Thermodynamic study of (heptane+amine) mixtures. II. Excess and partial molar volumes at 298.15K

Thermodynamic study of heptane+secondary, tertiary and cyclic amines mixtures. Part IV. Excess and solvation enthalpies at 298.15K

“…As a general observation, the main result that H E andH j are positive in the whole mole fraction range for all mixtures examined can be qualitatively explained with a net destruction, during the mixing process, of the structural order present in the neat liquids (H-bonding and dipole-induced dipole interactions in amines), in agreement with the interpretative scheme proposed by Patterson [19], and confirmed by the positive V E [2,3,20], G E [21] and H E [1,21] for n-alkane + alkylamine mixtures. Moreover, all amine categories show H E and H • j (j = 1,2) (except H • 2 of cy-heptylamine) that decrease as the amine size increases, exhibiting nicely parallel trends.…”

“…To fill this gap, in previous papers in this series, we reported and discussed H E [1] and V E [2] of heptane + primary amines, and V E [3] of heptane + secondary and tertiary n-alkyl, primary cycloalkyl, heterocyclic secondary amines. As a continuation, for the same mixtures of Ref.…”

Thermodynamic study of (heptane+amine) mixtures. III: Excess and partial molar volumes in mixtures with secondary, tertiary, and cyclic amines at 298.15K

“…No significant difference was found with respect to the impurity content declared by the factories. Comparisons of the behavior of different mixtures should not be biased by the slightly different purity degree of the amines, since purity of substances is not a crucial factor in V E measurements, as shown in previous investigations [2,12]. This is confirmed by the close similarity of V E obtained using two different samples of the same amine (cy-pentylamine) coming from different factories and characterized by a different purity degree.…”

“…Calibration was carried out with dry nitrogen and degassed water. Details of the experimental procedure, including vapor phase corrections due to evaporation of volatile components in the space above the liquid, were reported previously [2]. By comparing density measurements with values obtained for the same samples via the pyknometric technique, the precision was evaluated to within ±5 Á 10 À6 g Á cm À3 .…”

“…In previous works (Parts I and II of this series) we reported excess molar enthalpies H E and volumes V E , respectively, for binary mixtures of heptane with primary alkyl amines with the aim of characterizing the interaction between hydrocarbon and the NH 2 group [1,2]. This investigation has been extended to the study of the NH and N groups, and here we report excess molar volumes V E for mixtures of heptane with open chain secondary (diethyl to dibutyl) and tertiary (triethyl to tripentyl) amines as well as with cyclic imines (C 2 to C 7 ) and primary cycloalkylamines (C 5 to C 7 , C 12 ).…”