- Method for Producing Acyloxysilanes, Acyloxysilanes Obtained Thereby, and Use of Same
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An object of the invention is to provide a method for efficiently producing an acyloxysilane which is useful as a functional chemical, an acyloxysilane obtained thereby, and the use thereof. The present invention provides: a method for producing an acyloxysilane, including a reaction step of reacting an alkoxysilane with a carboxylic anhydride in the presence of a catalyst, wherein the alkoxysilane is a specified alkoxysilane represented by General Formula (I), the carboxylic anhydride is a specified carboxylic acid represented by General Formula (IIA) or (IIB), the catalyst is an acid catalyst, and an acyloxysilane obtained in the reaction step is a specified acyloxysilane represented by General Formula (IIIA) or (IIIB); and the use of the acyloxysilane as a surface treatment agent or the like.
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Paragraph 0131; 0167; 0168; 0169; 0170; 0171; 0172; 0173
(2018/03/25)
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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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- Steady state and time-resolved spectroscopic studies of the photochemistry of 1-arylsilacyclobutanes and the chemistry of 1-arylsilenes
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Direct photolysis of 1-phenylsilacyclobutane and 1-phenyl-, 1-(2-phenylethynyl)-, and 1-(4'-biphenylyl)-1-methylsilacyclobutane in hexane solution leads to the formation of ethylene and the corresponding 1-arylsilenes, which have been trapped by photolysis in the presence of methanol. Quantum yields for photolysis of the three methyl-substituted compounds have been determined to be 0.04, 0.26, and 0.29, respectively, using the photolysis of 1,1-diphenylsilacyclobutane (Φ(silene) = 0.21) as the actinometer. The corresponding silenes have been detected by laser flash photolysis; they have lifetimes of several microseconds, exhibit UV absorption maxima ranging from 315 to 330 nm, and react with methanol with rate constants on the order of (2-5) x 109 M-1 s-1 in hexane. Absolute rate constants for reaction of 1-phenylsilene and 1-methyl-1-phenylsilene with water, methanol, tert-butanol, and acetic acid in acetonitrile solution have been determined, and are compared to those of 1,1-diphenylsilene under the same conditions. With the phenylethynyl- and biphenyl-substituted methylsilacyclobutanes, the triplet states can also be detected by laser flash photolysis, and are shown to not be involved in silene formation on the basis of triplet sensitization and (or) quenching experiments. Fluorescence emission spectra and singlet lifetimes have been determined for the three 1-aryl-1-methylsilacyclobutanes, 1,1-diphenylsilacyclobutane, and a series of acyclic arylmethylsilane model compounds. These data, along with the reaction quantum yields, allow estimates to be made of the rate constants for the excited singlet state reaction responsible for silene formation. 1-Methyl-1-phenylsilacyclobutane undergoes reaction from its lowest excited singlet state with a rate constant 10-80 times lower than those of the other three derivatives. The results are consistent with a stepwise mechanism for silene formation, involving a 1,4-biradicaloid intermediate that partitions between product and starting material.
- Leigh,Boukherroub,Bradaric,Cserti,Schmeisser
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p. 1136 - 1147
(2007/10/03)
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- Esters of (Hydroxymethyl)diorganylsilanes: Synthesis and Thermally Induced Rearrangement
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Twenty silanes of the type R1R2Si(H)CH3OR3 (A) were synthesized 1,R2 = Me, Ph, 1-naphthyl, PhCH2, Me3SiCH2; OR3 = OC(O)Me, OC(O)CF3, OS(O)CF3, OP(O)Ph2, OC(O)Cl> and studied for their thermal behaviour.The silanes A undergo a thermally induced rearrangement to give the corresponding silanes R1R2Si(OR3)Me (B).For compounds with OR3 = OC(O)Cl, an additional decarboxylation takes place to yield the chlorosilanes R1R2Si(Cl)Me.Except for the derivatives with OR3 = OC(O)Cl, the energetic (reaction enthalpy) and kinetic data (reaction order, frequency factor, enthalpy and entropy of activation) of these reactions were studied by means of differential scanning calorimetry (DSC).In addition the kinetics of all reactions were investigated by 1H-NMR spectroscopy.The transition state of the rearrangement was investigated by an ab initio study based on the model compound H3SiCH2OC(O)H MeH2SiOC(O)H>.The theoretical data and the experimentally obtained energetic and kinetic data are discussed in terms of mechanistic aspects of the rearrangement reaction A -> B.
- Tacke, Reinhold,Wiesenberger, Frank,Becker, Beate,Rohr-Aehle, Regine,Schneider, Petra B.,et al.
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p. 591 - 606
(2007/10/02)
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- REACTIONS IN THE CHLOROSILANE-SILANOL-SILOXANE SYSTEM
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We obtained the first ?*-values and ES-values for siloxy groups by spectroscopic and kinetic methods.Detailed mechanistic investigations are performed on the hydrolysis of chlorosilanes, the cleavage of Si-O-Si bonds by HCl, and the substituent exchange reaction between silanols and chlorosilanes.
- Ruehlmann, K.
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p. 139 - 152
(2007/10/02)
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- ZUR SYNTHESE VON SILOXANEN. II, STERISCHE SUBSTITUENTENKONSTANTEN FUER SILOXYRESTE
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The acetolysis reactions of compounds of the type XSiMe2Cl (I) with acetic acid in the presence of acetic anhydride were studied kinetically by means of 1H NMR spectroscopy.We found these reactions exclusively influenced by steric effects (ρ=0).The steric susceptibility constant (δ) of the acetolysis reaction, using alkylchlorodimethylsilanes was found to be 1.3.In this investigation the Taft Es nvalues showed a better correlation than the Es(Si) values of Cartledge.From the rate constants of the acetolysis reactions with I (X=Cl, acetoxy or siloxy) we could then obtain for the first time Es values for Cl, acetoxy and a series of siloxy groups at silicon.
- Scheim, U.,Grosse-Ruyken, H.,Ruehlmann, K.,Porzel, A.
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- Thermally Induced Rearrangement of (Acyloxymethyl)diorganylsilanes
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The (acyloxymethyl)diorganylsilanes R1R2Si(H)CH2OC(O)R3 (2a-d) rearrange to the corresponding acyloxy(methyl)diorganylsilanes R1R2Si(CH3)OC(O)R3 (3a-d).This reaction is formally equivalent to an exchange of the hydrogen bound to silicon and acyloxy group bound to carbon.The 1,2-hydrogen shift could be shown experimentally to be an intramolecular process.
- Tacke, Reinhold,Lange, Hartwig
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p. 3685 - 3691
(2007/10/02)
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