Study of the polar interactions between metallic oxides and model organic molecules

In a previous paper, we studied the acid-base behaviour of some metallic oxides (ZnO, Zn (OH)(2), MgO, etc.) in organic or aqueous media by measuring their zeta potential. In this study, we are interested in the acid-base characterization of these oxides by using inverse gas chromatography technique, We determined the specific interactions between them and model organic molecules and proved the amphoteric feature of such oxides by calculating their acidic and basic parameters. It was proved that MgO is more basic than the other oxides and ZnO is rather acidic. We propose a new method to calculate acidic K-A and basic K-D parameters of a solid by adding a third parameter K in the relationship that related specific enthalpy variation (Delta H-sp) of polar molecules to their acceptor number AN and their donor number DN. The parameter K can reflect the amphoteric feature of a solid. The proposed relationship is: (-Delta H-sp)=K-A.ND + K-D.NA - K.NA.ND We prove that our model gives the best results relatively to those obtained by the classic equation.