- 1,1,1-Trimethyl-3,3,3-trichlorodisiloxane as a source and a trapping agent for silanones
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The pyrolysis of 1,1,1-trimethyl-3,3,3-trichlorodisiloxane (1) was studied and its mechanism involving the formation of dichloro-and dimethylsilanones was proposed. The composition of the condensate from the co-pyrolysis of siloxane 1 and hexamethyldisiloxane indicated that under the pyrolysis conditions the simplest siloxanes can be both the sources and the trapping agents of silanones.
- Krasnova,Chernyshev,Sergeev
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- Pd/C-catalyzed cross-coupling reaction of benzyloxysilanes with halosilanes for selective synthesis of unsymmetrical siloxanes
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A new protocol for the nonhydrolytic synthesis of unsymmetrical siloxanes has been developed. The cross-coupling reaction of benzyloxysilanes with halosilanes catalyzed by Pd/C afforded various unsymmetrical siloxanes with co-production of benzyl halides. the Partner Organisations 2014.
- Igarashi, Masayasu,Kubo, Keiko,Matsumoto, Tomohiro,Sato, Kazuhiko,Ando, Wataru,Shimada, Shigeru
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- Siloxanes as sources of silanones
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Pyrolysis of hexamethyldisiloxane (HMDS) and its copyrolysis with chlorotrimethylsilane and tetrachlorosilane were studied. Based on the data of GLC analysis and on the mass spectrum of the condensate obtained after the pyrolysis of HMDS, it was concluded that HMDS acts as a source of dimethylsilanone. The results of the copyrolysis of HMDS with chlorotrimethylsilane used as a trapping reagent indicate that the dimethylsilanone generated from HMDS can be inserted into the Si-Cl and Si-O bonds. In the copyrolysis of HMDS with tetrachlorosilane serving as a trapping reagent for dimethylsilanone, both dimethylsilanone and dichlorosilanone are generated.
- Chernyshev,Krasnova,Sergeev,Abramova
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- One-Step Synthesis of Siloxanes from the Direct Process Disilane Residue
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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
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supporting information
p. 17165 - 17168
(2016/11/23)
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- Method for producing polyimidesiloxane
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PROBLEM TO BE SOLVED: To provide a method for synthesizing siloxanes at will in good yield while maintaining high structural controllability, which can be applied to substrates having various substituents.SOLUTION: The method comprises reacting benzyloxysilanes and silicon halides in the absence of hydrogen using a catalyst comprising a transition metal or a compound thereof, preferably a metal of group 9 or group 10 of the periodic table or a compound thereof. Thereby, corresponding siloxanes can be produced safely and simply in high yield under a mild reaction condition accompanied by elimination of a benzyl halide. Especially, by using an active carbon-supported catalyst as a heterogeneous catalyst, the target siloxanes can be separated easily.
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Paragraph 0040
(2018/10/16)
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- Rapid assembly of explicit, functional silicones
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The impressive surface activity of silicones can be enhanced by the incorporation of hydrophilic organic functional groups and polymers. Traditional routes to such compounds, which typically involve platinum-catalyzed hydrosilylation, suffer from incompatibility with certain functional groups. B(C6F5)3-catalyzed condensation of hydrosilanes with alkoxysilanes offers new opportunities to prepare explicit silicone structures. We demonstrate here that conversion of alcohols to silyl ethers competes unproductively with alkoxysilane conversion to disiloxanes. By contrast, a wide range of structurally complex alkyl halide and oligovinyl compounds can be readily made in high yield. Thermal 3+2-cycloadditions and thiol-ene click reactions are used to convert these compounds into surface active materials. The Royal Society of Chemistry.
- Grande, John B.,Gonzaga, Ferdinand,Brook, Michael A.
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experimental part
p. 9369 - 9378
(2011/01/07)
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- Monosodiumoxyorganoalkoxysilanes: Synthesis and properties
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The reaction of organoalkoxysilanes with sodium hydroxide was studied in detail. Studies indicate that this reaction involves more than one stage and involves rather complex multistep process, which leads to the formation of both monosodiumoxyorganoalkoxysilanes (MSOAS) and several secondary products. Analysis of experimental evidence makes it possible to advance the mechanism behind this phenomenon and to define the optimum conditions for the preparation of pure MSOAS with high yields. Different MSOAS were synthesized and their basic physicochemical properties were studied. MSOAS are shown to constitute multifunctional reagents with chemically independent functional groups, and their reaction with trimethylchlorosilane selectively proceeds via - ONa groups, whereas their interaction with triethylesilanol and higher alcohols proceeds exclusively via - OAlk groups. Exchange interaction between MSOAS and organoalkoxysilanes via - ONa and - OAlk groups was found and studied in detail. Temperature corresponding to the onset of thermal degradation of MSOAS was estimated to be equal to ～ 180-190°C.
- Rebrov,Muzafarov
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p. 514 - 541
(2007/10/03)
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- PROCESS FOR STABILIZATION OF SILOXANE COMPOUNDS
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A method for stabilizing silicone dry cleaning solvents containing impurities, comprising contacting the silicone solvent with an adsorbent, neutralizing agent or combination thereof to purify the solvent and prevent reequilibration and polymerization, and separating the silicone solvent.
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- Reaction of the dioxane complex of dichlorogermylene with siloxanes
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The major organogermanium compounds formed by reactions of the dioxane complex of dichlorogermylene with hexamethyldisiloxane, octamethyltrisiloxane, and hexamethyltricyclotrisiloxane are bis(trimethylsiloxy)dichlorogermane, 3,3-dichloro-1,1,1,5,5,7,7,7-o
- Shcherbinin,Pushkina,Krivolapova,Bykovchenko,Khromykh,Komalenkova,Chernyshev
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p. 1907 - 1910
(2007/10/03)
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- Reaktionen von Trimethylsiloxychlorsilanen (Me3SiO)Me2-nPhnSiCl (n = 0, 1, 2) mit Lithium - Bildung von Trimethylsiloxy-substituierten Silyl- und Disilanyllithiumverbindungen sowie Di- und Trisilanen
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The trimethylsiloxychlorosilanes (Me3SiO)Me2-nPhnSiCl (1: n=0; 2: n=1; 3: n=2) were allowed to react with lithium metal in tetrahydrofuran (THF) and in a mixture of THF-diethylether-n-pentane in volume ratio 4:1:1 (Trapp mixture). The reaction of 1 with lithium metal in THF under refluxing leads to the homo-coupling product [(Me3SiO)Me2Si]2 (4). A mixture of 1 and Me3SiCl in molar ratio 1:2 reacts with lithium metal in THF to give 4 and the cross-coupling product (Me3SiO)Me2SiSiMe3 (7). The silyllithium derivatives Me3SiO(SiMePh)nLi (8: n = 1; 9: n = 2; 10: n = 3) and Me3SiSiMePhLi (11) are formed in the reaction of 2 with lithium metal in THF at -78°C and in the Trapp mixture at -110°C. Main product in both cases is 9. 8-11 are trapped by Me3SiCl and HMe2SiCl. The trapping products (Me3SiO)SiMePhSiMe3 (13a), Me3SiO(SiMePh)2SiMe2R (14a, 14b; a: R = Me, b: R = H), Me3SiO(SiMePh)3SiMe2R (15a, 15b) and Me3SiSiMePhSiMe2R (16a, 16b) are obtained. The reaction of 3 with lithium metal like 2 produces the silyllithium derivatives Me3SiO(SiPh2)nLi (18: n = 1, 19: n = 2) and Me3SiSiPh2Li (20), wich are trapped by Me3SiCl and HMe2SiCl to give the corresponding disilanes (Me3SiO)SiPh2SiMe2R (23a, 23b) and trisilanes Me3SiO(SiPh2)2SiMe2R (24a, 24b) as well as Me3SiSiPh2SiMe2R (25a, 25b). In addition to 18, 19 and 20 LiSiPh2SiPh2Li (21) is formed in a small amount in the reaction of 3 with lithium metal at -78°C to afford tetrasilanes [RMe2SiPh2Si]2 (26a, 26b) after trapping by Me3SiCl and HMe2SiCl. The disilane (Me3SiO)SiMeR′SiMe3 (17) (R′ = 3,4,5,6-tetrakis(trimethylsilyl)cyclohex-1-enyl) is produced by reaction of a mixture of 2 and Me3SiCl in molar ratio 1:6 with 6 equivalents of lithium at -78°C in THF. The reaction of a mixture of 3 and Me3SiCl in the molar ratio 1:10 with 11 equivalents of lithium under the same conditions gives (Me3SiO)SiR′2SiMe3 (27).
- Harloff, Joerg,Popowski, Eckhard,Fuhrmann, Hans
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p. 136 - 146
(2007/10/03)
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- Simethicone containing pharmaceutical compositions
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A method of making solid oral dosage form for the treatment of gastrointestinal disorders comprising a therapeutically effective amount of a pharmaceutical suitable for the treatment of gastric disorders selected from the group consisting of cimetidine, ranitidine, famotidine, diphenoxylate, loperamide, loperamide-N-oxide, pharmaceutically acceptable salts thereof and combinations thereof; and a therapeutically effective amount of simethicone wherein the pharmaceutical and simethicone are separated by a barrier. The barrier is formed by coating with a polymer impermeable to simethicone.
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- Interactions of hexachlorodiphosphazenium ion with an alcohol and with some silicon-oxygen reagents and their role in the catalysis of polycondensation in silanol-alkoxysilane systems
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Condensation reactions of trimethylethoxysilane (MOEt) and pentamethyldisiloxanol in n-heptane catalysed by hexachloro-1λ-diphosphaza-1-enium salts were studied. Although the substrate conversion vs. time dependences point to domination by heterofunctional condensation, the process is more complex. Homofunctional condensation as well as fast consecutive hydrolysis and ethanolysis strongly contribute to the overall process. Results of kinetic studies point to inhibition of these component reactions by an excess of MOEt. Interactions of the hexachloro-1λ-diphosphaza-1-enium salts with MOEt, ethanol and silanol were studied by 31P NMR. It was demonstrated that a fast substitution reaction of chloride by ethoxy group takes place when ethanol or ethoxysilane is introduced into solutions of hexachlorodiphosphazenium salts. This process is responsible for the decrease in condensation activity of the catalyst.
- Chojnowski, Julian,Cypryk, Marek,Fortuniak, Witold,Kazmierski, Krzysztof,Taylor, Richard G.
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p. 351 - 361
(2007/10/03)
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- MUTUAL EFFECT OF SOLUTIONS OF SALTS AND HCl ON COHYDROLYSIS OF METHYLCHLOROSILANES
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In hydrolytic polycondensation of Me2SiCl2, the combined effect of salts and HCl causes a decrease in the yield of 4, and this effect increases with an increase in the binding strength of the water with the salt in hydrate complexes and the concentration of HCl.The combined effect of salts and HCl on the composition of the products of the reaction in hydrolytic copolycondensation of Me2SiCl2 with Me3SiCl and MeSiCl3 with Me3SiCl increases with an increase in the degree of binding of water in hydrate complexes, caused by competition in the formation of hydrate complexes between the salt and HCl.
- Kopylov, V. M.,Agashkov, S. P.,Sunkovich, G. V.,Prikhod'ko, P. L.
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p. 692 - 697
(2007/10/02)
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- FEATURES OF INFLUENCE OF HCl ON HYDROLYTIC COPOLYCONDENSATION OF BIFUNCTIONAL ORGANOCHLOROSILANES WITH TRIMETHYLCHLOROSILANE
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The hydrogen chloride that is formed in the hydrolytic copolycondensation of R'RSiCl2 with Me3SiCl affects the composition of the reaction products only at cocentrations above 30-35percent, where it is responsible for splitting out the terminal trimethylsiloxy group.The stability of the terminal groups increases with increasing size of the substituents on the silicon atom in the R'RSiCl2.The total yield of Me3SiO(R'RSiO)mSiMe3 with m = 1-4 also increases with increasing size of the substituents on the silicon atom in the R'RSiCl2.The total yield of p with p = 3-5 increases with decreasing tendency of the R'RSiCl2 to form rings by hydrolytic polycondensation, and with increasing sensitivity of the terminal trimethylsiloxy group in the cocondensation products to the action of HCl and its activity with respect to the siloxane bond.
- Kopylov, V. M.,Agashkov, S. P.,Sunkovich, G. V.,Prikhod'ko, P. L.
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p. 1257 - 1261
(2007/10/02)
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- Siloxane basicity toward strong acid in nonpolar solution
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The relative basicities of ten siloxanes and an ether were studied in benzene by determining from visible spectroscopic measurements the thermodynamic constants for the competition between the substrate and a reference base (4-chloro-2-nitroaniline) for acid (trifluoromethanesulfonic acid): RB-HA + S ? RB + S·HA. The Keq values were considered as a measure of basicity with the following order established and explained by inductive effects in the protonated species: permethyl linear siloxanes (Me3Si(OSiMe2)nOSiMe3, n = 0-3) > dibutyl ether > HMe2SiOSiMe2H > branched siloxanes ((Me3SiO)3SiMe, (Me3SiO)4Si) > cyclic siloxanes ((Me2SiO)n, n = 3-5). The ΔH and ΔS values were positive and increased with higher basicity; this behavior was attributed to differential solvation of ion pairs.
- Shepherd, Brian D.
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p. 5581 - 5583
(2007/10/02)
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- Method for the cleavage of organic siloxanes, and products and applications thereof
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A method for the cleavage of organosiloxanes with chlorosilanes in the presence of ferric chloride and hydrogen chloride as catalysts resulting in chloroalkyl silanes or chloroaryl silanes, and organosiloxanes, which are characterized by one or more --O--Si--R3 groups, (R=alkyl or aryl), which are directly bound to a silicon atom which in turn is bound either to the same grouping or to an alkyl or aryl moiety.
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- METAL COMPLEX-CATALYZED REDISTRIBUTION REACTIONS OF ORGANOSILANES. IV. REDISTRIBUTION REACTIONS OF METHYLSILOXANES CATALYZED BY TRANSITION METAL COMPLEXES
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Redistribution reactions of a variety of hydrogen-substituted siloxanes are catalyzed by various transition metal complexes of iridium and rhodium.The products arise from breaking and remaking of Si-C, Si-H, and Si-O bonds.Siloxanes not possessing a Si-H bond are inert under the conditions studied.The most favored reaction pathway appears to scramble preferentially the groups directly attached to the silicon bearing the hydrogen atom.A new cyclo-iridiadisiloxane, (L = Ph3P; R = Me3SiO) is reported.This compound exists in three isomeric forms as a consequence of the spatial arrangements of the R and Me groups on the ring.
- Gustavson, Wayne A.,Epstein, Paul S.,Curtis, M.D.
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