18148-13-5Relevant academic research and scientific papers
Disilane Cleavage with Selected Alkali and Alkaline Earth Metal Salts
Santowski, Tobias,Sturm, Alexander G.,Lewis, Kenrick M.,Felder, Thorsten,Holthausen, Max C.,Auner, Norbert
supporting information, p. 13202 - 13207 (2019/10/22)
The industry-scale production of methylchloromonosilanes in the Müller–Rochow Direct Process is accompanied by the formation of a residue, the direct process residue (DPR), comprised of disilanes MenSi2Cl6-n (n=1–6). Great research efforts have been devoted to the recycling of these disilanes into monosilanes to allow reintroduction into the siloxane production chain. In this work, disilane cleavage by using alkali and alkaline earth metal salts is reported. The reaction with metal hydrides, in particular lithium hydride (LiH), leads to efficient reduction of chlorine containing disilanes but also induces disproportionation into mono- and oligosilanes. Alkali and alkaline earth chlorides, formed in the course of the reduction, specifically induce disproportionation of highly chlorinated disilanes, whereas highly methylated disilanes (n>3) remain unreacted. Nearly quantitative DPR conversion into monosilanes was achieved by using concentrated HCl/ether solutions in the presence of lithium chloride.
SILYL AND SILYLMETHYL RADICALS, SILYLENES, SILA-ALKENES, AND SMALL RING SILACYCLES IN REACTIONS OF ORGANOCHLOROSILANES WITH ALKALI METAL VAPOURS
Gusel'nikov, L. E.,Polyakov, Yu. P.,Volnina, E. A.,Nametkin, N. S.
, p. 189 - 204 (2007/10/02)
Dehalogenation of the organochlorosilanes Me3SiCl (I), Me2PrSiCl (II), Me3SiSiMe2Cl (III), Me3SiCH2SiMe2Cl (IV), ClCH2SiMe3 (V), ClCH2SiMe2SiMe3 (VI), ClCH2Me2SiSiMe2CH2Cl (VII), Me2SiCl2 (VIII), MePrSiCl2 (IX), Me3SiCH2SiMeCl2 (X), Me3SiCH2CH2SiMeCl2 (XI), Me3SiCH2CH2CH2SiMeCl2 (XII), ClCH2Si(H)MeCl (XIII), ClCH2SiMe2Cl (XIV), ClMe2SiSiMe2Cl (XV), ClCH2CH2CH2Si(H)MeCl (XVI), ClCH2CH2CH2SiMe2Cl (XVII), ClCH2CH2OSiMe2Cl (XVIII), ClMe2SiCH2SiMe2Cl (XIX), ClMe2SiCH2CH2SiMe2Cl (XX), and ClMe2SiCH2CH2CH2SiMe2Cl (XXI) with K/Na alloy vapours at 0.1-1 Torr and 300-320 deg C yields products derived from the reactions of short-lived intermediates, such as silyl and silylmethyl radicals, silylenes, and sila-alkenes.In addition, small-ring silacycles of low stability are formed as the intermediates in some of the dehalogenation reactions.Combination and H-atom abstraction are the main reactions of silyl and silyl-methyl radicals.These radicals are not prone to decomposition reactions when C-H, C-C, or Si-C bonds are at the β(Si-Si) bond with the formation of Me2Si=CH2 and the trimethylsilyl radical.The generation of alkylmethylsilylenes is accompanied by their decomposition processes, which involves intramolecular β(C-H) insertion of alkylmethylsilylenes and 2+1>-thermocyclodecomposition of intermediate silacyclopropanes.The contribution of δ(C-H) and ε(C-H) insertion reactions is much less pronounced, and in the formation of five- or six-membered silacycles.We did not succeed in obtaining monosilacyclobutanes, as the intramolecular γ(C-H) insertion is not typical for silylenes with alkyl substituents.Dehalogenation of chloromethylchlorosilanes with alkali metal vapours yields sila-alkenes, and that of 1,2-dichlorodisilanes gives disilenes. 1-Methyl-1-silaethylene, obtained by this method, does not rearrange into dimethylsilene, but dimerizes to give 1,3-dimethyl-1,3-disilacyclobutane.The formation of 1,3,5-trisilacyclohexanes takes place due to subsequent radical addition at the silicon-carbon double bond and cyclization of 1,6-biradicals.Dehalogenation of organochlorosilanes XVI, XVII, and XX opens up possibilities for the gas-phase synthesis of small organosilicon heterocycles: monosilecyclobutanes and 1,2-disilacyclobutanes.A new, low-stability heterocycle, i.e. 1,1,2,2-tetramethyl-1,2-disilacyclobutane, has been obtained, which enables a new, high polymer, polyethylenetetramethyldisilene, to be obtained.In the case of organochlorosilanes XVIII and XIX, cyclization is accompanied by secondary reactions of silacycles, rearrangements, dimerization, or decomposition.
