FORMATION OF FREE-RADICALS UPON INTERACTION OF (SI-O-)(2)SI-O-O GROUPS WITH H-2 CH4, AND C2H6 MOLECULES

The reactivity of bissiloxydioxasilirane groups (DOSGs) [GRAPHICS] sta bilized at the silica surface with respect to H-2, CH4, C2H6, C2H4, an d C2H4O molecules, is studied. The H-2, CH4, and C2H6 molecules are sh own to interact with these groups with the formation of free radical c enters: [GRAPHICS] The rate constants and activation energies are dete rmined (the latter are equal to 39 and 18 KJ/mol, respectively) for th e reactions involving methane and ethane molecules. When the low-molec ular radical product R' is accepted by another surface group the resul ting free radical is stabilized. The structure of the resultant center s is identified, and a mechanism for the formation of these centers is proposed. It is established that DOSGs interact with C2H4 and C2H4O m olecules at a hi,oh rate (at 300 K); however, these reactions produce no free radical species.