- Hydrosilane σ-Adduct Intermediates in an Adaptive Zinc-Catalyzed Cross-dehydrocoupling of Si?H and O?H Bonds
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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)
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- POLYMERIZABLE DENTAL COMPOSITION BASED ON CONDENSED SILANES
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The present invention relates to novel polymerizable dental compositions comprising, (A) polysiloxanes, wherein the polysiloxanes comprise a mixture of the condensates of the three silanes (a1), (a2) and (a3) and/or a cocondensate of a mixture of the three silanes (a1), (a2) and (a3) and/or a mixture of at least two of the cocondensates (a1)/(a2), (a1)/(a3) and (a2)/(a3) and/or a mixture of the condensate of one of the three silanes (a1), (a2) or (a3) with the cocondensate of the other two silanes, (B) fillers and (C) initiators and/or catalysts and/or activators for the polymerization.
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Paragraph 0552
(2021/02/26)
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- Method for industrially producing dialkyl dialkoxy silane
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The invention discloses a method for industrially producing dialkyl dialkoxy silane, which comprises the following steps: in the presence of a catalyst and a solvent A, heating brominated hydrocarbonA and metal magnesium to reflux, and initiating reaction to obtain a first reaction solution; synchronously and dropwise adding chlorinated hydrocarbon and brominated hydrocarbon B which are diluted by a solvent B into the first reaction solution, and continuing reaction to obtain a second reaction solution; dropwise adding the second reaction solution into alkyl trialkoxy silane, and carrying outreflux reaction to obtain a third reaction solution; and cooling the third reaction solution, carrying out solid-liquid separation, and finally, carrying out washing and rectifying to obtain the dialkyl dialkoxy silane. The Grignard reaction of the chlorinated hydrocarbon is promoted by utilizing the high activity of the brominated hydrocarbon, so that on one hand, the overall conversion rate ofthe Grignard reaction can be remarkably improved, byproducts are reduced, the yield of a final product is improved, and on the other hand, the production cost can be reduced.
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Paragraph 0058-0060
(2020/04/17)
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- A process for preparing high-purity methyl phenyl dimethoxy silane method
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The invention relates to a preparation method for high-purity methylphenyl-dimethoxysilane. The preparation method is characterized in that high-purity methylphenyl-dimethoxysilane is prepared through four-step deacidification. The method comprises the following steps: 1) adding dichloromethyl phenylsilane and a hydrogen chloride absorbent into an alcoholysis enclosed agitation reactor, then slowly adding a mixed liquor of absolute methanol and a catalyst drop by drop, controlling a certain reaction temperature, carrying out reflux deacidification at a certain temperature after completion of dropwise addition, carrying out filtering after complete reaction so as to obtain a crude methylphenyl-dimethoxysilane product and recovering the tail gas--hydrogen chloride gas by using a falling film absorption system for preparation of hydrochloric acid; and 2) adding the crude methylphenyl-dimethoxysilane product into a self-made gradient high-efficiency rectifying tower bottom, controlling rectification temperature for fractionation and recovery of methanol and adjusting a reflux ratio to rectify high-quality methylphenyl-dimethoxysilane with quality reaching an international advanced level. The preparation method for methylphenyl-dimethoxysilane has the advantages of environment friendliness, cyclic utilization of resources, stable process, simple operation and product purity of more than 99.5%.
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Paragraph 0019-0022
(2017/10/06)
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- Platinum-Catalyzed Multicomponent Alcoholysis/Hydrosilylation and Bis-hydrosilylation of Alkynes with Dihydrosilanes
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A new method for the hydrosilylation of alkynes controlled by a platinum catalyst with a monophosphine ligand (called TBSO-MOP) was explored. The platinum-catalyzed multicomponent and sequential silylation reaction involving alkynes, alcohols, and dihydrosilanes resulted in the highly stereoselective and high-yielding construction of functional (E)-vinylsilyl ethers. Moreover, the one-pot bis-hydrosilylation of terminal alkynes with dihydrosilanes was also achieved with the same platinum catalyst system.
- Xu, Jian-Xing,Chen, Mu-Yi,Zheng, Zhan-Jiang,Cao, Jian,Xu, Zheng,Cui, Yu-Ming,Xu, Li-Wen
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p. 3111 - 3116
(2017/08/29)
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- Nucleophilic method used for preparing phenylmethyldialkoxysilanes
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The invention relates to a nucleophilic method used for preparing phenylmethyldialkoxysilanes. The nucleophilic method comprises following steps: 1) under protection of insert gas, metallic sodium is cut into small pieces and is added into an organic solvent, a dispersing agent is added, and an obtained solution is heated so as to obtain a brightly silvery sodium particle suspension; and 2) the brightly silvery sodium particle suspension is added into a mixed solution of halogeno benzene and methyl trialkoxysilane, and a reaction accelerator is added so as to obtain a phenylmethyldialkoxysilane product, or halogeno benzene is added into the brightly silvery sodium particle suspension so as to obtain a phenyl alkali metal sodium suspension, and the phenyl alkali metal sodium suspension is added into a mixed solution of methyl trialkoxysilane and the reaction accelerator so as to obtain the phenylmethyldialkoxysilane product. Operation of the nucleophilic method is carried out under normal pressure; the nucleophilic method is mild and controllable; phenylmethyldialkoxysilane can be obtained with high yield; and the nucleophilic method is suitable for industrialized and large-scale production.
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Paragraph 0058; 0061
(2017/01/09)
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- Synthesis of phenyl-methyl dialkoxy silane method of the
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The invention relates to a method for synthesizing phenyl methyl dialkoxyl silane with high selectivity. The structural formula of phenyl methyl dialkoxyl silane is PhMeSi(OR)2, in which R is alkyl with 1-6 carbons. The method is characterized by comprising the following steps of: performing reaction with methyl trialkoxyl silane based on non-cyclic ether compounds such as ethyl ether as a reaction liquor and a bromobenzene Grignard reagent as a raw material; and then, obtaining the target compound, i.e., phenyl methyl dialkoxyl silane with high selectivity and high yield through simple filtering and fractional purification, and meanwhile, greatly inhibiting the generation of a byproduct diphenyl methyl alkoxyl silane.
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Paragraph 0051; 0052
(2017/03/14)
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- Synthetic method of methyl phenyl dimethoxysilane
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The invention relates to a synthetic method of methyl phenyl dimethoxysilane, belonging to the technical field of organic synthetic chemistry. The synthetic method comprises the following steps: (1) adding magnesium powder and proper amounts of tetrahydrofuran, methyl trimethoxysilane and chlorobenzene into a reactor, and reacting by virtue of a conventional method; (2) adding mixed liquid of chlorobenzene, methyl trimethoxysilane and methyl trichlorosilane at a constant speed when reflux conditions are maintained, maintaining the temperature, and carrying out reflux for several hours until the reaction is finished; (3) cooling, and filtering to obtain filtrate; and (4) distilling the filtrate, recycling unreacted materials at a normal pressure, and carrying out reduced pressure distillation, so as to obtain methyl phenyl dimethoxysilane. The synthetic method has the beneficial effects that the process is simple, and the operation is easy; products are easily separated; the operation is safe and reliable; and the raw material utilization rate is high, and the raw material cost is low. The synthetic method is applicable to large-scale industrial production.
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Paragraph 0018; 0019
(2016/10/10)
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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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- 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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experimental part
p. 181 - 191
(2011/10/13)
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- Reactions of dihydrofurylsilanes with O- and N-nucleophiles
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It was shown that the reaction of 4,5-dilydro-2-furylsilanes with alcohols and lithium N,N-diethylamide leads to substitution of the dihydrofuryl group by the nucleophilic residue. 1997 Plenum Publishing Corporation.
- Lukevics,Gevorgyan,Borisova
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p. 161 - 163
(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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- Concerning the Mechanism for Bifunctional Catalysis in the Methanolysis of Methoxymethylphenoxyphenylsilane
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The formic acid-formate-catalyzed methanolysis of methoxy-d3-methylphenoxyphenylsilane (1D) was studied.The formation of phenol and the exchange of the deuterated methoxy group with solvent was studied as a function of total buffer concentration.Both processes show bifunctional catalysis involving a molecule of acid and a molecule of base in the transition state.The observation of bifunctional catalysis suggests a mechanism in which formation of the silicon-solvent bond is concerted with breaking of the silicon-leaving group bond (-OC6H5 or -OCD3).From analysis of the kinetic data it is concluded that the concerted bond-forming and bond-breaking processes do not occur on a pentavalent silicon species formed by a preequilibrium addition of solvent or formate anion to 1D.The results are interpreted in terms of a mechanism in which solvent attack occurs on a tetravalent silicon center with simultaneous breaking of the silicon leaving group bond.
- Dietze, Paul E.
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p. 5653 - 5662
(2007/10/02)
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- LE PROBLEME DE LA CONJUGAISON A TRAVERS UN ATOME DE SILICIUM ?-LIE DANS LES SYSTEMES SILA-2 BUTADIENIQUES
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The chemical behaviour of sila-2 butadienes, formed as transient intermediates either by thermolysis or by photolysis of various 1-vinylsilacyclobutanes, was studied with respect to hydroxylated compounds of different pKa values.Two mechanisms can explain the nature of the products obtained on the co-thermolysis of the cyclic compounds with phenol, one with 1-silacyclobut-1-ene intermediate and the other involving an allylic silicenium cation.In both hypothetical mechanisms, the 2-silabutadienes behave as a conjugated system since they lead either to cycloaddition or to (1,2)- and (1,4)-electrophilic addition.This evidence for a conjugation phenomenon through a silicon atom is supported by the calculation of the delocalisation energies of butadiene and 2-silabutadiene.
- Bertrand, G.,Manuel, G.,Mazerolles, P.,Trinquier, G.
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p. 2875 - 2880
(2007/10/02)
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