Infrared Study of the Adsorption of Aromatic Esters on Silica Immersed in Carbon Tetrachloride

Abstract

Infrared spectra are reported of silica preheated at 843–948 K and immersed in solutions of benzyl acetate, ethyl benzoate and benzyl benzoate in carbon tetrachloride. The predominant surface–adsorbate interaction involved the formation of hydrogen bonds between isolated surface silanol groups and the (C[double bond, length as m-dash]O)-groups of adsorbed ester molecules. A small proportion of the adsorbed ester molecules were each linked to the silica surface via two hydrogen bonds, one involving the (C[double bond, length as m-dash]O)-group and the other involving aromatic π-electrons. The results are compared with previous data for the adsorption of ethyl acetate and ethyl cyanoacetate and are discussed in relation to the electronic effects of substituent groups in the ester molecules.