56240-55-2Relevant articles and documents
One-Step Synthesis of Siloxanes from the Direct Process Disilane Residue
Neumeyer, Felix,Auner, Norbert
supporting information, p. 17165 - 17168 (2016/11/23)
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.
Reaktionen von Trimethylsiloxychlorsilanen (Me3SiO)Me2-nPhnSiCl (n = 0, 1, 2) mit Lithium - Bildung von Trimethylsiloxy-substituierten Silyl- und Disilanyllithiumverbindungen sowie Di- und Trisilanen
Harloff, Joerg,Popowski, Eckhard,Fuhrmann, Hans
, p. 136 - 146 (2007/10/03)
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).
