Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

Excess molar volumes at 298.15 K were determined by means of a vibrating tube densimeter for binary mixtures of {heptane + open chain secondary (diethyl to dibutyl) and tertiary (triethyl to tripentyl) amines} as well as for cyclic imines (C2, C3, C4, C6, and C7) and primary cycloalkylamines (C5, C6, C7, and C12). The excess molar volume values were found positive for mixtures involving small size amines, with excess molar volume decreasing as the size increases. Negative excess molar volume values were found for tributyl- and tripentylamine, heptamethylenimine, and cyclododecylamine. Mixtures of heptane with cycloheptylamine showed an s-shaped curve. Partial molar volumes of amines at infinite dilution in heptane were obtained from excess molar volume and compared with partial molar volume of hydrocarbons and other classes of organic compounds taken from literature. An additivity scheme, based on the intrinsic volume approach, was applied to estimate group (CH3, CH2, CH, C, NH2, NH, N, OH, O, CO, and COO) contributions to partial molar volume. These contributions, the effect of cyclization on partial molar volume, and the limiting slope of the apparent excess molar volumes were discussed in terms of solute solvent and solute solute interactions.