SOLUBILITY IN BINARY SOLVENT SYSTEMS .9. ESTIMATION OF THE CARBAZOLE-TETRAHYDROPYRAN ASSOCIATION CONSTANT BASED UPON MOBILE ORDER THEORY

A relatively simple equation is derived from Mobile Order theory for calculating solute-solvent association constants from measured solubility data in binary solvent mixtures. The newly-derived expression was found to describe carbazole solubilities in five binary tetrahydropyran + alkane solvent mixtures to within an overall average absolute deviation of 2.5% using a single association constant. For four of the five systems studied, the calculated association constant was found to vary only slightly with inert hydrocarbon cosolvent, with the numerical values ranging from a lower limit of K(AC) = 5,090 for n-hexadecane to an upper value of K(AC) = 5,976 for 2,2,4-trimethylpentane. A much larger value of K(AC) = 11,290 was obtained in the n-hexane + tetrahydropyran system.