The reactions of N-methylformamide and N,N-dimethylformamide with OH and their photo-oxidation under atmospheric conditions: experimental and theoretical studies

Bunkan, Arne Joakim Coldevin; Hetzler, J.; Mikoviny, Tomáš; Wisthaler, Armin; Nielsen, Claus J.; Olzmann, Matthias

doi:10.1039/c4cp05805d

Cited by 36 publications

(45 citation statements)

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“…ported by Borduas et al (2016), k hdyr for CH 3 NCO from this work, and k hydr for ClCN from Bailey and Bishop (1973). Deposition of a compound to the surface can be parameterized as essentially two processes taking place in series, physical transport within the planetary boundary layer to the surface and then chemical uptake on the surface (see, for example, Cano-Ruiz et al, 1993). In this formulation, the deposition velocity, v d (the inverse of the total resistance), is expressed as follows:…”

Section: Atmospheric and Environmental Chemistry Implicationsmentioning

confidence: 99%

“…CH 3 NCO is also produced in photochemical reactions of methylisothiocyanate (CH 3 NCS), which is the main degradation product of the agricultural fungicide metam sodium (CH 3 NHCS 2 Na) (Geddes et al, 1995). In addition, CH 3 NCO has been observed in studies of the photooxidation of amides (Barnes et al, 2010;Borduas et al, 2015;Bunkan et al, 2015) and by extension will be formed in dimethyl amine oxidation. To the best of our knowledge there is only one reported set of ambient measurements of CH 3 NCO, conducted near a field where metam sodium was being used as a soil fumigant (Woodrow et al, 2014), and the resulting CH 3 NCO mixing ratios were as high as 1.7 ppbv.…”

Section: Introductionmentioning

confidence: 99%

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Solubility and solution-phase chemistry of isocyanic acid, methyl isocyanate, and cyanogen halides

Roberts

Liu

2019

Atmos. Chem. Phys.

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Abstract. Condensed-phase uptake and reaction are important atmospheric removal processes for reduced nitrogen species, isocyanic acid (HNCO), methyl isocyanate (CH3NCO), and cyanogen halides (XCN, X = Cl, Br, I); yet many of the fundamental quantities that govern this chemistry have not been measured or are not well studied. These nitrogen species are of emerging interest in the atmosphere as they have either biomass burning sources, i.e., HNCO and CH3NCO, or, like the XCN species, have the potential to be a significant condensed-phase source of NCO− and therefore HNCO. Solubilities and the first-order reaction rate of these species were measured for a variety of solutions using a bubble flow reactor method with total reactive nitrogen (Nr) detection. The aqueous solubility of HNCO was measured as a function of pH and had an intrinsic Henry's law solubility of 20 (±2) M atm−1 and a Ka of 2.0 (±0.3) × 10−4 M (pKa = 3.7±0.1) at 298 K. The temperature dependence of HNCO solubility was very similar to other small nitrogen-containing compounds, such as HCN, acetonitrile (CH3CN), and nitromethane, and the dependence on salt concentration exhibited the “salting out” phenomenon. The rate constant of reaction of HNCO with 0.45 M NH4+, as NH4Cl, was measured at pH = 3 and found to be 1.2 (±0.1) × 10−3 M−1 s−1, faster than the rate that would be estimated from rate measurements at much higher pHs. The solubilities of HNCO in the non-polar solvents n-octanol (n-C8H17OH) and tridecane (C13H28) were found to be higher than aqueous solution for n-octanol (87±9 M atm−1 at 298 K) and much lower than aqueous solution for tridecane (1.7±0.17 M atm−1 at 298 K), features that have implications for multi-phase and membrane transport of HNCO. The first-order loss rate of HNCO in n-octanol was determined to be relatively slow, 5.7 (±1.4) × 10−5 s−1. The aqueous solubility of CH3NCO was found to be 1.3 (±0.13) M atm−1 independent of pH, and CH3NCO solubility in n-octanol was also determined at several temperatures and ranged from 4.0 (±0.5) M atm−1 at 298 K to 2.8 (±0.3) M atm−1 at 310 K. The aqueous hydrolysis of CH3NCO was observed to be slightly acid-catalyzed, in agreement with literature values, and reactions with n-octanol ranged from 2.5 (±0.5) to 5.3 (±0.7) × 10−3 s−1 from 298 to 310 K. The aqueous solubilities of XCN, determined at room temperature and neutral pH, were found to increase with halogen atom polarizability from 1.4 (±0.2) M atm−1 for ClCN and 8.2 (±0.8) M atm−1 for BrCN to 270 (±54) M atm−1 for ICN. Hydrolysis rates, where measurable, were in agreement with literature values. The atmospheric loss rates of HNCO, CH3NCO, and XCN due to heterogeneous processes are estimated from solubilities and reaction rates. Lifetimes of HNCO range from about 1 day against deposition to neutral pH surfaces in the boundary layer, but otherwise can be as long as several months in the middle troposphere. The loss of CH3NCO due to aqueous-phase processes is estimated to be slower than, or comparable to, the lifetime against OH reaction (3 months). The loss of XCNs due to aqueous uptake is estimated to range from being quite slow, with a lifetime of 2–6 months or more for ClCN and 1 week to 6 months for BrCN to 1 to 10 days for ICN. These characteristic times are shorter than photolysis lifetimes for ClCN and BrCN, implying that heterogeneous chemistry will be the controlling factor in their atmospheric removal. In contrast, the photolysis of ICN is estimated to be faster than heterogeneous loss for average midlatitude conditions.

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Section: Atmospheric and Environmental Chemistry Implicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solubility and solution-phase chemistry of isocyanic acid, methyl isocyanate, and cyanogen halides

Roberts

Liu

2019

Atmos. Chem. Phys.

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“…potassium methylate). [27] Similarly, phosphorene can donate its unpaired electrons to DMF molecules and remove hydrogen atoms from their methyl groups. Therefore, it is rational to propose the following growth mechanisms (Figure 2 g):…”

Section: Resultsmentioning

confidence: 99%

Topochemical Synthesis of Two‐Dimensional Transition‐Metal Phosphides Using Phosphorene Templates

et al. 2019

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Transition‐metal phosphides (TMPs) have emerged as a fascinating class of narrow‐gap semiconductors and electrocatalysts. However, they are intrinsic nonlayered materials that cannot be delaminated into two‐dimensional (2D) sheets. Here, we demonstrate a general bottom‐up topochemical strategy to synthesize a series of 2D TMPs (e.g. Co2P, Ni12P5, and CoxFe2−xP) by using phosphorene sheets as the phosphorus precursors and 2D templates. Notably, 2D Co2P is a p‐type semiconductor, with a hole mobility of 20.8 cm2 V−1 s−1 at 300 K in field‐effect transistors. It also behaves as a promising electrocatalyst for the oxygen evolution reaction (OER), thanks to the charge‐transport modulation and improved surface exposure. In particular, iron‐doped Co2P (i.e. Co1.5Fe0.5P) delivers a low overpotential of only 278 mV at a current density of 10 mA cm−2 that outperforms the commercial Ir/C benchmark (304 mV).

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“…S1 † for different DMF/DMSO ratios). The saturated vapor pressures of GBL, DMF, and DMSO were 0.23 mmHg, 31 2.99 mmHg, 32 and 0.42 mmHg 33 at 20 C, respectively. Higher solvent vapor pressures yield greater volatility and lower boiling points, which resulted in a faster evaporation and thicker thin lms.…”

Section: Solvent Effects On Morphologymentioning

confidence: 98%

Modifying morphology and defects of low-dimensional, semi-transparent perovskite thin films via solvent type

et al. 2019

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The reactions of N-methylformamide and N,N-dimethylformamide with OH and their photo-oxidation under atmospheric conditions: experimental and theoretical studies

Cited by 36 publications

References 36 publications

Solubility and solution-phase chemistry of isocyanic acid, methyl isocyanate, and cyanogen halides

Solubility and solution-phase chemistry of isocyanic acid, methyl isocyanate, and cyanogen halides

Topochemical Synthesis of Two‐Dimensional Transition‐Metal Phosphides Using Phosphorene Templates

Modifying morphology and defects of low-dimensional, semi-transparent perovskite thin films via solvent type

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