¹³C-NMR Spectra and Adsorbed States of N, N-Diethylaniline Adsorbed on Silica Gel

Abstract

¹³C-NMR spectra of N, N, T: diethylaniline (DEA) adsorbed on silica gel (LS 310) and octadecylsilanized silica gel (ODS-silica, LS 410) were observed. ¹³C-spin-lattice relaxation times (T¹) of DEA were also measured in liquid state and in adsorbed states. Large chemical shifts were found for DEA adsorbed on silica gel, whereas DEA adsorbed on ODS-silica gave small chemical shifts (Table 1). These results suggest the weaker interaction of DEA with ODSsilica. compared to that of silica gel. Adsorption of DEA on the surface of the silica gel or ODS-silica resulted in the decrease of T¹ Methyl carbon of the adsorbed states gave a long T¹, because of its free rotation. Correlation times evaluated from T¹, data provided the evidence of the remaining free rotation of methyl carbon and indicated the different mecha- nisms of adsorption on silica gel or on ODS-silica.