One-Electron Standard Reduction Potentials of Nitroaromatic and Cyclic Nitramine Explosives
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS ENVIRONMENTAL LAB
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Extensive studies have been conducted in the past decades to predict the environmental abiotic and biotic redox fate of nitroaromatic and nitramine explosives. However, surprisingly little information is available on one-electron standard reduction potentials EoR-NO2R-NO2. The EoR-NO2R-NO2 is an essential thermodynamic parameter for predicting the rate and extent of reductive transformation for energetic residues. In this study, experimental linear free energy relationships and theoretical ab initio calculation approaches were employed to determine EoR-NO2R-NO2 for nitroaromatic, caged cyclic nitramine, and nitroimino explosives that are found in military installations or are emerging contaminants. The results indicate a close agreement between experimental and theoretical EoR-NO2R-NO2 and suggest a key trend EoR-NO2R-NO2 value decreases from di- and tri-nitroaromatic e.g., 2,4- dinitroanisole to nitramine e.g., RDX to nitroimino compound e.g., nitroguanidine. The observed trend in EoR-NO2R-NO2 agrees with reported rate trends for reductive degradation, suggesting a thermodynamic control on the reduction rate under anoxicsuboxic conditions.
- Organic Chemistry
- Ammunition and Explosives