When the reaction of metallic silicon with methanol in the presence of a small amount of thiophene was carried out at 653 K, methyldimethoxysilane was formed together with trimethoxysilane and tetramethoxysilane, the selectivity for methyldimethoxysilane being 22%. Further adding a small amount of trioxane, trimer of formaldehyde, to the reaction system improved the selectivity for methyldimethoxysilane. This indicates that ...