Figure 1. Gibbs free-energy profile for the substitution reaction of the amino group of FOX-7 by CH₃NHNH₂

In Figure 2, the subsequent reaction of the intermediate IM2 is carried out according to the reaction path proposed by Xu [20]. The H on the -NHNHCH₃ group of IM2 is transferred to another C on the alkenyl group, via the transition state TS3 with an energy barrier of 44.3 kcal/mol, forming the intermediate IM3. Subsequently, the H on the C of the alkenyl group of the intermediate IM3 is transferred to the O of the nitro group to form the intermediate IM4, in which the energy barrier of the transition state TS4 is higher, and this step is difficult to carry out. The H on the N of the -NNHCH₃group of IM4 is approached to the O on the nitro group through the rotation of the dihedral angle to form IM5, which is conducive to the next H transfer reaction. The H on the N of the -NNHCH₃group of IM5 is transferred to the O on the nitro group, forming the intermediate IM6 with two H atoms in the nitro group. Subsequently, the N atom on the nitro group is approached by the N atom on -NNCH₃ group, forming IM7 with a triazole ring structure. IM7 is unstable, and the -OH group on the N of the triazole ring is immediately combined by H to decompose into a H₂O molecule and stable IM8 intermediates. The NH₃ generated earlier in this reaction is combined with IM8 to form the product MNTzA. According to the reaction energy barrier, it can be seen that the TS4 is higher in the reaction path of the transfer of H on the alkenyl group of IM3 to O on the nitro group, so the reaction path proposed by Xu is carried out difficultly.