Rate constants for the reactions of H atoms and OH radicals with ethers at 753 K

2001 ◽  
Vol 3 (21) ◽  
pp. 4722-4732 ◽  
Author(s):  
R. S. Tranter ◽  
R. W. Walker
Keyword(s):  
Rate Constants ◽  
Oh Radicals

scholarly journals Structure–activity relationship for the estimation of OH-oxidation rate constants of carbonyl compounds in the aqueous phase

2013 ◽  
Vol 13 (23) ◽  
pp. 11625-11641 ◽  
Author(s):  
J.-F. Doussin ◽  
A. Monod
Keyword(s):  
Aqueous Phase ◽  
Rate Constants ◽  
Oxidation Rate ◽  
Carbonyl Compounds ◽  
Estimation Method ◽  
Structure Activity Relationship ◽  
Activity Relationship ◽  
Oh Radicals ◽  
Structure Activity ◽  
Polyfunctional Compounds

Abstract. In the atmosphere, one important class of reactions occurs in the aqueous phase in which organic compounds are known to undergo oxidation towards a number of radicals, among which OH radicals are the most reactive oxidants. In 2008, Monod and Doussin have proposed a new structure–activity relationship (SAR) to calculate OH-oxidation rate constants in the aqueous phase. This estimation method is based on the group-additivity principle and was until now limited to alkanes, alcohols, acids, bases and related polyfunctional compounds. In this work, the initial SAR is extended to carbonyl compounds, including aldehydes, ketones, dicarbonyls, hydroxy carbonyls, acidic carbonyls, their conjugated bases, and the hydrated form of all these compounds. To do so, only five descriptors have been added and none of the previously attributed descriptors were modified. This extension leads now to a SAR which is based on a database of 102 distinct compounds for which 252 experimental kinetic rate constants have been gathered and reviewed. The efficiency of this updated SAR is such that 58% of the rate constants could be calculated within ±20% of the experimental data and 76% within ±40% (respectively 41 and 72% for the carbonyl compounds alone).

An experimental and theoretical study of the kinetics of the reaction between 3-hydroxy-3-methyl-2-butanone and OH radicals

RSC Advances ◽  
2015 ◽  
Vol 5 (34) ◽  
pp. 26559-26568 ◽  
Author(s):  
Angappan Mano Priya ◽  
Gisèle El Dib ◽  
Lakshmipathi Senthilkumar ◽  
Chantal Sleiman ◽  
Alexandre Tomas ◽  
...  
Keyword(s):  
Rate Constants ◽  
Theoretical Study ◽  
Oh Radicals ◽  
First Time ◽  
Kinetics Of

Absolute experimental and theoretical rate constants are determined for the first time for the reaction of 3-hydroxy-3-methyl-2-butanone with OH as a function of temperature. The atmospheric implications are discussed.

Rate constants for the reactions of OH radicals with CF3OCF=CF2 and CF3CF=CF2

2000 ◽  
Vol 325 (1-3) ◽  
pp. 189-195 ◽  
Author(s):  
Kazuaki Tokuhashi ◽  
Akifumi Takahashi ◽  
Masahiro Kaise ◽  
Shigeo Kondo ◽  
Akira Sekiya ◽  
...  
Keyword(s):  
Rate Constants ◽  
Oh Radicals

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>

scholarly journals Theoretical Study of the Iron Complexes with Lipoic and Dihydrolipoic Acids: Exploring Secondary Antioxidant Activity

Antioxidants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 674
Author(s):  
Roger Monreal-Corona ◽  
Jesse Biddlecombe ◽  
Angela Ippolito ◽  
Nelaine Mora-Diez
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Rate Constant ◽  
Thermodynamic Stability ◽  
Rate Constants ◽  
Theoretical Study ◽  
Oh Radicals ◽  
Single Electron Transfer ◽  
Coordination Numbers ◽  
Ph Conditions

The thermodynamic stability of twenty-nine Fe(III) complexes with various deprotonated forms of lipoic (LA) and dihydrolipoic (DHLA) acids, with coordination numbers 4, 5 and 6, is studied at the M06(SMD)/6-31++G(d,p) level of theory in water under physiological pH conditions at 298.15 K. Even though the complexes with LA- are more stable than those with DHLA−, the most thermodynamically stable Fe(III) complexes involve DHLA2−. The twenty-four exergonic complexes are used to evaluate the secondary antioxidant activity of DHLA and LA relative to the Fe(III)/Fe(II) reduction by O2•− and ascorbate. Rate constants for the single-electron transfer (SET) reactions are calculated. The thermodynamic stability of the Fe(III) complexes does not fully correlate with the rate constant of their SET reactions, but more exergonic complexes usually exhibit smaller SET rate constants. Some Cu(II) complexes and their reduction to Cu(I) are also studied at the same level of theory for comparison. The Fe(III) complexes appear to be more stable than their Cu(II) counterparts. Relative to the Fe(III)/Fe(II) reduction with ascorbate, DHLA can fully inhibit the formation of •OH radicals, but not by reaction with O2•−. Relative to the Cu(II)/Cu(I) reduction with ascorbate, the effects of DHLA are moderate/high, and with O2•− they are minor. LA has minor to negligible inhibition effects in all the cases considered.

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