Steele Brad A, Zhang Mao-Xi, Kuo I-Feng W
Lawrence Livermore National Laboratory, Physical and Life Sciences Directorate, P. O. Box 808, Livermore, California 94550, United States.
J Phys Chem A. 2022 Aug 11;126(31):5089-5098. doi: 10.1021/acs.jpca.2c02124. Epub 2022 Aug 2.
The energetics of the regioselective mononitration of 9,10-BN-naphthalene with acetyl nitrate (HCNO) were modeled with simulations in the gas phase and an acetonitrile solvent. The single-electron-transfer (SET) nitration mechanism leading to a σ-complex and a single-step nitration mechanism were modeled. The energy barrier for the single-step mechanism was lower than that for the SET mechanism in the gas phase. However, the two are much more energetically competitive in the solvent. The σ-complex was found to be unstable in the gas phase owing to the interaction with the counterion. Using the single-step mechanism, the carbon site 1 nearest boron had the lowest activation energy for nitration of 22.6 kcal/mol, while site 3 had the second lowest barrier of 24.6 kcal/mol. Details on the molecular structures at intermediate and transition states as well as charges in different configurations are discussed.
采用气相和乙腈溶剂中的模拟方法，对9,10-硼氮萘与乙酰硝酸酯（HCNO）进行区域选择性单硝化反应的能量学进行了建模。对导致σ-络合物的单电子转移（SET）硝化机理和单步硝化机理进行了建模。在气相中，单步机理的能垒低于SET机理。然而，在溶剂中两者在能量上更具竞争性。由于与抗衡离子的相互作用，发现σ-络合物在气相中不稳定。采用单步机理时，最靠近硼的碳位点1的硝化活化能最低，为22.6 kcal/mol，而位点3的能垒次之，为24.6 kcal/mol。讨论了中间体和过渡态的分子结构细节以及不同构型中的电荷情况。
