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1.
The thermal decomposition of trifluoromethoxycarbonyl peroxy nitrate, CF3OC(O)O2NO2, has been studied between 278 and 306 K at 270 mbar total pressure using He as a diluent gas. The pressure dependence of the reaction was also studied at 292 K between 1.2 and 270 mbar total pressure. The rate constant reaches its high‐pressure limit at 70 mbar. The first step of the decomposition leads to CF3OC(O)O2 and NO2 formation, that is, CF3OC(O)O2NO2 + M ? CF3OC(O)O2 + NO2 + M (k1, k?1). Reaction (?1) was prevented by adding an excess of NO that reacts with the peroxy radical intermediate and leads to carbonyl fluoride (CF2O), carbon dioxide (CO2), nitrogen dioxide (NO2), and small quantities of CF3OC(O)O2C(O)OCF3. The kinetics of reaction (1) was determined by following the loss of CF3OC(O)O2NO2 via IR spectroscopy. The temperature dependence of the decomposition follows the equation k1(T) = 1.0 × 1016 e?((111±3)/(RT)) for the exponential term expressed in kJ mol?1. The values obtained for the kinetic parameters such as k1 at 298 K, the activation energy (Ea), and the preexponential factor (A) are compared with literature data for other acyl peroxy nitrates. The atmospheric thermal stability of CF3OC(O)O2NO2 and its dependence with altitude is discussed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 831–838, 2008 相似文献
2.
Jens Sehested Lene K. Christensen Ole J. Nielsen Merete Bilde Timothy J. Wallington William F. Schneider John J. Orlando Geoffrey S. Tyndall 《国际化学动力学杂志》1998,30(7):475-489
Pulse radiolysis was used to study the kinetics of the reactions of CH3C(O)CH2O2 radicals with NO and NO2 at 295 K. By monitoring the rate of formation and decay of NO2 using its absorption at 400 and 450 nm the rate constants k(CH3C(O)CH2O2+NO)=(8±2)×10−12 and k(CH3C(O)CH2O2+NO2)=(6.4±0.6)×10−12 cm3 molecule−1 s−1 were determined. Long path length Fourier transform infrared spectrometers were used to investigate the IR spectrum and thermal stability of the peroxynitrate, CH3C(O)CH2O2NO2. A value of k−6≈3 s−1 was determined for the rate of thermal decomposition of CH3C(O)CH2O2NO2 in 700 torr total pressure of O2 diluent at 295 K. When combined with lower temperature studies (250–275 K) a decomposition rate of k−6=1.9×1016 exp (−10830/T) s−1 is determined. Density functional theory was used to calculate the IR spectrum of CH3C(O)CH2O2NO2. Finally, the rate constants for reactions of the CH3C(O)CH2 radical with NO and NO2 were determined to be k(CH3C(O)CH2+NO)=(2.6±0.3)×10−11 and k(CH3C(O)CH2+NO2)=(1.6±0.4)×10−11 cm3 molecule−1 s−1. The results are discussed in the context of the atmospheric chemistry of acetone and the long range atmospheric transport of NOx. © John Wiley & Sons, Inc. Int J Chem Kinet: 30: 475–489, 1998 相似文献
3.
The reactions of CCl3 with O(3P) and O2 and those of CCl3O2 with NO have been studied at 295 K using discharge flow methods with helium as the bath gas. The rate coefficient for the reaction of CCl3 with O was found to be (4.2 ± 0.6) × 10?11 cm3/s and that for CCl3O2 with NO was (18.6 ± 2.8) × 10?12 cm3/s with both coefficients independent of [He]. For reaction between CCl3 and O2 the rate coefficient was found to increase from 1.51 7times; 10?14 cm3/s to 7.88 × 10?14 cm3/s as the [He] increased from 3.5 × 1016 cm?3 to 2.7 × 1017 cm?3. There was no evidence for a direct two-body reaction, and it is concluded that the only product of this reaction is CCl3O2. Examination of these results for CCl3 + O2 in terms of current simplified falloff treatment suggests that the high-pressure limit for this reaction is ~ 2.5 × 10?12 cm3/s, which may be compared with a direct measurement of the high-pressure limit of 5 × 10?12 cm3/s. A value of (5.8 ± 0.6) × 10?31 cm6/s has been obtained for k0, the coefficient in the low-pressure region. This value is compared with corresponding values found earlier for the (CH3, O2) and (CF3, O2) systems and with estimates based on unimolecular rate theory. 相似文献
4.
Hari Ji Singh Bhupesh Kumar Mishra Nand Kishor Gour 《Theoretical chemistry accounts》2010,125(1-2):57-64
The unimolecular decomposition reaction of CF3CCl2O radical has been investigated using theoretical methods. Two most important channels of decomposition occurring via C–C bond scission and Cl elimination have been considered during the present investigation. Ab initio quantum mechanical calculations are performed to get optimized structure and vibrational frequencies at DFT and MP2 levels of theory. Energetics are further refined by the application of a modified Gaussian-2 method, G2M(CC,MP2). The thermal rate constants for the decomposition reactions involved are evaluated using Canonical Transition State Theory (CTST) utilizing the ab initio data. Rate constants for C–C bond scission and Cl elimination are found to be 6.7 × 106 and 1.1 × 108 s?1, respectively, at 298 K and 1 atm pressure with an energy barrier of 8.6 and 6.5 kcal/mol, respectively. These values suggest that Cl elimination is the dominant process during the decomposition of the CF3CCl2O radical. Transition states are searched on the potential energy surface of the decomposition reactions involved and are characterized by the existence of only one imaginary frequency (NIMAG = 1) during frequency calculation. The existence of transition states on the corresponding potential energy surface is further ascertained by performing intrinsic reaction coordinate (IRC) calculation. 相似文献
5.
Rate coefficients, k, and ClO radical product yields, Y, for the gas‐phase reaction of O(1D) with CClF2CCl2F (CFC‐113) (k2), CCl3CF3 (CFC‐113a) (k3), CClF2CClF2 (CFC‐114) (k4), and CCl2FCF3 (CFC‐114a) (k5) at 296 K are reported. Rate coefficients for the loss of O(1D) were measured using a competitive reaction technique, with n‐butane (n‐C4H10) as the reference reactant, employing pulsed laser photolysis production of O(1D) combined with laser‐induced fluorescence detection of the OH radical temporal profile. Rate coefficients were measured to be k2 = (2.33 ± 0.40) × 10?10 cm3 molecule?1 s?1, k3 = (2.61 ± 0.40) × 10?10 cm3 molecule?1 s?1, k4 = (1.42 ± 0.25) × 10?10 cm3 molecule?1 s?1, and k5 = (1.62 ± 0.30) × 10?10 cm3 molecule?1 s?1. ClO radical product yields for reactions (2)–(5) were measured using pulsed laser photolysis combined with cavity ring‐down spectroscopy to be 0.80 ± 0.10, 0.79 ± 0.10, 0.85 ± 0.12, and 0.79 ± 0.10, respectively. The quoted errors in k and Y are at the 2σ (95% confidence) level and include estimated systematic errors. © 2011 Wiley Periodicals, Inc. 1 This article is a U.S. Government work and, as such, is in the public domain of the United States of America Int J Chem Kinet 43: 393–401, 2011 相似文献
6.
(Perhalomethylthio)heterocycles XII. Preparation of Perfluoroalkylsulfonylurea Derivatives as well as CCl3?nFnX-Substituted Heterocycles and Their Biological Activity 1 XI, Mitt., s.[1] In the presence of CF3SO3H (chlorodifluoromethylthio)thiophene 1 reacts with CClF2SCl to give the 2,5-disubstituted thiophene 2a which on oxidation with 30% H2O2-solution yields the corresponding sulfonyl compound 2b · R1SO2NCO adds amines to give R1SO2NHC(O)NHR 3a – g . Some biological properties of these compounds were investigated. 相似文献
7.
Peroxynitrates are thermally unstable intermediates (at ambient temperatures) in the atmospheric degradation of hydrocarbons. In this work, thermal lifetimes of nine peroxynitrates have been measured as a function of temperature and, for two of them, also, as a function of total pressure. In the presence of excess NO, relative concentrations of the peroxynitrates were followed in a 420 I reaction chamber as a function of time by means of longpath IR absorption using a Fourier transform spectrometer. Original data on the unimolecular decomposition rate constants are presented for the peroxynitrates RO2NO2 with R = C6H11, CH3C(O)CH2, C6H5CH2, CH2I, CH3C(O)OC(H)CH3, C6H5OCH2, (CH3)2NC(O), C6H5OC(O), and C2H5C(O). Thermal lifetimes at room temperature and atmospheric pressure are very short (in the order of seconds) for substituted methyl peroxynitrates (i.e., R'CH2O2NO2) but rather long for substituted formyl peroxynitrates (i.e., R″C(O)O2NO2). Kinetic data from this and previous work from our laboratory are used to derive structure‐stability relationships which allow an estimate of the thermal lifetimes of peroxynitrates from readily available 13C n.m.r. shift data. ©1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 127–144, 1999 相似文献
8.
The thermal decomposition of CCl3O2NO2,CCl2FO2NO2, and CClF2O2NO2 was studied in a temperature-controlled 420 l reaction chamber using in situ detection of peroxynitrates by long-path IR absorption. The temperature dependence of the unimolecular dissociation rate constants was determined at total pressures of 10 and 800 mbar in nitrogen as buffer gas, and the pressure dependence was measured at 273 K between 10 and 800 mbar. In Troe's notation, the data are represented by the following values for the limiting low and high pressure rate constants k0/[N2] and k∞ and the fall-off curvature parameter Fc (in units of cm3 molecule?1 s?1, s?1): CCl3O2NO2,k0/[N2] = 6.3 × 10?3 exp(?85.1 kJ · mol?1/RT), k∞ = 4.8 × 1016 exp(?98.3 kJ · mol?1/RT), Fc = 0.22; CCl2FO2NO2, k0/[N2] = 1.01× 10?2 exp(?90.3 kJ · mol?1/RT), k∞ = 6.6 × 1016 exp(?101.8 kJ · mol?1/RT), Fc = 0.28; and CClF2O2NO2, k0/[N2] = 1.80 × 10?3 exp(?87.3 kJ · mol?1/RT), k∞ = 1.60 × 1016exp(?99.7 kJ · mol?1/RT), Fc = 0.30. From these dissociation rate constants and recently measured rate constants for the reverse reaction (see Caralp, Lesclaux, Rayez, Rayez, and Forst [19]), bond energies (=ΔH) of 100, 103, and 104 kJ/mol were derived for the RO2–NO2 bonds in CCl3O2NO2, CCl2FO2NO2, and CClF2O2NO2, respectively. The kinetic and thermochemical parameters of these decomposition reactions are compared with those of the dissociation of other peroxynitrates. Atmospheric implications of the thermal stability of chlorofluoromethyl peroxynitrates are briefly discussed. 相似文献
9.
A Bayard-Alpert (BA) gauge was used to determine apparent relative sensitivites Srel,X for O2, N2O, NO, NO2, NH3, CClF3 and CH3OH from gauge calibration measurements in the range 1.3×10?1 Pa≤p≤1.3·10?3Pa. Nitrogen was used as a calibration standard. 相似文献
10.
The kinetics of the gas phase reaction between NO2 and CF2CCl2 has been investigated in the temperature range from 50 to 80°C. The reaction is homogeneous. Three products are formed: O2NCF2CCl2NO2 and equimolecular amounts of CINO and of O2NCF2C(O)Cl. The rate of consumption of the reactants is independent of the total pressure, the reaction products, and added inert gases and can be represented by a second-order reaction: However, the distribution of the products is influenced by the pressure of the present gases, which favor the formation of the dinitro-compound in a specific way. The effect of CF2CCl2 is the greatest. In the absence of added gases, the ratio of O2NCF2CCl2NO2 to that of O2NCF2C(O)Cl is proportional to (CF2CCl2 + γP products). The experimental results can be explaned by the following mechanism: P and X represent the products and the added gases: 相似文献
11.
CCl2 free radicals were produced by a pulsed dc discharge of CCl4 in Ar. Ground electronic state CCl2(X) radicals were electronically excited to the A1B1 (0,4,0) vibronic state with an Nd:YAG laser pumped dye laser at 541.52 nm. Experimental quenching data of excited CCl2(A1B1 and a3B1) by O2, N2, NO, N2O, NH3, NH(CH3)2, NH(C2H5)2, and N(C2H5)3 molecules were obtained by observing the time‐resolved total fluorescence signal of the excited CCl2 radical in a cell, which showed a superposition of two exponential decay components under the presence of quencher. The quenching rate constants kA of CCl2(A) state and ka of CCl2(a) state were derived by analyzing the experimental data according to a proposed three‐level model to deal with the CCl2(X1A1, A1B1, a3B1) system. The formation cross sections of complexes of electronically excited CCl2 radicals with O2, N2, NO, N2O, NH3, and aminated molecules were calculated by means of a collision‐complex model. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 351–356, 2002 相似文献
12.
Rate constants for the gas‐phase reactions of CH3OCH2CF3 (k1), CH3OCH3 (k2), CH3OCH2CH3 (k3), and CH3CH2OCH2CH3 (k4) with NO3 radicals were determined by means of a relative rate method at 298 K. NO3 radicals were prepared by thermal decomposition of N2O5 in a 700–750 Torr N2O5/NO2/NO3/air gas mixture in a 1‐m3 temperature‐controlled chamber. The measured rate constants at 298 K were k1 = (5.3 ± 0.9) × 10?18, k2 = (1.07 ± 0.10) × 10?16, k3 = (7.81 ± 0.36) × 10?16, and k4 = (2.80 ± 0.10) × 10?15 cm3 molecule?1 s?1. Potential energy surfaces for the NO3 radical reactions were computationally explored, and the rate constants of k1–k5 were calculated according to the transition state theory. The calculated values of rate constants k1–k4 were in reasonable agreement with the experimentally determined values. The calculated value of k5 was compared with the estimate (k5 < 5.3 × 10?21 cm3 molecule?1 s?1) derived from the correlation between the rate constants for reactions with NO3 radicals (k1–k4) and the corresponding rate constants for reactions with OH radicals. We estimated the tropospheric lifetimes of CH3OCH2CF3 and CHF2CF2OCH2CF3 to be 240 and >2.4 × 105 years, respectively, with respect to reaction with NO3 radicals. The tropospheric lifetimes of these compounds are much shorter with respect to the OH reaction. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 490–497, 2009 相似文献
13.
Data on the tropospheric degradation of proposed substitutes for ozone depleting CFCs were obtained by conducting photochemical oxidation studies of HCFCs and HFCs using long path Fourier transform infrared spectroscopy. The hydrogen abstraction reactions were initiated using Cl radicals rather than OH radicals because of the rather unreactive nature of the compounds. The experimental product yields at T = 25 ± 3°C and 700 Torr of dry air were: CHClF2 (1.11 ± 0.06 C(O)F2); CClFHCF3 (1.00 ± 0.04 CF3C(O)F); CF3CHF2 (1.09 ± 0.05 C(O)F2); CClF2CH3 (0.98 ± 0.03 C(O)F2); CHF2CH3 (1.00 ± 0.05 C(O)F2); CF3CH2F (0.16 ± 0.03 CF3CF(O), and 0.83 ± 0.22 HFC(O)), where all standard deviations are 2σ. For each compound, the critical step in determining the oxidation products was the decomposition of a halogenated alkoxy radical. For HCFC-22 and HCFC-124, the major alkoxy radical decomposition route was Cl elimination. The HFC-125 product data were consistent with C? C cleavage of a two carbon alkoxy radical as the major decomposition route whereas both C? C cleavage and H abstraction by O2 were significant contributors to the decomposition of the HFC-134a alkoxy radical. Secondary Cl reactions in the HCFC-142b and HFC-152a experiments prevented an unambiguous determination of the decomposition modes; the data are consistent with both C? C bond scission and Cl reactions with halogenated aldehydes producing the oxidation product C(O)F2. With the exception of the HFC-134a and HFC-125 data, the proposed mechanisms can account for the major oxidation products. For HFC-134a and HFC-125, a number of product bands could not be identified. The bands are likely due to products from reactions involving the CF3O2 radical. © John Wiley & Sons, Inc. 相似文献
14.
Grigorii A. Tikhomirov Konstantin O. Znamenkov Igor V. Morozov Erhard Kemnitz Sergei I. Troyanov 《无机化学与普通化学杂志》2002,628(1):269-273
Crystalline NO[Mn(NO3)3] ( I ) and (NO)2[Co(NO3)4] ( II ) were synthesized by reaction of the corresponding metal and a liquid N2O4/ethylacetate mixture. I is orthorhombic, Pca21, a = 9.414(2), b = 15.929(3), c = 10.180(2) Å, Z = 4, R1 = 0.0286. II is monoclinic, C2/c, a = 14.463(3), b = 19.154(4), c = 13.724(3) Å, β = 120.90(3), Z = 12, R1 = 0.0890. Structure I consists of [Mn(NO3)3]– sheets with NO+ cations between them. Two types of Mn atoms have CNMn = 7 and 8. Structure II is ionic containing isolated [Co(NO3)4]‐anions and NO+ cations with CNCo = 8. Crystals of Mn(NO3)2 ( III ) and Co(NO3)2 ( IV ) were obtained by concentration of metal nitrate hydrate solutions in 100% HNO3 in a desiccator with P2O5. III is cubic, Pa 3, a = 7.527(2) Å, Z = 4, R1 = 0.0987. IV is trigonal, R 3, a = 10.500(2), c = 12.837(3) Å, Z = 12, R1 = 0.0354. The three dimensional structure III is isotypic to the strontium and barium dinitrates. Structure IV contains a three dimensional network of interconnected Co(NO3)6/3 units with a distorted octahedral coordination environment of Co atoms. General correlations between central atom coordination and coordination modes of NO3 groups are discussed. 相似文献
15.
Saeed Dehghanpour Richard Welter Aliou Hamady Barry Farzaneh Tabasi 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(4):1236-1243
Synthetic methods for several novel phosphoramidate compounds containing the P(O)NHC(O) bifunctional group were developed. These compounds with the general formula R1C(O)NHP(O)(N(R2)(CH2C6H5))2, where R1 = CCl2H, p-ClC6H4, p-BrC6H4, o-FC6H4 and R2 = hydrogen, methyl, benzyl, were characterized by several spectroscopic methods and analytical techniques. The effects of phosphorus substituents on the rotation rate around the P–Namine bond were also investigated. 1H NMR study of the synthesized compounds demonstrated that the presence of bulky groups attached to the phosphorus center and electron withdrawing groups in the amide moiety lead to large chemical-shift non-equivalence (ΔδH) of diastereotopic methylene protons. The crystal structures of CCl2HC(O)NHP(O)(NCH3(CH2C6H5))2, p-ClC6H4C(O)NHP(O)(NCH3(CH2C6H5))2, CCl2HC(O)NHP(O)(N(CH2C6H5)2)2 and p-BrC6H4C(O)NHP(O)(N(CH2C6H5)2)2 were determined by X-ray crystallography using single crystals. The coordination around the phosphorus center in these compounds is best described as distorted tetrahedral and the P(O) and C(O) groups are anti with respect to each other. In the compound Br-C6H4C(O)NHP(O)(N(CH2C6H5)2)2 (with two independent molecules in the unit cell), two conformers are connected to each other via two different N–H?O hydrogen bonds forming a non-centrosymmetric dimer. In the crystalline lattice of other compounds, the molecules form centrosymmetric dimers via pairs of same N–H?O hydrogen bonds. The structure of CCl2HC(O)NHP(O)(N(CH2C6H5)2)2 reveals an unusual intramolecular interaction between the oxygen of CO group and amine nitrogen. 相似文献
16.
《Vibrational Spectroscopy》2007,43(2):290-296
FTIR, Raman and NMR spectra of N-trichlorophosphazotrifluoroacetyl, CF3C(O)NPCl3 (1) and N-trichlorophosphazotrichloroacetyl, CCl3C(O)NPCl3 (2) were obtained. The experimental data are compared with results of ab initio and density functional theory (DFT) calculations. According the theoretical studies the main conformer for both molecules possesses Cs symmetry (CO bond syn respect to the NP bond). The preference of the syn conformation has been rationalized based on the natural bond orbital formalism. The vibrational spectra of 1 in the liquid phase and 2 in the solid phase are in good agreement with theoretical results. 相似文献
17.
Tetranitratogold(III) Acid, (H5O2)[Au(NO3)4]·H2O: Synthesis, Crystal Structure, and Thermal Behaviour of the First Acidic Nitrate of Gold Yellow single crystals of (H5O2)[Au(NO3)4]·H2O grow upon cooling of a solution of Au(OH)3 in conc. nitric acid. The crystal structure contains (monoclinic, C2/c, Z = 4, a = 1214.5(2), b = 854.4(1), c = 1225.7(2) pm, β = 117.75(1)°, Rall = 0.0331) the Au3+ ion in coordination of four monodentate NO3— ligands. The [Au(NO3)4]— units are linked by H5O2+‐ions. Significant hydrogen bonding is observed in the crystal structure between the H5O2+ ions and the H2O molecules. The thermal analysis reveals a five step decomposition leading to elemental gold. 相似文献
18.
E. N. Shaposhnikova S. R. Sterlin S. P. Solodovnikov N. N. Bubnov I. V. Stankevich A. L. Chistyakov B. L. Tumanskii 《Russian Chemical Bulletin》1998,47(11):2160-2163
The ESR spectra of radical anions formed by reduction of α-diketones RC(O)C(O)CF3 (R=(CF3)2CF, C6F5, (CF3)3C) with metals (Li, Na, K, Mg, Cd, Zn, Hg, In, and TI) in THF were studied. For R=(CF3)2CF and C6F5, the radical anions are formed ascis-isomers, whereas for R=(CF3)3C,trans-isomers are obtained. Line broadening due to solvation and desolvation of the cation is observed in the latter case. The
reduction of α-diketone (CF3)2CFC(O)C(O)CF3 with Group II metals (Mg, Cd, Zn) results in the formation of radical pairs.
Translated fromIzvestiya Akadmii Nauk. Seriya Khimicheskaya, No. 11, pp. 2228–2231, November, 1998. 相似文献
19.
The oxidation of CFClCFCl and CF2CCl2 were studied at room temperature by chlorine- and oxygen-atom initiation. The chlorine-atom initiated oxidation of CFClCFCl yields CCl2FCF(O) as the exclusive product. Its quantum yield is ~420, which gives k3a/k3b=210 where reactions (3a) and (3b) are The O(3P)? CFClCFCl reaction gives CClFO with a quantum yield of 0.80, polymer, and small amounts of an unidentified product which is probably cyclo-(CFCl)3. Thereaction paths are with k9a/k9=0.80. The overall reaction of O(3P) with CFClCFCl proceed one fifth as fast as the O(3P)-C2F4 reaction. When O2 is also present, the same free-radical chain oxidation occurs by O(3P)initiation as by chlorine-atom initiation. The chlorine-atom initiated oxidation of CF2CCl2 gives CF2ClCCl(O) as the major product, with quantum yields ranging from 42 to 85. Smaller amounts of CF2O and CCl2O are produced in equal amounts with quantum yields of ~3.5. The reactions responsible for the products are The O(3P)-CF2CCl2interaction yields CF2O and with quantum yields of 1.0 and ~0.85, respectively. In thepresence of O2 the radical chain products are observed, but the mechanism is different than that for other chloroolefins. 相似文献
20.
Molecular and Crystal Structure of Ytterbium(III)-triaqua-trinitrate, Yb(H2O)3(NO3)3 Yb(H2O)3(NO3)3 crystallizes from a concentrated solution of Yb2O3 in nitric acid in a vacuum desiccator at ambient temperature as colourless single crystals. The crystal structure was determined from single crystal four-circle diffractometer data (R3 , Z = 6, a = 1175.5(1), c = 1117.7(2) pm, Vm = 134.25 cm3/mol, R = 3.0%, Rw = 2.9%). The structure may be viewed at as a heavily compressed packing of [Yb(H2O)3(NO3)3] molecules. Yb3+ is coordinated by three bidentate nitrate ligands and three water molecules so that a tricapped trigonal prism (C.N. 9) of oxygen atoms results as the coordination polyhedron. 相似文献