Molecular Structure, Electronic Structure and Heats of Formation of Explosive Sensitizers

Quantum chemical calculations at the HF/6-31G* and B3LYP/6-31G* levels have been carried out on five explosive sensitizers: ethyl nitrate (EN), n-propyl nitrate (NPN), isopropyl nitrate (IPN), 2-ethylhexyl nitrate (EHN), and tetraethylene glycol dinitrate (TEGDN). Theoretical studies have yielded a wealth of quantum chemical information on the molecular geometries, electronic structures, and energies of the title compounds. On the basis of the Mulliken populations and bond lengths, the O2-N3 fission is acceptable. Charge distribution analysis indicates that the five nitrates produce NO2 gas during the dissociation of the O2-N3 weak bond. The relative thermal stability ordering of the five nitrates was estimated on the basis of the frontier orbital energy (EHOMO, ELUMO) and the energy gap (ΔE). The heats of formation (HOFs) of the five sensitizers, EN, IPN, NPN, EHN, and TEGDN, were calculated from the isodesmic reactions and were -155.972, -190.896, -175.279, -272.376, and -790.733 kJ·mol−1, respectively.