- Simplified preparations of trialkylsilyl- and bis(trialkylsilyl)dihalomethanes via the deprotonation of dihalomethanes
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Simple, high-yield routes to trialkylsilyl- and bis(trialkylsilyl)dihalomethanes are described. These compounds are prepared by the deprotonation of dibromomethane or dichloromethane by lithium diisopropylamide in the presence of a chlorosilane. The reactions are carried out at temperatures below - 70°C in THF/hexane solvent mixtures. After aqueous workup, the air- and water-stable products are isolated by either distillation or crystallization. Further reactions on these compounds are possible, as illustrated by one example.
- Yoon, Kunsang,Son, David Y.
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p. 185 - 189
(2007/10/03)
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- POLYMETHYLATION OF ORGANOCHLOROSILANES
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Polychloromethylation of Me3SiCl, Me2PhSiCl, Me2SiCl2, and MePhSiCl2 in the system magnesium-chloroform-THF has been studies under mild conditions (in the temperature renge 60 -65 deg C), and a scheme of formation of the main and by-products has been proposed.
- Podol'skii, A. V.,Khonina, T. G.,Lyampasova, T. P.,Kodess, M. I.
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p. 1476 - 1480
(2007/10/03)
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- Electrosynthese en chimie organosilicique: silylation selective de polychloromethanes
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Silylation by electroreduction of carbon tetrachloride, chloroform or methylene chloride is more selective than the common organometallic route.Me3SiCCl3 (94percent) and (Me3Si)2Cl2 (68percent) were thus obtained from CCl4, Me3SiCHCl2, (94percent) and (Me3Si)2CHCl (56percent) from CHCl3 and Me3SiCH2Cl (90percent) from CH2Cl2.Complete silylation of polychloromethanes was also successful by electrosynthesis and gave satisfactory yields.
- Pons, P.,Biran, C.,Bordeau, M.,Dunogues, J.
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- SILYL-NITROGEN COMPOUNDS I. REACTIONS OF DILITHIUM BIS(TRIMETHYLSILYLL)HYDRAZINE WITH GROUP IV HALIDES
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Dilithium 1,2-bis(trimethylsilyl)hydrazine (1) reacts with CCl4, Me3SiCCl3 and CBr4 to form predominantly bis(trimethylsilyl)aminocarbonimidic dichloride, bis(trimethylsilyl)aminoisocyanide and bis(trimethylsilyl)diazene, whereas similar reactions with HCCl3, HCI3, H2CCl2, H2CI2, C2H4Cl2 or C2H2Cl4 lead to increasing amounts of bis(trimethylsilyl)hydrazine.In addition to the hydrazone, (Me3Si)2N-N=CH(Cl), the reaction of 1 with CHCl3 forms a small amount of triazasilacyclopentane,.............. .In contrast, Me2SnCl2 reacts with 1 to give tetraazadistannacyclohexane (Me2Sn(NSiMe3)2)2, whereas SnCl4, SnCl2 and PbCl2 act mainly as oxidants and Me2SiCl2 forms polymers.Another product of the reaction of 1 with SnCl2 or PbCl2 is LiN(SiMe3)2 originating perhaps from LiNH(SiMe3) or (LiNN(SiMe3)2)2.
- Vasisht, Sham Kumar,Sood, Mohini,Sood, Nirupma,Singh, Gursharan
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- Base cleavage of R-SiMen(OMe)3-n bonds (R m-ClC6H4CH2, PhC, or Cl2CH) and alkoxy exchange in RSiMen(OMe)3-n (R = m-ClC6H4CH2)
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The rates of cleavage of R-SiMen(OMe)3-n bonds (n = 0-3) in NaOMe-MeOH have been measured for R = (i) -ClC6H4CH2, (ii) Ph, and (iii) Cl2CH.The relative reactivities as n is varied in the sequence 3, 2, 1, 0 within each series are: (i) 1,7.2, 2.7, 0.13; (ii) 1, 27, 24, 5.5; (iii) 1, 38, 93, 29.These reactivity variations are discussed in terms of opposition between the rate-enhancing polar effects of the OMe groups and a unusual type of steric affect which arises on introduction of OMe in place of Me.The rates of replacement of one OMe group of m-ClC6H4CH2Men(OMe)3-n by an OEt group in EtOH containing a base have also been measured; in this case the rates rise progressively with the value of n, the relative reactivities for n = 2,1, and 0 being 1, 4.4, and 27, respectively.
- Chmielecka, Jadwiga,Chojnowski, Julian,Eaborn, Colin,Stanczyk, Wlodzimierz A.
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p. 1779 - 1784
(2007/10/02)
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