Direct synthesis of alkoxysilanes: current state, challenges and prospects

Abstract

В настоящем обзоре проанализировано современное состояние области прямого синтеза алкоксисиланов. Освещены основные подходы, проблемы и перспективы данного процесса. Рассмотрен предполагаемый механизм реакции, а также факторы, оказывающие существенное влияние на ход процесса, среди которых можно выделить температуру, тип и концентрацию катализатора, промотирующие добавки, метод проведения процесса и др.<br> Библиография — 232 ссылки.

Study of the Effect of Zn, Sn, and Pb Additives on the Direct Mechanochemical Synthesis of Tetramethoxysilane in the Presence of CuCl and CuO Catalysts

“…Summarizing the works in which the mechanism of DSAlk ,,, has been studied, it can be simplified into two main steps (Figure ).…”

“…The reaction of silicon with different copper sources (see Figure 1, reaction 1), which is described in many publications, is usually employed to prepare CMs active in the direct synthesis of alkoxy-or organochlorosilanes. 32 The most typical product of such a reaction using excess silicon is the intermetallide Cu 3 Si, but with different sources of copper, the reaction can occur in different ways (and at different rates). Usually Cu 3 Si is formed at the step of CM preparation in the reaction of Si with Cu.…”

“…29,30 The MC mode of the DSAlk makes it possible to use larger-grain, unactivated silicon and to perform the reaction at low temperatures, such as 100 °C29 or even near-room temperature. 30 The state of the art in the DSAlk is highlighted in reviews by Pakuła et al 31 and Temnikov et al 32 The authors note that this process is very challenging and depends on many factors, which greatly complicates an adequate and in-depth study of its mechanism. The complexity is mainly due to the heterophase nature of the process, the variety of conditions, catalysts, precursors, promoters used, and also the equipmentspecific implementation.…”

From silicon to silicones without dimethyldichlorosilane: direct green mechanochemical synthesis of methylmethoxysilanes from silicon and dimethyl ether

“…As a result, the separation of commercial methylchlorosilanes requires the use of huge rectification columns, more than 50 m high and arranged in cascades. 9 Obviously, the capital investment to build and maintain such cascades is significant.…”

“…21 However, to date, examples of the use of DME in methylmethoxysilane synthesis can only be found in the patents. [22][23][24][25] The principle of the methods, described in a review, 9 is the in situ generation of methyl halosilanes, which then cleave DME to form methylmethoxysilanes and recover methyl halides. Another approach presented in the patent 26 could be mentioned, where the authors used a mixture of dimethyl ether and carbon dioxide as organic precursors, probably assuming the existence of an equilibrium between a mixture of DME with CO 2 and dimethyl carbonate, which is known from some studies.…”