Molecular structures of mononitroanilines and their thermal decomposition products

The molecular structures of 2-nitro, 3-nitro, and 4-nitroaniline and their internal rotational isomers were calculated by an ab-initio method using HF/6-31G* basis set. The geometries were influenced by the nitro group's position. The perturbation of the amino group on the nitro group was observed in a 2-nitroaniline isomer having a molecular structure distinct from that of the other two isomers. Among them, 4-nitroaniline is the most stable one. Internal rotation tests of either the nitro or amino group of 3-nitro and 4-nitroaniline indicate that no significant deformations of the phenyl ring occurred after internal rotation; however, the internal rotational isomers of 2-nitroaniline differed from its original structure. Relatively easier internal rotation of the nitro group than the amino group and different C-NO2 and C-NH2 bonds indicate the bond-breaking message of nitroanilines. As products of explosives induced by thermal or shock are of interest, five products of 2-nitroaniline were selected to assess their geometries and energies. The above calculations revealed that these products are thermodynamically unfavorable.