A theoretical and experimental study on the structure and dipole moment of phloroglucinol in ethanol

Abstract The dipole moment and structural properties of phloroglucinol in ethanol have been investigated using experimental dielectric procedures and theoretical ab initio and density functional methods. Applying Buckingham's method, it was determined that the dipole moment of phloroglucinol in ethanol is 7.70 D. It was proposed that phloroglucinol interacts with the solvent by means of moderate hydrogen bonds, in which the solvent exerts its hydrogen-bond-donor capability forming solvent–solute association complexes of 3:1 stoichiometry. The main molecular regions implied in these interactions comprise the hydroxyl groups of phloroglucinol. On the other hand, the calculated data at the B3LYP/6-31G(d) level of theory with Onsager's method permitted to conclude that two related association complexes for a conformational equilibrium are the predominant species of phloroglucinol in ethanol. Also, the percentages of these complexes in equilibrium determine the magnitude of the analyzed properties of phloroglucinol.