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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. January 2004, Volume 3, Number 1, 11-28 |
Structure and Dipole Moment of Catechol in Hydroxylic Solvents
Roxana A. Rudyk, María A. A. Molina, María I. Gómez, Sonia E. Blanco, and Ferdinando H. Ferretti
Internet Electron. J. Mol. Des. 2004, 3, 11-28
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Abstract:
Various classes of flavonoids of great importance for
medicine have a molecular structure containing a resorcinol
in its A-ring whereas the B-ring is a catechol derivative. With
a future view to establishing correlations between the
physicochemical and biological properties of flavonoids and
catechols and with the specific aim of explaining the dipole
moment of catechol in water, we investigated the molecular
conformations and solute-solvent interactions of catechol in
ethanol, methanol and water. Basis sets at two levels of
theory: HF/6-31G(d,p) and B3LYP/6-31G(d,p) were used for
calculations. Onsager's method was used to analyze the
solvent effects on the conformers of catechol. A
conformational equilibrium between the two main
conformers of non-solvated catechol was proposed. The total
energies, dipole moments, structural molecular and reactivity
parameters of the conformers and transition states involved
were calculated. These theoretical magnitudes were
correlated with properties of the solvating solvents. The
properties of solute-solvent association complexes formed by
a molecule of catechol and three molecules of water by
means of intermolecular hydrogen bonds were also
calculated. The stability of the conformer that has one
intramolecular hydrogen bond increases with the
hydrogen-bond donor capability and polarity of the solvents. The dipole
moment of catechol in water (11.45 D) is due to the
solute-solvent association complexes, which are the predominant
forms of the compound in aqueous solutions.
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