- Charge Modified Porous Organic Polymer Stabilized Ultrasmall Platinum Nanoparticles for the Catalytic Dehydrogenative Coupling of Silanes with Alcohols
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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
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- Mechanistic Studies on the Hexadecafluorophthalocyanine–Iron-Catalyzed Wacker-Type Oxidation of Olefins to Ketones**
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The hexadecafluorophthalocyanine–iron complex FePcF16 was recently shown to convert olefins into ketones in the presence of stoichiometric amounts of triethylsilane in ethanol at room temperature under an oxygen atmosphere. Herein, we describe an extensive mechanistic investigation for the conversion of 2-vinylnaphthalene into 2-acetylnaphthalene as model reaction. A variety of studies including deuterium- and 18O2-labeling experiments, ESI-MS, and 57Fe M?ssbauer spectroscopy were performed to identify the intermediates involved in the catalytic cycle of the oxidation process. Finally, a detailed and well-supported reaction mechanism for the FePcF16-catalyzed Wacker-type oxidation is proposed.
- Grinenko, Vadim,Klau?, Hans-Henning,Kn?lker, Hans-Joachim,Puls, Florian,Seewald, Felix
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p. 16776 - 16787
(2021/11/04)
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- Environment-friendly preparation method of diphenyldimethoxysilane
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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 0090; 0091; 0108; 0109
(2019/01/08)
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- Pollution-free method for preparing diphenyldiethoxysilane
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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 0090; 0093; 0094-0095; 0097; 0099
(2019/01/08)
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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)
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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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- Metal-Free Ammonium Iodide Catalyzed Oxidative Dehydrocoupling of Silanes with Alcohols
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An ammonium iodide catalyzed direct oxidative coupling of silanes with alcohols to give various alkoxysilane derivatives was discovered. tert -Butyl hydroperoxide proved to be an efficient oxidant for this transformation. Attractive features of this protocol include its transition-metal-free nature and the mild reaction conditions.
- Yuan, Yan-Qin,Kumar, Pailla Santhosh,Guo, Sheng-Rong
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supporting information
p. 1620 - 1623
(2017/08/11)
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- Chlorosilane alcoholysis acid removing agent and regeneration method thereof
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The invention discloses a chlorosilane alcoholysis acid removing agent and a regeneration method thereof. The regeneration method is characterized in that at a temperature of -10-130 DEG C, a substituting agent and an acid removing agent are added into a reactor in advance, chlorosilane is gradually added, the liquid phase obtained through filtration separation is subjected to rectification after the alcoholysis reaction is completed so as to obtain a silane finished product and the excessive substitution agent, the excessive substitution agent is recycled, and the acid removing agent obtained through filtration separation is recycled after being regenerated. According to the present invention, the yield of the silane prepared by using the process is more than or equal to 95%, and the recovery rate of the acid removing agent is more than or equal to 95%.
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Paragraph 0020
(2017/04/28)
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- Nucleophilic attack of R-lithium at tetrahedral silicon in alkoxysilanes. An alternate mechanism
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The currently accepted mechanism for nucleophilic attack at silicon in tetraalkoxysilanes, e.g. Si(OEt)4 is suggested to involve formation of penta- and then hexacoordinated intermediates as supported by the apparent exclusive formation of R3SiOR′ and R4Si from nucleophilic attack by RLi and RMgX. Our recent discovery of a direct route from biogenic silica to tetraalkoxyspirosiloxanes prompted us to revisit this reaction as a potential route to diverse silicon-containing species with single SiC bonds as early studies demonstrate that spirosiloxanes form quite stable pentacoordinated alkoxysilane compounds. As anticipated, Si(2-methyl-2,4-pentanediolato)2 (SP) reacts with RLi (R = Ph, anthracene, phenylacetylene, etc.) at -78 °C to form pentacoordinated Si, e.g. LiPhSP equilibrates with the starting reagents even at 3:1 ratios of PhLi:SP with no evidence for formation of hexacoordinated species by mass spectral, NMR and quenching studies. Thus, quenching with MeI or Me3SiCl allows isolation of monosubstituted products from RLi:SP; RSi(OR′)3 including some ring-opened oligomers. Comparative studies of reactions of PhLi with Si(OEt)4 allows isolation of mono- and disubstituted products again even at 1:1 ratios of PhLi:Si(OEt)4. However, on standing at -78 °C for long periods of time or on warming to 0 °C, the primary product for both reactions is Ph4Si even with 0.5 equivalents of PhLi. At reaction temperatures ≥0 °C the primary product is again Ph4Si. These results suggest that hexacoordinated intermediates are not part of the substitution mechanism and may suggest that the higher-substituted compounds arise from disproportionation processes. We also briefly describe the conversion of anthracenylSP and 9,9-dimethylfluoreneSP to silsesquioxanes.
- Furgal, Joseph C.,Laine, Richard M.
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p. 705 - 725
(2016/07/14)
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- 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 0028
(2016/10/08)
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- Dehydrogenative silylation of alcohols catalysed by half-sandwich iron N-heterocyclic carbene complexes
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A new series of tetramethylcyclopentadienyl-functionalised N-heterocyclic carbene complexes of iron bearing different wingtips of general type (Cp?-NHCR)Fe(CO)I (R = nBu, iBu, Et, CH2CH2OMe, CH2Ph) were prepared by direct reaction of Fe3(CO)12 and the corresponding imidazolium proligands. These new iron-NHC complexes have been found to be efficient catalysts for the dehydrogenative silylation of alcohols with silanes. Iron metal complexes bearing iso-butyl and n-butyl wingtips displayed slightly better catalytic performances than the related complexes (Cp?-NHCR)Fe(CO)I (R = Et, CH2CH2OMe, CH2Ph), affording quantitative yields of the corresponding silylethers in 8 h at 70 °C in acetonitrile.
- Cardoso, Jo?o M.S.,Lopes, Rita,Royo, Beatriz
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p. 173 - 177
(2015/02/19)
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- Hydrosilylation of Aldehydes and Ketones Catalyzed by a Terminal Zinc Hydride Complex, [κ3-Tptm]ZnH
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Tris(2-pyridylthio)methyl zinc hydride, [κ3-Tptm]ZnH, is an effective catalyst for multiple insertions of carbonyl groups into the Si-H bonds of PhxSiH4-x (x = 1, 2). Specifically, [κ3-Tptm]ZnH catalyzes the insertion of a variety of aldehydes and ketones into the Si-H bonds of PhSiH3 and Ph2SiH2 to afford PhSi[OCH(R)R′]3 and Ph2Si[OCH(R)R′]2, respectively. The mechanism for hydrosilylation is proposed to involve insertion of the carbonyl group into the Zn-H bond to afford an alkoxy species, followed by metathesis with the silane to release the alkoxysilane and regenerate the zinc hydride catalyst. Multiple insertion of prochiral ketones results in the formation of diastereomeric mixtures of alkoxysilanes that can be identified by NMR spectroscopy.
- Sattler, Wesley,Ruccolo, Serge,Rostami Chaijan, Mahnaz,Nasr Allah, Tawfiq,Parkin, Gerard
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p. 4717 - 4731
(2015/10/28)
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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)
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- N-heterocyclic carbene organocatalysts for dehydrogenative coupling of silanes and hydroxyl compounds
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Go organic! N-Heterocyclic carbene (NHC) 1,3-diisopropyl-4,5- dimethylimidazol-2-ylidene (IiPr) has been found to be an efficient and selective catalyst for the dehydrogenative coupling of a wide range of silanes and hydroxyl groups to form Si-O bonds under mild and solvent-free conditions (see scheme). Mechanistic studies indicated that the activation of hydroxyl groups by the NHC is the most plausible initial step for the process. Copyright
- Gao, Dongjing,Cui, Chunming
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supporting information
p. 11143 - 11147
(2013/09/02)
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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
(2013/02/28)
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- Reactions of organolanthanide compounds RLnI (Ln = Yb, Eu, Sm) with organic derivatives of silicon, tin, lead, and antimony
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Reactions of compounds RLnI (R = Alk, Ar; Ln = Yb, Eu, Sm) with hexaalkyl(aryl)-distannanes, trimethylsilyltriphenyltin, and lead and antimony acetates were studied. The reactions with Sn-Sn and Si-Sn organic derivatives result in cleavage of Sn-Sn amd Sn-Si bonds with formation of tetrasubstituted stannanes and reactive organometallic derivatives with an Sn-Ln or Si-Ln bond. The reactions of RYbI with lead and antimony acetates and with tetraethoxysilane cause cleavage of the Pb-O, Sb-O, or Si-O bond with formation of tetrasubstituted derivatives of lead and silicon or trisubstituted antimony derivatives.
- Rybakova,Syutkina,Petrov
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p. 244 - 246
(2007/10/03)
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- Utilization of bottoms of the direct synthesis of methylchlorosilanes in production of the crude mixtures of phenylethoxysilanes by continuous organomagnesium Procedure
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Utilization of the bottoms after distillation of methylchlorosilanes in continuous organomagnesium synthesis of organosilicon raw materials for production of polyphenylsiloxane resins and lacquers and enamels based on them was analyzed.
- Klokov
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p. 476 - 478
(2007/10/03)
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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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- Reactions of silanes with allylic alcohols catalyzed by titanocene derivatives: an approach to catalytic cross dehydrocoupling/ co-intramolecular hydrosilation
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A preliminary study of the dimethyltitanocene, 7, and rac-5-4,5,6,7-tetrahydroindenyl)>TiMe2, 8, catalyzed reactions of silanes with allylic and homoallylic alcohols is described.In the presence of catalysts 7 or 8, tertiary silanes bearing at least one phenyl group react with 2-methyl-but-1-ene-4-ol, 2a, to produce the 4-siloxy-2-methylbut-1-ene, 3a.Secondary silanes react with either 2a, or 2-methylpropen-3-ol, 2b, to give different product distributions depending on the catalyst type, concentration, and the substituents on the silicon atom.With high catalyst concentration and diphenylsilane, a redistribution reaction substantially converts the initially produced allyloxydiphenylsilane to bis(allyloxy)diphenylsilane.Low catalyst concentrations give primarily the intramolecular hydrosilation product.Under the same reaction conditions, phenylmethylsilane gives more intramolecular hydrosilation product than diphenylsilane does.Phenylsilane reacts with 2b, to give a polymeric product, 6b (R = Ph, R' = H), via intermolecular hydrosilation.Under the same conditions phenylsilane reacts with 2a to give primarily the hydrogenation product tris(3-methylbutoxy)phenylsilane, Sa (R = Ph, R' = -OCH2CH2CH(CH3)2), together with traces of oligosilane and intermolecular hydrosilation product 6a.Some possible reaction pathways, including the observed side reactions, are discussed.Keywords: Titanium; Silicon; Hydrosilation; Allylic; Titanocene; Alcohols
- Xin, Shixuan,Harrod, John F.
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p. 181 - 192
(2007/10/02)
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- Conversion of hydrosilanes to alkoxysilanes catalyzed by Cp2TiCl2/nBuLi
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The combination of Cp2TiCl2 and nBuLi provides an effective catalyst for alcoholysis of the model silanes n-HexSiH3, PhMeSiH2, Ph2SiH2 and PhMe2SiH by ethanol, isopropanol, t-butyl alcohol and phenol.Increasing the steric bulk of the substituents on either the alcohol or the silane generally requires longer reaction periods and/or increasing temperature.All SiH bonds are converted to SiOEt groups by ethanol and a single SiH bond in secondary silanes and two SiH bonds in tertiary silanes are replaced by t-butyl alcohol.Diols including pinacol, 2,4-pentanediol and 2,5-hexanediol react with PhRSiH2 (R = Me, Ph) to give 1,3-dioxa-2-silacyclopentanes, -hexanes and -heptanes, respectively.Attempts to form caged structures by condensation of primary silanes and triols was unsuccessful.Hydrolysis of PhRSiH2 is promoted by Cp2TiCl2/n-BuLi and the siloxane is produced in quantitative yield when R = Ph and a mixture of linear disiloxanes and trisiloxanes in addition to cyclopolysilanes are produced when R = Me.Other protic reagents including acids, mercaptans, amines and enolizable ketones did not react.The effects of reaction parameters such as temperature, silane to catalyst ratio, solvent, transition metal and replacements for nBuLi were also determined.
- Bedard, Thomas C.,Corey, Joyce Y.
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p. 315 - 333
(2007/10/02)
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- TRICYCLIC HETEROCYCLES WITH BIFUNCTIONAL SILICON CENTERS
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Condensation of the diorganometallic reagents, (o-MC6H4)2X (M = Li, MgCl) with HSiCl3 followed by reduction with LiAlH4 provides dibenzosilacycles, I (a, X = -; b, X = NMe; c, X = CH2; d, X = CH2CH2) with two exocyclic H-substituents, =SiH2.Conditions for the stepwise conversion of I to mixed bifunctional systems, =SiHX (II, X = Cl, Br; III, X = OR), and bifunctional derivatives, =SiX2 (IV, X = Cl; V, X = OR) were determined.Controlled halogenation of I to II was accomplished with one molar equivalent of SO2Cl2 or NBS although CCl4 in the presence of ClRh(PPh3)3 or PdCl2 results in slow monochlorination.The reaction of I with excess SOCl2 or SO2Cl2 converts I to III but the latter is faster and provides fewer side reactions.Conversion of I to IV with excess alcohols occurs in high yield with ClRh(PPh3)3 but in low yield with H2PtCl6.Controlled alcoholysis of I to III could not be achieved except with tBuOH.The dichlorides, IV, are methylated in high yield to VII, =SiMe2.Reaction of Ib with ClRh(PPh3)3 results in elimination of H2 and formation of disilanes as indicated by trapping reactions with alcohols (formation of Vb).
- Corey, Joyce Y.,Jonh, Christy S.,Ohmsted, Martha C.,Chang, Lihsueh S.
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