- The behaviour of medium-sized permethylated cyclosilanes towards SOCl2 and SOCl2-HC(OCH3)3
-
Treatment of Si6Me12 with SOCl2 in various solvents gives α,ω-dichloropermethylpolysilanes (nSi = 2,3,4,6) at temperatures above 80 deg C.In contrast to an earlier report, treatment of the α,ω-dichloropermethylpolysilanes with HC(OCH3)3 in the presence of SOCl2 does not give Si6Me12.
- Jenkner, P.K.,Spielberger, A.,Hengge, E.
-
-
Read Online
- Synthesis of α,ω-dichloropermethyloligosilanes by reactions of polydimethylsilane with metal chlorides
-
The reactions of high-molecular-weight polydimethylsilane with metal chlorides in variable oxidation states at high temperature in the absence of a solvent afford mixtures of α,ω-dichloropermethyloligosilanes Cl(Me2Si)mCl (m = 2-9). The influence of the reaction conditions (temperature, reaction time, and the reagent ratio) on the composition and yields of the reaction products was examined.
- Chernyavskii, A. I.,Chernyavskaya, N. A.
-
-
Read Online
- Katalytische Hydrierung chlorhaltiger Disilane mit Tributylstannan
-
Partial hydrogenation of methylchlorodisilanes and hexachlorodisilane to methylchlorohydrogendisilanes and chlorohydrogendisilanes respectively, is possible by the use of tri-n-butylstannane.Electron-pair donators catalyse the hydrogenation reaction.The 29Si NMR chemical shifts and coupling constants 1JSiH of some new methylchlorohydrogendisilanes are reported.Keywords: Silicon; Catalysis; Partial hydrogenation
- Herzog, U.,Roewer, G.,Paetzold, U.
-
-
Read Online
- ?-BOND CONJUGATION IN POLYSILANES, A PES SCALED FREE-ELECTRON APPROACH FOR THE INTERPRETATION OF SKELETAL CLEAVAGE REACTION
-
The ?-orbital energies calculated by the simple free-electron model with a parametrization procedure recently by Von Szentpaly correlate very closely with the ?-band positions of the corresponding photoelectron spectra.For the ?-orbitals of three series of molecules: H(CH2)nH (n=2-4); H(SiH2)nH (n=2-5); Me(SiMe2)nMe (n=2-4) the FEMO model yields a standard error (SE) of 0.060 eV.Compared with HMO results (LCGO, LCBO and Sandorfy C) the correlation is significantly improved.The free-electron results are more accurate than those obtained using the PPP, CNDO/2, MINDO/3, SAMO and ab initio methods.The free-electron frontier orbital densities were successfully used to account for features of the skeletal cleavage reactions of polysilanes.
- Herman, Aleksander,Dreczewski, Boguslaw,Wojnowski, Wieslaw
-
-
Read Online
- Synthesis of dichloro derivatives of linear and cyclic permethyloligosilanes and cyclolinear permethylpolysilane-siloxanes and permethylpolyoxysilane based on them
-
The reactions of dodecamethylcyclohexasilane with chlorides of I, II, IV-VI, and VIII Group metals were studied as a promising approach to the synthesis of functional oligosilanes. When cyclohexasilane reacts with metal chlorides without a solvent at elevated temperatures, the process is intensified and, in some cases, the selectivity of formation of chloro derivatives of linear and cyclic permethyloligosilanes increases. The cyclolinear permethylpolysilane-siloxanes were prepared by heterofunctional polycondensation of the resulting oligosilanes with bifunctional cyclic and linear permethyloligosiloxanes. Cyclolinear permethylpolyoxysilane was synthesized for the first time by the reaction of 1,3-dihydroxycyclo-hexasilane with 1,3-dichlorohexamethyltrisilane.
- Chernyavskii, A. I.,Larkin, D. Yu.,Chernyavskaya, N. A.
-
-
Read Online
- Disilane Cleavage with Selected Alkali and Alkaline Earth Metal Salts
-
The industry-scale production of methylchloromonosilanes in the Müller–Rochow Direct Process is accompanied by the formation of a residue, the direct process residue (DPR), comprised of disilanes MenSi2Cl6-n (n=1–6). Great research efforts have been devoted to the recycling of these disilanes into monosilanes to allow reintroduction into the siloxane production chain. In this work, disilane cleavage by using alkali and alkaline earth metal salts is reported. The reaction with metal hydrides, in particular lithium hydride (LiH), leads to efficient reduction of chlorine containing disilanes but also induces disproportionation into mono- and oligosilanes. Alkali and alkaline earth chlorides, formed in the course of the reduction, specifically induce disproportionation of highly chlorinated disilanes, whereas highly methylated disilanes (n>3) remain unreacted. Nearly quantitative DPR conversion into monosilanes was achieved by using concentrated HCl/ether solutions in the presence of lithium chloride.
- Santowski, Tobias,Sturm, Alexander G.,Lewis, Kenrick M.,Felder, Thorsten,Holthausen, Max C.,Auner, Norbert
-
supporting information
p. 13202 - 13207
(2019/10/22)
-
- PROCESS FOR THE PRODUCTION OF ORGANOHYDRIDOCHLOROSILANES FROM HYDRIDOSILANES
-
The invention relates to a process for the manufacture of organomonosilanes bearing both hydrogen and chlorine substituents at the silicon atom by subjecting one or more organomonosilanes to the reaction with one or more di- or carbodisilanes in the presence of one or more compounds (C) acting as a redistribution catalyst, wherein at least one of the silanes has only hydrogen and organic residues at the silicon atoms.
- -
-
Page/Page column 45; 46
(2019/04/16)
-
- Making Use of the Direct Process Residue: Synthesis of Bifunctional Monosilanes
-
The industrial production of monosilanes MenSiCl4?n (n=1–3) through the Müller–Rochow Direct Process generates disilanes MenSi2Cl6?n (n=2–6) as unwanted byproducts (“Direct Process Residue”, DPR) by the thousands of tons annually, large quantities of which are usually disposed of by incineration. Herein we report a surprisingly facile and highly effective protocol for conversion of the DPR: hydrogenation with complex metal hydrides followed by Si?Si bond cleavage with HCl/ether solutions gives (mostly bifunctional) monosilanes in excellent yields. Competing side reactions are efficiently suppressed by the appropriate choice of reaction conditions.
- Sturm, Alexander G.,Santowski, Tobias,Schweizer, Julia I.,Meyer, Lioba,Lewis, Kenrick M.,Felder, Thorsten,Auner, Norbert,Holthausen, Max C.
-
supporting information
p. 8499 - 8502
(2019/06/13)
-
- CLEAVAGE OF METHYLDISILANES TO METHYLMONOSILANES
-
The invention relates to a process for the manufacture of methylmonosilanes comprising the step of subjecting one or more methyldisilanes to the cleavage reaction of the silicon-silicon bond, and optionally a step of separating the resulting methylmonosilanes.
- -
-
Paragraph 27; 28
(2019/04/16)
-
- One-Step Synthesis of Siloxanes from the Direct Process Disilane Residue
-
The well-established Müller–Rochow Direct Process for the chloromethylsilane synthesis produces a disilane residue (DPR) consisting of compounds MenSi2Cl6?n(n=1–6) in thousands of tons annually. Technologically, much effort is made to retransfer the disilanes into monosilanes suitable for introduction into the siloxane production chain for increase in economic value. Here, we report on a single step reaction to directly form cyclic, linear, and cage-like siloxanes upon treatment of the DPR with a 5 m HCl in Et2O solution at about 120 °C for 60 h. For simplification of the Si?Si bond cleavage and aiming on product selectivity the grade of methylation at the silicon backbone is increased to n≥4. Moreover, the HCl/Et2O reagent is also suitable to produce siloxanes from the corresponding monosilanes under comparable conditions.
- Neumeyer, Felix,Auner, Norbert
-
supporting information
p. 17165 - 17168
(2016/11/23)
-
- Surface Active Organosilicone Compounds
-
The present invention relates to new organodisilanes or carbodisilanes, a process for manufacturing the same and their use, in particular, as surface active agents, especially as spreading agents.
- -
-
Page/Page column 6-7
(2008/12/09)
-
- Reactions of dodecamethylcyclohexasilane and polydimethylsilane with metal chlorides
-
The reactions of dodecamethylcyclohexasilane and high-molecular-weight polydimethylsilane with chlorides of I, II, IV-VI and VIII Group metals at high temperature in the absence of a solvent were studied. The interaction of (Me2Si)6 with metal chlorides proceeds with the cleavage of Si-Si and Si-C bonds with the formation of chloro derivatives of linear and cyclic permethyloligosilanes. The reactions of polydimethylsilane with metal chlorides afford mixtures of α,ω-dichlorooligosilanes, Cl(Me2Si)nCl (n=2-9). The influence of the reaction conditions (temperature, reaction time and the reagent ratio) on the composition and yields of the reaction products was examined.
- Chernyavskii,Larkin,Chernyavskaya
-
-
- Palladium-Catalyzed Silylation of Aryl Bromides Leading to Functionalized Aryldimethylsilanols
-
Equation presented. A mild and general palladium-catalyzed insertion of 1,2-diethoxy-1,1,2,2-tetramethyldisilane into a variety of aryl bromides affords the aryldimethylsilyl ethers in high yields. Hydrolysis of the ethers under pH-optimized conditions results in the exclusive formation of the desired aryldimethylsilanols.
- Denmark, Scott E.,Kallemeyn, Jeffrey M.
-
p. 3483 - 3486
(2007/10/03)
-
- Interactions of chloromethyldisilanes with tetrakis(dimethylamino)ethylene (TDAE), formation of [TDAE] [Si3Me2Cl7]
-
The chlorodisilanes SiClMe2-SiClMe2 (1), SiCl2Me-SiCl2Me (2), SiCl3-SiCl3 (3) and a 9:1 mixture of 2 and SiCl3-SiCl2Me (4) were reacted with the electron-rich alkene tetrakis-(dimethylamino)-ethylene (TDAE) in n-hexane as well as in polar solvents. While 1 gave no reaction at all, 3 underwent a disproportionation reaction into SiCl4 and Si(SiCl3)4. Also 2 and mixtures of 2 and 4 were disproportionated into MeSiCl3 (2a) and methylchlorooligosilanes. Additionally a crystalline mixture of Si3Me3Cl6 -TDAE (5a) plus Si3Me2Cl7 -TDAE (5b) was obtained by reaction of a 9:1 mixture of 2 and 4 with TDAE in n-hexane as well as in 1,2-dimethoxyethane. The reaction of 2 with TDAE in acetonitrile (MeCN) led to a crystalline precipitation of [TDAE]Cl2 -MeCN (6.MeCN) in addition to MeSiCl3 and methylchlorooligosilanes. The structures of 5b and 6.MeCN were determined by X-ray crystallography beside their NMR and IR spectroscopic characterization. Compound 5b crystallizes in the monoclinic space group P2/c (Z = 4), 6.MeCN in the orthorhombic space group Pna21 (Z = 4). The structure of 5b reveals a [TDAE].+ radical cation and a 1, 2-Me2Si3Cl7- anion with a pentacoordinated central silicon atom.
- Knopf,Herzog,Roewer,Brendler,Rheinwald,Lang
-
-
- Gas-phase acidities of aryldimethylsilanes
-
Gas-phase acidities of aryldimethylsilanes have been determined by measuring equilibrium constants of proton-transfer reactions using a FT ion cyclotron resonance mass spectrometer. The acidity of dimethylphenylsilane was found to be 370.5 kcal mol-1, i.e., it is a stronger acid than dimethylsilane by 2.7 kcal mol-1. The acid-enhancing effect of the phenyl group is significantly smaller than in the carbon analog. In addition, the acidities of aryldimethylsilanes were linearly correlated with the standard substituent constant (σ°), giving a ρ of 4.6, indicating that the thermodynamic stabilities of silyl anions are less sensitive to the polar effects of substituents than benzoate, phenoxide, anilide, and benzyl anions. More importantly, it was found that the p-nitro group, which has a large π-electron-accepting ability, also conforms to the ?° correlation, suggesting that π-delocalization does not play a role in the stabilization of silyl anions; this is in contrast to the π-effects observed in carbon analogs. This is supported by theoretical stabilization energies and optimized geometrical features based on ab initio calculations.
- Irie,Kikukawa,Shimizu,Mishima
-
p. 923 - 928
(2007/10/03)
-
- Complexation of paramagnetic intermediates formed in the photolysis of 7,7-dimethyl-1,4,5,6-tetraphenyl-2,3-benzo-7-silanorbornadiene: A study by spin chemistry methods
-
Complexation of paramagnetic intermediates formed in the photolysis of 7,7-dimethyl-1,4,5,6-tetraphenyl-2,3-benzo-7-silanorbornadiene with n-donors (PPh3, O2) was studied by spin chemistry methods.
- Leshina,Taraban,Plyusnin,Volkova,Egorov
-
p. 421 - 426
(2007/10/03)
-
- New bisphenols with silylene fragments: Synthesis and spectra
-
A series of bisphenols containing silylene sequences were prepared by condensation of 4-(trimethylsiloxy)phenylmagnesium bromide with αω-dichloropermethylsilanes and studied by fluorescence spectroscopy.
- Pushkarev
-
p. 1749 - 1751
(2007/10/03)
-
- Homoconjugation in allyl silicon derivatives
-
New diallyl derivatives of mono- and disilane were obtained and characterized. Fluorescence, 1H, C, and 29Si NMR, as well as IR and Raman spectroscopy were used to show the presence of intramolecular donor-acceptor β-coupling between the silicon atom and the allyl groups, which is realized directly through space by the homoconjugation mechanism (i.e. direct conjugation between vacant 3d orbitals of the silicon atom and the allyl π bonds, not involving σ orbitals of the allyl methylene groups).
- Osadchev,Pushkarev,Nikitina,Shamanin,Skorokhodov
-
p. 1378 - 1382
(2007/10/03)
-
- Kinetic Control in the Cleavage of Unsymmetrical Disilanes
-
A series of 12 phenyl-substituted arylpentamethyldisilanes 1a-1 have been synthesized in order to examine the regioselectivity of their nucleophilic Si,Si bond cleavage reactions under Still's conditions (MeLi/HMPA/0°C). It has been found that the sensitivity of these reactions to the electronic effects of the substituents in the phenyl ring could be described by the Hammett-type equation log(kA/kB) = 0.4334 + 2.421(Σσ); (correlation coefficient R = 0.983). The kA/kB ratio represents the relative rate of attack at silicon atom A (linked to the aryl ring) or at silicon atom B (away from the aryl ring) of the unsymmetrical disilanes. Thus, the present investigation shows that the earlier belief according to which the nucleophilic cleavage of unsymmetrical disilanes always produces the more stable silyl anionic species (thermodynamic control) should be abandoned, or at least seriously amended: kinetic factors appear to exert a primary influence on the regioselectivity of such reactions. Since the two major kinetic factors (i.e., electrophilic character of and steric hindrance at a given silicon atom) have opposite effects on the orientation of the reaction, it may happen that kinetic and thermodynamic control lead to the same result. For some of the unsymmetrical disilanes studied, the major reaction path was not the Si,Si bond cleavage; instead, Si-aryl bond breaking occurred, producing the corresponding aryl anions.
- Hevesi, Laszlo,Dehon, Michael,Crutzen, Raphael,Lazarescu-Grigore, Adriana
-
p. 2011 - 2017
(2007/10/03)
-
- Synthesis of α,ω-dihalopermethyloligosilanes and silane-siloxane copolymers
-
α,ω-Dibromopermethyloligosilanes, Br(SiMe2)nBr (n = 2-4, 6), were prepared by the reaction of dodecamethylcyclohexasilane with bromine. The reaction of (Me2Si)6 with MCl4 (M = Sn, Ti) proceeds with the cleavage of Si-Si-and Si-C-bonds with the formation of α,ω-dichloropermethyloligosilanes, Cl(SiMe2)nCI (n = 2-4, 6), and chloro derivatives of cyclohexasilane, ClmSi6Me12-m (m = 1, 2). Silane-siloxane copolymers of regular structure were obtained by heterofunctional copolycondensation of α,ω-dihalopermethyloligosilanes with 1,5-dihydroxyhexamethyltrisiloxane.
- Chernyavskii,Zavin
-
p. 1449 - 1453
(2007/10/03)
-
- Methylchlorooligosilanes as products of the basecatalysed disproportionation of various methylchlorodisilanes
-
The methylchlorodisilanes SiCl2Me-SiCl2Me (1), SiCl2Me-SiClMe2 (2) and SiClMe2-SiClMe2 (3) disproportionate in the presence of a basic catalyst into methylchloromonosilanes and various methylchlorooligosilanes. Oligosilanes involving up to seven silicon atoms were identified by means of 29Si-, 13C-1H-NMR and GC-MS measurements. Formation of methylchlorooligosilanes is thought to take place via silylene intermediates.
- Herzog,Richter,Brendler,Roewer
-
p. 221 - 228
(2007/10/03)
-
- Process for preparing cyclopentadienyl group-containing silicon compound or cyclopentadienyl group-containing germanium compound
-
Disclosed is a process for preparing a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, comprising reacting (i) a lithium, sodium or potassium salt of a cyclopentadiene derivative with (ii) a silicon halide compound or a germanium halide compound in the presence of a cyanide or a thiocyanate. The cyanide or the thiocyanate is preferably a copper salt. According to the process of the invention, a cyclopentadienyl group-containing silicon compound or a cyclopentadienyl group-containing germanium compound, which is very useful for the preparation of a metallocene complex catalyst component, can be prepared in a high yield for a short period of time.
- -
-
-
- Photolysis of 1,1,2,2-tetramethyl-1,2-bis-(2'-thienyl)disilane
-
Photolysis of 1,1,2,2-tetramethyl-1,2-bis-(2'-thienyl)disilane (I) in methanol/benzene leads to dimethyl-bis-(2'-thienyl)silane (III), 2-methoxydimethylsilylthiophene (IV) and 2-dimethylsilylthiophene (V) as a major products.The mechanism of this reaction, has been explored by use of methanol-d4.The predominant pathway leading to IV and V appears to involve direct reaction of methanol with the photoexcited state of I.
- Hu, Shui-Sheng,Weber, William P.
-
p. 155 - 164
(2007/10/02)
-
- AEQUILIBRIERUNGSREAKTIONEN AN DISILANEN
-
Redistribution reactions of Si2Me6 and Si2Cl6 and of Si2Me2Cl4 and Si2Me2H4 are discussed.While the high temperature necessary for the exchange between methyl and chlorine leads to rupture of the silicon-silicon bond in the case of the Si2Me6/Si2Cl6 system, redistribution of chlorine and hydrogen proceeds at room temperature with AlCl3 as catalyst.The reaction between Si2Me2Cl4 and Si2Me2H4 at 90 deg C is examined in detail by 1H NMR spectroscopy.This reaction is a useful route for preparation of the new compounds Me2Si2ClxH4-x (x=1-3). 1H NMR, 13C NMR, 29Si NMR, IR and Raman spectroscopic data of the partly unknown 1,2-dimethylchlorodisilanes are reported.
- Schmoelzer, H.,Hengge, E.
-
-
- A CONVENIENT SYNTHESIS OF BENZYLMETHYLCHLOROSILANES BY THE PALLADIUM-CATALYZED DECHLORINATIVE SILYLATION OF BENZYLIC CHLORIDES WITH METHYLCHLORODISILANES
-
Benzylmethylchlorosilanes were prepared in high yields by the dechlorinative silylation of benzylic chlorides with methylchlorodisilanes MenSi2CI6-n (n = 2, 3, and 4) in the presence of a catalytic amount of Pd(PPh3)4.
- Matsumoto, Hideyuki,Kasahara, Miyuki,Matsubara, Ikuya,Takahashi, Masatoshi,Nakano, Taichi,Nagai, Yoichiro
-
p. 399 - 400
(2007/10/02)
-
- The synthesis of novel chlorosilyl and chlorogermyl mercurials with some of their chemical reactions
-
When a mercury alkyl is irradiated in the presence of trichlorosilane, bis(trichlorosilyl)mercury, a white crystalline solid, and the alkane are formed. In a similar reaction with methyldichlorosilane, bis(methyldichlorosilyl)mercury is a product. With trichlorogermane as a reactant a similar light-induced reaction produces bis(trichlorogermyl)mercury. These novel mercurials react with compounds possessing a silicon-hydrogen bond to form disilanes. Preparations are described for methylpentachlorodisilane, 1,1-dimethyltetrachlorodisilane, 1,2-dimethyltetrachlorodisilane, 1,1,1,-trimethyltrichlorodisilane, 1,1,2-trimethyltrichlorodisilane, 1,1,1,2-tetramethyldichlorodisilane, 1,1,2,2-tetramethyldichlorodisilane, pentamethylchlorodisilane, trichlorosilyltrichlorogermane, and trimethylsilylmethyltrichlorogermane using various modifications of this reaction. Syntheses have been devised for the mercurials, bis(trichlorosilyl)mercury, bis(methyldichlorosilyl)mercury, bis(trichlorogermyl)mercury, and (trimethylsilylmethyl)trichlorogermylmercury. Bis(dimethylchlorosilyl)mercury is formed at low temperatures but decomposes at temperatures above -79°. Bis(trichlorosilyl)mercury also reacts with dimanganese decacarbonyl to form trichlorosilylmanganese pentacarbonyl.
- Bettler, Charles R.,Sendra, Joseph C.,Urry, Grant
-
p. 1060 - 1065
(2007/10/05)
-
