Disilane Cleavage with Selected Alkali and Alkaline Earth Metal Salts

Abstract

The industry-scalep roduction of methylchloromonosilanes in the Müller-Rochow Direct Process is accompanied by the formation of ar esidue,t he direct process residue (DPR), comprised of disilanes Me n Si 2 Cl 6-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, disilanec leavage 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-a nd oligosilanes. Alkali and alkaline earth chlorides, formed in the courseo ft he reduction, specifically induce disproportionation of highly chlorinatedd isilanes, 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.[a] T.

Müller–Rochow Reloaded: Single-Step Synthesis of Bifunctional Monosilanes

“…At this point, we thus conclude that LiCl represents a redistribution catalyst, , albeit with low activity (Table ).…”

“…Comparable yields were obtained with nBu 3 P and Ph 3 P at 160 °C with prolonged reaction time. nBu 3 N is the least active catalyst, and the activity of 2methylimidazole (2-MIA) as a representative for N-heterocyclic catalysts ranks between that of R 3 P and R 3 N. These reactions are readily transferred to the preparative ( At this point, we thus conclude that LiCl represents a redistribution catalyst, 73,85 albeit with low activity (Table 4).…”

“…The disilane component is transformed to Me 2 HSi–SiHMe 2 (4%) and Me 2 ClSi–SiHMe 2 (17%). Prolonged reaction times reduced the molar amounts of the disilanes, and instead, trisilanes formed in about 5% yield. , …”

“…Prolonged reaction times reduced the molar amounts of the disilanes, and instead, trisilanes formed in about 5% yield. 85,86 Single-Step Conversion of a Crude Muller−Rochow Chlorosilane Mixture. As a model for the Muller−Rochow crude product mixture, we prepared a stock solution consisting of 96.8 wt % monosilanes (Me 2 SiCl 2 : 86.7 wt %) and 3.2 wt % of disilanes (MeCl 2 Si−SiCl 2 Me: 1.8 wt %).…”

Oligosilanes as Silyl Radical Precursors through Oxidative Si−Si Bond Cleavage Using Redox Catalysis

“…Indeed, oligosilanes can undergo photolysis of a Si−Si bond, albeit only under ultraviolet irradiation , [11] limiting the practical application of this approach in synthesis. Other Si−Si bond‐breaking reactions in disilanes rely on the participation of a transition metal complex, [12a] alkali and alkaline earth metal salts [12b,c] or strong Brønsted acid [12d] . Therefore, the development of a mild and practical method for Si−Si bond cleavage in oligosilanes is still demanded.…”