1992 Volume 8 Issue 6 Pages 773-777
The aggregation equilibria of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH(EHP)) and di(2-ethylhexyl)phosphoric acid (HDEHP) dissolved in toluene has been investigated by vapor-pressure osmometry at different temperatures. The experimental data have been treated both graphically and numerically, and the average aggregation number n of organophosphorus acids, as well as the aggregation constants, has been determined. The results suggest that dimers are formed and the dimerization constant decreases with temperature. Finally, an estimated enthalpy value for the aggregation of organophosphorus acids in toluene has been calculated by using the van′t Hoff equation.
