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

Abstract

The first example of a gram-scale synthesis of methylmethoxysilanes using the direct reaction of silicon with dimethyl ether (DME) is presented. The direct synthesis (DS) of methylmethoxysilanes was carried out in a high-pressure mechanochemical reactor (HPMR) at 250 °C using CuCl as a catalyst and Sn and Zn as promoters. The mechanochemical approach allows the use of large-grain inactivated technical grade silicon without preliminary stages of contact mass (CM) preparation usually required in such works. Under these conditions, the direct synthesis of organoalkoxysilanes proceeds with almost complete silicon conversion and high selectivity (81.6%) for dimethyldimethoxysilane and dimethylsilyl siloxanes. Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) studies of the CM confirmed that the reaction proceeds with very high (90–100%) silicon conversions when the products are produced in gram quantities.