2278-22-0Relevant articles and documents
Cold-surface photochemistry of selected organic nitrates
O'Sullivan, Daniel,McLaughlin, Ryan P.,Clemitshaw, Kevin C.,Sodeau, John R.
, p. 9890 - 9900 (2014)
Reflection-absorption infrared (RAIR) spectroscopy has been used to explore the low temperature condensed-phase photochemistry of atmospherically relevant organic nitrates for the first time. Three alkyl nitrates, methyl, isopropyl, and isobutyl nitrate together with a peroxyacyl nitrate, peroxyacetyl nitrate (PAN), were examined. For the alkyl nitrates, similar photolysis products were observed whether they were deposited neat to the gold substrate or codeposited with water. In addition to peaks associated with the formation of an aldehyde/ketone and NO, a peak near 2230 cm-1 was found to emerge in the RAIR spectra upon UV photolysis of the thin films. Together with evidence obtained by thermal programmed desorption (TPD), the peak is attributed to the formation of nitrous oxide, N2O, generated as a product during the photolysis. On the basis of the known gas-phase photochemistry for the alkyl nitrates, an intermediate pathway involving the formation of nitroxyl (HNO) is proposed to lead to the observed N2O photoproduct. For peroxyacetyl nitrate, CO2 was observed as a predominant product upon photolytic decomposition. In addition, RAIR absorptions attributable to the formation of methyl nitrate were also found to appear upon photolysis. By analogy to the known gas-phase and matrix-isolated-phase photochemistry of PAN, the formation of methyl nitrate is shown to likely result from the combination of alkoxy radicals and nitrogen dioxide generated inside the thin films during photolysis.
Linear-Reactor-IR.-Matrix and Microwave Spectroscopy of the System O3/NO2/(Z)-2-Butene
Dommen, Joseph,Forster, Martin,Rupreccht, Heidi,Bauder, Alfred,Guenthard, Hans-Heinrich
, p. 504 - 520 (1982)
Investigation of the formation of complex reaction products in the gas-phase system O3/NO2/(Z)-2-butene by combination of linear reactors with IR. matrix and microwave Stark spectroscopy is reported.Besides the polyatomic products observed earlier in the gas-phase ozonolysis of (Z)-2-butene, the following products were identified: N2O5, HNO3, HNO4, CH3NO2, CH3ONO, CH3COONO2 and CH3COO2NO2 (peroxyacetyl nitrate PAN).Matrix IR spectra of N2O5, HNO3, CH3COONO, CH3COONO2 required for reference purposes are presented.It is shown that PAN-formation occurs already in the absence of light.A reaction scheme is proposed for explanation of the observed complex NOx-containing products, which assumes methyldioxirane as a central intermediate.Particular reaction steps of the scheme will be discussed, including thermochemical estimates of reaction enthalpies.
Kinetic and Theoretical Studies of the Reactions (CH3C(O)O2 + NO2 + M ->/<- CH3C(O)O2NO2 + M between 248 and 393 K and between 30 and 760 Torr
Bridier, I.,Caralp, F.,Loirat, H.,Lesclaux, R.,Veyret, B.,et al.
, p. 3594 - 3600 (1991)
The kinetics of the thermal decomposition and formation reactions of acetyl peroxynitrate (PAN) CH3C(O)O2 + NO2 + M ->/1 and k-1, the equilibrium constant K1(T) was calculated to be 0.9 x 10-28 exp((14000 +/- 200)/T) cm3 molecule-1.Quantum chemical and RRKM calculations were performed to obtain accurate and predictive representations of the data.In Troe's notation, the RRKM curves corresponding to the experimental results are represented by the following expressions for the limiting low- and high-pressure rate constants, with Fc = 0.30; k0(-1) = 4.9 x 10-3 exp(-(12100 +/- 500)/T) cm3 molecule-1 s-1; kinfinite(-1) = 4.0 x 1016 exp(-(13600 +/- 350)/T) s-1; k0(1) = 2.7 x 10-28(T/298)-7.1 +/- 1.7 cm6 molecule-2 s-1; kinfinite(1) = (12.1 +/- 0.5) x 10-12(T/298)-0.9 +/- 0.15 cm3 molecule-1 s-1.The thermochemistry of reactions 1 and -1 and the atmospheric implications of the thermal stability of PAN are briefly discussed.
FTIR studies of the NO3 initiated degradation of but-2-yne: Mechanism and rate constant determination
Seland, John G.,Noremsaune, Ingse M. W.,Nielsen, Claus J.
, p. 3459 - 3465 (1996)
The products and mechanism of the gas-phase reaction of NO3 radicals with but-2-yne in purified air have been investigated by FTIR spectroscopy. The experiments were carried out at 298 ± 3 K and 760 ± 5 Torr in a 250 1 stainless-steel reactor in which NO3 was generated by the thermal dissociation of N2O5. Experiments with 15NO3 were also performed. Products include butadione, peroxyacetyl nitrate, ketene and acetic acid. Ketene was observed to react further with NO3 and this reaction was also investigated. The rate constants for the NO3 reaction with but-2-yne and ketene were determined by the relative-rate method as 7.0 ± 0.8 and 10.6 + 1.3 × 10-14 cm3 molecule-1 s-1, respectively, using (E)-but-2-ene as a reference. Reaction mechanisms for the but-2-yne and the ketene degradations are proposed.
Formation of nitrogenous compounds in the photooxidation of n-butane under atmospheric conditions
Evmorfopoulou, Efthalia,Glavas, Sotirios
, p. 1151 - 1159 (1998)
The photooxidation of n-butane under atmospheric conditions in the presence of NOx resulted in the formation of the following nitrogenous products: peroxy acetyl nitrate 23, sec-butyl nitrate 16, n-butyl nitrate 1.3, ethyl nitrate 1.3, peroxy n-butyryl nitrate 1.3, and peroxy propionyl nitrate 0.5% of the initially added odd nitrogen. In addition, an electron capturing compound eluting at the retention time of sec-propyl nitrate was also observed accounting for 5% of initial NOx. Butan-2-one was the major product of conversion of n-butane with a yield of 37%. From product ratios it is evident that the formation of sec-butyl nitrate is favored over that of n-butyl nitrate by a factor of 2.1. The rate of reaction of sec-butoxy radicals with oxygen is equal to their decomposition rate.
Promotion of the Oxidation of Nitric Oxide and Hydrocarbon by the Thermal Decomposition of Peroxyacetyl Nitrate (PAN) at Night
Iwamoto, Issei,Tanihara, Hitoshi,Kawahara, Masaaki,Otsuka, Soichi,Sakamoto, Kazuhiko
, p. 251 - 254 (1994)
The decomposition of PAN in the presence of nitric oxide and propene in the air was investigated at 30 deg C under dark conditions.The number of nitric oxide molecules oxidized per each PAN molecule decomposed varied from 3.7 to above 5 with increase of the ratio of initial concentration of propene to that of nitric oxide.
Branching ratios for the reaction of selected carbonyl-containing peroxy radicals with hydroperoxy radicals
Hasson, Alam S.,Tyndall, Geoffrey S.,Orlando, John J.,Singh, Sukhdeep,Hernandez, Samuel Q.,Campbell, Sean,Ibarra, Yesenia
experimental part, p. 6264 - 6281 (2012/08/28)
An important chemical sink for organic peroxy radicals (RO2) in the troposphere is reaction with hydroperoxy radicals (HO2). Although this reaction is typically assumed to form hydroperoxides as the major products (R1a), acetyl peroxy radicals and acetonyl peroxy radicals have been shown to undergo other reactions (R1b) and (R1c) with substantial branching ratios: RO2 + HO2 → ROOH + O2 (R1a), RO 2 + HO2 → ROH + O3 (R1b), RO2 + HO2 → RO + OH + O2 (R1c). Theoretical work suggests that reactions (R1b) and (R1c) may be a general feature of acyl peroxy and α-carbonyl peroxy radicals. In this work, branching ratios for R1a-R1c were derived for six carbonyl-containing peroxy radicals: C2H 5C(O)O2, C3H7C(O)O2, CH3C(O)CH2O2, CH3C(O)CH(O 2)CH3, CH2ClCH(O2)C(O)CH 3, and CH2ClC(CH3)(O2)CHO. Branching ratios for reactions of Cl-atoms with butanal, butanone, methacrolein, and methyl vinyl ketone were also measured as a part of this work. Product yields were determined using a combination of long path Fourier transform infrared spectroscopy, high performance liquid chromatography with fluorescence detection, gas chromatography with flame ionization detection, and gas chromatography-mass spectrometry. The following branching ratios were determined: C2H5C(O)O2, YR1a = 0.35 ± 0.1, YR1b = 0.25 ± 0.1, and YR1c = 0.4 ± 0.1; C3H7C(O)O2, YR1a = 0.24 ± 0.15, YR1b = 0.29 ± 0.1, and YR1c = 0.47 ± 0.15; CH3C(O)CH2O2, Y R1a = 0.75 ± 0.13, YR1b = 0, and YR1c = 0.25 ± 0.13; CH3C(O)CH(O2)CH3, Y R1a = 0.42 ± 0.1, YR1b = 0, and YR1c = 0.58 ± 0.1; CH2ClC(CH3)(O2)CHO, Y R1a = 0.2 ± 0.2, YR1b = 0, and YR1c = 0.8 ± 0.2; and CH2ClCH(O2)C(O)CH3, YR1a = 0.2 ± 0.1, YR1b = 0, and YR1c = 0.8 ± 0.2. The results give insights into possible mechanisms for cycling of OH radicals in the atmosphere.
Atmospheric chemistry of two biodiesel model compounds: Methyl propionate and ethyl acetate
Andersen, Vibeke F.,Berhanu, Tesfaye A.,Nilsson, Elna J. K.,Jorgensen, Solvejg,Nielsen, Ole John,Wallington, Timothy J.,Johnson, Matthew S.
experimental part, p. 8906 - 8919 (2011/10/17)
The atmospheric chemistry of two C4H8O2 isomers (methyl propionate and ethyl acetate) was investigated. With relative rate techniques in 980 mbar of air at 293 K the following rate constants were determined: k(C2H5C(O)OCH3 + Cl) = (1.57 ± 0.23) × 10-11, k(C2H5C(O) OCH3 + OH) = (9.25 ± 1.27) × 10-13, k(CH 3C(O)OC2H5 + Cl) = (1.76 ± 0.22) × 10-11, and k(CH3C(O)OC2H5 + OH) = (1.54 ± 0.22) × 10-12 cm3 molecule -1 s-1. The chlorine atom initiated oxidation of methyl propionate in 930 mbar of N2/O2 diluent (with, and without, NOx) gave methyl pyruvate, propionic acid, acetaldehyde, formic acid, and formaldehyde as products. In experiments conducted in N 2 diluent the formation of CH3CHClC(O)OCH3 and CH3CCl2C(O)OCH3 was observed. From the observed product yields we conclude that the branching ratios for reaction of chlorine atoms with the CH3-, -CH2-, and -OCH3 groups are 9 ± 2%, respectively. The chlorine atom initiated oxidation of ethyl acetate in N2/O 2 diluent gave acetic acid, acetic acid anhydride, acetic formic anhydride, formaldehyde, and, in the presence of NOx, PAN. From the yield of these products we conclude that at least 41 ± 6% of the reaction of chlorine atoms with ethyl acetate occurs at the -CH2- group. The rate constants and branching ratios for reactions of OH radicals with methyl propionate and ethyl acetate were investigated theoretically using transition state theory. The stationary points along the oxidation pathways were optimized at the CCSD(T)/cc-pVTZ//BHandHLYP/aug-cc-pVTZ level of theory. The reaction of OH radicals with ethyl acetate was computed to occur essentially exclusively (～99%) at the -CH2- group. In contrast, both methyl groups and the -CH2- group contribute appreciably in the reaction of OH with methyl propionate. Decomposition via the α-ester rearrangement (to give C2H5C(O)OH and a HCO radical) and reaction with O 2 (to give CH3CH2C(O)OC(O)H) are competing atmospheric fates of the alkoxy radical CH3CH2C(O)OCH 2O. Chemical activation of CH3CH2C(O)OCH 2O radicals formed in the reaction of the corresponding peroxy radical with NO favors the α-ester rearrangement.
Relative and absolute kinetic studies of 2-butanol and related alcohols with tropospheric Cl atoms
Ballesteros, Bernabe,Garzon, Andres,Jimenez, Elena,Notario, Alberto,Albaladejo, Jose
, p. 1210 - 1218 (2008/04/05)
A newly constructed chamber/Fourier transform infrared system was used to determine the relative rate coefficient, ki, for the gas-phase reaction of Cl atoms with 2-butanol (k1), 2-methyl-2-butanol (k 2), 3-methyl-2-butanol (k3), 2,3-dimethyl-2-butanol (k4) and 2-pentanol (k5). Experiments were performed at (298 ± 2) K, in 740 Torr total pressure of synthetic air, and the measured rate coefficients were, in cm3 molecule-1 s -1 units (±2σ): k1 = (1.32 ± 0.14) × 10-10, k2 = (7.0 ± 2.2) × 10 -11, k3 = (1.17 ± 0.14) × 10-10, k4 = (1.03 ± 0.17) × 10-10 and k5 = (2.18 ± 0.36) × 10-10, respectively. Also, all the above rate coefficients (except for 2-pentanol) were investigated as a function of temperature (267-384 K) by pulsed laser photolysis-resonance fluorescence (PLP-RF). The obtained kinetic data were used to derive the Arrhenius expressions: k1(T) = (6.16 ± 0.58) × 10 -11exp[(174 ± 58)/T], k2(T) = (2.48 ± 0.17) × 10-11exp[(328 ± 42)/T], k3(T) = (6.29 ± 0.57) × 10-11exp[(192 ± 56)/T], and k 4(T) = (4.80 ± 0.43) × 10-11exp[(221 ± 56)/T] (in units of cm3 molecule-1 s-1 and ±σ). Results and mechanism are discussed and compared with the reported reactivity with OH radicals. Some atmospheric implications derived from this study are also reported. This journal is the Owner Societies.
Atmospheric chemistry of diethyl methylphosphonate, diethyl ethylphosphonate, and triethyl phosphate
Aschmann, Sara M.,Tuazon, Ernesto C.,Atkinson, Roger
, p. 2282 - 2291 (2007/10/03)
Rate constants for the reactions of OH radicals and NO3 radicals with diethyl methylphosphonate [DEMP, (C2H5O) 2P(O)CH3], diethyl ethylphosphonate [DEEP, (C 2H5O)2P(O)C2H5], and triethyl phosphate [TEP, (C2H5O)3PO] have been measured at 296 ± 2 K and atmospheric pressure of air using relative rate methods. The rate constants obtained for the OH radical reactions (in units of 10-11 cm3 molecule-1 s-1 were as follows: DEMP, 5.78 ± 0.24; DEEP, 6.45 ± 0.27; and TEP, 5.44 ± 0.20. The rate constants obtained for the NO3 radical reactions (in units of 10-16 cm3 molecule-1 s-1) were the following: DEMP, 3.7 ± 1.1; DEEP, 3.4 ± 1.4; and TEP, 2.4 ± 1.4. For the reactions of O3 with DEMP, DEEP, and TEP, an upper limit to the rate constant of -20 cm3 molecule-1 s-1 was determined for each compound. Products of the reactions of OH radicals with DEMP, DEEP, and TEP were investigated using in situ atmospheric pressure ionization mass spectrometry (API-MS) and, for the TEP reaction, gas chromatography with flame ionization detection (GC-FID) and in situ Fourier transform infrared (FT-IR) spectroscopy. The API-MS analyses show that the reactions are analogous, with formation of one major product from each reaction: C2H5OP(O)(OH)CH3 from DEMP, C 2H5OP(O)(OH)C2H2 from DEEP, and (C2H5O)2P(O)OH from TEP. The FT-IR and GC-FID analyses showed that the major products (and their molar yields) from the TEP reaction are (C2H5O)2P(O)OH (65-82%, initial), CO2 (80 ± 10%), and HCHO (55 ± 5%), together with lesser yields of CH3CHO (11 ± 2%), CO (11 ± 3%), CH3C(O)OONO2 (8%), organic nitrates (7%), and acetates (4%). The probable reaction mechanisms are discussed.
