Schrittweise Darstellung von verzweigten tripodalen Chlor‐Methyl‐Siloxanen der allgemeinen Formel tBuSi[{OSiMe2}yOSiMe3–xClx]3 [x = 0–3; y = 0–2] sowie Synthese der Silanole tBuSi[(OSiMe2)xOH]3 [x = 1, 2] und des bicyclischen Siloxans tBuSi(OSiMe2O)3SitBu

Abstract

AbstractThe branched tripodal chloro‐methyl‐siloxanes of the general formula tBuSi[{OSiMe2}yOSiMe3–xClx]3 [x = 0–3; y = 0–2] were synthesized, starting with tert‐Butyl‐trisilanol (1). The treatment of 1 with the chloro‐methyl‐silanes (Me3–xSiClx+1) (x = 0–3) in the presence of triethylamine leads to the compounds tBuSi(OSiMe2Cl)3 (2), tBuSi(OSiMeCl2)3 (3) and tBuSi(OSiCl3)3 (4). The siloxanes 2–4 are colourless oily liquids, which can be purified by distillation. Their yields decrease with the number of chloro substituents. In the reaction of compound 2 with three equivalents of water the silantriol tBuSi(OSiMe2OH)3 (5) is generated which is used to create the branched tripodal chloro‐methyl‐siloxanes tBuSi(OSiMe2OSiMe3)3 (6), tBuSi(OSiMe2OSiMe2Cl)3 (7), tBuSi(OSiMe2OSiMeCl2)3 (9) and tBuSi(OSiMe2OSiCl3)3 (10). Compound (7) is only a side product with a yield of 25 %., The cyclic tBuSi[{(OSiMe2)2Cl}(OSiMe2)3O] (8) can be isolated and characterised. The transformation of the compound tBuSi(OSiMe2OSiMe2Cl)3 (7) into the trisilanol tBuSi(OSiMe2OSiMe2OH)3 (11) allows to prepare the tripodale siloxane tBuSi(OSiMe2OSiMe2OSiMe3)3 (12) in good yields., The reaction of tBuSi(OSiMe2Cl)3 (2) with tert‐butyl trisilanol 1 leads to the formation of bicyclic tBuSi(OSiMe2O)3SitBu (13). An X‐ray structure determination on 13 reveals a [3.3.3]‐bicycle with a C3 axis, which crystallizes in the cubic crystal system in the space group Pa$\bar{3}$. The reported compounds 2–13 were characterised by NMR‐ and IR spectroscopy (5, 11) and show correct elemental analyses. The 29Si‐NMR‐data of the compounds show interesting trends with respect to the Si–O chain length and the chloro substistuents.