Pictures of the highest MOs for each compound are shown in Figure . The Γ coefficients from HOMO to HOMO-3 for O and C1-C6 atoms of all compounds can be find in Supplementary Material. For the simplest compound, phenol (01), protonation in H2SO4 medium occurs only in the oxygen atom. An analysis performed with the MOLPROJ software returned a slightly higher Γ coefficient value for the HOMO-2 (0.505728), located at the oxygen atom, in relation to the HOMO orbital (0.500961), which is mainly located at the C4 carbon atom (the para-hydroxy carbon; Figure ). With that, it can be understood that protonation would be more favored in this oxygen atom, which agrees with the experimental results in H2SO4 solvent, indicating that, in this case, HOMO-2 is the FERMO of the reaction. Analyzing the figure of the orbitals for compound 01, we can see that HOMO-2 describes the protonation site better than the HOMO-1 orbital.