Studies on the Surface Group of Silica Gels Treated with Mixtures of Two Kinds of Alcohols through the Infrared Spectra

Abstract

The silica gels containing two different surface groups were obtained through the surface-treatment of silica gels with the mixtures of two kinds of alcohol or of alcohol and phenol in autoclave. The quantitative determination of their component surface group was performed from their infrared absorption spectra, since the carbon contents of the component surface group can be reasonably determined in comparison with the total carbon contents from elemental analysis by using Lambert-Beer's law and the ratio of the absorbancy of the respective characteristic absorption of surface group against the absorbancy at 800cm-1 due to skeltal vibration of _??_Si-O-Si_??_. The argon surface area of surface-treated silica gels was discussed on the basis that the area covered by each surface group was constant for the silica gel prepared under the same condition. The silica gels pretreated with n-octanol were treated furthermore with methanol or benzyl alcohol. The former showed only the simple increase of numbers of the methyl group, whereas the substitution of the n-octyl group to the benzyl group was observed in the latter. Thus this reaction was regarded as the transesterification of the surface esters.