Alkoxylation of Silica Surfaces under Ordinary Contact with Alcohols

Abstract

Surface alkoxyl reaction of silica gels was investigated under ordinary contact with some of the low molecular weight saturated aliphatic alcohols. Silica gels were in contact with liquid alcohols by using Soxhlet's extractor below their boiling points. The degree of alkoxylation for surface hydroxyls was examined by an infrared spectra and with T. G, analysis. It was shown that some of the surface hydroxyls were easily esterified to alkoxyl groups even by contact with alcohols under ordinary conditions.
Adsorption isotherms of methanol vapor at room temperature (25°C) were measured on silica samples which were previously activated at various temperatures. Adsorption equilibria depend upon the pre-treated temperature, and surface methylation reaction took place not only on surface hydroxyls but also on siloxane bridges even at room temperature.