- Synthesis of 1,1-bis(silyl)-1-alkene derivatives bearing Si-H functional groups via Peterson protocol
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Various aromatic aldehydes were converted to one-carbon elongate 1,1-bis(silyl)-1-alkene derivatives bearing Si-H functional and reactive groups in a convenient one-pot operation via the Peterson protocol. Then poly(styrene) and poly(α-methylstyrene) (I{cyrillic, ukrainian}&II) random homopolymers were synthesized by solution free radical polymerization at 70(±1) °C using α,α′-azobis(isobutyronitrile) (AIBN) as an initiator. The aldehyde group is introduced by direct electrophilic substitution of polymers I{cyrillic, ukrainian} and II. This formylation reaction was conducted in two different solvents: dichloromethane (CH2Cl2) and nitrobenzene (PhNO2). The results indicate that PhNO2 appeared to be a more suitable solvent for such an aldehyde functionalization of the polymers. The formylated polymers (ICHO, IICHO) were then converted to Si-H functionalized polymers (ISi-H, IISi-H) via reaction with tris(dimethylsilyl)methyllithium, (HMe2Si)3CLi.
- Safa, Kazem D.,Hassanpour, Akbar,Tofangdarzadeh, Shahin
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experimental part
p. 3622 - 3626
(2009/03/11)
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- Dimethoxydimethylsilane from silicon atoms and dimethyl ether: A combined matrix-spectroscopic and density functional theory study
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The reaction between silicon atoms and dimethyl ether (6) has been studied in an argon matrix at 10 K and in solid dimethyl ether (6) at temperatures up to 80 K. In the initial step, a triplet n-adduct T-5 is formed between a silicon atom and 6. The next step needs photochemical activation. Depending on the relative dimethyl ether/argon ratio, the photoproduct is either dimethylsilanone (1) or singlet methoxymethylsilylene (S-2), which, in the presence of an excess of 6, exists as a dimethyl ether complex 8 of silylene S-2. Longer irradiation transforms dimethyl ether addition compounds S-8-t/ S-8-c into dimethoxydimethylsilane (7). If irradiation is applied directly during cocondensation of silicon atoms with 6, the only detectable products are 8 and 7. Upon further irradiation of the pure dimethyl ether matrix, the rest of 8 is also photoisomerized, and dimethoxydimethylsilane (7) is observed exclusively. The structural elucidation of all new species is based on comparison of the experimental observations with density functional theory calculations. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Maier, Guenther,Glatthaar, Joerg
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p. 3350 - 3363
(2007/10/03)
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- Base Cleavage of the Benzyl-Silicon Bonds in m-ClC6H4CH2SiMe(OH)2 and m-ClC6H4CH2Si(OH)3. Proposed Formation of Metasilicate Intermediates
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A kinetic study of the base-catalysed cleavage of the diol RSiMe(OH)2 (R = m-ClC6H4CH2) in Me2SO-H2O or MeOH-H2O has indicated that at high base concentrations the main process is the unimolecular dissociation of the dianion RSiMe(O-)2 into R- and Me(O-)Si=O (an analogue of acetate ion), both of which then react rapidly with the solvent.Likewise for the triol RSi(OH)3 in Me2SO-H2O the main process appears to be the formation of R- and the metasilicate ion HO(O-)Si=O from the dianion R(OH)Si(O-)2.Base cleavage of the silanols RSiMe2OH (R = PhCH2 or m-ClC6H4CH2) in Me2SO-H2O probably involves a contribution from the unimolecular dissociation of the anion RSiMe2O- to give R- and Me2Si=O.
- Chmielecka, Jadwiga,Chojnowski, Julian,Stanczyk, Wlogdzimierz A.,Eaborn, Colin
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p. 865 - 872
(2007/10/02)
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- Matrix IR spectroscopic study of the vacuum pyrolysis of octamethylcyclotetrasiloxane, allyloxy- and allyl(allyloxy)dimethylsilanes as well as 2,2,6-trimethyl-2-silapyrane as potential sources of dimethylsilanone
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The mechanism of vacuum pyrolysis of octamethylcyclotetrasiloxane, allyloxy- and allyl(allyloxy)-dimethylsilanes, and 2,2,6-trimethyl-2-silapyrane, potential sources of transient dimethylsilanone, has been studied by matrix isolation IR spectroscopy.Only in the case of allyloxydimethylsilane is there direct evidence of silanone (CH3)2Si=O formation, by observation of its most intense band at 798 cm-1 in the matrix IR spectrum of pyrolysis products.In all other cases the intermediate, (CH3)2Si=O, was found to be thermally unstable, undergoing fragmentation into SiO molecules and CH3 radicals, thus indicating silanone participation in the reactions studied.
- Khabashesku, V. N.,Kerzina, Z. A.,Maltsev, A. K.,Nefedov, O. M.
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p. 301 - 312
(2007/10/02)
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- Direct spectroscopic study of unstable molecules with silicon-oxygen multiple bonds: Low temperature matrix stabilization of (CH3)2Si=O and (CD3)2Si=O in the gas phase
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To continue the IR spectroscopic investigations of intermediates with doublebonded silicon, the silanones (CH3)2Si=O and (CD3)2Si=O have been generated by vacuum pyrolysis of the corresponding 6-oxa-3-silabicyclohexanes and of Diels-Alder adducts of silapyranes with maleic anhydride.The above silanones have first been stabilized from the gas phase in argon matrices at 12 K and studied by IR spectroscopy.Using the dependence of the spectra on temperature and pressure in the pyrolysis zone or in warming-up experiments (to 35-40 K) the following vibrational bands of silanones have been revealed: (CH3)2Si=O 1244, 1240, 1210, 822, 798, 770, 657 cm-1; (CD3)2Si=O 1215, 1032, 1007, 995, 712, 685, 674 cm-1.The limits of thermal ( 850 deg C) and kinetic (5 x 10E-4 torr) stability of dimethylsilanone were determined.By comparison of frequencies found with computed values the band 1210 cm-1 in (CH3)2Si=O (1215 cm-1 in (CD3)2Si=O) was assigned to a Si=O streching vibration.This frequency as well as the calculated force constant (8.32 mdyn/Angstroem) and order (1.45) of the Si=O bond are considered as evidence of significant double bonding in dimethylsilanone.
- Khabashesku, V. N.,Kerzina, Z. A.,Baskir, E. G.,Maltsev, A. K.,Nefedov, O. M.
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p. 277 - 294
(2007/10/02)
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- Reaction of 6-Oxa-3-silabicyclohexanes with Phosphinimines. Synthesis of 6-Vinyl-1,3-dioxa-2,4-disilacyclohexanes
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Reaction of 3,3-dimethyl-6-oxa-3-silabicyclohexane with N-benzyltriphenylphosphinimine yields 1,3-butadiene and 2,2,4,4-tetramethyl-6-vinyl-1,3-dioxa-2,4-disilacyclohexane (3).A mechanism for the formation of (3) which involves the reaction of dimethylsilanone with 2,2-dimethyl-4-vinylsilaoxetane is proposed.
- Baceiredo, Antoine,Juengst, Clifford D.,Manuel, Georges,Weber, William P.
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p. 237 - 240
(2007/10/02)
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- Reaction of O(3P) with Trimethylsilane
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The title reaction has been investigated at room temperature in a discharge flow system as well as by stationary Hg(3P1) sensitized N2O photolysis experiments.O(3P) atoms abstract hydrogen from the silicon center with a rate constant of k(1) = (2.6 +/= 0.3)E-12 cm3s-1.Hydroxyl radicals formed in the primary step react in a second abstraction reaction to yield H2O with a rate constant larger than k(1) by a factor of about 20.The fate of trimethylsilyl radical, the other primary product, depends on the experimental conditions.In the flow system they combine with O and OH; the combination products decompose unimolecularly, yielding CH3 and CH4, respectively, and the common product (CH3)2SiO.In stationary photolyses they mainly abstract O from N2O to ultimately form (CH3)3SiOSi(CH3)3.In a separate static experiment a ratio of k(14)/k1/2(7) = 2.5E-12 cm3/2s-1/2 has been determined for oxygen abstraction of trimethylsilyl radicals from N2O vs. combination of two trimethylsilyl radicals.The rate constant of N(4S) with trimethylsilane has been measured in the flow system to be k(2) = (2.6 +/= 0.8)E-14 cm3s-1.
- Hoffmeyer, H.,Horie, O.,Potzinger, P.,Reimann, B.
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p. 2901 - 2905
(2007/10/02)
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- PHOTOLYSIS AND PYROLYSIS OF POLYSILYLATED DIAZOMETHANES. EFFECTIVE MIGRATING TENDENCY OF TRIMETHYLSILYL GROUP TO A CARBENE CENTER
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Photolysis and pyrolysis of polysilylated diazomethanes were investigated, and a selective migration of trimethylsilyl group to a carbene center was observed.
- Sekiguchi, Akira,Ando, Wataru
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p. 871 - 874
(2007/10/02)
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- THE SILICON-OXYGEN DOUBLE-BONDED INTERMEDIATES. A NEW METHOD FOR THE FORMATION OF ORGANOSILANONES
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The kinetics and mechanism of thermal decomposition of R1R2(H)SiOOR3 silylperoxides have been studied.It has been shown that peroxides generated diorganosilanones, R1R2Si=O, with a high yield in the temperature range 130-180 deg C.A mechanism is suggested for the silanone formation.The interaction of silanones with cyclosiloxanes, triethylsilane, α-methylstyrene has been investigated as well as the cyclisation of silanones.
- Tomadze, A. V.,Yablokova, N. V.,Yablokov, V. A.,Razuvaev, G. A.
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- METALLA IV-b-PHOSPHOLANNES II-METALLA-2 (OXA-, THIA- ou AZA-)-3 PHOSPHOLANNES
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2-sila-, germa- or stanna- 3-(oxa-, thia- or aza-) phospholanes have been synthesized by reactions of dihalometalla-IV-b compounds with dilithiated β-phosphorus alcohols, thiols or amines HYCH2CH2P(H)Ph (Y=O, S, NMe).Germa- and stanna- heterocycles can also be obtained from germyl- or stannyldiamines and the same β-phosphorus alcohols, thiols or amines. 2-sila 3-(oxa- or thia-) phospholanes are of particular interest for their decomposition reaction leading to silanone or silathione and phosphirane.
- Andriamizaka, J. D.,Escudie, J.,Couret, C.,Satge, J.
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p. 279 - 286
(2007/10/02)
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