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 H-2, dipalladium silicide (Pd2Si) is produced. The silicon of the Pd2Si readily reacts with MeCl under Muller-Rochow reaction conditions, to produce methyl chlorosilanes at yield ratios analogous to those of the traditional process. The dominant product is Me2SiCl2 (selectivity > 30%), followed by MeSiCl3 and Me3SiCl, 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 Pd2Si at the next H-2/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 Pd2Si followed by the reaction with MeCl can be repeated until the starting SiO2 converts completely to methyl chlorosilanes.