Single-ion free energies for transfers to benzonitrile derived from solubility and complexing data

Abstract

Free energies of solution derived from solubility data of 24 1 : 1 electrolytes in benzonitrile and the transfer free energy for these electrolytes from water to benzonitrile are reported. Single-ion ΔG°t values are obtained using the Ph4AsPh4B convention. Stability constants between cryptand 222 and metal ions in benzonitrile have been determined and the data used to derive single-ion ΔG°t values for the alkali metal and silver cations among dipolar aprotic solvents. Good agreement is found between the single-ion values obtained from complexing data and those derived from solubility measurements. Transfer free energies for the metal-ion cryptates in solvent systems of low mutual solubility, such as water–benzonitrile and water–nitrobenzene, are reported. Single-ion molar transfer constants for 17 cations and six anions were calculated. The results show a remarkable increase in the transfer constants for the alkali metal when complexed with cryptand 222 with respect to the uncomplexed cations.