The nitration products of trifluoromethoxybenzene (TFMB) are important chemical intermediates, widely used in the synthesis of pharmaceuticals, pesticides, and functional materials. The efficient preparation and clear elucidation of their reaction mechanisms are of significant guiding importance for the optimization of related industries. The nitration of aromatic compounds is essentially a typical electrophilic aromatic substitution (EAS) reaction. To explore the intrinsic nature of the EAS reaction of TFMB in the mixed acid system, this study employed density functional theory (DFT) to perform simulation calculations and analyses on the process at the M06-2X/6-311+G** theoretical level. The results show that the electrochemical potential difference between TFMB and the actual nitrating agent NO₂⁺ is 6.28 eV, indicating a good electron transfer capability. Analyses of average local ionization energy (ALIE) and electrostatic potential (ESP) reveal that the para position is the optimal site for electrophilic attack. Thermodynamic calculations demonstrate that the reaction enthalpies for the formation of ortho-, meta-, and para-nitrotrifluoromethoxybenzene are -97.3, -122.2, and -127.6 kJ/mol, respectively, with all Gibbs free energy changes being negative.The reaction follows a two-step mechanism, with the energy barrier of the rate-determining step ranging from 4.0 to 7.8 kcal/mol. The para reaction pathway exhibits the lowest energy barrier, followed by the ortho pathway, while the meta pathway accounts for the smallest proportion due to its highest energy barrier and the instability of the intermediate, which is consistent with experimental results. This study not only clarifies the microscopic mechanism and regulatory rules of the nitration reaction of TFMB, but also provides an important theoretical basis for the design and optimization of nitration reactions of similar aromatic compounds.

Key words: TFMB, nitration reaction mechanism, DFT, EAS, NO₂⁺