THE MOLECULAR-STRUCTURES OF NITROTOLUENES AND THEIR THERMAL-DECOMPOSITION TAUTOMERS

The molecular structures of 2-nitro-, 3-nitro-, and 4-nitrotoluene and their internal rotation isomers were calculated by the ab initio method with an HF/6-31G* basis set. The geometries were influenced by the position of the nitro group. Perturbation of the methyl group on the nitro group is found in 2-nitrotoluene, which has a molecular structure distinct from that of the other two isomers. Among them, 4-nitrotoluene is the most stable. Tests of internal rotation of 3-nitro- and 4-nitrotoluene indicate that they have geometries similar to their original structures, but the geometries of 2-nitrotoluene differ between its internal rotational isomer and its original structure. As tautomers of explosives induced by heat or shock are of interest, we chose three tautomers of 2-nitrotoluene to assess their geometries and energies. The calculations showed that aci-2-nitrotoluene is unfavorable thermodynamically, but the nitrosoaromatic compound and anthranil are thermally favorable.