INFRARED-SPECTRA OF CHLORINATED SILICA

The purpose of this paper is to establish infrared criteria for the di rect chlorination of silica surfaces. Chlorination can be carried out with various chlorinating agents, such as SOCl2, Cl-2, CCl4 SiCl4, and OPCl3, but the reactions must be carried out at high temperatures, fr om 200 to 800 degrees C, depending on the reactant and the degree of c hlorination required. Ln all cases, a pair of LR bands near 710 and 63 5 cm(-1) is generated, and their relative intensities vary according t o the reactant used and the temperature of the reaction. The 710-cm(-1 ) band can be assigned to a single surface SiCl2 species, and the 635- cm(-1) band is most probably due to a geminal surface SiCl2 species. T he observation of these IR bands during the reaction of other chlorine -containing reactants with silica can be taken, for mechanistic purpos es, as evidence for the direct chlorination of silica surfaces.