Hydrogen bonding of O-Nitroaniline in water-DMSO mixtures

Abstract

From solubilities of O-nitroaniline (ONA) and p-nitroaniline (PNA) at 2SOCin Hp-DMSO mixtures, the free energies of transfer (1'1: GO)from water to mixed solvents were estimated. From 1'1: Go values for both ONA and PNA, the internal hydrogen bonding of ONA has been evaluated. Furthermore the ion-pair formation constant (Kass) between similar molecules in each ONA and PNA were also theoretically calculated. The transfer free energies for ONA and PNA molecules were increased by increasing in the mole fraction of DMSO (Xs) in the mixed solvents, due to the increase in solute-solvent interactions.