Solubilities and thermodynamics of transfer of o- and m-substituted benzoic acids in aqueous binary mixtures of 2-methoxyethanol and 1,2-dimethoxyethane

Abstract

The solubilities of <em>o- </em>and <em>m</em>-substituted benzoic acids in 2-methoxyethanol (ME) + water and 1,2- dimethoxyethane (DME) + water mixtures (0-100%) have been measured at 25 ±0.01°C. The thermodynamic dissociation constants of the acids have been determined from <em>p</em>H and solubility measurements. The free energies of transfer of the substituted benzoate ions [D<em>G</em><img src='http://www.niscair.res.in/jinfo/zerot.gif' border=0> (A^‑)] from water to mixed solvent systems have been evaluated from the corresponding D<em>G</em><img src='http://www.niscair.res.in/jinfo/zerot.gif' border=0> values of the acids and D<em>G</em><img src='http://www.niscair.res.in/jinfo/zerot.gif' border=0>(H⁺) values previously determined in these solvent systems. The results have been interpreted in terms of the structural changes occurring in the solvent mixtures with the change in solvent composition.