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.
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.
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.
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.
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.
