Atmospheric fate of methyl pivalate: OH/Cl-initiated degradation and the roles of water and formic acid

2018 ◽  
Vol 15 (4) ◽  
pp. 246
Author(s):  
Feng-Yang Bai ◽  
Chun-Yu Liu ◽  
Jin-Ting Ye ◽  
Xiu-Mei Pan
Keyword(s):  
Formic Acid ◽  
Degradation Mechanism ◽  
Oxidative Degradation ◽  
Decomposition Reaction ◽  
State Theory ◽  
Organic Nitrates ◽  
Oh Radicals ◽  
Alkyl Radicals ◽  
Peroxyacyl Nitrates ◽  
Cl Atoms

Environmental contextOxygenated volatile organic compounds can lead to the formation of tropospheric ozone, and thus have an impact on climate and human health. Methyl pivalate is one such compound, but the way it breaks down in the atmosphere is not well understood. We investigate the oxidative degradation of methyl pivalate, and show that harmful peroxyacyl nitrates and organic nitrates are the major products. AbstractThe atmospheric degradation mechanism and dynamics of methyl pivalate (MP) by OH radicals and Cl atoms are explored. The rate constants, computed using variational transition-state theory over the range of 200–2000 K at the CCSD(T)/6-311++G(d,p)//B3LYP/6-311G(d,p) level, are all in agreement with the experimental data. The alkyl radicals, which are formed from the reactions of OH or Cl with MP, can react with O2 and NO to produce the peroxyacyl nitrates, organic nitrates, and alkoxy radicals. The atmospheric evolution mechanisms for the (CH3)3CCOOCH2O•, •OCH2(CH3)2CCOOCH3, and •O(CH3)2CCOOCH3 radicals are also clarified. The OH- and Cl-determined atmospheric lifetimes and the global warming potentials (GWPs) of MP are shown to be low, suggesting that its environmental impact can be ignored. The Arrhenius expressions of kOH = 3.62 × 10−23T3.80exp(522.66/T) and kCl = 1.76 × 10−15T1.79exp(−55.89/T) cm3 molecule−1 s−1 are fitted within 200–2000 K. Compared with the OH/Cl-initiated degradation of (CH3)3CCOOCH3, the auto-decomposition reaction of (CH3)3CCOOCH3 → (CH3)2C=CH2 + HCOOCH3 may be more important at the high temperature range of 1500–2000 K. Moreover, the results show that the water and formic acid molecules can promote the degradation of MP. This study is helpful for evaluating the atmospheric implications of gaseous MP.

The atmospheric chemical reaction of 4-tert-butylphenol initiated by OH radicals

2013 ◽  
Vol 10 (2) ◽  
pp. 111 ◽  
Author(s):  
Chen Gong ◽  
Xiaomin Sun ◽  
Chenxi Zhang
Keyword(s):  
Rate Constants ◽  
Degradation Mechanism ◽  
Degradation Process ◽  
State Theory ◽  
Oh Radicals ◽  
Atmospheric Lifetime ◽  
Computational Theory ◽  
Developmental Problems ◽  
First Order ◽  
First Order Kinetics

Environmental context 4-tert-Butylphenol, an environmental endocrine disruptor, can be taken in by humans and animals resulting in reproductive and developmental problems. We report a theoretical study on the degradation mechanism of 4-tert-butylphenol in the atmosphere, and calculate the atmospheric lifetime of this chemical. The data will help our understanding of the behaviour of 4-tert-butylphenol in the environment and thereby provide valuable information about its possible effect on human health. Abstract 4-tert-Butylphenol (TBP) is a typical environmental endocrine. In this paper, the OH-initiated degradation mechanism of TBP in the atmosphere is studied at the MPWB1K/6-31+G(d,p)//MPWB1K/6-311+G(3df,2p) level of computational theory. A profile of the potential energy surface is constructed and reaction pathways are analysed. The addition reactions of TBP with OH radicals are more important than abstraction reactions in the atmosphere. In subsequent reactions, O2 and NO may play an important role in the degradation process of TBP. The rate constants are calculated using the transition state theory and a canonical variational transition with small-curvature tunnelling correction. The Arrhenius equations of rate constants in the temperature range of 200–500K are fitted. The rate constant of the degradation of the TBP at 298.15K is 3.56×10–14cm3 molecule–1s–1 and the atmospheric lifetime is 10.8 months according to the pseudo-first-order kinetics.

scholarly journals Atmospheric oxidation of α,β-unsaturated ketones: kinetics and mechanism of the OH radical reaction

2021 ◽  
Author(s):  
Niklas Illmann ◽  
Rodrigo Gastón Gibilisco ◽  
Iustinian Gabriel Bejan ◽  
Iulia Patroescu-Klotz ◽  
Peter Wiesen
Keyword(s):  
Radical Reaction ◽  
Rate Coefficients ◽  
Organic Nitrates ◽  
Oh Radicals ◽  
Oh Radical ◽  
Peroxyacetyl Nitrate ◽  
Unsaturated Ketones ◽  
Product Yields ◽  
Mechanistic Investigation ◽  
Cl Atoms

Abstract. The OH radical initiated oxidation of 3-methyl-3-penten-2-one and 4-methyl-3-penten-2-one was investigated in two atmospheric simulation chambers at 298 ± 3 K and 990 ± 15 mbar using long-path FTIR spectroscopy. The rate coefficients of the reactions of 3-methyl-3-penten-2-one and 4-methyl-3-penten-2-one with OH radicals were determined to be (6.5 ± 1.2) × 10−11 cm3 molecule−1 s−1 and (8.1 ± 1.3) × 10−11 cm3 molecule−1 s−1, respectively. To enlarge the kinetics data pool the rate coefficients of the target species with Cl atoms were determined to be (2.8 ± 0.4) × 10−10 cm3 molecule−1 s−1 and (3.1 ± 0.4) × 10−10 cm3 molecule−1 s−1, respectively. The mechanistic investigation of the OH initiated oxidation focuses on the RO2 + NO reaction. The quantified products were acetoin, acetaldehyde, biacetyl, CO2 and peroxyacetyl nitrate (PAN) for the reaction of 3-methyl-3-penten-2-one with OH radicals and acetone, methyl glyoxal, 2-hydroxy-2-methylpropanal, CO2 and peroxyacetyl nitrate (PAN) for the reaction of 4-methyl-3-penten-2-one with OH, respectively. Based on the calculated product yields an upper limit of 0.15 was determined for the overall organic nitrates (RONO2) yield derived from the OH reaction of 4-methyl-3-penten-2-one. By contrast, no RONO2 formation was observed for the OH reaction of 3-methyl-3-penten-2-one. Additionally, a simple model is presented to correct product yields for secondary processes.

Atmospheric Chemistry of CH3CH2OCH3: Kinetics and Mechanism of Reactions with Cl Atoms and OH Radicals

2016 ◽  
Vol 49 (1) ◽  
pp. 10-20 ◽  
Author(s):  
Mads P. Sulbaek Andersen ◽  
Sissel Bjørn Svendsen ◽  
Freja From Østerstrøm ◽  
Ole John Nielsen
Keyword(s):  
Atmospheric Chemistry ◽  
Kinetics And Mechanism ◽  
Oh Radicals ◽  
Cl Atoms

Atmospheric Degradation of CF3OCFCF2:  Kinetics and Mechanism of Its Reaction with OH Radicals and Cl Atoms

2000 ◽  
Vol 104 (13) ◽  
pp. 2925-2930 ◽  
Author(s):  
M. Mashino ◽  
M. Kawasaki ◽  
T. J. Wallington ◽  
M. D. Hurley
Keyword(s):  
Kinetics And Mechanism ◽  
Oh Radicals ◽  
Atmospheric Degradation ◽  
Cl Atoms

Atmospheric chemistry of trans-CF3CHCHCl: Kinetics of the gas-phase reactions with Cl atoms, OH radicals, and O3

2008 ◽  
Vol 199 (1) ◽  
pp. 92-97 ◽  
Author(s):  
M.P. Sulbaek Andersen ◽  
E.J.K. Nilsson ◽  
O.J. Nielsen ◽  
M.S. Johnson ◽  
M.D. Hurley ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Oh Radicals ◽  
Gas Phase Reactions ◽  
Kinetics Of ◽  
Cl Atoms

scholarly journals Experimental and computational kinetics investigations for the reactions of Cl atoms with series of unsaturated ketones in gas phase

2017 ◽  
Author(s):  
Siripina Vijayakumar ◽  
Avinash Kumar ◽  
Balla Rajakuma
Keyword(s):  
Gas Phase ◽  
State Theory ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Temperature Dependent ◽  
Unsaturated Ketones ◽  
Temperature Range ◽  
Computational Calculations ◽  
Temperature Rate ◽  
Cl Atoms

Abstract. Temperature dependent rate coefficients for the gas phase reactions of Cl atoms with 4-hexen-3-one and 5-hexen-2-one were measured over the temperature range of 298–363 K relative to 1-pentene, 1,3-butadiene and isoprene. Gas Chromatography (GC) was used to measure the concentrations of the organics. The derived temperature dependent Arrhenius expressions are k4-hexen-3-one+Cl (298–363 K) = (2.82 ± 1.76)×10−12exp [(1556 ± 438)/T] cm3 molecule−1 s−1 and k5-hexen-2-one+Cl (298–363 K) = (4.6 ± 2.4)×10−11exp[(646 ± 171)/T] cm3 molecule−1 s−1. The corresponding room temperature rate coefficients are (5.54 ± 0.41)×10−10 cm3 molecule−1 s−1 and (4.00 ± 0.37)×10−10 cm3 molecule−1 s−1 for the reactions of Cl atoms with 4-hexen-3-one and 5-hexen-2-one respectively. To understand the mechanism of Cl atom reactions with unsaturated ketones, computational calculations were performed for the reactions of Cl atoms with 4-hexen-3-one, 5-hexen-2-one and 3-penten-2-one over the temperature range of 275–400 K using Canonical Variational Transition state theory (CVT) with Small Curvature Tunneling (SCT) in combination with CCSD(T)/6-31+G(d, p)//MP2/6-311++G(d, p) level of theory. Atmospheric implications, reaction mechanism and feasibility of the title reactions are discussed in this manuscript.

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