Thermodynamic properties of binary mixtures containing aldehydes. III. Analysis of the excess enthalpies and excess Gibbs energies of n-alkanal + cyclohexane mixtures in terms of an extended quasichemical group contribution model (DISQUAC)

Abstract

The data available in the literature for the excess enthalpies of ethanal, propanal, butanal, or pentanal + cyclohexane and for the liquid—vapour equilibria of propanal + cyclohexane are examined on the basis of DISQUAC, a very simple extension of the quasi-chemical group contribution theory applied in Parts I and II to correlate and predict excess enthalpies and excess Gibbs energies of n-alkanal + n-alkane mixtures. Using the same four alkyl group increments as in Part II, to account for intramolecular effects in the n-alkanals, and adjusted values for the Gibbs energy and enthalpy of interchange of the formyl(CHO)-cyclohexane contact, the model provides a fairly consistent description of the excess enthalpies as functions of composition and n-alkanal chain length. Molar excess Gibbs energies are estimated for several n-alkanal + cyclohexane mixtures. The (CHO)-cyclohexane interchange parameters are slightly larger than the (CHO)-normal alkane parameters. Ketones (CO group) and esters (COO group) behave similarly.