Effect of Media on the Properties of Monoterpene Cyclic Eucalyptol

MAXIMILIANO ALBERTO IRAMAIN; JOSE RUIZ HIDALGO; SILVIA ANTONIA. BRANDÁN

Indian Journal of Research

Paripex

Año: 2019 vol. 12 p. 70 - 101

2250-1991

Structural, electronic, topological and vibrational properties of Eucalyptol have been theoretically studied in the gas phase and in acetone, chloroform, ethanol, and water solutions by using the hybrid B3LYP/6-31G* level of theory. The properties were evaluated in function of the solvent's permittivities. A higher dipole moment and lower volume values were observed for eucalyptol in water due probably to the higher permittivity. Also, higher corrected solvation energy is predicted for eucalyptol in water (-22.51 kJ/mol) in agreement with the higher volume contraction observed in this medium (-0.4 Å3). Atomic charges reveal the most negative values on the O atoms and the most positive values on the C3 and C4 atoms. MEP surfaces of eucalyptol in all media evidence clear nucleophilic sites on the O atoms. NBO analyses show two E→* and ELP→* transitions while the AIM studies reveal two new H---H interactions which support visibly the stabilities of eucalyptol in all studied media. The gap values show a decreasing in the reactivity of eucalyptol in gas phase and mainly in chloroform and acetone solutions while in aqueous solution eucalyptol is slightly most reactive. Besides, the higher nucleophilic indexes of eucalyptol in all solvents support the characteristic nucleophilic of eucalyptol, as compared with scopolamine and tropane alkaloids. The harmonic force fields and their complete vibrational assignments of 81 normal vibration modes were performed. The predicted IR, ATR, Raman, 1H- and 13C-NMR and UVvisible spectra show reasonable concordance with the corresponding experimental ones.