scholarly journals Theoretical Studies on the Reaction Mechanism and Kinetics of Ethylbenzene-OH Adduct with O2 and NO2

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1118
Author(s):  
Tingting Lu ◽  
Mingqiang Huang ◽  
Xin Lin ◽  
Wei Zhang ◽  
Weixiong Zhao ◽  
...  
Keyword(s):  
Density Functional ◽  
Hydrogen Abstraction ◽  
State Theory ◽  
Major Product ◽  
Oxidation Products ◽  
Peroxy Radicals ◽  
Atmospheric Conditions ◽  
Radical Intermediate ◽  
Functional Theory ◽  
Kinetics Of

The OH-initiated reaction of ethylbenzene results in major OH addition, and the formed ethylbenzene-OH adducts subsequently react with O2 and NO2, which determine the components of the oxidation products. In this study, nine possible reaction paths of the most stable ethylbenzene-OH adduct, EB-Ortho (2-ethyl-hydroxycyclohexadienyl radical intermediate), with O2 and NO2 were studied using density functional theory and conventional transition state theory. The calculated results showed that ethyl-phenol formed via hydrogen abstraction was the major product of the EB-Ortho reaction with O2 under atmospheric conditions. Peroxy radicals generated from O2 added to EB-Ortho could subsequently react with NO and O2 to produce 5-ethyl-6-oxo-2,4-hexadienal, furan, and ethyl-glyoxal, respectively. However, nitro-ethylbenzene formed from NO2 addition to EB-Ortho was the predominant product of the EB-Ortho reaction with NO2 at room temperature. The total calculated rate constant of the EB-Ortho reaction with O2 and NO2 was 9.57 × 10−16 and 1.78 × 10−11 cm3 molecule−1 s−1, respectively, approximately equivalent to the experimental rate constants of toluene-OH adduct reactions with O2 and NO2. This study might provide a useful theoretical basis for interpreting the oxygen-containing and nitrogen-containing organics in anthropogenic secondary organic aerosol particles.

Theoretical study on the chemical formation mechanism of a β-myrcene ozonolysis reaction under atmospheric conditions

2012 ◽  
Vol 90 (8) ◽  
pp. 708-715 ◽  
Author(s):  
Yuyang Zhao ◽  
Jing Bai ◽  
Chenxi Zhang ◽  
Chen Gong ◽  
Xiaomin Sun
Keyword(s):  
Rate Constants ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Single Point ◽  
State Theory ◽  
Tunneling Effect ◽  
Atmospheric Conditions ◽  
Functional Theory ◽  
Real Atmosphere ◽  
Energy Surfaces

Density functional theory (DFT) was used to study the β-myrcene ozonolysis reaction. The reactants, intermediates, transition states, and products were optimized at the MPWB1K/6–31G(d,p) level. The single-point energies were performed at the MPWB1K/6–311+G(3df,2p) level. The profiles of the potential energy surfaces were constructed and the rate constants of the reaction steps were analyzed. The possible reaction mechanisms for the ozonolysis intermediates in real atmosphere are also discussed. Based on quantum chemistry information, the rate constants were calculated using Rice–Ramsperger–Kassel–Marcus (RRKM) theory and the canonical variational transition-state theory (CVT) with small curvature tunneling effect (SCT). Arrhenius equations of rate constants over the temperature range of 200–800 K are provided, and the lifetimes of the reaction species in the troposphere were estimated according to rate constants.

Abstraction and addition kinetics of C2H radicals with CH4, C2H6, C3H8, C2H4, and C3H6: CVT/SCT/ISPE and hybrid meta-DFT methods

2015 ◽  
Vol 17 (5) ◽  
pp. 3142-3156 ◽  
Author(s):  
Manas Ranjan Dash ◽  
B. Rajakumar
Keyword(s):  
Density Functional ◽  
Transition State Theory ◽  
State Theory ◽  
Rate Coefficients ◽  
Dft Methods ◽  
Functional Theory ◽  
Variational Transition State Theory ◽  
Wide Range ◽  
P Rate ◽  
Kinetics Of

Rate coefficients for the reactions of C2H radicals with methane (k1), ethane (k2), propane (k3), ethylene (k4), and propylene (k5) were computed using canonical variational transition state theory (CVT) coupled with hybrid-meta density functional theory (DFT) over a wide range of temperatures from 150 to 5000 K.

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

scholarly journals Thermal Stability and Decomposition Kinetics of 1-Alkyl-2,3-Dimethylimidazolium Nitrate Ionic Liquids: TGA and DFT Study

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2560
Author(s):  
Jianwen Meng ◽  
Yong Pan ◽  
Fan Yang ◽  
Yanjun Wang ◽  
Zhongyu Zheng ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Density Functional Theory ◽  
Ionic Liquids ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Nitrogen Atmosphere ◽  
Decomposition Kinetics ◽  
Heating Rates ◽  
Functional Theory ◽  
Kinetics Of

The thermal stability and decomposition kinetics analysis of 1-alkyl-2,3-dimethylimidazole nitrate ionic liquids with different alkyl chains (ethyl, butyl, hexyl, octyl and decyl) were investigated by using isothermal and nonisothermal thermogravimetric analysis combined with thermoanalytical kinetics calculations (Kissinger, Friedman and Flynn-Wall-Ozawa) and density functional theory (DFT) calculations. Isothermal experiments were performed in a nitrogen atmosphere at 240, 250, 260 and 270 °C. In addition, the nonisothermal experiments were carried out in nitrogen and air atmospheres from 30 to 600 °C with heating rates of 5, 10, 15, 20 and 25 °C/min. The results of two heating modes, three activation energy calculations and density functional theory calculations consistently showed that the thermal stability of 1-alkyl-2,3-dimethylimidazolium nitrate ionic liquids decreases with the increasing length of the alkyl chain of the substituent on the cation, and then the thermal hazard increases. This study could provide some guidance for the safety design and use of imidazolium nitrate ionic liquids for engineering.

Photooxidation and ozonolysis of Δ3-carene and its oxidation product caronaldehyde in the atmospheric simulation chamber SAPHIR

2021 ◽  
Author(s):  
Luisa Hantschke ◽  
Anna Novelli ◽  
Birger Bohn ◽  
Changmin Cho ◽  
David Reimer ◽  
...  
Keyword(s):  
Oxidation Product ◽  
Boreal Forests ◽  
Oxidation Products ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Peroxy Radicals ◽  
Atmospheric Conditions ◽  
Oxidation Reactions ◽  
Reaction Rate Constants ◽  
Simulation Chamber

<p>Of the total global annual monoterpene emissions, Δ<sup>3</sup>-carene contributes 4.5 %, making it the 7<sup>th</sup> most abundant monoterpene worldwide. As it is primarily emitted by pine trees, Δ<sup>3</sup>-carene can regionally gain in importance, for example in boreal forests and Mediterranean regions.  Oxidation products of monoterpenes such as organic nitrates and aldehydes are known to impact the formation of secondary pollutants such as ozone and particles, so understanding their atmospheric formation and fate is crucial.</p><p>The photooxidation and ozonolysis of Δ<sup>3</sup>-carene and the photooxidation and photolysis of its main daytime photooxidation product caronaldehyde were investigated in the atmospheric simulation chamber SAPHIR. Oxidation reactions were studied under atmospheric conditions with high (> 8 ppbv) and low (< 2 ppbv) NOx concentrations. Reaction rate constants of the reaction of Δ<sup>3</sup>-carene with OH and O<sub>3</sub>, and of the reaction of caronaldehyde with OH as well as photolysis frequencies of caronaldehyde were determined. Production and destruction rates of the sum of hydroxyl and peroxy radicals (ROx = OH+HO2+RO2) were analysed to determine if there were unaccounted production and loss processes of radicals in the oxidation of Δ<sup>3</sup>-carene. The yield of Δ<sup>3</sup>-carene’s oxidation product caronaldehyde was determined from measured timeseries from OH photooxidation and ozonolysis experiments. Additionally, the OH yield from ozonolysis of Δ<sup>3</sup>-carene was determined.</p><p>Organic nitrate (RONO<sub>2</sub>) yields of the reaction of RO<sub>2</sub> + NO, from RO<sub>2</sub> produced from the reactions of Δ<sup>3</sup>-carene and caronaldehyde with OH were determined by analyzing the reactive nitrogen species (NOy) in the chamber.</p>

Sign in / Sign up

Export Citation Format

Share Document