Atmospheric Oxidation Mechanism of Sabinene Initiated by the Hydroxyl Radicals

2018 ◽  
Vol 122 (44) ◽  
pp. 8783-8793 ◽  
Author(s):  
Lingyu Wang ◽  
Liming Wang
Keyword(s):  
Hydroxyl Radicals ◽  
Oxidation Mechanism ◽  
Atmospheric Oxidation

scholarly journals The Atmospheric Oxidation Mechanism of o-Xylene Initiated by Hydroxyl Radicals

2015 ◽  
Vol 31 (12) ◽  
pp. 2259-2268 ◽  
Author(s):  
Shan-Shan. PAN ◽  
◽  
Li-Ming. WANG ◽  
Keyword(s):  
Hydroxyl Radicals ◽  
Oxidation Mechanism ◽  
Atmospheric Oxidation

scholarly journals Atmospheric oxidation reactions of imidazole initiated by hydroxyl radicals: kinetics and mechanism of reactions and atmospheric implications

2019 ◽  
Vol 21 (16) ◽  
pp. 8445-8456 ◽  
Author(s):  
Zahra Safaei ◽  
Abolfazl Shiroudi ◽  
Ehsan Zahedi ◽  
Mika Sillanpää
Keyword(s):  
Quantum Chemistry ◽  
Transition State ◽  
Reaction Kinetics ◽  
Hydroxyl Radicals ◽  
Transition State Theory ◽  
Oxidation Mechanism ◽  
State Theory ◽  
Atmospheric Oxidation ◽  
Oxidation Reactions ◽  
Quantum Chemistry Calculations

The atmospheric oxidation mechanism of imidazole initiated by hydroxyl radicals is investigated via OH-addition and H-abstraction pathways by quantum chemistry calculations at the M06-2X/aug-cc-pVTZ level of theory coupled with reaction kinetics calculations using statistical Rice–Ramsperger–Kassel–Marcus (RRKM) theory and transition state theory (TST).

scholarly journals H–Abstraction from Dimethyl Sulfide in the Presence of an Excess of Hydroxyl Radicals. A Quantum Chemical Evaluation of Thermochemical and Kinetic Parameters Unveil an Alternative Pathway to Dimethyl Sulfoxide.

2020 ◽  
Author(s):  
Zoi Salta ◽  
Jacopo Lupi ◽  
Vincenzo Barone ◽  
Oscar Ventura
Keyword(s):  
Dimethyl Sulfoxide ◽  
Hydroxyl Radicals ◽  
Quantum Chemical ◽  
Dimethyl Sulfide ◽  
Computational Study ◽  
Alternative Pathway ◽  
Oxidation Mechanism ◽  
State Theory ◽  
Rate Coefficients ◽  
Reduced Sulfur Compounds

<div> Elucidation of the oxidation mechanism of naturally emitted reduced sulfur compounds, especially dimethyl sulfide, plays a central role in understanding background acid precipitation in the natural environment. Most frequently, theoretical studies of the addition and H-elimination reactions of dimethyl sulfide with hydroxyl radicals are studied considering the presence of oxygen that further reacts with the radicals formed in the initial steps. Although the reaction of intermediate species with additional hydroxyl radicals has been considered as part of the global mechanism of oxidation, few if any attention has been dedicated to the possibility of reactions of the initial radicals with a second •OH molecule. In this work we performed a computational study using quantum-chemical methods, of the mechanism of H-abstraction from dimethyl sulfide under normal atmospheric conditions and in reaction chambers at different O2 partial pressure, including complete absence of oxygen. Additionally, important rate coefficients were computed using canonical and variational transition state theory. The rate coefficient for abstraction affords a 4.72 x 10-12 cm3 molecule1 s-1 value, very close to the most recent experimental one (4.13 x 10-12 cm3 molecule-1 s-1). According to our best results, the initial methyl thiomethyl radical was obtained at -25.2 kcal/mol (experimentally -22.4 kcal/mol), and four important paths were identified on the potential energy surface. From the interplay of thermochemical and kinetic arguments, it was possible to demonstrate that the preferred product of the reaction of dimethyl sulfide with two hydroxyl radicals, is actually dimethyl sulfoxide. </div><div> </div>

Atmospheric Oxidation Mechanism of 1,2-Dibromoethane†

2009 ◽  
Vol 113 (26) ◽  
pp. 7189-7204 ◽  
Author(s):  
Carrie J. Christiansen ◽  
Joseph S. Francisco
Keyword(s):  
Oxidation Mechanism ◽  
Atmospheric Oxidation

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.

An electrochemical mechanisms study on steel/IrO2–Sb2O3 electrodes for oxidation of phenol in water

2015 ◽  
Vol 93 (5) ◽  
pp. 536-541
Author(s):  
Pavithra Bhakthi Jayathilaka ◽  
Gayani Chathurika Pathiraja ◽  
Athula Bandara ◽  
Nalaka Deepal Subasinghe ◽  
Nadeeshani Nanayakkara
Keyword(s):  
Chemical Oxygen Demand ◽  
Removal Efficiency ◽  
Hydroxyl Radicals ◽  
Oxygen Demand ◽  
Oxidation Mechanism ◽  
Constant Current ◽  
Anode Surface ◽  
Radical Scavenger ◽  
Chemical Oxygen Demand Removal ◽  
Constant Current Density

Phenol, a known water pollutant, was electrochemically oxidized on a steel/IrO2–Sb2O3 novel anode. Since the oxidation mechanisms vary based on the anode material, a mechanisms study of electrooxidation of phenol on it was conducted. The phenol oxidation was carried out at 20 mA/cm2 constant current density with a pH 11.00 Na2SO4 medium at room temperature. During 6 h of electrolysis, samples were tested for chemical oxygen demand removal efficiency of the anode. The steel/IrO2–Sb2O3anode showed 76.3% chemical oxygen demand removal efficiency. Both 4-nitroso-N,N-dimethylaniline and the HCO3–/CO32– radical scavenger tests confirmed the formation and presence of the hydroxyl radicals in the system. Therefore, it was concluded that the hydroxyl radicals that are generated on the anode surface are the main cause for the oxidation mechanism. Moreover, ICE, HPLC, and UV-vis absorbance and cyclic voltammetry results confirmed the presence of catechol and benzoquinone as intermediates and the reaction mechanism.

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