The need for the development of munitions that have reduced response to external stimuli and thus safe in handling, and without compromising the energetic yield, is driving research on modern explosives known as insensitive munitions compounds. The 2,4-dinitroanisole (DNAN), nitroguanidine (NQ) and 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO) are important insensitive munitions (IMs) compounds currently being used in various insensitive munitions formulations. These munition compounds are more soluble in water than well-known and widely used explosive compound 2,4,6-trinitrotoluene (TNT). Therefore, the production, transportation, storage, and application of insensitive munitions compounds may result in their occurrences in the environment and particularly water bodies due to their enhanced solubility. It is expected that these munitions compounds would interact with different reactive species in the environment. Moreover, these compounds may also undergo photodegradation due to the solar radiation. Therefore, it is important to understand the degradation of these compounds in the presence of different reactive species and due to solar radiation. Such understanding would also lead to the development of technologies for the remediation of wastewater from the manufacturing plants. In the present work, we have used Density Functional theory utilizing M06-2X and B3LYP functionals and large basis set to investigate detailed degradation mechanisms of these compounds in the water solution. The time-dependent DFT was used to compute electronic transitions and to optimize geometries in the electronic excited states. It was found that degradation is a complex process involving various reactive species. The first step in the photodegradation can involve the direct dissociation of the nitro group consequent to the photoexcitation or the population of the electronic triplet state. Detailed reaction pathways leading to the degradation of these compounds will be discussed.

Degradation of some insensitive munitions compounds in water through computational chemistry approach

2019 Fall National Meeting

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