Thermochemical investigations of associated solutions. Part 11.—Calculation of pyrene–dichlorobutane association parameters from measured solubility data

Experimental solubilities are reported for pyrene dissolved in binary solvent mixtures containing 1,4-dichlorobutane with n-hexane, n-heptane, n-octane, cyclohexane, methylcyclohexane and iso-octane at 26°C. Results of these measurements, combined with estimates for the excess Gibbs free energies of the binary solvents, are used to evaluate the equilibrium constant for a presumed pyrene–dichlorobutane molecular complex from the extended nearly ideal binary solvent model. A single equilibrium constant was needed to describe the experimental data to within an average deviation of ca. 3%. The numerical value of the calculated association constant varied slightly with inert hydrocarbon cosolvent, the numerical values ranging from a lower limit of KϕAC= 11.0 for iso-octane to KϕAC= 18.0 for the cyclohexane cosolvent.