Mechanisms and Kinetics of Alkaline Hydrolysis of the Energetic Nitroaromatic Compounds 2,4,6-Trinitrotoluene (TNT) and 2,4-Dinitroanisole (DNAN)

Salter-Blanc, Alexandra J.; Bylaska, Eric J.; Ritchie, Julia; Tratnyek, Paul G.

doi:10.1021/es304461t

Cited by 42 publications

(59 citation statements)

References 47 publications

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“…3 This application of green chemistry principals 4 to the design and selection of new energetic 15 3 compounds requires data on their chemical fate properties, often in the early stages of evaluation (including prior to synthesis) when experimentation with the candidate compounds is impractical. 3, 5 To overcome this obstacle, robust models are needed to predict key environmental fate properties, including rate constants for nitro reduction, which is a major determinant of their fate. 6, 7…”

Section: Introductionmentioning

confidence: 99%

“…8, 9 Only data for which E 1 red was measured were included in the fits. The data were fit to (A) Equation 1 or (B) Equation 5. In (B), an extrapolation of the fit is shown (as a dashed line) for cases where the data is well fit to Equation 5.…”

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confidence: 99%

“….e., "Marcus plots" 17 ) are shown inFigure 1for various λ. Non-linear regression of Equation5 (where λ is the only fitting parameter) to data for log(k) and ΔG°′ is one way to evaluate the consistency of a dataset with the model assumption that the observed rate is controlled by outer-sphere electron transfer. Generic Marcus plot ofEquation 5 for various values of λ (labeled on the curves in kcal mol -1 ).…”

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Predicting Reduction Rates of Energetic Nitroaromatic Compounds Using Calculated One-Electron Reduction Potentials

Salter-Blanc

Bylaska

Johnston

et al. 2015

Environ. Sci. Technol.

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The evaluation of new energetic nitroaromatic compounds (NACs) for use in green munitions formulations requires models that can predict their environmental fate. Previously invoked linear free energy relationships (LFER) relating the log of the rate constant for this reaction (log(k)) and one-electron reduction potentials for the NAC (E1NAC) normalized to 0.059 V have been re-evaluated and compared to a new analysis using a (nonlinear) free-energy relationship (FER) based on the Marcus theory of outer-sphere electron transfer. For most reductants, the results are inconsistent with simple rate limitation by an initial, outer-sphere electron transfer, suggesting that the linear correlation between log(k) and E1NAC is best regarded as an empirical model. This correlation was used to calibrate a new quantitative structure-activity relationship (QSAR) using previously reported values of log(k) for nonenergetic NAC reduction by Fe(II) porphyrin and newly reported values of E1NAC determined using density functional theory at the M06-2X/6-311++G(2d,2p) level with the COSMO solvation model. The QSAR was then validated for energetic NACs using newly measured kinetic data for 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), and 2,4-dinitroanisole (DNAN). The data show close agreement with the QSAR, supporting its applicability to other energetic NACs.

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Section: Introductionmentioning

confidence: 99%

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Predicting Reduction Rates of Energetic Nitroaromatic Compounds Using Calculated One-Electron Reduction Potentials

Salter-Blanc

Bylaska

Johnston

et al. 2015

Environ. Sci. Technol.

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“…A recent investigation revealed substantial aerobic biodegradation of DNAN by enrichment cultures derived from activated sludge, but the responsible bacteria were not isolated (9). During alkaline hydrolysis, DNAN is converted to 2,4-dinitrophenolate via an unstable hydride-Meisenheimer complex (10). Phototransformation of DNAN resulted in 2-hydroxy-4-nitroanisole and 2,4-dinitrophenol (2,4-DNP) as major and minor products, respectively (5,11).…”

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Aerobic Biodegradation of 2,4-Dinitroanisole by Nocardioides sp. Strain JS1661

Fida

Palamuru

Pandey

et al. 2014

Appl Environ Microbiol

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DNAN (2,4-dinitroanisole) is one of the insensitive nitroaromatic ingredients increasingly used as a replacement for 2,4,6-trinitrotoluene (TNT) in munitions. DNAN or its metabolites can be toxic to earthworms, bacteria, algae, and plants (1, 2). Therefore, the release of DNAN to the environment could pose ecological and health risks. There is little information about the environmental behavior of DNAN (2), and no bacteria capable of complete biodegradation have been reported.The initial reaction in the biotransformation of DNAN by bacteria and in abiotic transformation with zero valent iron is the reduction of the nitro group in the ortho position to yield 2-amino-4-nitroanisole (3-5). Under anoxic conditions, DNAN is biotransformed to toxic metabolites such as diaminoanisole (3,(5)(6)(7)(8). A Bacillus strain was reported to transform DNAN slowly under aerobic conditions to 2-amino-4-nitroanisole as a predominant dead-end product (4). A recent investigation revealed substantial aerobic biodegradation of DNAN by enrichment cultures derived from activated sludge, but the responsible bacteria were not isolated (9). During alkaline hydrolysis, DNAN is converted to 2,4-dinitrophenolate via an unstable hydride-Meisenheimer complex (10). Phototransformation of DNAN resulted in 2-hydroxy-4-nitroanisole and 2,4-dinitrophenol (2,4-DNP) as major and minor products, respectively (5, 11). The pathway of 2,4-DNP biodegradation under aerobic conditions is well-known, and the genes involved have been characterized for Rhodococcus erythropolis and Nocardia (12, 13). A Rhodococcus sp. has been reported to degrade 4-nitroanisole by a pathway involving removal of the methyl group and subsequent degradation of the resulting 4-nitrophenol via 4-nitrocatechol and 1,2,4-trihydroxybenzene (14). Biotransformation of DNAN to 2,4-DNP has been reported in mammals (15).We isolated bacteria able to grow on DNAN as the sole carbon source under aerobic conditions and elucidated the catabolic pathway. An initial O-demethylation catalyzed by a hydrolase was followed by degradation of the resultant 2,4-dinitrophenol by a pathway involving formation of a hydride-Meisenheimer complex (16,17). MATERIALS AND METHODSIsolation of DNAN-degrading bacteria. An activated sludge sample from Holston Army Ammunition Plant was inoculated (20% [vol/vol]) into 1/4-strength minimal salts medium (MSB) (18) (pH 6.5) containing 2,4-dinitroanisole (DNAN) (100 M), and the suspension was incubated at 30°C with shaking. Following the disappearance of DNAN as monitored by high-performance liquid chromatography (HPLC) (see below), samples (20% [vol/vol]) were repeatedly transferred into fresh medium and then spread on MSB agar (1.5%) plates containing DNAN (100 M). Individual colonies that appeared after 4 days of incubation were tested for the ability to degrade DNAN in carbon-and nitrogen-free MSB. Isolates that used DNAN as the sole source of carbon, nitrogen, and energy were selected for further study. 16S rRNA gene analysis was used for identification of the strains...

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“…[1,2] Previous studies have been introduced to elucidate reduction mechanisms controlling the fate of NACs in anoxic environments. [3,4] Reduction of NACs to the corresponding degradation products was observed in contaminated soil. [5] Reductively produced Fe(II) was found to play a key role during the NACs biodegradation process in an anoxic sediment containing abundant iron oxide with the mediation of anaerobic bacteria activities.…”

Section: Introductionmentioning

confidence: 99%

The characteristics and two-step reaction model ofp-nitroacetophenone biodegradation mediated byShewanella decolorationisS12 and electron shuttle in the presence/absence of goethite

Zhu

Wang

2014

Environmental Technology

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The current study mainly focused on the biodegradation process of p-nitroacetophenone (NP) in the presence and absence of goethite mediated by iron-reducing microbe (Shewanella decolorationis S12) and electron shuttle. The results showed that introduction of electron shuttle could obviously lead to an accumulation of biodegradation intermediate, especially in reaction systems containing high content of electron shuttle in the absence of goethite. Goethite could enhance the degree and rate of NP biodegradation. The microbial reductively generated Fe(II) played an active role in the biodegradation process. The relationship between the concentrations of biodegradation end product and the reaction times could be fitted by a consecutive reaction model with correlation coefficients (adjusted R(2)) in the range from 0.9241 to 0.9831 during the biodegradation stage from the beginning to about 250 h of incubation. However, during the subsequent biodegradation stages, in the presence and absence of goethite, transitions from the consecutive reaction model to zero-order reaction model and from the consecutive reaction model to exponential growth reaction model were observed, respectively. The newly proposed two-step reaction model will help understand the mechanism of the biodegradation process of nitroaromatic compounds and related pollutants.

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Mechanisms and Kinetics of Alkaline Hydrolysis of the Energetic Nitroaromatic Compounds 2,4,6-Trinitrotoluene (TNT) and 2,4-Dinitroanisole (DNAN)

Cited by 42 publications

References 47 publications

Predicting Reduction Rates of Energetic Nitroaromatic Compounds Using Calculated One-Electron Reduction Potentials

Predicting Reduction Rates of Energetic Nitroaromatic Compounds Using Calculated One-Electron Reduction Potentials

Aerobic Biodegradation of 2,4-Dinitroanisole by Nocardioides sp. Strain JS1661

The characteristics and two-step reaction model ofp-nitroacetophenone biodegradation mediated byShewanella decolorationisS12 and electron shuttle in the presence/absence of goethite

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