Thermodynamics of organic mixtures containing amines

Abstract

Abstract Excess molar volumes at 298.15 K and atmospheric pressure over the entire composition range for binary mixtures of triethylamine (TEA) or tributylamine (TBA) with n -hexane, n -octane, n -decane, n -decane, n -tetradecane, or n -hexadecane, or of TBA with n -dodecane are reported from densities measured with a vibrating-tube densimeter. At equimolar composition, the excess molar volume for TEA+ n -alkane systems increases up to heptane and then decreases, being negative for the larger alkanes. In the case of TBA mixtures, the excess molar volume increases regularly with the chain length of the alkane, and is negative when a shorter alkane is the second component. The negative values of the excess molar volumes indicate that the contribution from free volume effects to excess volume is predominant over the interactional contribution. For the investigated solutions, the Flory theory represents the dependence of the excess molar enthalpy and of the excess molar volume with the size of the n -alkane.