Role of charge transfer in aromatic electrophilic substitution reactions

Conclusions

• 1. Calculations of the energy of the reaction, the characteristics of the electron distribution, and an analysis of the triplet instability of the RHF solution in the reaction of benzene, furan, and pyrrole with the electrophilic particles H⁺, F⁺, Cl⁺, Br⁺, NO₂ ⁺, and CH₃ ⁺ in the starting stage of electrophilic substitution were performed by the method of SCF MO LCAO in the CNDO/2 approximation in the formalism of the restricted (RHF) and unrestricted Hartree-Fock (UHF) method.

• 2. Based on an analysis of the zone of the triplet instability of the RHF solution, it was shown that the observed characteristics of the activity, positional and substrate selectivity of aromatic and heteroaromatic molecules begins to be established in the zone of electron transfer from the substrate to the electrophilic reagent with distances between reagents of less than 2.5 Å.

• 3. The effect of a polar solvent on the parameters of the electron transfer zone was analyzed. It was shown that electron transfer is possible in the attack of benzene by H⁺, F⁺, and NO₂ ⁺ particles and in attack of furan and pyrrole by H⁺, F⁺, Cl⁺, and N0² cations in this case.