Solubility of Anthracene in Binary Alcohol + 2-Ethyl-1-hexanol Solvent Mixtures

Abstract

Experimental solubilities are reported for anthracene dissolved in seven binary mixtures containing 2-ethyl-1-hexanol with 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-octanol, 2-methyl-1-propanol, and 3-methyl-1-butanol at 25 C. Results of these measurements are used to test two mathematical representations based upon the combined nearly ideal binary solvent (NIBS)/Redlich-Kister equation and modified Wilson model. For the seven systems studied, both equations were found to provide an accurate mathematical representation of the experimental data, with an overall average absolute deviation between measured and calculated values on the order of 0.6%. solvent mixtures. Results of these measurements are used to further test the descriptive abilities of several previously derived expressions. Experimental Methods Anthracene (Aldrich, 99.9+%) was used as received. 2-Ethyl-1-hexanol (Aldrich, 99+%), 1-propanol (Aldrich, 99+%, anhydrous), 2-propanol (Aldrich, 99+%, anhydrous), 1-butanol (Aldrich, HPLC, 99.8+%), 2-butanol (Aldrich, 99+%, anhydrous), 2-methyl-1-propanol (Aldrich, 99+%, anhydrous), 3-methyl-1-butanol (Aldrich, 99+%, anhy- drous), and 1-octanol (Aldrich, 99+%, anhydrous) were stored over both anhydrous sodium sulfate and molecular sieves before being fractionally distilled. Gas chromato- graphic analysis showed solvent purities to be 99.7 mol % or better. Karl Fischer titration gave water contents (mass1 mass %) of <0.01% for all seven alcohols used. Binary solvent mixtures were prepared by mass so that composi- tions could be calculated to 0.0001 mole fraction. Excess solute and solvent were placed in amber glass bottles and allowed to equilibrate in a constant tempera- ture water bath at (25.0 f 0.1) C for at last 3 days (often longer). Attainment of equilibrium was verified by repeti- tive measurements after a mimimum of three additional days and by approaching equilibrium from supersaturation by preequilibrating the solutions at a higher temperature. Aliquots of saturated anthracene solutions were trans- ferred through a coarse filter into a tared volumetric flask to determine the amount of sample and diluted quantita- tively with methanol. Concentrations were determined spectrophotometrically at 356 nm on a Bausch and Lomb Spectronic 2000. Experimental anthracene solubilities in the seven binary alcohol + 2-ethyl- 1-hexanol mixtures studied are listed in Table 1. Numerical values represent the average of between four and eight independent deter- minations, with the measured values being reproducible to within f1.3%.