Monofunctional (Dimethylamino)silane as Silylating Agent

The reaction of triorganyl(dimethylamino)silanes with surface‐hydrated silicon dioxide has been studied. These silylating agents are easy to prepare from the corresponding chloro or bromosilanes with dimethylamine. The resulting products are thermally stable and relatively volatile. Reaction with surface‐hydrated silicon‐dioxide preparations at 150–250°C for 170 h yields a dense grafted layer. However, with (dimethylamino)silanes having strongly polar substituents, a retreatment of the surface‐modified silica seems to be necessary in order to attain maximum coverage.