Molecular interactions in binary mixtures of non-electrolytes: Molar excess enthalpies

Molar excess enthalpies, H^E, for pyridine (i) + α-picoline (j), + β-picoline (j), + γ-picoline (j); pyridine (i) + cyclohexane (j); β-picoline (i) + cyclohexane (j); methylenebromide (i) + pyridine (j), + β-picoline (j) mixtures have been measured calorimetrically as a function of temperature and composition. The H^E data at 298.15 and 308.15 K have been analysed in terms of the Sanchez and Lacombe theory and the “graph theoretical approach”. The graph theoretical approach describes the H^E data well for all these mixtures. This approach has been critically examined and it is found to provide an insight into the nature of molecular interactions between the components of these mixtures. NMR studies on methylene bromide (i) + β-picoline (j) andβ-picoline (i) + pyridine (j) further support these conclusions.