Direct Synthesis of Methyl Chlorosilanes from Pd-Mg-SiO₂ Substrates Using Mechanochemistry

The direct reaction of methyl chloride with magnesium and palladium infused silica substrates to synthesize methyl chlorosilanes is reported. First, high energy ball milling on solid Mg-SiO₂ mixtures produces elemental silicon and MgO. When PdCl₂ is infused into the mixture, after additional ball milling and high-temperature reduction under H₂ , dipalladium silicide (Pd₂ Si) is produced. The silicon of the Pd₂ Si readily reacts with MeCl under Müller-Rochow reaction conditions, to produce methyl chlorosilanes at yield ratios analogous to those of the traditional process. The dominant product is Me₂ SiCl₂ (selectivity > 30%), followed by MeSiCl₃ and Me₃ SiCl, with minor amounts of the remaining chlorosilanes. Silicon conversion exceeds 20% for most of the substrates. The elemental palladium, which remains within the Pd-Mg-SiO₂ contact mass is re-converted to Pd₂ Si at the next H₂ /high-temperature treatment and reacts again with MeCl to repeat the methyl chlorosilane production. In principle, the resulting cycle of the mechanochemically induced formation of Pd₂ Si followed by the reaction with MeCl can be repeated until the starting SiO₂ converts completely to methyl chlorosilanes.