- An ultrahigh-loading single-site Zn catalyst for efficient and ambient hydrogen generation from silanes
-
A nitrogen-doped carbon-supported ultrahigh-loading single-site Zn catalyst (Zn1-N-C, 28.3 wt%) was facilely constructed by using a ball milling strategy. With atomically dispersed ZnN3O sites, the catalyst showed superior catalytic properties for the generation of H2 from silane/alcohol pairs, and scale-up and recycling tests demonstrated its great potential in practical applications.
- Chen, Hongyu,He, Qian,He, Xiaohui,Ji, Hongbing,Wang, Pengbo
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supporting information
p. 3828 - 3832
(2022/03/31)
-
- Production of acyloxysilane
-
[A] a method for producing functional chemicals useful as efficient acyloxysilane. The silanol Si-to-OH bond [a], in the presence of a catalyst, comprising the step of reacting a carboxylic acid anhydride, Si-to-OCO bond (OCO is, oxycarbonyl groups (=O) O-a C shown. ) Having an acyloxysilane manufacturing method, wherein the catalyst, or (2) (1) production of acid catalyst selected from the next acyloxysilane. (1) 3 - 15 Of the periodic table of the first group the first group element selected from the perchlorate salt, trifluoromethanesulfonic acid salt, a bis (trifluoromethanesulfonyl imide) salt, lithium hexafluorophosphate salt, chloride, or bromide; inorganic acids; or an organic acid. (2) Inorganic or organic solid acid compounds[Drawing] no
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-
Paragraph 0065-0066
(2021/10/30)
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- Hydrosilane σ-Adduct Intermediates in an Adaptive Zinc-Catalyzed Cross-dehydrocoupling of Si?H and O?H Bonds
-
Three-coordinate PhBOX (Formula presented.) ZnR (PhBOX (Formula presented.) =phenyl-(4,4-dimethyl-oxazolinato; R=Me: 2 a, Et: 2 b) catalyzes the dehydrocoupling of primary or secondary silanes and alcohols to give silyl ethers and hydrogen, with high turnover numbers (TON; up to 107) under solvent-free conditions. Primary and secondary silanes react with small, medium, and large alcohols to give various degrees of substitution, from mono- to tri-alkoxylation, whereas tri-substituted silanes do not react with MeOH under these conditions. The effect of coordinative unsaturation on the behavior of the Zn catalyst is revealed through a dramatic variation of both rate law and experimental rate constants, which depend on the concentrations of both the alcohol and hydrosilane reactants. That is, the catalyst adapts its mechanism to access the most facile and efficient conversion. In particular, either alcohol or hydrosilane binds to the open coordination site on the PhBOX (Formula presented.) ZnOR catalyst to form a PhBOX (Formula presented.) ZnOR(HOR) complex under one set of conditions or an unprecedented σ-adduct PhBOX (Formula presented.) ZnOR(H?SiR′3) under other conditions. Saturation kinetics provide evidence for the latter species, in support of the hypothesis that σ-bond metathesis reactions involving four-centered electrocyclic 2σ–2σ transition states are preceded by σ-adducts.
- Patnaik, Smita,Kanbur, Uddhav,Ellern, Arkady,Sadow, Aaron D.
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supporting information
p. 10428 - 10436
(2021/05/27)
-
- Charge Modified Porous Organic Polymer Stabilized Ultrasmall Platinum Nanoparticles for the Catalytic Dehydrogenative Coupling of Silanes with Alcohols
-
Developing an ideal stabilizer to prevent the aggregation of nanoparticles is still a big challenge for the practical application of noble metal nanocatalysts. Herein, we develop a charge (NTf2?) modified porous organic polymer (POP-NTf2) to stabilize ultrasmall platinum nanoparticles. The catalyst is characterized and applied in the catalytic dehydrogenative coupling of silanes with alcohols. The catalyst exhibits excellent catalytic performance with highly dispersed ultrasmall platinum nanoparticles (ca. 2.22?nm). Moreover, the catalyst can be reused at least five times without any performance significant loss and Pt NPs aggregation. Graphic Abstract: [Figure not available: see fulltext.]
- Chen, Chao,Cheng, Dan,Ding, Shunmin,Liang, Sanqi,Liu, Senqun,Ma, Xiaohua,Su, Tongtong,Wu, Shaohua,Zeng, Rong
-
-
- N-Heterocyclic Carbene Complexes of Nickel, Palladium, and Iridium Derived from Nitron: Synthesis, Structures, and Catalytic Properties
-
The mesoionic compound (1,4-diphenyl-1,2,4-triazol-4-ium-3-yl)phenylazanide, commonly referred to as Nitron, has been employed as a "crypto-NHC"to afford 1,2,4-triazolylidene compounds of nickel, palladium, and iridium. Specifically, Nitron reacts with NiBr2, PdCl2, and [Ir(COD)Cl]2 to afford the N-heterocyclic carbene complexes (NitronNHC)2NiBr2, (NitronNHC)2PdCl2, and (NitronNHC)Ir(COD)Cl, respectively. The lattermost compound reacts with (i) CO to afford the dicarbonyl compound (NitronNHC)Ir(CO)2Cl and (ii) CO, in the presence of PPh3, to afford the monocarbonyl compound (NitronNHC)Ir(PPh3)(CO)Cl. Structural studies on (NitronNHC)Ir(COD)Cl and (NitronNHC)Ir(CO)2Cl indicate that NitronNHC has a stronger trans influence than does Cl; furthermore, IR spectroscopic studies on (NitronNHC)Ir(CO)2Cl indicate that NitronNHC is electronically similar to the structurally related Enders carbene but is less electron donating than imidazol-2-ylidenes with aryl substituents. Significantly, the NitronNHC ligand affords catalytic systems, as illustrated by the ability of (NitronNHC)Ir(CO)2Cl to effect (i) the dehydrogenation of formic acid, (ii) aldehyde hydrosilylation, (iii) dehydrocoupling of hydrosilanes and alcohols, and (iv) ketone reduction via transfer hydrogenation.
- Quinlivan, Patrick J.,Loo, Aaron,Shlian, Daniel G.,Martinez, Joan,Parkin, Gerard
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p. 166 - 183
(2021/02/05)
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- Highly Selective Hydroxylation and Alkoxylation of Silanes: One-Pot Silane Oxidation and Reduction of Aldehydes/Ketones
-
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
-
p. 165 - 171
(2020/01/21)
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- Carbon dioxide hydrosilylation to methane catalyzed by zinc and other first-row transition metal salts
-
We accomplished zinc catalyzed hydrosilylation of carbon dioxide (CO2) to silyl formate (C+II), bis(silyl)acetal (C0), methoxysilane (C1II), and finally methane (C1IV). Among several zinc salts, we found that Zn(OAc)2 with ligand 1,10-phenanthroline was the best. A turnover number of 815000 was achieved using the zinc catalyst to yield C+II. Unexpectedly, we observed the generation of CO from CO2 and hydrosilane for the first time. In addition to Zn, other first-row transition metals (Mn, Fe, Co, Ni, and Cu) also served as Lewis acid catalysts for CO2 hydrosilylation, regardless of the nature of the metal.
- Zhang, Qiao,Fukaya, Norihisa,Fujitani, Tadahiro,Choi, Jun-Chul
-
p. 1945 - 1949
(2019/12/12)
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- Environment-friendly preparation method of diphenyldimethoxysilane
-
The invention relates to a preparation method of phenyl alkoxysilane, which includes: dissolving phenyl chlorosilane in an organic solvent, adding alcohol-alkoxide solution and performing a reaction in an inert atmosphere; when the reaction is carried out to a certain degree, adding a sodium alkoxide solution, continuously carrying out the reaction; when the reaction is finished, distilling the reaction product to form the phenyl alkoxysilane.
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Paragraph 0068; 0069; 0086; 0087
(2019/01/08)
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- Pollution-free method for preparing diphenyldiethoxysilane
-
The invention relates to a synthetic method of phenyl alkoxysilane, which includes: dissolving phenyl chlorosilane in an organic solvent, and adding an alcohol-alkoxide solution, performing a reactionin an inert atmosphere; when the reaction is carried out to a certain degree, adding a sodium alkoxide solution, continuously carrying out the reaction; when the reaction is finished, distilling thereaction product to form the phenyl alkoxysilane.
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Paragraph 0069; 0071; 0072-0073; 0075; 0077
(2019/01/08)
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- Zerovalent Nickel Compounds Supported by 1,2-Bis(diphenylphosphino)benzene: Synthesis, Structures, and Catalytic Properties
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Zerovalent nickel compounds which feature 1,2-bis(diphenylphosphino)benzene (dppbz) were obtained via the reactivity of dppbz towards Ni(PMe3)4, which affords sequentially (dppbz)Ni(PMe3)2 and Ni(dppbz)2. Furthermore, the carbonyl derivatives (dppbz)Ni(PMe3)(CO) and (dppbz)Ni(CO)2 may be obtained via the reaction of CO with (dppbz)Ni(PMe3)2. Other methods for the synthesis of these carbonyl compounds include (i) the formation of (dppbz)Ni(CO)2 by the reaction of Ni(PPh3)2(CO)2 with dppbz and (ii) the formation of (dppbz)Ni(PMe3)(CO) by the reaction of (dppbz)Ni(CO)2 with PMe3. Comparison of the ν(CO) IR spectroscopic data for (dppbz)Ni(CO)2 with other (diphosphine)Ni(CO)2 compounds provides a means to evaluate the electronic nature of dppbz. Specifically, comparison with (dppe)Ni(CO)2 indicates that the o-phenylene linker creates a slightly less electron donating ligand than does an ethylene linker. The steric impact of the dppbz ligand in relation to other diphosphine ligands has also been evaluated in terms of its buried volume (%Vbur) and steric maps. The nickel center of (dppbz)Ni(PMe3)2 may be protonated by formic acid at room temperature to afford [(dppbz)Ni(PMe3)2H]+, but at elevated temperatures, effects catalytic release of H2 from formic acid. Analogous studies with Ni(dppbz)2 and Ni(PMe3)4 indicate that the ability to protonate the nickel centers in these compounds increases in the sequence Ni(dppbz)2 3)2 3)4; correspondingly, the pKa values of the protonated derivatives increase in the sequence [Ni(dppbz)2H]+ 3)2H]+ 3)4H]+. (dppbz)Ni(PMe3)2 and Ni(PMe3)4 also serve as catalysts for the formation of alkoxysilanes by (i) hydrosilylation of PhCHO by PhSiH3 and Ph2SiH2 and (ii) dehydrocoupling of PhCH2OH with PhSiH3 and Ph2SiH2.
- Neary, Michelle C.,Quinlivan, Patrick J.,Parkin, Gerard
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p. 374 - 391
(2018/01/10)
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- High Production of Hydrogen on Demand from Silanes Catalyzed by Iridium Complexes as a Versatile Hydrogen Storage System
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The catalytic dehydrogenative coupling of silanes and alcohols represents a convenient process to produce hydrogen on demand. The catalyst, an iridium complex of the formula [IrCp?(Cl)2(NHC)] containing an N-heterocyclic carbene (NHC) ligand functionalized with a pyrene tag, catalyzes efficiently the reaction at room temperature producing H2 quantitatively within a few minutes. As a result, the dehydrogenative coupling of 1,4-disilabutane and methanol enables an effective hydrogen storage capacity of 4.3 wt % that is as high as the hydrogen contained in the dehydrogenation of formic acid, positioning the silane/alcohol pair as a potential liquid organic hydrogen carrier for energy storage. In addition, the heterogenization of the iridium complex on graphene presents a recyclable catalyst that retains its activity for at least 10 additional runs. The homogeneous distribution of catalytic active sites on the basal plane of graphene prevents diffusion problems, and the reaction kinetics are maintained after immobilization.
- Ventura-Espinosa, David,Sabater, Sara,Carretero-Cerdán, Alba,Baya, Miguel,Mata, Jose A.
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p. 2558 - 2566
(2018/03/13)
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- Dehydrogenative Coupling of Hydrosilanes and Alcohols by Alkali Metal Catalysts for Facile Synthesis of Silyl Ethers
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Cross-dehydrogenative coupling (CDC) of hydrosilanes with hydroxyl groups, using alkali metal hexamethyldisilazide as a single-component catalyst for the formation of Si-O bonds under mild condition, is reported. The potassium salt [KN(SiMe3)2] is highly efficient and chemoselective for a wide range of functionalized alcohols (99% conversion) under solvent-free conditions. The CDC reaction of alcohols with silanes exhibits first-order kinetics with respect to both catalyst and substrate concentrations. The most plausible mechanism for this reaction suggests that the initial step most likely involves the formation of an alkoxide followed by the formation of metal hydride as active species.
- Harinath, Adimulam,Bhattacharjee, Jayeeta,Anga, Srinivas,Panda, Tarun K.
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p. 724 - 730
(2017/05/31)
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- Catalytic Dehydrogenative Coupling of Hydrosilanes with Alcohols for the Production of Hydrogen On-demand: Application of a Silane/Alcohol Pair as a Liquid Organic Hydrogen Carrier
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The compound [Ru(p-cym)(Cl)2(NHC)] is an effective catalyst for the room-temperature coupling of silanes and alcohols with the concomitant formation of molecular hydrogen. High catalyst activity is observed for a variety of substrates affording quantitative yields in minutes at room temperature and with a catalyst loading as low as 0.1 mol %. The coupling reaction is thermodynamically and, in the presence of a Ru complex, kinetically favourable and allows rapid molecular hydrogen generation on-demand at room temperature, under air, and without any additive. The pair silane/alcohol is a potential liquid organic hydrogen carrier (LOHC) for energy storage over long periods in a safe and secure way. Silanes and alcohols are non-toxic compounds and do not require special handling precautions such as high pressure or an inert atmosphere. These properties enhance the practical applications of the pair silane/alcohol as a good LOHC in the automotive industry. The variety and availability of silanes and alcohols permits a pair combination that fulfils the requirements for developing an efficient LOHC.
- Ventura-Espinosa, David,Carretero-Cerdán, Alba,Baya, Miguel,García, Hermenegildo,Mata, Jose A.
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supporting information
p. 10815 - 10821
(2017/08/18)
-
- Synthesis of dimethylmanganese(II) complexes bearing N-heterocyclic carbenes and nucleophilic substitution reaction of tetraalkoxysilanes by diorganomanganese(II) complexes
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Reactions of manganese(II) dichlorides bearing a N-heterocyclic carbene ligand (L), [MnCl(μ-Cl)(L)]2(1a, L?=?1,3-diisopropyl-4,5-dimethylimidazole-2-ylidene (IiPr); 1b, L?=?1,3-bis(2,4,6-trimethylphenyl)imidazole-2-ylidene (IMes); 1c, L?=?1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene (IPr)) with MeLi afford the dinuclear dimethylmanganese(II) complexes, [MnMe(μ-Me)(L)]2(2a, L?=?IiPr; 2b, L?=?IMes; 2c, L?=?IPr). Complexes 2a-c achieve nucleophilic substitution of Si(OEt)4to selectively form MeSi(OEt)3. Related arylmanganese(II) complexes analogously react with Si(OEt)4to afford ArSi(OEt)3and Ar2Si(OEt)2(Ar?= Ph, 2,6-Me2(C6H3)). Kinetic studies support an associative mechanism for the observed transformation of Si(OEt)4, in which both the manganese species and Si(OEt)4are involved in the rate-limiting step.
- Hashimoto, Takayoshi,Kawato, Yuko,Nakajima, Yumiko,Ohki, Yasuhiro,Tatsumi, Kazuyuki,Ando, Wataru,Sato, Kazuhiko,Shimada, Shigeru
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- Alkyl silane compound (or arylsilanes compd.) manufacturing method (by machine translation)
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PROBLEM TO BE SOLVED: alkyl silane compound (or arylsilanes compd.) in order to obtain an effective compd. perfluoroalkylated (or aryl-) is found, novel alkyl silane compound (or aryl compound) and to provide a method of manufacturing. SOLUTION: the following eq. (A-1), (A-2), (A-3), or (A-4) alkylalkoxysilane compd. represented by, alkyl (or aryl demanganese compd.) demanganese compd. reacting and, by perfluoroalkylated (or aryl-), alkyl silane compound (or arylsilanes compd.) can be efficiently manufactured. ( Eq. (A-1), (A-2), (A-3), during and (A-4), R 1 to 1-20 hydrocarbon groups, R 2 silicon atoms and oxygen atoms are each independently selected from the group consisting of at least 1 may also include a kind of carbon number 1-20 hydrocarbon group. ) Selected drawing: no (by machine translation)
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Paragraph 0031
(2016/10/08)
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- NOVEL IMINES WITH TUNABLE NUCLEOPHILICITY AND STERIC PROPERTIES THROUGH METAL COORDINATION: APPLICATIONS AS LIGANDS AND METALLOORGANOCATALYSTS
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The invention describes phospho-amino pincer-type ligands, metal complexes thereof, and catalytic methods comprising such metal complexes for conversion of carbon dioxide to methanol, conversion of aldehydes into alcohols, conversion of aldehydes in the presence of a trifluoromethylation agent into trifluorinated secondary alcohols, cycloaddition of carbon dioxide to an epoxide to provide cyclic carbonates or preparation of an amide from the combination of an alcohol and an amine.
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Paragraph 0182; 0188
(2016/04/20)
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- Dehydrogenative coupling of silanes with alcohols catalyzed by Cu3(BTC)2
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Cu3(BTC)2 is an efficient and reusable heterogeneous catalyst for the dehydrogenative coupling of silanes with alcohols. Activity data and CO adsorption suggest that Cu(ii) and in situ generated Cu(i) are the active species. Other MOFs such as Fe(BTC), MIL-101(Cr) and UiO-66(Zr) are unable to promote this cross-coupling.
- Dhakshinamoorthy, Amarajothi,Concepcion, Patricia,Garcia, Hermenegildo
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supporting information
p. 2725 - 2728
(2016/02/19)
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- η3-silaallyl/alkenylsilyl molybdenum complex: Synthesis, structure, and reactivity toward primary amines to form Mo-N-Si three-membered cyclic complexes
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The new η3-silaallyl/alkenylsilyl molybdenum complex CpMo(CO)2(η3-Ph2SiCHCMe2) (3) was synthesized by the reaction of CpMo(CO)2(py)Me with Ph2HSiCH-CMe2. Reactions of 3 with primary amines RNH2 (R = tBu, iPr, Et) gave Mo-N-Si three-membered cyclic complexes CpMo(CO)2(η2-N,Si-RHNSiPh2) (5a, R = tBu; 5b, R = iPr; 5c, R = Et) with elimination of isobutene. In NMR tube reactions using iPrNH2 and EtNH2, the Mo-N-Si-C four-membered cyclic complexes CpMo(CO)2(η2-N,C-RHNSiPh2CHiPr) (4b, R = iPr; 4c, R = Et) were observed as intermediates leading to 5b and 5c, respectively. Complex 4c was successfully isolated in a preparative reaction. The molecular structures of 3, 4c, and 5b were determined by X-ray crystal analyses. Interestingly, the contribution of silylene character was suggested for the SiPh2 moiety of 5b from the X-ray structure. The reaction of 5b with MeOH gave the dinuclear complex Cp(CO)2Mo(η-OMe)(η -H)Mo(CO)2Cp as a major product.
- Sakaba, Hiroyuki,Tonosaki, Hiroki,Isozaki, Kazuyoshi,Kwon, Eunsang
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p. 1029 - 1037
(2015/03/31)
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- Dinuclear zinc hydride supported by an anionic bis(N-heterocyclic carbene) ligand
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Methylene-linked bis(N,N′-di-tert-butylimidazol-2-ylidene) 1 reacted with diethylzinc to give dinuclear zinc ethyl compound 2, which contains a formally anionic bis(carbene) ligand as a result of deprotonation of the methylene bridge. The reaction of 2 with PhSiH3 gave the phenylsilyl compound 3. The zinc hydride 4 was obtained by the reaction of 2 with LiAlH 4 or Ph3SiOH followed by treatment with PhSiH3. X-ray diffraction studies show that compounds 2, 3, and 4 all have a similar dimeric structure with D2h symmetry. The reaction of hydride 4 with carbon dioxide and N,N′-diisopropylcarbodiimide gave formato (5) and formamidinato (7) derivatives as a result of the insertion of the heterocumulene into both Zn-H bonds. Reaction with Ph2CO gave the diphenylmethoxy compound 6. Hydride 4 shows catalytic activity in the hydrosilylation of 1,1-diphenylethylene and methanolysis of silanes. Copyright
- Rit, Arnab,Spaniol, Thomas P.,Okuda, Jun
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p. 612 - 619
(2014/02/14)
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- Copper nanoparticles supported on doped graphenes as catalyst for the dehydrogenative coupling of silanes and alcohols
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Copper nanoparticles (NPs) supported on a series of undoped and doped graphene materials (Gs) have been obtained by pyrolysis of alginate or chitosan biopolymers, modified or not with boric acid, containing Cu2+ ions at 900 °C under inert atmosphere. The resulting Cu-G materials containing about 17 wt% Cu NPs (from 10 to 200 nm) exhibit high catalytic activity for the dehydrogenative coupling of silanes with alcohols. The optimal material consisting on Cu-(B)G is more efficient than Cu NPs on other carbon supports.
- Blez, Juan F.,Primo, Ana,Asiri, Abdullah M.,lvaro, Mercedes,Garc, Hermenegildo
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supporting information
p. 12581 - 12586
(2015/04/16)
-
- METHOD OF PRODUCING AN ORGANIC SILICON COMPOUND
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A method of producing an organic silicon compound includes a step of reaction of the following: (A) a reactive silane compound represented by General Formula (1) below: R1mSiY(4-m) (wherein R1 is a monovalent organic group (except for the group represented by Y) or a hydrogen atom; Y indicates a chlorine atom or a group represented by -OR2; R2 indicates a monovalent hydrocarbon group having 1 to 30 carbon atoms; and m is a number in the range of 0 to 3), (B) a halogenated organic compound represented by General Formula (2) below: R3-X (wherein R3 indicates a monovalent organic group; and X is a halogen atom), and (C) metallic magnesium (Mg) in the presence of (D) an organic solvent containing at least one type of ether type compound.
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Paragraph 0048
(2013/07/19)
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- METHOD OF SYNTHESIZING SILOXANE MONOMERS AND USE THEREOF
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A method for preparation and polymerization of siloxane monomers of Formula I is presented. The synthesis includes the selective reaction between silanol containing unit and alkoxy containing units in the presence of basic catalyst. The siloxane monomers of the invention can be used for preparation of siloxane polymers with good flexibility and cracking threshold, and functional sites, useful for applications requiring low metal content in semiconductor industry.
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Page/Page column 19-20
(2013/02/28)
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- Using the nonaqueous electrolytic solution and secondary battery
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PROBLEM TO BE SOLVED: To provide nonaqueous electrolyte solution capable of improving at least either large-current charge/discharge characteristics or charge/discharge capacity, and a nonaqueous electrolyte solution secondary battery using it. SOLUTION: Electrolyte solution that is liquid electrolyte is immersed in a separator 23. The electrolyte solution contains a liquid solvent, for instance, a nonaqueous solvent such as an organic solvent, and electrolyte salt dissolved in the nonaqueous solvent. Further, as additives, it contains at least one type selected from tris (penta-fluorophenyl) borane (TPFPB) and tris-borate (2H-hexafluoro isopropyl) (THFPB), and at least one type selected from vinylene carbonate (VC) and vinyl ethylene carbonate (VEC). COPYRIGHT: (C)2008,JPO&INPIT
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- Studies of the Henry reaction catalyzed by Cu-O and Zn-O complexes with dimethoxysilane-bridged derivatives
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Dimethyldimethoxysilane, methylphenyldimethoxysilane, and diphenyldimethoxysilane have been synthesized by a one-step, simple method and used as catalysts in the Henry reaction with Cu(OAc)2.H2O and Zn(OAc)2.2H2O, affording 60-96% conversion under the optimum catalytic conditions. Springer Science+Business Media B.V. 2010.
- Mei, Luo,Yang, Han Bing,Song, Shu
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body text
p. 181 - 191
(2011/10/13)
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- Reactions of cationic PNP-supported iridium silylene complexes with polar organic substrates
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Reactions of PNP-supported silylene complexes [(PNP)(H)Ir-SiRR′] [B(C6F5)4] (R = R′ = Ph (1) and R = H, R′ = Mes (2)) with Lewis bases, carbonyl compounds, alcohols, and amines were investigated. Addition of DMAP (4-dimethylaminopyridine) to 1 and 2 produced base-stabilized silylene complexes [(PNP)(H)IrSiRR′(DMAP)] [B(C6F5)4] (R = R′ = Ph (3) and R = H, R′ = Mes (4)). Reactions of 2 with benzophenone and benzaldehyde afforded the products of stoichiometric hydrosilylation, heteroatom-substituted silylene complexes [(PNP)(H)Ir-SiMes(OCH(Ph)(R))][B(C6F5) 4] (R = Ph (5) and R = H (6)). Complex 1 reacted with DMF or benzophenone, and 2 reacted with DMF, to afford base-stabilized silylene complexes of the type [(PNP)(H)IrSiRR′(B)][B(C6F 5)4] (R = H, R′ = Mes, B = DMF (7); R = R′ = Ph, B = DMF (8) and O-CPh2 (9)). In contrast, treatment of 1 with acetophenone afforded {(PNPH)IrH[SiPh2(OC(-CH2)Ph)]} [B(C6F5)4] (10), from activation of a C-H bond at the α-carbon position of acetophenone. Reactions of alcohols and amines with 1 afforded [(PNPH)IrH(SiPh2OR)][B(C6F 5)4] (R = 3,5-tBu2C 6H3 (11), R = Ph (12), R = iPr (13), and R = tBu (14)) and [(PNPH)IrH(SiPh2NHR)][B(C6F 5)4] (R = Ph (15), R = 3,5-(CF3) 2C6H3 (16)). Exploration of the catalytic activity of iridium silylene complexes with these organic substrates demonstrated that 1 is an effective catalyst for silane alcoholysis and aminolysis and for the hydrosilylation of ketones.
- Calimano, Elisa,Tilley, T. Don
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experimental part
p. 1680 - 1692
(2010/06/13)
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- An efficient solvent-free route to silyl esters and silyl ethers
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Dinuclear metal complexes, especially (p-cymene)ruthenium dichloride dimer {[RuCl2(p-cymene)]2}, have been found to exhibit high catalytic performance for the dehydrosilylation of various kinds of carboxylic acids and alcohols. The dehydrosilylation with [RuCl2(p-cymene)] 2 proceeded efficiently with only one equivalent of silane with respect to substrate (carboxylic acids or alcohols) under solvent-free conditions to give the corresponding silyl esters and ethers in excellent yields with a high turnover number (TON) and frequency (TOF). The 1H NMR spectrum of a toluene-d8 solution of [RuCl2(p-cymene)] 2 and a silane showed a signal assignable to the ruthenium hydride species. In contrast, no new signals were detected in the 1H NMR spectrum of a toluene-d8 solution of [RuCl2(p-cymene)] 2 and a carboxylic acid or an alcohol. There-fore, the ruthenium metal in [RuCl2(p-cymene)]2 activates a silane to afford the hydride intermediate, possibly a silylmetal hydride species. Then, the nucleophilic attack of a substrate (carboxylic acid or alcohol) to the hydride intermediate proceeds to give the corresponding silylated product. The present dehydrosilylation with an optically active silane proceeded exclusively under inversion of stereochemistry at the chiral silicon center, suggesting that the nucleophilic attack of a substrate to the hydride intermediate occurs from the backside of the ruthenium-silicon bond.
- Ojima, Yuko,Yamaguchi, Kazuya,Mizuno, Noritaka
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scheme or table
p. 1405 - 1411
(2009/12/07)
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- Research on the cyanosilylation of prochiral aldehydes catalyzed by alkyldimethoxyl silylene-bridged lanthanide complexes
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A series of novel silylene-bridged Ln-O rare earth complexes are very efficient Lewis acidic catalysts in cyanosilylation of aldehydes, giving some cyano trimethylsilyl ethers of aldehydes in >99% yields. Copyright Taylor & Francis Group, LLC.
- Mei, Luo,Ping, Ke Yu,Xuan, Li Xiao,Hao, Yin,Liang, Hu Ke,Ying, Jiang
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p. 2483 - 2490
(2007/10/03)
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- Convenient synthesis of alkoxyhalosilanes from hydrosilanes
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Selective dehydrogenative coupling of di- and trihydrosilanes with alcohols catalyzed by PdCl2 or NiCl2 afforded alkoxyhydro- and dialkoxyhydrosilanes in good yield. Further treatment of the resulting alkoxyhydrosilanes with carbon tetrachloride or allyl bromide in the presence of the same catalyst led to the formation of alkoxychloro- and alkoxybromosilanes, respectively. Similar reactions of dialkoxyhydrosilanes with carbon tetrachloride afforded dialkoxychlorosilanes in good yield, although contamination of small amounts of trialkoxysilanes and alkoxydichlorosilanes was detected in the products. Selective substitution of the alkoxyhalosilanes with nucleophiles is also reported.
- Ohshita, Joji,Taketsugu, Ryosuke,Nakahara, Yuki,Kunai, Atsutaka
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p. 3258 - 3264
(2007/10/03)
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- Process for preparing low-chloride or chloride-free alkoxysilanes
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A process for preparing an alkoxysilane with an acidic chloride content of less than 10 ppm by weight, comprising: reacting a chlorosilane with an alcohol in a water-free and solvent-free phase to form a product mixture containing alkoxysilane and residual acidic chloride, with removal of resultant hydrogen chloride from the product mixture, then adding liquid or gaseous ammonia, in an amount corresponding to a stoichiometric excess, based on the content of acidic chloride, to form an ammonia-containing product mixture, treating the ammonia-containing product mixture at a temperature between 10 and 50 DEG C., wherein the ammonia and acidic chloride undergo neutralization, to form a crude product, and optionally, then separating off a salt formed in the course of neutralization, from the crude product, and recovering the alkoxysilane by distilling the crude product.
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- An Efficient Catalyst for the Conversion of Hydrosilanes to Alkoxysilanes
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The copper(I) hydride 6 is an efficient catalyst for the alcoholysis of primary and secondary silanes.The reactions proceed at room temperature within a few hours and give the alkoxysilanes in high yields.Only with bulky alcohols or silanes are longer reaction times and/or increased temperatures required.The presence of air accelarates the reactions and gives rise to higher yields of alkoxysilanes, particularly with bulky alcohols.Diols react with PhRSiH2 (R = Me, Ph) to afford 1,3-dioxo-2-silacycloalkanes and with tertiary silanes to furnish the bissilylated diols.When unsaturated alcohols (2-propen-1-ol or 2-propyn-1-ol) are employed, the double or triple bond is retained. - Keywords: Catalytic silane alcoholysis; Alkoxysilanes
- Lorenz, Catrin,Schubert, Ulrich
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p. 1267 - 1270
(2007/10/03)
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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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- Process for making silyl ethers
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Organic silyl ethers are prepared by contacting an acyclic carbonate ester with an organic silyl halide in the presence of an initiator compound at a temperature from about 50° C. to about 250° C.
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