10102-03-1Relevant articles and documents
Heterogeneous kinetics of the uptake of ClONO2 on NaCl and KBr
Caloz, Francois,Fenter, Frederick F.,Rossi, Michel J.
, p. 7494 - 7501 (1996)
The uptake kinetics of ClONO2 on NaCl (reaction 1) and on KBr (reaction 2) have been studied in a low-pressure, Teflon-coated Knudsen reactor at room temperature. The initial uptake coefficient for both reactions has been measured as 0.23 ± 0.06 and 0.35 ± 0.06 for reactions 1 and 2, respectively, and is independent of reactant density in the range 1010-1013 molecules cm-3. The values of the uptake coefficients are independent of presentation of the salt substrates: identical results are obtained on powder, grains, single-crystal surfaces, and thin deposited salt layers. The only product of reaction 1 is Cl2. Reaction 2 initially produces Br2, followed by BrCl and Cl2. In our proposed mechanism, BrCl is the product of reaction 2, and secondary reactions between BrCl and the KBr substrate yield Br2 at short reaction times and Cl2 under prolonged exposure.
Johnston, H. S.,Yost, D. M.
, p. 386 - 392 (1949)
Temperature-Dependent Ultraviolet Absorption Spectrum for Dinitrogen Pentoxide
Yao, Francis,Wilson, Ivan,Johnston, Harold
, p. 3611 - 3615 (1982)
The ultraviolet absorption cross sections for N2O5 are presented for wavelengths between 200 and 380 nm and for temperatures between 223 and 300 K.The absorption spectrum above 290 nm shows a pronounced temperature dependence.
Nitrate radical quantum yield from peroxyacetyl nitrate photolysis
Flowers, Bradley A.,Angerhofer, Mark E.,Simpson, William R.,Nakayama, Tomoki,Matsumi, Yutaka
, p. 2552 - 2558 (2005)
Peroxyacetyl nitrate (PAN, CH3C(O)OONO2) is a ubiquitous pollutant that is primarily destroyed by either thermal or photochemical mechanisms. We have investigated the photochemical destruction of PAN using a combination of laser pulsed photolysis and cavity ring-down spectroscopic detection of the NO3 photoproduct. We find that the nitrate radical quantum yield from the 289 nm photolysis of PAN is φNO3PAN = 0.31 ± 0.08 (±2σ). The quantum yield is determined relative to that of dinitrogen pentoxide, which is assumed to be unity, under identical experimental conditions. The instrument design and experimental procedure are discussed as well as auxiliary experiments performed to further characterize the performance of the optical cavity and photolysis system.
Kinetics of ClONO2 reactive uptake on ice surfaces at temperatures of the upper troposphere
Fernandez, Miguel A.,Hynes, Robert G.,Cox, Richard A.
, p. 9986 - 9996 (2005)
The reactive uptake kinetics of ClONO2 on pure and doped water-ice surfaces have been studied using a coated wall flow tube reactor coupled to an electron impact mass spectrometer. Experiments have been conducted on frozen film ice surfaces in the temperature range 208-228 K with P ClONO2 ≤ 10-6 Torr. The uptake coefficient (γy) of ClONO2 on pure ice was time dependent with a maximum value of γmax ～0.1. On HNO3-doped ice at 218 K the γmax was 0.02. HOCl formation was detected in both experiments. On HCl-doped ice, uptake was gas-phase diffusion limited (γ > 0.1) and gas-phase Cl2 was formed. The uptake of HCl on ice continuously doped with HNO3 was reversible such that there was no net uptake of HCl once the equilibrium surface coverage was established. The data were well described by a single site 2-species competitive Langmuir adsorption isotherm. The surface coverage of HCl on HNO3-doped ice was an order of magnitude lower than on bare ice for a given temperature and PHCl. ClONO2 uptake on this HCl/HNO3-doped ice was studied as a function of PHClHci. γmax was no longer gas-phase diffusion limited and was found to be linearly dependent on the surface concentration of HCl. Under conditions of low HCl surface concentration, hydrolysis of ClONO2 and reaction with HCl were competing such that both Cl2 and HOCl were formed. A numerical model was used to simulate the experimental results and to aid in the parametrization of ClONO2 reactivity on cirrus ice clouds in the upper troposphere.
A Fourier Transform Infrared Study of the Rate Constant of the Homogeneous Gas-Phase Reaction N2O5 + H2O and Determination of Absolute Infrared Band Intensities of N2O5 and HNO3
Hjorth, J.,Ottobrini, G.,Cappellani, F.,Restelli, G.
, p. 1565 - 1568 (1987)
N2O5 was reacted with water vapor in large FEP-Teflon bags and its decay followed by samplig in a White gas cell using infrared Fourier transform spectroscopy.A rate constant for the homogeneous N2O5 + H2O gas-phase reaction at 296 +/- 2 K and 740 Torr total pressure equel to (1.48 +/- 0.42)E-21 cm3/molecule*s was observed.Critical analysis of the results suggested that the true homogeneous rate constant might be lower.The measured HNO3 absolute intensities of the overlapping band systes $v5, 2$v9 and $v5 + $v9 - $v9 (840-930/cm) and $v3,$v4 (1270-1350/cm) were 2.21E-17 and 4.29E-17 cm/molecule, respectively.
Aerosol chamber study of optical constants and N2O5 uptake on supercooled H2so4/H2O/HNO3 solution droplets at polar stratospheric cloud temperatures
Wagner, Robert,Naumann, Karl-Heinz,Mangold, Alexander,Moehler, Ottmar,Saathoff, Harald,Schurath, Ulrich
, p. 8140 - 8148 (2005)
The mechanism of the formation of supercooled ternary H2SO 4/H2O/HNO3 solution (STS) droplets in the polar winter stratosphere, i.e., the uptake of nitric acid and water onto background sulfate aerosols at T a simulation experiment at the large coolable aerosol chamber AIDA of Forschungszentrum Karlsruhe. Supercooled sulfuric acid droplets, acting as background aerosol, were added to the cooled AIDA vessel at T = 193.6 K, followed by the addition of ozone and nitrogen dioxide. N2O5, the product of the gas phase reaction between O3 and NO2, was then hydrolyzed in the liquid phase with an uptake coefficient γ(N2O5). From this experiment, a series of FTIR extinction spectra of STS droplets was obtained, covering a broad range of different STS compositions. This infrared spectra sequence was used for a quantitative test of the accuracy of published infrared optical constants for STS aerosols, needed, for example, as input in remote sensing applications. The present findings indicate that the implementation of a mixing rule approach, i.e., calculating the refractive indices of ternary H2SO4/H2O/HNO3 solution droplets based on accurate reference data sets for the two binary H2SO4/H2O and HNO3/H2O systems, is justified. Additional model calculations revealed that the uptake coefficient γ(N2O5) on STS aerosols strongly decreases with increasing nitrate concentration in the particles, demonstrating that this so-called nitrate effect, already well-established from uptake experiments conducted at room temperature, is also dominant at stratospheric temperatures.
Atom-efficient electrophilic aromatic nitration by dinitrogen pentoxide catalysed by zirconium(IV) 2,4-pentanedionate
Hill, Adrian J.,Millar, Ross W.,Sandall, John P.B.
, p. 90 - 92 (2004)
An atom-efficient, non-acidic, catalytic process is described for the nitration of electron deficient arenes such as o-nitrotoluene using a dinitrogen pentoxide-zirconium(IV) 2,4-pentanedionate system in dichloromethane solvent. Kinetic studies showed the nitration process to be first-order with respect to the aromatic substrate and higher than first-order with respect to the catalyst. Addition of the catalyst at ca. 0.1-1 mol% compared with both N2O5 and the organic substrate results in an increase in the first-order rate constant for nitration by a factor of approximately 5000 with a turnover number of at least 500. The orientation of the nitration products (2,4-/2,6-dinitrotoluenes) is consistent with attack of nitronium ion. The apparently high order of reaction with respect to the catalyst suggests a possible heterogeneous process.
Synthesis and Mid-IR Absorption Cross Sections of BrNO2
Frenzel, Andreas,Scheer, Volker,Behnke, Wolfgang,Zetzsch, Cornelius
, p. 16447 - 16450 (1996)
A method for the synthesis of gaseous BrNO2 at concentrations of the order of 1E-9 mol/cm3 at atmospheric pressure is described, based on the heterogeneous reaction of ClNO2 with aqueous bromide solutions.We measured the gas-phase infrared absorption cross sections in the range 700-1800 cm-1.The matrix isolation spectrum was recorded for identification by comparison with literature data.
Physicochemical characterization of the decomposition course of hydrated ytterbium nitrate: Thermoanalytical studies
Balboul, Basma A.A.
, p. 173 - 179 (2004)
Yb(NO3)3·6H2O was used as a parent compound for the formation of Yb2O3 at up to 800°C in atmosphere of air. Thermal processes occurring during the decomposition course were monitored by means of differential thermal analysis (DTA), thermogravimetry (TG), and the gaseous decomposition products were identified by mass spectrometry (GC-MS). The intermediates and final solid products were characterized by IR-spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that, Yb(NO3) 3·6H2O decomposes completely through 11 endothermic mass loss processes. The dehydration occurs through the first six steps at 95, 145, 165, 175 and 200°C, forming crystalline nitrate Yb(NO3) 3, which decomposes to YbO0.5(NO3)2 at 250°C. The latter, decomposes to non-stoichiometric unstable intermediate YbO0.75(NO3)1.5 at 335°C, which decompose immediately to a stable and crystalline YbONO3 at 365°C, then to a non-stoichiometric unstable intermediate Yb(O)1.25(NO 3)0.5 at 470°C. Finally, Yb2O3 was formed at 510°C. The decomposition course and surface morphology were supported and followed by SEM and textural studies (SBET).The final product Yb2O3 at 600°C has a large irregular sheet shaped particles containing a large pores, voids and cracks and has S BET=45 m2/g. The gaseous decomposition products are water vapor, nitric acid and nitrogen oxides (NO, NO2 and N 2O5). The activation energy (ΔE in kJ/mol) was calculated non-isothermally for each thermal processes.
Dziegielewski, Jan O.,Filipek, Krzysztof,Jezowska-Trzebiatowska, Boguslawa
, p. 429 - 432 (1991)
Electrochemical synthesis of N2O5 by oxidation of N2O4 in nitric acid with PTFE membrane
Wang, Qingfa,Su, Min,Zhang, Xiangwen,Wang, Li,Wang, Jixiao,Mi, Zhentao
, p. 3667 - 3672 (2007)
Electrochemical synthesis of dinitrogen pentoxide (N2O5) by oxidation of dinitrogen tetroxide (N2O4) in a plate-and-frame electrolyzer was investigated. As the separator, different porous polytetrafluoroethylene (PTFE) membranes were tested in this process and the effects of hydrophilicity and of hydrophobicity on the electrolysis were discussed. The transport of N2O4 and water from catholyte to anolyte through membrane occurred in the electrolysis, especially at the end of the electrolysis. The water transport had a much more effect on the electrolysis than that of the N2O4 diffusion. The hydrophobic PTFE membranes had better performance on control of water transport from catholyte to anolyte than that of the hydrophilic ones. Hydrophobicity can increase the chemical yield of N2O5. The membranes with a low hydrophobic surface were preferred. All the hydrophobic PTFE membranes with low resistance have the specific energy of 1.1-1.5 kWh kg-1 N2O5. The current efficiency of 67.3-80.2% and chemical yield of 58.9-60.9% were achieved in production of N2O5. The technique of replacing the catholyte with fresh nitric acid can minimize the transport of N2O4 and water to a great extent, it can further improve the chemical yield and reduce the specific energy.
Crystal structures of nitronium tetranitratogallate and its reversible solid-state phase transition mediated by nonmerohedral twinning
Colombo, Daniel G.,Young Jr., Victor G.,Gladfelter, Wayne L.
, p. 4621 - 4624 (2000)
Single-crystal X-ray crystallographic analyses of [NO2][Ga(NO3)4] reveal that it undergoes a reversible phase transition without any apparent damage to the crystal during repeated temperature cyclings. The room-temperature, noncentrosymmetric, body-centered tetragonal (I 4), polymorph 1 (a = 9.2774(3) A, c = 6.1149(2) A, Z = 2) consists of well-separated nitronium and tetranitratogallate ions. The [Ga(NO3)4]- units exhibit a slightly squashed tetrahedral geometry in which all of the ligands are monodentate. Below approximately 250 K, distortions lower the symmetry to the chiral, body-centered monoclinic nonstandard space group I2. Both components (2a: a = 9.5857(2) A, b = 5.9399(1) A, c = 8.9759(2) A, β = 90.409(1)°, Z = 2. 2b: a = 9.5898(2) A, b = 5.9376(1) A, c = 8.9784(1) A, β = 90.420(1)°, Z = 2) of the nonmerohedrally twinned structure are independently refined and found to be enantiomeric with nearly identical distance and angle parameters. As in the high-temperature polymorph, the cations and anions are well separated. The most notable change involves two of the nitrato ligands in the [Ga(NO3)4]- ions that have become bidendate, causing the molecular structure to distort toward octahedral geometry.
Thermolabile noble metal precursors: (NO)[Au(NO3)4], (NO)2[Pd(NO3)4], and (NO) 2[Pt(NO3)6]
Wickleder, Mathias S.,Gerlach, Frauke,Gagelmann, Steffen,Bruns, Joern,Fenske, Mandus,Al-Shamery, Katharina
, p. 2199 - 2203 (2012)
Oxidizing noble metals: Pure N2O5 can oxidize elemental gold and palladium. The complex nitrates obtained by these reactions, (NO)[Au(NO3)4], (NO)2[Pd(NO3) 4], and also the first nitrate of tetravalent platinum, (NO) 2[Pt(NO3)6] (see picture for the anion: Pt-gray, N-green, O-blue), have the potential to act as precursors owing to their high thermolability. The thermal decomposition of (NO)[Au(NO 3)4] was elucidated in detail by several methods. Copyright
Broadband cavity ringdown spectroscopy of the NO3 radical
Ball, Stephen M.,Povey, Ian M.,Norton, Emily G.,Jones, Roderic L.
, p. 113 - 120 (2001)
Cavity ringdown spectroscopy (CRDS) has been demonstrated using a broadband (20 nm) laser source and a two-dimensional clocked detector array. Absorption spectra of dilute samples (50-500 parts per trillion) of the nitrate radical, NO3, have been obtained between 650 and 670 nm by monitoring simultaneously the time and wavelength resolved output of a ringdown cavity. The potential of broadband CRDS for making measurements on samples containing multiple absorbers (e.g., atmospheric samples) is shown by applying analysis methods from differential optical absorption spectroscopy to quantify the NO3 concentration in the presence of nitrogen dioxide impurities.
Relative reaction rates of HCHO, HCDO, DCDO, H13CHO, and HCH18O with OH, Cl, Br, and NO3 radicals
Fellberg, Karen L.,Johnson, Matthew S.,Nielsen, Claus J.
, p. 7393 - 7398 (2004)
Formaldehyde (HCHO) is a principal intermediate in the photochemical oxidation of hydrocarbons in the troposphere. Isotopic analysis is an important tool for tracing the atmospheric path of gaseous species, and for this purpose, characterization of the isotope effects in the loss processes for formaldehyde is needed. The main loss pathways for formaldehyde in the atmosphere are photolysis and reactions with the radical species of OH, Cl, Br, and NO 3. In this study, the kinetic isotope effects in the reactions of five different isotopomers of formaldehyde (HCHO) with OH, Cl, Br, and NO 3 radicals are studied in a relative-rate experiment at 298 ± 2 K and 1013 ± 10 mbar. The reaction rates of DCDO, HCDO, H 13CHO, and HCH18O with the four radicals are measured relative to H2CO in a smog chamber using long-path FTIR detection. The experimental data are analyzed with a nonlinear least-squares spectral-fitting method using measured high-resolution infrared spectra and cross sections from the HITRAN database. The reaction rates of HCDO and HCH 13O with OH and Cl are determined relative to HCHO as k OH+HCHO/kOH+HCDO = 1.28 ± 0.01, k OH+HCHO/kOH+HCH18O = 0.967 ± 0.006, k Cl+HCHO/kCl+HCDO = 1.201 ± 0.002, and k Cl+HCHO/kCl+HCH18O = 1.08 ± 0.01. The reaction rates of HCDO and HCH18O with Br and NO3 are determined relative to HCHO as kBr+HCHO/kBr+HCDO = 3.27 ± 0.03, k Br+HCHO/kBr+HCH18O = 1.275 ± 0.008, k NO3+HCHO/kNO3+HCDO = 1.78 ± 0.01, and k NO3+HCHO/kNO3+HCH18O = 0.98 ± 0.01. The errors represent 2σ from the statistical analyses, and do not include possible systematic errors.
Fowles, Martin,Mitchell, David N.,Morgan, Jonathan W. L.,Wayne, Richard P.
, (1982)
Rate constants for the collisional dissociation of N2O5 by N2
Viggiano, A. A.,Davidson, J. A.,Fehsenfeld, F. C.,Ferguson, E. E.
, p. 6113 - 6125 (1981)
The rate constants for the collisional dissociation of N2O5 by N2 are measured over the pressure and temperature ranges of 10 to 800 Torr and 285 to 384 K, respectively.The measurements are carried out in flow-through reaction cells of different volumes, the N2O5 being detected by selected ion-molecule reactions in a flowing afterglow apparatus.The present rate constants are somewhat smaller than those of earlier studies and also suggest that the transition from second- to first-order kinetics occurs at lower pressures than was earlier thought.The data are fitted to theoretical models of varying sophistication.The recommended values for use in extrapolation for the limiting low-pressure and high-pressure rate constants corresponding to the first-order Troe extension of the Lindeman-Hinshelwood model for FcentSC=0.572 are k0=1.15*10-5 exp(-19.70 kcal/mol/RT) cm3 s-1 and k=1.21*1017 exp(-25,41 kcal/mol/RT) s-1.Other forms yield similar results.
Absorption Spectrum of NO3 and Kinetics of the Reactions of NO3 with NO2, Cl, and Several Stable Atmospheric Species at 298 K
Burrows, J. P.,Tyndall, G. S.,Moortgat, G. K.
, p. 4848 - 4856 (1985)
The absorption spectrum of NO3 has been measured between 615 and 670 nm in the photolysis of Cl2-ClONO2-N2 and F2-HNO3-N2 mixtures.The absorption cross section was found to be (1.19 +/- 0.36) x 10-17 cm2 molecule-1 at 622.3 nm, and this leads to a value of (1.85 +/- 0.56) x 10-17 cm2 molecule-1 at 662 nm in good agreement with most recent studies.The rate coefficient for the reaction NO3 + NO2 -> N2O5 was measured to be (4.8 +/- 0.3) x 10-13 and (5.8 +/- 0.8) x 10-13 cm3 molecule-1 at total pressures of 24 and 40 torr of N2, respectively.A rate coefficient for the reaction between Cl and NO3 was derived from the NO3 behavior in the photolysis of Cl2 and ClONO2 mixtures and its value at 298 K is (2.7 +/- 1.0) x 10-11 cm3 molecule-1 s-1.In addition, upper limits were determined for the rates of reaction of NO3 with SO2, CO, CH4, H2O2, and CS2.
Lemon, J. T.,Lowry, T. M.
, (1936)
Temperature and Pressure Dependence of the Rate Coefficient for the Reaction NO3 + NO2 + N2 -> N2O5 + N2
Orlando, John J.,Tyndall, Geoffrey S.,Cantrell, Christopher A.,Calvert, Jack G.
, p. 2345 - 2349 (1991)
A discharge flow tube experiment has been conducted to determine the rate coefficient, k2, for reaction (2): NO3 + NO2 + N2 -> N2O5 + N2 from 236 to 358 K and 0.5 to 8 Torr.This represents the first study of the temperature dependence of k2 at low pressure, i.e. under conditions relevant to the middle and upper stratosphere.The data obtained here have been combined with other measurements of k2 and the following fall-off parameters are recommended: k0 = (2.8 +/- 0.4) x 10-30 (T/300)(-3.5 +/- 0.5) cm6 s-1, kinfinite = (1.66 +/- 0.25) x 10-12 (T/300)(0.2 +/- 0.2) cm3 s-1, for Fc = 2.5 exp(-1950/T) + 0.9 exp(-T/430).
Hydrolysis of N2O5 on submicron sulfuric acid aerosols
Hallquist, Mattias,Stewart, David J.,Baker, Jacob,Cox, R. Anthony
, p. 3984 - 3990 (2000)
The hydrolysis of N2O5 on the surfaces of aerosol particles and cloud droplets is the dominant removal channel for NOx at night. Thus, it is important in determining the oxidative capacity of the atmosphere as the concentrations of NOx strongly affect the rate of tropospheric O3 formation. NOx levels in the stratosphere were depleted due to hydrolysis of N2O5 on the large quantity of sulfuric acid aerosol generated by volcanic gases. The kinetics of reactive uptake of gaseous N2O5 on submicron sulfuric acid aerosol particles was studied using a laminar flow reactor coupled with a differential mobility analyzer to characterize the aerosol. At 26.3-64.5 wt % H2SO4 concentration, the uptake coefficient (γ) was 0.033 ± 0.004, independent of acid strength and of relative humidity at 8-80%. For an acid strength of 45 wt %, Γ decreased with increasing temperature at 263-298 K. Temperature dependence values of -115 ± 30 kJ/mole and -25.5 ± 8.4 J/mole were determined for the changes in enthalpy and entropy of the uptake process, respectively. The results were consistent with a previous model of N2O5 hydrolysis involving a direct and an acid catalyzed mechanism, with uptake under the experimental conditions limited by mass accommodation.
Microwave spectrum, large-amplitude motions, and ab initio calculations for N2O5
Grabow,Andrews,Fraser,Irikura,Suenram,Lovas,Lafferty,Domenech
, p. 7249 - 7262 (1996)
The rotational spectrum of dinitrogen pentoxide (N2O5) has been investigated between 8 to 25 GHz at a rotational temperature of ～2.5 K using a pulsed-molecular-beam Fourier-transform microwave spectrometer. Two weak b-dipole spectra are observed for two internal-rotor states of the molecule, with each spectrum poorly characterized by an asymmetric-rotor Hamiltonian. The observation of only 6-type transitions is consistent with the earlier electron-diffraction results of McClelland et al. [J. Am. Chem. Soc. 105, 3789 (1983)] which give a C2 symmetry molecule with the b inertial axis coincident with the C2 axis. Analysis of the 14N nuclear hyperfine structure demonstrates that the two nitrogen nuclei occupy either structurally equivalent positions or are interchanging inequivalent structural positions via tunneling or internal rotation at a rate larger than ～1 MHz. For the two internal rotor states, rotational levels with Ka + Kc even have IN=0, 2, while levels with Ka + Kc odd have IN= 1, where IN is the resultant nitrogen nuclear spin. This observation establishes that the equilibrium configuration of the molecule has a twofold axis of symmetry. Guided by ab initio and dynamical calculations which show a planar configuration is energetically unfavorable, we assign the spectrum to the symmetric and antisymmetric tunneling states of a C2 symmetry N2O5 with internal rotation tunneling of the two NO2 groups via a geared rotation about their respective C2 axes. Because of the Bose-Einstein statistics of the spin-zero oxygen nuclei, which require that the rotational-vibrational-tunneling wave functions be symmetric for interchange of the O nuclei, only four of the ten vibrational-rotational-tunneling states of the molecule have nonzero statistical weights. Model dynamical calculations suggest that the internal-rotation potential is significantly more isotropic than implied by the electron-diffraction analysis.
An efficient method to synthesize TNAD by the nitration of 1,4,5,8-tetraazabicyclo-[4,4,0]-decane with N2O5 and acidic ionic liquids
Cao, Xiao-Feng,Li, Bin-Dong,Wang, Min
, p. 423 - 426 (2014)
An experimental study was carried out on the direct nitration of 1,4,5,8-tetraaza-bicyclo-[4,4,0]-decane to synthesize 1,4,5,8-tetranitro-1,4,5, 8-tetraazabicyclo-[4,4,0]-decane (TNAD) with N2O5 catalyzed by acidic ionic liquids. Var
Ogg, R. A.,Wilson, M. K.
, p. 900 - 901 (1950)
Nitration of aromatics with dinitrogen pentoxide in a liquefied 1,1,1,2-tetrafluoroethane medium
Fauziev, Ruslan V.,Kharchenko, Alexandr K.,Kuchurov, Ilya V.,Zharkov, Mikhail N.,Zlotin, Sergei G.
, p. 25841 - 25847 (2021/08/09)
Regardless of the sustainable development path, today, there are highly demanded chemical productions still operating that bear environmental and technological risks inherited from the previous century. The fabrication of nitro compounds, and nitroarenes in particular, is traditionally associated with acidic wastes formed in nitration reactions exploiting mixed acids. However, nitroarenes are indispensable for industrial and military applications. We faced the challenge and developed a greener, safer, and yet effective method for the production of nitroaromatics. The proposed approach comprises the application of an eco-friendly nitrating agent, namely dinitrogen pentoxide (DNP), in the medium of liquefied 1,1,1,2-tetrafluoroethane (TFE) - one of the most non-hazardous Freons. Importantly, the used TFE is not emitted into the atmosphere but is effortlessly recondensed and returned into the process. DNP is obtainedviathe oxidation of dinitrogen tetroxide with ozone. The elaborated method is characterized by high yields of the targeted nitro arenes, mild reaction conditions, and minimal amount of easy-to-utilize wastes.
Gas-Phase Oxidation of Allyl Acetate by O3, OH, Cl, and NO3: Reaction Kinetics and Mechanism
Wang, Shuyan,Du, Lin,Zhu, Jianqiang,Tsona, Narcisse T.,Liu, Shijie,Wang, Yifeng,Ge, Maofa,Wang, Wenxing
, p. 1600 - 1611 (2018/02/22)
Allyl acetate (AA) is widely used as monomer and intermediate in industrial chemicals synthesis. To evaluate the atmospheric outcome of AA, kinetics and mechanism of its gas-phase reaction with main atmospheric oxidants (O3, OH, Cl, and NO3) have been investigated in a Teflon reactor at 298 ± 3 K. Both absolute and relative rate methods were used to determine the rate constants for AA reactions with the four atmospheric oxidants. The obtained rate constants (in units of cm3 molecule-1 s-1) are (1.8 ± 0.3) × 10-18, (3.1 ± 0.7) × 10-11, (2.5 ± 0.5) × 10-10, and (1.1 ± 0.4) × 10-14, for reactions with O3, OH, Cl, and NO3, respectively. While results for reactions with O3, OH and Cl are in good agreement with previous studies, the kinetics for the reaction with NO3 is reported for the first time in this study. On the basis of determined rate constants, the tropospheric lifetimes of AA are ρO3 = 9 days, ρOH = 5 h, ρCl = 5 days, ρNO3 = 2 days. On the basis of the products study, reaction mechanisms for these oxidations have been proposed and the reaction products were detected using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) and Fourier transform infrared spectroscopy (FTIR). Results show that the main products formed in these reactions are carbonyl compounds. In particular, 2-oxoethyl acetate was detected in all four AA oxidation reactions. Compared to previous studies, several new products were determined for reactions with OH and Cl. These results form a set of comprehensive kinetic data for AA reactions with main atmospheric oxidants and provide a better understanding of the degradation and atmospheric outcome of unsaturated acetate esters in the troposphere, during both daytime and nighttime.
