Publications by authors named "Liudmyla Sviatenko"
Large-scale implementation of NTO (5-nitro-1,2,4-triazol-3-one), an energetic material used in military applications, causes its discharge to the environment. Reduction of NTO with bacterial nitroreductase or iron-containing minerals results in the formation of ATO (5-amino-1,2,4-triazol-3-one), which is an important intermediate in the process of NTO degradation in the environment. ATO may be dissolved in surface water and groundwater due to its good water solubility.
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- Sunlight creates reactive oxygen species that help break down environmental pollutants, including a chemical called ATO, which is derived from the munition ingredient NTO.
- A study was conducted to explore how ATO decomposes in water, focusing on different reactive agents like superoxide, hydroperoxyl radical, and singlet oxygen, through advanced computational methods.
- The findings indicate that while superoxide is less effective, hydroperoxyl radical and singlet oxygen can effectively decompose ATO in a multi-step process, ultimately leading to the formation of simpler inorganic compounds.
Degradation of NTO induced by superoxide and hydroperoxyl radicals: a comprehensive DFT study.
Phys Chem Chem Phys
December 2023
Article Synopsis
- Reactive oxygen species, like superoxide and hydroperoxyl radicals, play a key role in breaking down environmental pollutants, including NTO, which is used in insensitive munitions and can contaminate water sources.
- A computational study revealed that NTO decomposes in water through mechanisms initiated by these radicals, leading to the formation of various byproducts, including nitrous acid and nitrogen gas.
- The research shows that the anionic form of NTO is more reactive with hydroperoxyl radicals, and sunlight can enhance the degradation process, ultimately converting NTO into simpler inorganic compounds.
Article Synopsis
- Hydroxyl radicals, created by sunlight in aquatic environments, can break down organic pollutants like NTO, a military chemical known for its high water solubility.
- A study using computational methods examined how NTO decomposes when it interacts with hydroxyl radicals, revealing it involves multiple steps, starting with the radical adding to a C═N double bond.
- This process generates various low-weight inorganic compounds, and the negatively charged form of NTO is found to be more reactive with hydroxyl radicals, highlighting their role in NTO's environmental breakdown.
Article Synopsis
- * A computational study explored how singlet oxygen, generated by sunlight in aquatic environments, can trigger the decomposition of NTO through a series of chemical reactions.
- * The study revealed that NTO degradation begins with singlet oxygen reacting with a carbon bond, leading to the formation of nitrogen gas, carbon dioxide, and ammonia, with the anionic form of NTO being more reactive than its neutral counterpart.
Article Synopsis
- NTO (5-nitro-1,2,4-triazol-3-one) is an energetic material used in military settings that can pollute the environment during its life cycle, including manufacturing and disposal.
- A computational study examined how oxygen-insensitive nitroreductase, using flavin mononucleotide (FMN) as a cofactor, reduces NTO to ATO (5-amino-1,2,4-triazol-3-one) through a series of electron and proton transfers.
- The study found that the reduction process involves sequential transformations of the nitro and nitroso groups, and the efficiency of these reactions suggests that nitroreductase and similar enzymes play a key role in breaking
Article Synopsis
- Nitroguanidine (NQ) degrades when exposed to UV radiation, but the specific mechanism behind its photolysis is not completely clear.
- Earlier studies suggest that nitrocompounds, including NQ, can shift to a triplet state during electronic excitation, which may enhance their degradation.
- Detailed investigations reveal that in its electronic triplet state, NQ has a greater degradation ability, leading to the breakdown of bonds and the formation of various products like nitrite and hydroxyguanidine.
Article Synopsis
- DNAN, NTO, and NQ are energetic materials used in military settings that can contaminate the environment during various processes like manufacturing and disposal.
- A computational study examined how these compounds react with singlet oxygen, a potential method for their degradation.
- The results indicated that DNAN is the most reactive, followed by NTO, and then NQ, with specific chemical changes predicted for each compound through various mechanisms.
Article Synopsis
- HMX is a military energetic material that can enter the environment during various stages like production and disposal, raising concerns about its impact.
- A computational study explored how alkaline hydrolysis (breaking down HMX in a basic solution) could remediate this compound, revealing it as a complex, heat-releasing process with multiple steps and specific chemical transformations.
- Although the hydrolysis at pH 10 is slow, the study predicts that increasing the pH to 11, 12, or 13 could dramatically speed up the breakdown of HMX.
Article Synopsis
- The study investigates how the explosive compound CL-20 interacts with Leonardite Humic Acid (LHA) using advanced computational methods.
- It was found that for CL-20 to form stable complexes with LHA, the organic matter must undergo deprotonation, and the formation of hydrogen bonds was studied using specific theoretical frameworks.
- The research concludes that CL-20 remains unchanged during adsorption, suggesting that its presence in soil may slow down its breakdown and degradation.
Article Synopsis
- Reduction and oxidation (redox) reactions are effective for removing nitrocompounds like TNT and DNT from contaminated environments.
- The study investigates how these compounds interact with common inorganic ions (Na+, Cl-, NO3-) using advanced theoretical methods and aims to understand their bond interactions.
- Findings indicate that these interactions significantly reduce the redox activity of nitrocompounds, and sodium complexes of NTO could potentially be reduced by metallic iron.
Article Synopsis
- A cluster approximation was utilized to study how 5-amino-3-nitro-1H-1,2,4-triazole (ANTA) adsorbs onto the (001) surface of α-quartz, revealing a nearly parallel orientation of the compound.
- The binding between ANTA and the silica surface was analyzed using the atoms in molecules (AIM) method, highlighting that electron transfer affects the complex's structure and enhances hydrogen bonding.
- The study compared the redox properties of adsorbed ANTA with those in gas and hydrated forms, finding that the adsorbed form is less capable of redox transformations than the hydrated version.
Article Synopsis
- A computational study was conducted to investigate how alkaline hydrolysis affects RDX, a potential environmental contaminant, using advanced theoretical chemistry methods.* -
- The process begins with the removal of a proton from RDX by hydroxide, resulting in the elimination of nitrite and the formation of a cyclohexene intermediate, followed by a significant ring-opening reaction facilitated by hydroxide.* -
- The primary decomposition pathway produces 4-nitro-2,4-diazabutanal, leading to byproducts like formaldehyde and nitrous oxide, and the findings align well with existing experimental data on RDX hydrolysis.*
Article Synopsis
- The study compared the reduction and oxidation properties of four nitrocompounds in water and when adsorbed on a silica surface, which simulates soil conditions.
- Researchers used cluster models and solvation models to analyze important properties like electron affinity and Gibbs free energy.
- Results showed that nitrocompounds in water are more easily transformed than those on silica, with TNT being the most reactive for gaining electrons, while NTO showed deprotonation when adsorbed.
Article Synopsis
- The study focuses on the alkaline hydrolysis of three nitroaromatic compounds: TNT, DNT, and DNAN, using experimental and computational methods to understand their chemical reactions.
- Key findings indicate that DNT and DNAN are more resistant to hydrolysis compared to TNT, with common reaction pathways identified, particularly the formation of Meisenheimer complexes as intermediates.
- The research highlights the importance of specific chemical structures, such as the substitution of nitro groups, and proposes methyl group abstraction as a potential transformation pathway for DNAN during the hydrolysis process.
Article Synopsis
- A new computational method has been developed to analyze multistep chemical reactions and applied to study the interaction between 2'-deoxycytidine and cis-2-butene-1,4-dial, a metabolite of furan.
- This method involves predicting reaction mechanisms, calculating Gibbs free energies, and converting barrier energies to rate constants to construct detailed kinetic equations.
- Results indicate that 2'-deoxycytidine reacts to form primary products, which further change into stable secondary products through dehydration, highlighting the significant role of cis-2-butene-1,4-dial in furan-related cancer development.
Article Synopsis
- The study focused on using different density functionals to predict gas-phase adiabatic ionization potentials (IPs) for nitrogen-rich heterocyclic compounds.
- It applied various solvation models to accurately calculate the free energy differences between oxidized and reduced forms of these compounds in acetonitrile, aiding in the prediction of their standard oxidation potentials.
- The developed protocols effectively estimate both gas-phase IPs and oxidation potentials, supported by a specific level of theoretical calculations, with relatively low error margins (MAD and RMSE) for both ionization and oxidation potentials.
Article Synopsis
- The study focuses on the environmental impact and safe degradation methods for nitroaromatic compounds, specifically TNT, DNT, and DNAN, using alkaline hydrolysis.
- Computational simulations revealed potential initial intermediates in the reaction, such as Meisenheimer complexes and TNT anions, emphasizing their role in the degradation process.
- The research also found that TNT has the least resistance to alkaline hydrolysis compared to DNT and DNAN, and identified a secondary pathway that forms polymeric products.
Article Synopsis
- A computational study was conducted to analyze the multistep chemical reactions between 2'-deoxyadenosine and cis-2-butene-1,4-dial, using advanced methods to create a reaction profile and evaluate rate constants.
- The results identified four diastereomeric adducts with similar stability as primary products, while their acid-catalyzed dehydration yielded a more stable secondary product.
- Simulated UV and NMR spectra for these compounds were successfully compared with experimental data, confirming the accuracy of the computational findings.
Article Synopsis
- Density functional theory was applied to study hydrazinolysis of 4-substituted 2,3-dihydro-1,5-benzodiazepine-2-thiones, specifically focusing on the 4-phenyl-2,3-dihydro-1,5-benzodiazepine-2-thione compound.
- Advanced computational methods (MP2/6-311+G(d,p)//B3LYP/6-311+G(d,p)) were employed for accurate energy predictions, including solvent effects via the PCM methodology.
- The study concluded that the mechanism involves a series of steps, with hydrazine addition to specific bonds, resulting in key transformations, and identified the cyclization step
Article Synopsis
- - The study uses density functional theory to analyze how the compound 4-methyl-2,3-dihydro-1,5-benzodiazepin-2-one reacts with hydrazine, focusing on the mechanism of hydrazinolysis for similar compounds.
- - Advanced computational methods were employed to improve energy predictions, taking solvent effects into account through the PCM methodology, ensuring more accurate results.
- - Results indicate a multi-step mechanism starting with the addition of hydrazine to the compound, leading to ring formation and ultimately producing 3-methylpyrazolone-5, which aligns with experimental findings and identifies the final reaction step as the rate-determining one.