Solid-Liquid and Liquid-Liquid Equilibrium in the Formamide-Acetophenone System

Abstract

Solid-liquid (s-l) and liquid-liquid (l-l) equilibrium was determined in the binary system formamide-acetophenone. The s-l equilibrium was measured by recording time-temperature cooling and warming curves. The l-l equilibrium was obtained in a wide range of temperatures by the turbidity method. A considerable supercooling preceding solidification made it possible to examine metastable l-l equilibrium yet at temperatures lower than the solidus ones. Activity coefficients evaluated from the stable region of l-l equilibrium were correlated by Novák's modification of the Wilson equation. Calculation of the s-l equilibrium was performed with the obtained parameters. Heat capacity of solid and liquid acetophenone was measured and its dependence on temperature is given. The transition enthalpy betwen two solid modifications of acetophenone is also given.Since the Bronze Age mankind knows that mixing of two or more substances can lead to surprising results. Phase diagrams which are measured and studied also in our laboratory provide fundamental information on the equilibrium relations among different compounds. Our interest was especially focused on systems of strongly associating compounds. Binary phase equilibria provide information on the intermolecular forces between solvent and solute and s-l equilibria, eventually, on the formation and nature of intermolecular compounds in the solid phase. We found an addition compound in the solid phase in the systems propanoic acid-trifluoroacetic acid 1 , acetic acid-trichloroacetic acid 2 and acetic acid-formamide 3 . Although acetophenone is known to associate with acetic acid 4 , a simple sagged curve was obtained in the acetic acid-acetophenone system 3 with small positive deviations from Raoult′s law in the liquid phase.

Density, Viscosity, and Speed of Sound of (1-Octanol + 2-Methoxyethanol), (1-Octanol + N,N-Dimethylacetamide), and (1-Octanol + Acetophenone) at Temperatures of (298.15, 308.15, and 318.15) K

“…The purity of each compound was ascertained by the constancy of the density and also from viscosities, and their values were in good agreement with values found in the literature, ,– as reported in Table .…”

Reference materials for phase equilibrium studies. 1. Liquid–liquid equilibria (IUPAC Technical Report)

“…Special attention should be given to distinguishing LLE from SLE when turbidity measurements are used. LLE can be frequently supercooled to a metastable state [6], and either SLE or metastable LLE can be observed at the same temperature. Sample purity and chemical stability (e.g., possible hydrolysis) should also be carefully considered.…”