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 w as carried out by ESR spectroscopy, using a paramagnetic labeling tech nique, and by optical spectroscopy. Hydrogen atoms and methyl radicals were used as labels. It is concluded that the main active sites on th e 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 spectro scopic data of Morterra and Low were reinterpreted.