Prediction of liquid-liquid equilibria and of enthalpies of mixing in alkanoic acid anhydride + n-alkane mixtures using DISQUAC

Abstract

Abstract Kehiaian, H.V., Gonzalez, J.A., Garcia, I., Escarda, R., Cobos, J.C. and Casanova, C, 1991. Prediction of liquid-liquid equilibria and of enthalpies of mixing in alkanoic acid anhydride + n -alkane mixtures using DISQUAC. Fluid Phase Equilibria, 69: 91-98. The liquid-liquid equilibrium (LLE) data from the literature on acetic anhydride + heptane and our molar excess enthalpies measured previously, H E , of butyric or heptanoic anhydrides + n -alkanes (hexane through tetradecane) are examined on the basis of the DISQUAC group-contribution model. These experimental data, along with structure-property relationships derived from the properties of related classes of carbonylic compounds, were used to estimate the interaction parameters for symmetrical or asymmetrical carboxylic acid anhydride [CH 3 (CH 2 ) u -1 -CO-O-CO-(CH 2 )[ v -1 CH 3 ] + alkane [CH 3 (CH 2 ) m -2 CH 3 ] mixtures. The anhydride (CO-O-CO group)/alkane (CH 3 or CH 2 groups) interaction parameters are the same for the anhydrides of all the carboxylic acids ( u, v > 1), except for acetic acid anhydride ( u, v = 1). The model describes consistently H E , LLE and the vapor-liquid equilibrium diagram of acetic anhydride + cyclohexane.