- SYNTHESIS OF ORGANOSILICON ALCOHOLS BY CONDENSATION OF 1,1-DIMETHYLSILA-2,5-DIOXACYCLOHEXANE WITH SILANOLS
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The reaction of 1,1-dimethylsila-2,5-dioxacyclohexane with silanols and siloxanols has been studied for the purpose of synthesizing diatomic organosilicon alcohols.The reaction forms addition products at one and both silanol groups.The monoaddition products are apparently formed by retardation of the reaction of the heterocycle with the remaining silanol, due to participation of the latter in an intramolecular hydrogen bond.
- Makarova, L. I.,Sergienko, N. V.,Leites, L. A.,Yadritseva, T. S.,Zhdanov, A. A.
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- Synthesis and helix-sense-selective polymerization of a novel phenylacetylene having a trisiloxanyl group and two hydroxyl groups and enantioselective permeability of the resulting chiral polymeric membrane: Effect of the trisiloxanyl group on the polymerization and enantioselective permeability
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To develop a new phenylacetylene monomer suitable for helix-sense-selective polymerization (HSSP) we reported previously and to improve the efficiency of the HSSP and membrane performance of the resulting polymer, a novel phenylacetylene having a trisiloxanyl group (S3BDHPA) was synthesized and polymerized by using a chiral catalytic system and enantioselectivity in permeation of its membrane was examined. S3BDHPA was suitable for the HSSP and the CD absorption of poly(S3BDHPA) was stronger and more stable than that of the corresponding polymer having no siloxanyl groups. In addition, enantioselectivity in permeation of poly(S3BDHPA) was much higher than that of a polymer membrane having no siloxanyl groups. They are thought to be caused by the flexibility and hydrophobicity of the trisiloxane groups.
- Liu, Lijia,Oniyama, Yoshiyuki,Zang, Yu,Hadano, Shingo,Aoki, Toshiki,Teraguchi, Masahiro,Kaneko, Takashi,Namikoshi, Takeshi,Marwanta, Edy
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scheme or table
p. 2460 - 2464
(2011/11/12)
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- New achiral phenylacetylene monomers having an oligosiloxanyl group most suitable for helix-sense-selective polymerization and for obtaining good optical resolution membrane materials
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To develop new phenylacetylene monomers more suitable for helix-sense-selective polymerization (HSSP) we reported previously and to improve the efficiency of the HSSP and membrane performance of the resulting polymers, novel phenylacetylenes having a flexible oligosiloxanyl group (SnBDHPA)together with the other related three series of monomers were synthesized and polymerized by using a chiral catalytic system and enantioselectivity in permeation of the membranes from the resulting chiral polymers were examined. SnBDHPA was the most suitable for the HSSP and the CD absorptions (G values) of poly- (SnBDHPA) were stronger and more stable than those of the corresponding polymers having rigid alkyl groups. The polymers could be fabricated to flexible self-supporting membranes by using solvent-casting method. In addition, enantioselectivity in permeation of one of poly(SnBDHPA) membranes was much higher than that of a poly(phenylacetylene) membrane having alkyl groups. This was because the polymers having oligosiloxane groups had high regularity of structures, i.e., chemical structures of the macromolecules such as one handedness and high order structures such as columnar contents in the membranes, and the membranes were flexible and had almost no defects. These good properties as optical resolution membrane materials were caused by flexibility, hydrophobicity, and bulkiness of the oligosiloxane chains. S3BDHPA having a trisiloxanyl group was found to be the best monomer for the HSSP and for obtaining good optical resolution membrane materials.
- Liu, Lijia,Zang, Yu,Hadano, Shingo,Aoki, Toshiki,Teraguchi, Masahiro,Kaneko, Takashi,Namikoshi, Takeshi
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scheme or table
p. 9268 - 9276
(2011/11/14)
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- Surface Active Organosilicone Compounds
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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.
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Page/Page column 6-7
(2008/12/09)
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- Catalytic reactions of hydrosiloxanes with allyl chloride
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Catalytic reactivity of Si-H bond of di-, trisiloxanes with allyl chloride in the presence of platinum catalyst has been examined. Hydrosilylation process competes with hydrogen substitution by chlorine and/or propenyl group. The effect of the reaction conditions as well as structure of siloxane on the yield and selectivity of the number of products has been discussed. Several consecutive-competitive processes have been identified. The results obtained can be helpful in the study of the catalytic hydropolysiloxanes reactions with allyl derivatives-systems of great practical importance, to produce commercial functionalized silicones.
- Jankowiak, Marcin,MacIejewski, Hieronim,Gulinski, Jacek
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p. 4478 - 4487
(2007/10/03)
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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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- 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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p. 1586 - 1589
(2007/10/03)
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- 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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p. 1238 - 1239
(2007/10/03)
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- Synthesis of siloxanes. XII. Cleavage of siloxanes by hydrogen chloride
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1H NMR spectroscopy has been used in a kinetic study of the cleavage of siloxane bonds by hydrogen chloride in dioxane.The cleavages show an induction period which is associated with the autocatalytic effect of the water formed during the reaction.The kinetic behavior can be expressed in terms of a rate law that includes rate constants for cleavage by both dioxane*HCl (k1) and H2O*HCl (k2).The k'1 (k'1 = k1*-4) and k'2 (k'2 = k2*-3) values correlate with ?* values; thus ρ* values of -1.4 and -0.7 were obtained for k'1 and k'2, respectively.The ?* value of 0.35 that we previously derived for the Me3SiO group applies in this reaction.The reaction of 1,3-bis(p-methoxyphenyl)tetramethyldisiloxane with hydrogen chloride involves cleavage of silicon-aryl rather than Si-O bonds.
- Scheim, U.,Lehnert, R.,Porzel, A.,Ruehlmann, K.
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p. 141 - 150
(2007/10/02)
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- On the Problem of the Intermediate Formation of Silanone R2Si=O by Reactions of Silenes with Dinitrogen Oxide
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The silaethene Me2Si=C(SiMe3)2 (1a; unstable; from 1a * Ph2C=MSiMe3 = 4) forms with N2O an unstable cycloadduct, which decomposes under isomerization or cleavage.It was not possible to decide clearly, whether the last reaction, which leads to (Me3Si)2CN2 and polymers with (Me2SiO)n groups, proceeds with intermediate formation of silanone Me2Si=O or not (no trapping product with Et3SiH, but with Me3SiCl).The silanimines Me2Si=NSitBu3 (2a; unstable; from 2a * tBu3SiN3 = 7) and tBu2Si=NSitBu3 (2b; metastable) form with N2O unstable cycloadducts, which, under participation of the silanimines, react into products (10) being composed of a molecular silanone and a molecule silanimine.As has been shown by trapping experiments with Et3SiH, Me3SiCl, or Me3SiOMe, latter reaction involves unstable free silanones Me2Si=O (3a) or tBuSi=O (3b) as intermediates. 3b, generated in benzene from 2b/NO2 in the presence of equimolar amounts of tetrahydrofuran (THF), obviously forms an adduct 3b*THF, which is trapped by excess 2b.When 3b is produced in THF as solvent, the silanone starts THF polymerization, indicating a high Lewis acidity of silanones.
- Wiberg, Nils,Preiner, Gerhard,Schurz, Klaus
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p. 1407 - 1412
(2007/10/02)
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- Storing of the Labile Silaethene Me2Si=C(SiMe3)2 with Benzophenone
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Benzophenone Ph2C=O is able to "store" the silaethene Me2Si=C(SiMe3)2 (1), produced from Me2SiX-CLi(SiMe3)2 (X = F, Br, Ph2PO4), under formation of a cycloadduct (2b).At about 100 deg C, 2b by way of 1 transfers into the cycloadduct of 1 and Ph2C=O (3b), which in the course of transformation decomposes visibly (in the absence of Me3SiCl) or only by traces (in the presence of Me3SiCl) to secondary products.In the presence of ROH (R = H, Me, tBu, MeCO) or PhN=NSiMe3 or RN3 (R = tBu, Me3Si) or 2,3-dimethylbutadiene (dmb) about 100 deg C 2b and 3b form by way of 1 insertion products of 1 into the OH bond of ROH or a cycloadduct of 1 and PhN=NSiMe3 or cycloadducts of 1 and RN3 or cycloadduct and an ene reaction product of 1 and dmb.The rate constants/half lives of the first order transformation of 2b into 3b or of the first order decomposition of 2b or of 3b in the presence of reactive traps for 1 (ROH, Me3SiN3; benzene as solvent) are in the order of 0.3E-4 s-1/τ1/2 = 7 h (2b --> 3b; 90 deg C) 3E-4 s-1/τ1/2 = 3/4 h (2b + traps; 90 deg C), 0.4E-4 s-1/τ1/2 = 5 h (3b + traps, 110 deg C). - Keywords: Silaethene Me2Si=C(SiMe3)2, Insertions, Cycloadditions, Kinetic Studies
- Wiberg, Nils,Preiner, Gerhard,Schurz, Klaus,Fischer, Gerd
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p. 1468 - 1474
(2007/10/02)
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- Reactivity of the Labile Silaethene Me2Si=C(SiMe3)2, Stored as Ph2C=NSiMe3 Adducts
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Silaethene Me2Si=C(SiMe3)2 (1), stored as Ph2C=NSiMe3 adducts and regenerated from the adducts at about 100 deg C as a reaction intermediate, combines with reactants a-b (e.g.HO-H, RO-H, RCOO-H, RS-H, RHN-H, Ph2CN-H, RO-SiR3, R2N-SiR3, Ph2CN-SiR3, Cl-GeR3, Cl-SnR3) with insertion into the a-b bond, with a=b (e.g.O=CPh2, Me3SiN=CPh2, CH2=CHOMe, cis-piperylene), a=b=c (e.g.RN=N=N, O=N=N), a=b-c=d (e.g. butadiene, isoprene, trans-piperylene, 2,3-dimethylbutadiene, cyclopentadiene, anthracene, benzophenone, N-trimethylsilylbenzophenoneimine) under -, - as well as -c ycloaddition and with a=b-c-H (e.g. propene, butenes, isoprene, 2,3-dimethylbutadiene, acetone) under ene reaction.According to relative reaction rates, insertion and -cycloadditions seem to proceed in two reaction steps, whereas -cycloadditions and ene reactions with organic dienes and enes obviously are one step reactions.For reactivities cf.Table I. - Key words: Silaethene Me2Si=C(SiMe3)2, Insertions, Cycloadditions, Relative Reactivities
- Wiberg, N.,Preiner, G.,Wagner, G.,Koepf, H.
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p. 1062 - 1074
(2007/10/02)
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- OXIDATION OF n-DECAMETHYLTETRASILANE WITH PEROXYBENZOIC ACID
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It is shown, that the first stage of the reaction of n-decamethyltetrasilane with peroxybenzoic acid is oxidation of one of the two terminal Si-Si bonds, rather than oxidation of a central Si-Si bond.
- Razuvaev, G. A.,Semenov, V. V.,Brevnova, T. N.,Kornev, A. N.
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p. C31 - C33
(2007/10/02)
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- Direct Thermal and Photochemical Generation of Silanones
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2-Silapyrans (1,2-oxasilins) are synthesized by the pyrolysis of 1-disilanyl-4-methoxy-1,3-butadienes via initial 1,5-silyl migration to afford an intermediate 1-sila-1,3-butadiene.Diels-Alder reaction of the silapyrans and perfluoro-2-butyne does not lead to isolable adducts but rather leads to apparent extrusion of silanone (R2Si=O), which is trapped by a variety of reagents.Reaction of the silapyrans and maleic anhydride provides stable adducts that extrude silanones upon either thermolysis or photolysis.No evidence could not be found for rearrangement of a silylsilanone to a siloxysilylene.
- Hussmann, Gregory,Wulff, William D.,Barton, Thomas J.
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p. 1263 - 1269
(2007/10/02)
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