RESUMEN
The structure of the studied picolines [neutral and intermediate cationic species] have been optimized. The results of MO-calculations were interpreted in terms of energies and coefficients of their molecular orbitals [HOMO and LUMO], stabilization energy, dipole moments and gap energy. The computed electronic charge density of HOMO was located on CH2+ group or 2- and 3-picoline and their N-oxide cationic species, which prevented the formation of aldehyde diacetate. On the other hand, all charge densities of HOMO in 4-picoline and its N-oxide were mainly localized on the ring with no charge density located on the CH2+ group. The CH2+ group of 4-picoline and its N- oxide cationic species could eventually be easily attacked by acetate to form aldehyde diacetate