EFFECTS OF STEREOCHEMISTRY AND ALTERNATION ON THE ADSORPTION PROPERTIES OF SURFACE-ACTIVE CIS- AND TRANS-2-N-ALKYL-5-HYDROXY-1,3-DIOXANES

A systematic study of adsorption properties of cis- and trans-2-n-alkyl-5-hydroxy-1,3-dioxanes (alkyl: cis, C2H5, n-C3H7, n-C4H9, n-C5H11, n-C6H13, n-C7H15; trans, n-C3H7, n-C5H11, n-C7H15) at the air/water surface at 295 K has been undertaken by using surface tension measurements of their aqueous surface chemically pure solutions. The surface parameters, i.e. standard free energy of adsorption, minimum surface area demand per molecule, and surface interaction parameter, reveal distinct differences due not only to the stereochemical configuration of the molecules but also to even- and odd-numbered characteristics of the n-alkyl chain. The said differences become greater as the alkyl chain becomes shorter. It is concluded that surface tension is a very sensitive physical quantity reflecting even the slightest deviations in the structure of the molecules adsorbed provided that special requirements on the purity of the solutions are followed.