REACTIVE SILICA - A NEW CONCEPT OF THE STRUCTURE OF ACTIVE-SITES

The results of an experimental study of the surface active sites in ''reactive silica'' (RSi) are presented. Identification of the defects was carried out by ESR spectroscopy, using a paramagnetic labeling technique, and by optical spectroscopy. Hydrogen atoms and methyl radicals were used as labels. It is concluded that the main active sites on the RSi surface are twofold coordinated silicon atoms - silylene centers. Their conversion reactions were studied: [GRAPHICS]. On the basis of the obtained results on the structure of active sites, the IR spectroscopic data of Morterra and Low were reinterpreted.