Atmospheric oxidation mechanism of polyfluorinated sulfonamides — A quantum chemical and kinetic study

2013 ◽  
Vol 91 (6) ◽  
pp. 472-478 ◽  
Author(s):  
Xiaoyan Sun ◽  
Lei Ding ◽  
Qingzhu Zhang ◽  
Wenxing Wang
Keyword(s):  
Rate Constants ◽  
Density Functional ◽  
Single Point ◽  
Oxidation Mechanism ◽  
Basis Set ◽  
Atmospheric Oxidation ◽  
Oh Radicals ◽  
Oh Radical ◽  
Orbital Theory ◽  
Point Energy

Polyfluorinated sulfonamides (FSAs, F(CF2)nSO2NR1R2) are present in the atmosphere and may serve as the source of perfluorocarboxylates (PFCAs, CF3(CF2)nCOO–) in remote locations through long-range atmospheric transport and oxidation. Density functional theory (DFT) molecular orbital theory calculations were carried out to investigate OH radical-initiated atmospheric oxidation of a series of sulfonamides, F(CF2)nSO2NR1R2 (n = 4, 6, 8). Geometry optimizations of the reactants as well as the intermediates, transition states, and products were performed at the MPWB1K level with the 6-31G+(d,p) basis set. Single-point energy calculations were carried out at the MPWB1K/6-311+G(3df,2p) level of theory. The OH radical-initiated reaction mechanism is given and confirms that the OH addition to the sulfone double bond producing perfluoroalkanesulfonic acid directly cannot occur in the general atmosphere. Canonical variational transition-state (CVT) theory with small curvature tunneling (SCT) contribution was used to predict the rate constants. The overall rate constants were determined, k(T) (N-EtFBSA + OH) = (3.21 × 10−12) exp(–584.19/T), k(T) (N-EtFHxSA + OH) = (3.21 × 10−12) exp(–543.24/T), and k(T) (N-EtFOSA + OH) = (2.17 × 10−12) exp(–504.96/T) cm3 molecule−1 s−1, over the possible atmospheric temperature range of 180–370 K, indicating that the length of the F(CF2)n group has no large effect on the reactivity of FSAs. Results show that the atmospheric lifetime of FSAs determined by OH radicals will be 20–40 days, which agrees well with the experimental values (20–50 days), 20 thus they may contribute to the burden of perfluorinated pollution in remote regions.

Reaction kinetics of OH radicals with glutaric acid and adipic acid in the aqueous phase

2021 ◽  
Author(s):  
Liang Wen ◽  
Thomas Schaefer ◽  
Hartmut Herrmann
Keyword(s):  
Aqueous Phase ◽  
Adipic Acid ◽  
Rate Constants ◽  
Density Functional ◽  
Glutaric Acid ◽  
Radical Reaction ◽  
Basis Set ◽  
Oh Radicals ◽  
Oh Radical ◽  
Energy Barriers

<p>Dicarboxylic acids (DCAs) are widely distributed in atmospheric aerosols and cloud droplets and are mainly formed by the oxidation of volatile organic compounds (VOCs). For example, glutaric acid and adipic acid are two kinds of the DCAs that can be oxidized by hydroxyl radical (‧OH) reactions in the aqueous phase of aerosols and droplets. In the present study, the temperature- and pH-dependent rate constants of the aqueous OH radical reactions of the two DCAs were investigated by a laser flash photolysis-long path absorption setup using the competition kinetics method. Based on speciation calculations, the OH radical reaction rate constants of the fully protonated (H<sub>2</sub>A), deprotonated (HA<sup>-</sup>) and fully deprotonated (A<sup>2-</sup>) forms of the two DCAs were determined. The following Arrhenius expressions for the T-dependency of the OH radical reaction of glutaric acid, k(T, H<sub>2</sub>A) = (3.9 ± 0.1) × 10<sup>10</sup> × exp[(-1270 ± 200 K)/T], k(T, HA<sup>-</sup>) = (2.3 ± 0.1) × 10<sup>11</sup> × exp[(-1660 ± 190 K)/T], k(T, A<sup>2-</sup>) = (1.4 ± 0.1) × 10<sup>11</sup> × exp[(-1400 ± 170 K)/T] and adipic acid, k(T, H<sub>2</sub>A) = (7.5 ± 0.2) × 10<sup>10</sup> × exp[(-1210 ± 170 K)/T], k(T, HA<sup>-</sup>) = (9.5 ± 0.3) × 10<sup>10</sup> × exp[(-1200 ± 200 K)/T], k(T, A<sup>2-</sup>) = (8.7 ± 0.2) × 10<sup>10</sup> × exp[(-1100 ± 170 K)/T] (in unit of L mol<sup>-1</sup> s<sup>-1</sup>) were derived.</p><p>The energy barriers of the H-atom abstractions were simulated by the Density Functional Theory calculations run with the GAUSSIAN package using the M06-2X method and the basis set m062x/6-311++g(3df,2p). The results showed that the energy barriers were lower at the C<sub>β</sub>-atoms and are higher at the C<sub>α</sub>-atoms of the two DCAs, clearly suggesting that the H-atom abstractions occurred predominately at the C<sub>β</sub>-atoms. In addition, the ionizations can enhance the electrostatic effects of the carboxyl groups, significantly reducing the energy barriers, leading to the order of OH radical reactivity as  <  < . This study intends to better characterize the losing processes of glutaric acid and adipic acid in atmospheres.</p>

Kinetics and mechanism for chlorine-initiated atmospheric oxidation of ethyl formate

2014 ◽  
Vol 92 (7) ◽  
pp. 598-604 ◽  
Author(s):  
Yan Zhao ◽  
Xiaomin Sun ◽  
Wenxing Wang ◽  
Laixiang Xu
Keyword(s):  
Rate Constants ◽  
Density Functional ◽  
Single Point ◽  
Oxidation Mechanism ◽  
Density Functional Theory Method ◽  
Ethyl Formate ◽  
Stationary Points ◽  
Atmospheric Conditions ◽  
Point Energy ◽  
Rearrangement Reaction

The chlorine-initiated reaction mechanism of ethyl formate in the atmosphere was investigated using the density functional theory method. The geometry parameters and frequencies of all of the stationary points were calculated at the B3LYP/ 6-31G(d,p) level. The single-point energy calculations were carried out at different levels, including MP2/6-31G(d), MP2/6-311++G(d,p), and CCSD(T)/6-31G(d). A detailed oxidation mechanism is provided and discussed. Present results show that α-ester rearrangement reaction and the O2 direct abstraction from IM6 (HC(O)OCH(O)CH3) are the more favorable pathway and are competitive. The 1,4-H shift isomerization of IM6 proved to be feasible under general atmospheric conditions. The decomposition of IM18 (CH3CH2OC(O)O) is favorable both thermodynamically and kinetically. Canonical variational transition theory with small-curvature tunneling correction was employed to predict the rate constants. The overall rate constant of ethyl formate at 298 K is 8.63 × 10−12 cm3 molecule−1 s−1. The Arrhenius equations of rate constants at the temperature range of 200–380 K were fitted.

Quantum chemical study on the atmospheric photooxidation of ethyl acetate

2014 ◽  
Vol 92 (9) ◽  
pp. 814-820 ◽  
Author(s):  
Yan Zhao ◽  
Xiaomin Sun ◽  
Wenxing Wang ◽  
Laixiang Xu
Keyword(s):  
Acetic Anhydride ◽  
Ethyl Acetate ◽  
Density Functional ◽  
Single Point ◽  
Quantum Chemical Study ◽  
Density Functional Theory Method ◽  
Basis Set ◽  
Oh Radicals ◽  
Point Energy ◽  
Rearrangement Reaction

The mechanism for OH radical initiated atmospheric photoxidation reaction of ethyl acetate was carried out by using the density functional theory method. Geometries have been optimized at the B3LYP level with a standard 6-31G(d,p) basis set. The single-point energy calculations have been performed at the MP2/6-31G(d), MP2/6-311++G(d,p), and CCSD(T)/6-31G(d) levels, respectively. All of the possible degradation channels involved in the oxidation of ethyl acetate by OH radicals have been presented and discussed. Among the five possible hydrogen abstraction pathways of the reaction of ethyl acetate with OH radicals, the hydrogen abstractions from the C1–H3 and C2–H5 bonds are the dominant reaction pathways due to the low potential barriers and strong exothermicity. The β-ester rearrangement of IM6 is energetically favorable but is not expected to be important. The α-ester rearrangement reaction and O2 direct abstraction from IM17 are the more favorable pathways and are strongly competitive. In addition, the α-ester rearrangement reaction is confirmed to be a one-step process. Acetic acid, formic acetic anhydride, acetoxyacetaldehyde, and acetic anhydride are the main products for the reaction of ethyl acetate with OH radicals.

Theoretical study on NO3-initiated oxidation of acenaphthene in the atmosphere

2008 ◽  
Vol 86 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Xiaohui Qu ◽  
Qingzhu Zhang ◽  
Wenxing Wang
Keyword(s):  
Product Information ◽  
Environmental Concern ◽  
Single Point ◽  
Basis Set ◽  
Orbital Theory ◽  
Night Time ◽  
Point Energy ◽  
Secondary Reactions ◽  
Favorable Reaction ◽  
High Level

Acenaphthene is widespread and toxic, and thus of substantial environmental concern. The reaction with NO3 radicals is an important atmospheric loss process of acenaphthene at night time. In this work, the mechanism for the NO3-initiated atmospheric oxidation reaction of acenaphthene has been studied using high level molecular orbital theory. Geometries of all the related species have been optimized at the MPWB1K level with the 6–31G(d,p) basis set. The single-point energy calculations have been carried out at the MPWB1K/6–311+G(3df,2p) level. The possible secondary reactions were also studied. Several energetically favorable reaction pathways were revealed for the first time.Key words: acenaphthene, NO3 radicals, reaction mechanism, product information, oxidation degradation.

Mechanistic and Kinetic Study of Atmospheric Oxidation of Chlordane Initiated by OH Radicals

2019 ◽  
Vol 16 (8) ◽  
pp. 647-655
Author(s):  
Zhezheng Ding ◽  
Yayi Yi ◽  
Fei Xu ◽  
Qingzhu Zhang ◽  
Xiaoli Xu ◽  
...  
Keyword(s):  
Density Functional ◽  
Single Point ◽  
Oxidation Mechanism ◽  
Oxidation Products ◽  
Oh Radicals ◽  
Atmospheric Conditions ◽  
Geometrical Structures ◽  
Elementary Reactions ◽  
Atmospheric Fate ◽  
High Concentrations

Chlordane, one of the extremely hazardous Persistent Organic Pollutants (POPs), was widely used as pesticides all over the world and its residues have been detected at high concentrations in many areas. As a species of Semi-Volatile Organic Compounds (SVOCs), chlordane exists mainly in the atmosphere where it can be migrated and transformed. Due to the carcinogenic and mutagenic properties, understanding its atmospheric fate is of great significance. In the present work, the oxidation mechanism of chlordane initiated by OH radicals under the atmospheric conditions was investigated by using Density Functional Theory (DFT). The geometrical structures were optimized at the M06- 2X/6-311+g(d,p) level and single-point energies were calculated at the M06-2X/6-311+g(3df,2p) level. The relevant rate constants of the key elementary reactions were calculated by using Rice-Ramsperger- Kassel-Marcus (RRKM) theory at 298 K and 1 atm. All of the energetically favorable pathways were discussed in detail, and theoretical results showed that the oxidation products are dichlorochlordene, hydroxychlrodane, cycloketone and dichloracyl. Combined with available experimental observation, this study can, therefore, help to clarify the atmospheric fate of chlordane.

Theoretical study on the reaction mechanism of vinyl acetate with OH radicals in the atmosphere

2013 ◽  
Vol 91 (4) ◽  
pp. 241-247 ◽  
Author(s):  
Yan Zhao ◽  
Haitao Sun ◽  
Renjun Wang ◽  
Fei Gao
Keyword(s):  
Vinyl Acetate ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Theoretical Study ◽  
Single Point ◽  
Density Functional Theory Method ◽  
Basis Sets ◽  
Stationary Points ◽  
Oh Radicals ◽  
Point Energy

The reaction mechanisms of vinyl acetate with OH radicals in the atmosphere have been studied using the density functional theory method. The geometry parameters and frequencies of all of the stationary points are calculated at the MPWB1K level with the 6-31G(d,p) basis sets. The single-point energy calculations are carried out at the MPWB1K/6-311+G(3df,2pd) level. The detailed profiles of the potential energy surfaces for the reactions are constructed. Two OH addition and three H abstraction reaction pathways are considered for the reaction of vinyl acetate with OH radicals. The theoretical study shows that the most energetically favorable isomer is that of OH addition to the terminal carbon positions (C1 atom). The α-ester rearrangement, which is characteristic of ester oxidation processes, is confirmed to be thermodynamically and kinetically favorable. The main products of the OH-initiated atmospheric oxidation of vinyl acetate are formaldehyde, formic acetic anhydride, and acetic acid.

scholarly journals Study on the Product Formation of the Reaction between Criegee Compound and Propargyl Radical

2021 ◽  
Vol 31 (4) ◽  
pp. 80-84
Keyword(s):  
Density Functional ◽  
Single Point ◽  
Product Formation ◽  
Basis Set ◽  
Functional Theory ◽  
Point Energy ◽  
Propargyl Radical ◽  
The Density Functional Theory ◽  
Stable Product ◽  
Mechanism Of The Reaction

Mechanism of the reaction between Criegee compound (CH2OO) and Propargyl radical (C3H3) has been studied by using the density functional theory DFT/M06-2X in conjunction with the 6-311++G(3df,2p) basis set for both optimization and single-point energy calculations. The calculated results indicate that mechanism of the C3H3 + CH2OO reaction can occur in two different directions: H-atom abstraction and/or addition. As a result, 11 various products have been created from this reaction; in which, P10 (OCHCHCHCHO + H) is the most thermodynamically stable product and the reaction path leading to the P7 (CH2-[cyc-CCHCHOO] + H) product is the most energetically and kinetically favorable channel.

scholarly journals Theoretical investigation of the Anti-Parkinson drug rasagiline and its salts: conformations and infrared spectra

2012 ◽  
Vol 10 (2) ◽  
pp. 395-406 ◽  
Author(s):  
U. Başköse ◽  
Sevgi Bayarı ◽  
Semran Sağlam ◽  
Hacı Özışık
Keyword(s):  
Density Functional ◽  
Single Point ◽  
Normal Modes ◽  
Basis Set ◽  
Stable Conformer ◽  
Functional Theory ◽  
Point Energy ◽  
Vibrational Assignments ◽  
B3lyp Method ◽  
The Density Functional Theory

AbstractThe conformational analysis of rasagiline [N-propargyl-1(R)-aminoindan] was performed by the density functional theory (DFT) B3LYP method using the 6–31++G (d,p) basis set. A single point energy calculations based on the B3LYP optimized geometries were also performed at MP2/6-31++G (d, p) level. The vibrational frequencies of the most stable conformer of rasagiline was calculated at the B3LYP level and vibrational assignments were made for normal modes on the basis of scaled quantum mechanical force field (SQM) method. The influence of mesylate and ethanedisulfonate salts on the geometry of rasagiline free base and its normal modes are also discussed.

THEORETICAL STUDY OF MECHANISM FOR THE ATMOSPHERIC REACTION CF3CHFO2 + NO

2013 ◽  
Vol 12 (01) ◽  
pp. 1250101 ◽  
Author(s):  
YA-NA WENG ◽  
XIAO-JUAN YAN ◽  
SHU-JIN LI
Keyword(s):  
Density Functional ◽  
Energy Surface ◽  
Single Point ◽  
Basis Set ◽  
Stationary Points ◽  
Cluster Method ◽  
Radical Pairs ◽  
Functional Theory ◽  
Point Energy ◽  
Optimized Geometries

The mechanism of the reaction CF3CHFO2 + NO was investigated using ab initio and density functional theory (DFT). The optimized geometries for all stationary points on the reaction energy surface were calculated using MP2 and B3LYP methods with the aug-cc-pVDZ basis set. Single-point energy calculations were performed using the coupled cluster method with single, double and perturbative triple configurations, CCSD(T). The most important energy minima on the potential energy surface (PES) were found corresponding to two conformers of the peroxynitrite association adducts, cis- CF3CHFOONO and trans- CF3CHFOONO , and the nitrate, CF3CHFONO2 . The radical pairs ( CF3CHFO + NO2 ) and the nitrate are formed through the breaking of the peroxy bond of trans- CF3CHFOONO and the rearrangement of cis- CF3CHFOONO , respectively. The nitrate can be decomposed to carbonylated species ( CF3CHO or CF3CFO ), nitryl fluoride (NO2F), nitrous acid (HONO), and radical pairs ( CF3CHFO + NO2 ), which are of potential atmospheric importance.

scholarly journals Atmospheric oxidation of 4-(2-Methoxyethyl) phenol initiated by OH radical in the presence of O2 and NOx: A mechanistic and kinetic study

2020 ◽  
Author(s):  
Junfang Yao ◽  
Yanan Sun ◽  
Yizhen Tang ◽  
yunju zhang ◽  
Wenzhong Wu ◽  
...  
Keyword(s):  
Rate Constant ◽  
Density Functional ◽  
Oxidation Mechanism ◽  
Oxidation Products ◽  
Atmospheric Oxidation ◽  
Oh Radical ◽  
Quantum Chemical Methods ◽  
The Density Functional Theory ◽  
Reaction Channels ◽  
Individual Rate

4-(2-Methoxyethyl) phenol (MEP) is an significant methoxypheolic compound, which has been shown to play an important role in the formation of secondary organic aerosols(SOA). The present work focuses on the gas-phase oxidation mechanism and kinetics of MEP and OH radical by the density functional theory (DFT). Energetically favourable reaction channels and feasible products were identified. The initial reactions of MEP with OH radical have two different channels: OH addition and H abstraction. Subsequent reaction schemes of main intermediates in the presence of O2 and NOx are investigated using quantum chemical methods at M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p) level. Ketene, Phenyldiketones and nitrophenol compounds are demonstrated to be possible oxidation products. The total rate constant(1.69×10-11 cm3 molecule-1 s-1) and individual rate constant are calculated using the traditional transition state (TST) theory at 298K and 1atm. The lifetime of MEP is estimated to be 16.4 hours, which provides a comprehensive explanation for atmospheric oxidation pathway of MEP and shows MEP would be removed by OH radical in the atmosphere.

Sign in / Sign up

Export Citation Format

Share Document