The p-fluoro compound 3 shares the same 100% experimental protonation in the oxygen atom in H2SO4. For this compound, the MOLPROJ software returned the HOMO-2 as the FERMO of the reaction (centered at the oxygen atom). As with compound 01, HOMO-2 has a high localization coefficient Γ value in the oxygen atom (0.505810 over 0.454808 for the HOMO at C4). Thus, we understand that HOMO-2 would be the FERMO of this reaction as well. In the same way as compound 1, based on the analysis of the shape of the orbitals in Figure , it is possible to verify that HOMO-2 has, in fact, the characteristics of a favorable location for protonation.