A Thermodynamic Study of Molecular Association by Gas-Liquid Chromatography

Polymer Science Unit, Indian Association for the Cultivation of Science, Calcutta-700 032

Manuscript received 1 June 1995, revised 19 September 1995, accepted 7 March 1996

Of two gas-liquid chromatographic methods, the one developed by Martire and Riedl has been used to study thermodynamic param­eters of associated systems and the results with four donors and seven acceptors are presented. The donors are cetyldimethylamine (CDA),tri-n-octylamine (TOA), dilauryl ether (DLE) and dliauryl thioether (DITE), and acceptors are ethanol, two propanols and four butanols. It has been found that glc method is as competent as any other standard method for measuring interaction of molecular association and the data obtained are systematic. The magnitude of the equilibrium constants for any particular system determined by glc method is somewhat larger and with different methods (such as calorimetry), magnitudes are different but the enthalpies of forma­tion of molecular association are obtained close to each other indicating that the latter is less affected by side-effects. It has been con-chided, therefore, that the enthalpies measured are more reliable and have been subjected to Drago's double-scale equations to compute the average electrostatic and covalant contributions.