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Gavin Phillips - One of the best experts on this subject based on the ideXlab platform.
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comment on observations of ammonia nitric acid and fine particles in a rural gas production region by yi li florian m schwandnera h james sewell angela zivkovich mark tigges suresh raja stephen holcomb john v molenar lincoln sherman cassie archuleta
Atmospheric Environment, 2014Co-Authors: Gavin PhillipsAbstract:Abstract An artefact of the detection of nitric acid (HNO3) by denuder methods is discussed. This artefact arises from the likely reaction of Dinitrogen Pentoxide (N2O5) on the denuder train resulting in the report of some fraction of N2O5 as HNO3.
Yan Zhou - One of the best experts on this subject based on the ideXlab platform.
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nitrate formation from heterogeneous uptake of Dinitrogen Pentoxide during a severe winter haze in southern china
Atmospheric Chemistry and Physics, 2018Co-Authors: Hui Yun, Weihao Wang, Tao Wang, Men Xia, Zhe Wang, Steven Poon, Dingli Yue, Yan ZhouAbstract:Abstract. Nitrate ( NO 3 - ) has become a major component of fine particulate matter (PM 2.5 ) during hazy days in China. However, the role of the heterogeneous reactions of Dinitrogen Pentoxide ( N2O5 ) in nitrate formation is not well constrained. In January 2017, a severe haze event occurred in the Pearl River Delta (PRD) of southern China during which high levels of PM 2.5 ( ∼400 µ g m −3 ) and O3 ( ∼160 ppbv) were observed at a semi-rural site (Heshan) in the western PRD. Nitrate concentrations reached 108 µ g m −3 (1 h time resolution), and the contribution of nitrate to PM 2.5 was nearly 40 %. Concurrent increases in NO 3 - and ClNO2 (with a maximum value of 8.3 ppbv at a 1 min time resolution) were observed in the first several hours after sunset, indicating an intense N2O5 heterogeneous uptake by aerosols. The formation potential of NO 3 - via N2O5 heterogeneous reactions was estimated to be between 29.0 and 77.3 µ g m −3 in the early hours (2 to 6 h) after sunset based on the measurement data, which could completely explain the measured increase in the NO 3 - concentration during the same time period. Daytime production of nitric acid from the gas-phase reaction of OH+NO2 was calculated with a chemical box model built using the Master Chemical Mechanism (MCM v3.3.1) and constrained by the measurement data. The integrated nocturnal nitrate formed via N2O5 chemistry was comparable to or even higher than the nitric acid formed during the day. This study confirms that N2O5 heterogeneous chemistry was a significant source of aerosol nitrate during hazy days in southern China.
John R Sodeau - One of the best experts on this subject based on the ideXlab platform.
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a low temperature infrared study of the reactions of the stratospheric noy reservoir species Dinitrogen Pentoxide with water ice 80 160 k
The Journal of Physical Chemistry, 1994Co-Authors: Andrew B Horn, Thomas Koch, M A Chesters, Martin R S Mccoustra, John R SodeauAbstract:The low-temperature chemistry of thin films of water ice and the important stratospheric NO[sub y] species Dinitrogen Pentoxide have been investigated in order to spectroscopically characterize one of the principal heterogeneous reactions that occurs on polar stratospheric cloud particles (PSCs). This contributes to stratospheric denitrification. Using reflection-absorption infrared spectroscopy, we have observed the formation of both covalent and ionic forms of solid N[sub 2]O[sub 5] on both ice and the clean substrate. Thermal evolution experiments suggest that the solid covalent phase, which can only be formed at the lowest temperatures (T < 100 K), is metastable with respect to the ionic phase. However, we observe no reaction between the solid ionic form and the pure ice film at T < 170 K. Reaction does occur above 140 K between the ice film and gas-phase covalent N[sub 2]O[sub 5] to form a surface layer of hydroxonium ions, solvated nitrate ions, and molecular nitric acid. Annealing to 160 K introduces more water into the surface layer by diffusion and produces a further reaction of the excess NO[sub 2][sup +] and results in the formation of more molecular nitric acid. Some of the water reacts with molecular nitric acid to form an amorphousmore » hydrate (H[sub 2]O)[sub n][center dot]H[sub 3]O[sup +]NO[sub 3][sup [minus]]. From this, we conclude that only N[sub 2]O[sub 5] in the gas-phase covalent form reacts readily with ice and consequently that the reaction in the stratosphere is likely to involve the interaction between the gas phase and the ice surface and not a solid-solid interfacial one. 17 refs., 7 figs., 2 tabs.« less
Sergei G. Zlotin - One of the best experts on this subject based on the ideXlab platform.
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continuous nitration of alcohols in a freon flow
Reaction Chemistry and Engineering, 2019Co-Authors: Mikhail N. Zharkov, Ilya V. Kuchurov, Svetlana S. Arabadzhi, Sergei G. ZlotinAbstract:The first ever installation for continuous nitration in a liquefied gas mobile phase was developed. The installation was used to convert 2-ethylhexan-1-ol, diethylene glycol, and glycerol into their corresponding nitro esters. The starting compounds were treated with a 10% excess of Dinitrogen Pentoxide in liquefied 1,1,1,2-tetrafluoroethane (TFE) medium. The flow reactions proceeded at room temperature and ≤10 bar pressure with excellent conversion and selectivity. An important feature of the developed procedure is TFE recycling which prevents its release into the atmosphere. The proposed approach for nitro esters flow production outperforms the known batch-type analogs in terms of having a far better specific productivity (by two orders of magnitude), reduced fire and explosion risks, and less pronounced negative impact on the environment. The enumerated advantages along with equipment availability lay the foundation for the development of a highly efficient nitration technology, which is characterized by reduced amounts of waste by employing a TFE medium.
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Sustainable Synthesis of Polynitroesters in the Freon Medium and their in Vitro Evaluation as Potential Nitric Oxide Donors
2017Co-Authors: Ilya V. Kuchurov, Mikhail N. Zharkov, Svetlana S. Arabadzhi, Leonid L. Fershtat, Sergei G. ZlotinAbstract:A highly efficient, safe, and sustainable procedure was developed for the synthesis of various pharmacology-relevant and/or energy-rich nitroesters. It is based on nitration of corresponding alcohols with Dinitrogen Pentoxide in the liquid 1,1,1,2-tetrafluoroethane medium. The proposed approach is attractive for commercial applications because it offers significant advantages such as mild and clean reaction conditions, low operation pressure, available equipment, scalability, and facile fluid recycling. Structure–NO donor activity correlations were elucidated by an in vitro Griess assay for synthesized nitroesters and the obtained data may be useful for further in vivo experiments
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safe and convenient synthesis of primary n nitramines in the freon media
Synthesis, 2016Co-Authors: Mikhail N. Zharkov, Ilya V. Kuchurov, Igor V. Fomenkov, V A Tartakovsky, Ivan V Fedyanin, Sergei G. ZlotinAbstract:A convenient one-pot synthesis of primary aliphatic N-nitramines, which includes the nitration of available N,N′-dialkyloxalamides or N-alkylcarbamates with Dinitrogen Pentoxide in the 1,1,1,2-tetrafluoroethane media followed by ammonolysis of intermediate N-nitroamides in the same solvent has been developed. The method is environmentally safe, and affords target N-nitramines in up to 94% overall yield.
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Relative permittivity of monocomponent and binary solutions of N_2O_5 in liquid CO_2 and their activity in nitration of cellulose
Russian Journal of Physical Chemistry B, 2015Co-Authors: A. A. Guskov, Ilya V. Kuchurov, Sergei G. ZlotinAbstract:Static relative permittivity of liquid carbon dioxide solutions of Dinitrogen Pentoxide and its mixtures with nitric, acetic or trifluoroacetic acids is measured. The procedure for nitration of cellulose acquired from various natural noncotton sources (wood, linen, hemp) by mixtures of Dinitrogen Pentoxide and 100% nitric acid in a carbon dioxide medium is developed. A supercritical drying technique is implemented for dehydration of wet nitrocellulose.
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Nitration of glycoluril derivatives in liquid carbon dioxide
Mendeleev Communications, 2015Co-Authors: Mikhail N. Zharkov, Ilya V. Kuchurov, Igor V. Fomenkov, Sergei G. Zlotin, Vladimir A. TartakovskyAbstract:Dinitroglycolurils and 1,4,6-trinitrohexahydroimidazo[4,5-d]imidazol-2(1H)-one were prepared in 56–89% yield by N-nitration of the corresponding glycoluril precursors with Dinitrogen Pentoxide in liquid carbon dioxide.
Fuming Tao - One of the best experts on this subject based on the ideXlab platform.
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a density functional theory study of the gas phase hydrolysis of Dinitrogen Pentoxide
Journal of Physical Chemistry A, 1999Co-Authors: James A Snyder, Denise Hanway, Julio Mendez, And Alan J Jamka, Fuming TaoAbstract:The gas-phase hydrolysis of N2O5 in the clusters of one to four water molecules is investigated by density functional theory calculations. The excess water molecules beyond stoichiometry of the reaction function as a polar solvent medium that stabilizes an ionic pair in the transition state. The reaction energy barrier is progressively diminished by the successive addition of water molecules and is completely eliminated in the cluster of four water molecules, permitting the hydrolysis reaction to proceed directly to products. Atmospheric implications are discussed to understand the reaction mechanisms for the hydrolysis of N2O5 in the gas-phase homogeneous conditions as well as in the heterogeneous conditions.
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a density functional theory and ab initio study of the hydrolysis of Dinitrogen Pentoxide
Chemical Physics Letters, 1998Co-Authors: Denise Hanway, Fuming TaoAbstract:Abstract The density functional theory and ab initio methods are used to study two minimum energy pathways for the hydrolysis of N2O5 to form nitric acid, one involving a single water molecule and the other involving two water molecules. Both of the reactions are initiated by the nucleophilic attack on N2O5 by water while the additional water in the two-water reaction acts as a polar solvent to stabilize the ion pair resulted from the nucleophilic attack. The activation energy is 20 kcal/mol for the one-water reaction and it is reduced by half for the two-water reaction. The study suggests that the heterogeneous hydrolysis of N2O5 is likely more favorable than the homogeneous process.