanurate/polyisocyanates of enhanced stability are prepared by partial catalytic cyclotrimerization of a polyisocyanate in the presence of a catalytically effective amount of an aminosilyl catalyst and wherein the cyclotrimerization reaction is terminated when a predetermined desired amount of isocyanurate groups has been attained, by adding to the reaction mixture, after the cooling thereof to a temperature of below 50° C., a reaction terminating amount of an organic catalyst deactivating compound comprising at least one free hydroxyl moiety, or the reaction product of such hydroxylated organic catalyst deactivating compound with an isocyanate.
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