Aspects of the Atmospheric Chemistry of Amides

Barnes, Ian; Solignac, G.; Mellouki, Abdelwahid; Becker, K. H.

doi:10.1002/cphc.201000374

Cited by 91 publications

(152 citation statements)

References 52 publications

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“…In addition to the schematic gas phase degradation routes outlined by Nielsen et al (2011), kinetic and mechanistic information about the degradation of the major oxidation product, i.e. formamide, provided by Barnes et al (2010) was taken into account. Average branching ratios of the initial H-abstraction given by Nielsen et al (2011) are 8 % from −NH 2 , 84 % from −CH 2 − and 8 % from −CH 2 OH.…”

Section: Atmospheric Mechanism For the Oh-initiated Degradation Of Meamentioning

confidence: 99%

“…Formamide, one of the major gaseous oxidation products from MEA (Nielsen et al, 2011), will be oxidized to form isocyanic acid (H−N=C=O) in the atmosphere (Barnes et al, 2010). Isocyanic acid reacts only slowly with OH and other atmospheric oxidants (Wooldridge et al, 1996) and, due to its high solubility, will be taken up in water droplets and finally be removed from the atmosphere by wet deposition.…”

Section: Impact On Health and Environmentmentioning

confidence: 99%

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Study of OH-initiated degradation of 2-aminoethanol

et al. 2012

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Abstract. The degradation of 2-aminoethanol (MEA) by the hydroxyl radical (OH) was studied in the European Photoreactor (EUPHORE), a large outdoor environmental chamber. High-Temperature Proton-Transfer-Reaction Mass Spectrometry (HT-PTR-MS) and Fast Fourier Transform Infrared (FT-IR) were used to follow concentrations of reactants in the gas phase. Aerosol mass concentrations were tracked with Aerosol Mass Spectrometry (AMS). The chamber aerosol model MAFOR was applied to quantify losses of MEA to the particle phase. The rate constant k(OH + MEA) was determined relative to the rate constant of the 1,3,5-trimethylbenzene reaction with OH and was found to be (9.2 ± 1.1)×10 −11 cm 3 molecule −1 s −1 , and thus the reaction between OH radicals and MEA proceeds a factor of 2-3 faster than estimated by structure-activity relationship (SAR) methods. Main uncertainty of the relative rate determination is the unknown temporal behaviour of the loss rate of MEA to chamber wall surfaces during the sunlit experiments. Nucleation and growth of particles observed in the experiments could be reproduced by the chamber model that accounted for condensation of gaseous oxidation products, condensation of ethanolaminium nitrate and nucleation involving MEA and nitric acid.

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Section: Atmospheric Mechanism For the Oh-initiated Degradation Of Meamentioning

confidence: 99%

Section: Impact On Health and Environmentmentioning

confidence: 99%

Study of OH-initiated degradation of 2-aminoethanol

et al. 2012

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“…HNCO has been quantified from diesel engine exhaust (Kroecher et al, 2005;Wentzell et al, 2013) and light-duty vehicles (Brady et al, 2014) as well as from biogenic sources such as biomass burning (Roberts et al, , 2011Veres et al, 2010). There also exist secondary sources of HNCO to the atmosphere, including the gas phase oxidation of amines and amides by OH radicals producing HNCO via H-abstraction mechanisms (Barnes et al, 2010;Borduas et al, 2013Borduas et al, , 2015. Evidence of secondary sources of HNCO has also been demonstrated in the field, with peak HNCO concentrations occurring during daytime (Roberts et al, 2011Zhao et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Solubility and reactivity of HNCO in water: insights into HNCO's fate in the atmosphere

et al. 2016

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Abstract.A growing number of ambient measurements of isocyanic acid (HNCO) are being made, yet little is known about its fate in the atmosphere. To better understand HNCO's loss processes and particularly its atmospheric partitioning behaviour, we measure its effective Henry's Law coefficient K eff H with a bubbler experiment using chemical ionization mass spectrometry as the gas phase analytical technique. By conducting experiments at different pH values and temperature, a Henry's Law coefficient K H of 26 ± 2 M atm −1 is obtained, with an enthalpy of dissolution of −34 ± 2 kJ mol −1 , which translates to a K eff H of 31 M atm −1 at 298 K and at pH 3. Our approach also allows for the determination of HNCO's acid dissociation constant, which we determine to be K a = 2.1 ± 0.2 × 10 −4 M at 298 K. Furthermore, by using ion chromatography to analyze aqueous solution composition, we revisit the hydrolysis kinetics of HNCO at different pH and temperature conditions. Three pH-dependent hydrolysis mechanisms are in play and we determine the Arrhenius expressions for each rate to be k 1 = (4.4 ± 0.2) × 10 7 exp(−6000 ± 240/T ) M s −1 , k 2 = (8.9 ± 0.9) × 10 6 exp(−6770 ± 450/T ) s −1 and k 3 = (7.2 ± 1.5) × 10 8 exp(−10 900 ± 1400/T ) s −1 , where k 1 is for HNCO + H + + H 2 O → NH + 4 + CO 2 , k 2 is for HNCO + H 2 O → NH 3 + CO 2 and k 3 is for NCO − + 2 H 2 O → NH 3 + HCO − 3 . HNCO's lifetime against hydrolysis is therefore estimated to be 10 days to 28 years at pH values, liquid water contents, and temperatures relevant to tropospheric clouds, years in oceans and months in human blood. In all, a better parameterized Henry's Law coefficient and hydrolysis rates of HNCO allow for more accurate predictions of its concentration in the atmosphere and consequently help define exposure of this toxic molecule.

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“…As illustrated in Fig 1, the OH· radical first forms an encounter complex above the approximate center of the benzene plane, with a binding energy of E 1 . It then moves down towards one of the C atoms as it adds to that atom and changes its hybridization to sp 3 . In doing so, it first passes through a transition state which involves an energy barrier equal to E 2 .…”

Section: Individual Reaction Stepsmentioning

confidence: 99%

Evaluation of DFT methods to study reactions of benzene with OH radical

Scheiner

2011

Int J of Quantum Chemistry

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Several DFT methods are applied to two different reaction channels involving OH· + C 6 H 6 , and the results compared to high-level ab initio calculations. The OH· adds directly to one C atom in the first channel, first forming an encounter complex with the OH· poised above the aromatic plane. B3LYP, BH&HLYP, and MPW1K compute an accurate estimate of the overall exothermicity, while M05-2X, PBE0 and PBEPBE, overestimate this quantity to some degree. With the exceptions of PBEPBE and PBE0, the other methods produce an acceptable barrier to addition. All approaches except BH&HLYP correctly predict an exothermic H· abstraction, although PBEPBE is too exothermic. The BH&HLYP barrier to H· abstraction is too high while the MPW1K, PBE0, and B3LYP values are better, and M05-2X the best.

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Aspects of the Atmospheric Chemistry of Amides

Cited by 91 publications

References 52 publications

Study of OH-initiated degradation of 2-aminoethanol

Study of OH-initiated degradation of 2-aminoethanol

Solubility and reactivity of HNCO in water: insights into HNCO's fate in the atmosphere

Evaluation of DFT methods to study reactions of benzene with OH radical

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