Solvent effects on the structure and dipole moment of resorcinol

Abstract

With the specific aim of explaining the dipole moment (DM) of resorcinol in water, we investigated the molecular conformations and solute-solvent interactions of resorcinol in ethanol, methanol and water. In this work, experimental dielectric procedures and theoretical ab initio and density functional methods were used. Basis sets at the levels of theory HF/6-31G(d) and B3LYP/6-31G(d) were used for calculations. Onsager's method was used to analyze the solvent effects on the conformers of resorcinol. A conformational equilibrium between the two main conformers of non-solvated resorcinol was proposed. The total energies, DMs, structural molecular and reactivity parameters of the conformers and transition states involved were calculated. These theoretical magnitudes were correlated with parameters of the solvating solvents. The properties of the solute-solvent association complexes formed by a molecule of resorcinol and two molecules of water by means of intermolecular hydrogen bonds were also calculated. It was concluded that the DM of resorcinol in water (8.66D) is due to these solute-solvent association complexes, which are the predominant forms of resorcinol in aqueous solutions.