13C nuclear magnetic resonance and infrared spectroscopic investigations of the adsorption of isobutene molecules on partially dehydroxylated and methylated silica gel

Abstract

By means of combined 13C n.m.r. and infrared spectroscopic measurements the adsorption of isobutene molecules on partially dehydroxylated and methylated silica gel has been studied. Surface hydroxyl groups act as adsorption sites and the interaction of the isobutene molecules with them gives rise to the typical 13C resonance shift to lower field for the quarternary carbon atom of isobutene and to the decrease in the stretching band frequencies for the isolated hydroxyl groups. The results are interpreted in terms of the formation of a π-complex between the isobutene molecule and the surface hydroxyl groups.