scholarly journals Mechanistic and kinetics investigations of oligomer formation from Criegee intermediate reactions with hydroxyalkyl hydroperoxides

2019 ◽  
Vol 19 (6) ◽  
pp. 4075-4091 ◽  
Author(s):  
Long Chen ◽  
Yu Huang ◽  
Yonggang Xue ◽  
Zhenxing Shen ◽  
Junji Cao ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Organic Aerosol ◽  
Climate Forcing ◽  
Phase Reaction ◽  
Methyl Group ◽  
Consecutive Reactions ◽  
Mechanism And Kinetics ◽  
High Level ◽  
First Time ◽  
Kinetics Of

Abstract. Although secondary organic aerosol (SOA) is a major component of PM2.5 and organic aerosol (OA) particles and therefore profoundly influences air quality, climate forcing, and human health, the mechanism of SOA formation via Criegee chemistry is poorly understood. Herein, we perform high-level theoretical calculations to study the gas-phase reaction mechanism and kinetics of four Criegee intermediate (CI) reactions with four hydroxyalkyl hydroperoxides (HHPs) for the first time. The calculated results show that the consecutive reactions of CIs with HHPs are both thermochemically and kinetically favored, and the oligomers contain CIs as chain units. The addition of an −OOH group in HHPs to the central carbon atom of CIs is identified as the most energetically favorable channel, with a barrier height strongly dependent on both CI substituent number (one or two) and position (syn- or anti-). In particular, the introduction of a methyl group into the anti-position significantly increases the rate coefficient, and a dramatic decrease is observed when the methyl group is introduced into the syn-position. These findings are expected to broaden the reactivity profile and deepen our understanding of atmospheric SOA formation processes.

scholarly journals Oligomerization Reactions of Criegee Intermediates with Hydroxyalkyl Hydroperoxides: Mechanism, Kinetics, and Structure-Reactivity Relationship

2018 ◽  
pp. 1-35 ◽  
Author(s):  
Long Chen ◽  
Yu Huang ◽  
Yonggang Xue ◽  
Zhenxing Shen ◽  
Junji Cao ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Climate Forcing ◽  
Atmospheric Lifetime ◽  
Methyl Group ◽  
Criegee Intermediates ◽  
Sequential Addition ◽  
Structure Reactivity Relationship ◽  
High Level ◽  
First Time ◽  
Kinetics Of

<p><strong>Abstract.</strong> Although secondary organic aerosols (SOAs) are major components of PM<sub>2.5</sub> and organic aerosol (OA) particles and therefore profoundly influencing air quality, climate forcing and human health, the mechanism of SOAs formation via Criegee chemistry is poorly understood. Herein, we perform high-level theoretical calculations to study the reactivity and kinetics of four Criegee intermediates (CIs) reactions with four hydroxyalkyl hydroperoxides (HHPs) for the first time. The calculated results show that the sequential addition of CIs to HHPs affords oligomers containing CIs as chain units. The addition of -OOH group in HHPs to the central carbon atom of CIs is identified as the most energetically favorable channel, with a barrier height strongly dependent on both, CI substituent number (one or two) and position (<i>syn-</i> or <i>anti-</i>). In particular, the introduction of a methyl group into the <i>anti</i>-position significantly increase the rate coefficient, dramatic decrease is observed when the methyl group is introduced into the <i>syn</i>-position. Based on the collected data, the atmospheric lifetime of <i>anti</i>-CH<sub>3</sub>CHOO in the presence of HHPs is estimated as ~<span class="thinspace"></span>5.9<span class="thinspace"></span>×<span class="thinspace"></span>103<span class="thinspace"></span>s. These findings are expected to broaden the reactivity profile and deepen our understanding of atmospheric SOAs formation processes.</p>

Towards high-level theoretical studies of large biodiesel molecules: an ONIOM/RRKM/Master-equation approach to the isomerization and dissociation kinetics of methyl decanoate radicals

2019 ◽  
Vol 21 (9) ◽  
pp. 5232-5242 ◽  
Author(s):  
Qinghui Meng ◽  
Yicheng Chi ◽  
Lidong Zhang ◽  
Peng Zhang ◽  
Liusi Sheng
Keyword(s):  
Theoretical Calculations ◽  
Theoretical Studies ◽  
Equation Approach ◽  
Dissociation Kinetics ◽  
Master Equation Approach ◽  
High Layer ◽  
High Level ◽  
Kinetics Of ◽  
Oniom Method ◽  
Methyl Decanoate

The isomerization and dissociation reactions of methyl decanoate (MD) radicals were theoretically investigated by using high-level theoretical calculations based on a two-layer ONIOM method, employing the QCISD(T)/CBS method for the high layer and the M06-2X/6-311++G(d,p) method for the low layer.

Gas-phase basicity and proton affinity measurements of Alzheimer's disease drugs by the extended kinetic method and a theoretical investigation

2020 ◽  
Vol 26 (6) ◽  
pp. 388-399
Author(s):  
Voleti Nagaveni ◽  
Rajendiran Karthikraj ◽  
Ramesh Kumar Chitumalla ◽  
Kotamarthi Bhanuprakash ◽  
Mariappandar Vairamani ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Gas Phase ◽  
Proton Affinity ◽  
Theoretical Calculations ◽  
Kinetic Method ◽  
Amino Groups ◽  
Thermochemical Parameters ◽  
High Level ◽  
First Time

This study has been carried out to obtain the thermochemical parameters of drugs used for Alzheimer’s disease. The measurement of gas-phase basicity (GB) and proton affinity (PA) values of four important and commercially available drugs for Alzheimer's disease namely, rivastigmine, galantamine, memantine, and tacrine, is attempted for the first time. This study also includes the measurement of GB and PA values for the proposed drug curcumin, a natural product. We calculated the GB and PA values for all these drugs by applying electrospray ionization tandem mass spectrometry (ESI-MS/MS) with the extended kinetic method. Since, all these drugs possessing amino groups (basic nature), the PA values for all these drugs are high i.e., the PA values range from 923.6 to 979.7 kJ/mol and the GB values range from 886.2 to 943.3 kJ/mol. The GB and PA values obtained from the mass spectrometric experiments are well supported with the theoretical calculations. A high-level theoretical B3LYP/6-311 + G(d,p) method is used for the PA and GB calculation and the deviations are in the acceptable range.

scholarly journals Theoretical study of the reaction mechanism and kinetics of the phenyl + propargyl association

2020 ◽  
Vol 22 (13) ◽  
pp. 6868-6880 ◽  
Author(s):  
Alexander N. Morozov ◽  
Alexander M. Mebel
Keyword(s):  
Reaction Mechanism ◽  
Energy Surface ◽  
Theoretical Study ◽  
Recombination Reaction ◽  
Propargyl Radical ◽  
Dependent Rate ◽  
Mechanism And Kinetics ◽  
Temperature And Pressure ◽  
High Level ◽  
Kinetics Of

Potential energy surface for the phenyl + propargyl radical recombination reaction has been studied using high-level ab initio calculations and temperature- and pressure-dependent rate constants and product yields have been computed employing RRKM-ME.

scholarly journals Kinetic modeling of secondary organic aerosol formation: effects of particle- and gas-phase reactions of semivolatile products

2007 ◽  
Vol 7 (15) ◽  
pp. 4135-4147 ◽  
Author(s):  
A. W. H. Chan ◽  
J. H. Kroll ◽  
N. L. Ng ◽  
J. H. Seinfeld
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Laboratory Data ◽  
Organic Aerosol ◽  
Formation Mechanisms ◽  
Hydrocarbon Oxidation ◽  
Phase Reaction ◽  
Particle Phase ◽  
Aerosol Formation ◽  
Kinetics Of

Abstract. The distinguishing mechanism of formation of secondary organic aerosol (SOA) is the partitioning of semivolatile hydrocarbon oxidation products between the gas and aerosol phases. While SOA formation is typically described in terms of partitioning only, the rate of formation and ultimate yield of SOA can also depend on the kinetics of both gas- and aerosol-phase processes. We present a general equilibrium/kinetic model of SOA formation that provides a framework for evaluating the extent to which the controlling mechanisms of SOA formation can be inferred from laboratory chamber data. With this model we examine the effect on SOA formation of gas-phase oxidation of first-generation products to either more or less volatile species, of particle-phase reaction (both first- and second-order kinetics), of the rate of parent hydrocarbon oxidation, and of the extent of reaction of the parent hydrocarbon. The effect of pre-existing organic aerosol mass on SOA yield, an issue of direct relevance to the translation of laboratory data to atmospheric applications, is examined. The importance of direct chemical measurements of gas- and particle-phase species is underscored in identifying SOA formation mechanisms.

scholarly journals Kinetic modeling of Secondary Organic Aerosol formation: effects of particle- and gas-phase reactions of semivolatile products

2007 ◽  
Vol 7 (3) ◽  
pp. 7051-7085 ◽  
Author(s):  
A. W. H. Chan ◽  
J. H. Kroll ◽  
N. L. Ng ◽  
J. H. Seinfeld
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Laboratory Data ◽  
Organic Aerosol ◽  
Formation Mechanisms ◽  
Hydrocarbon Oxidation ◽  
Phase Reaction ◽  
Particle Phase ◽  
Aerosol Formation ◽  
Kinetics Of

Abstract. The distinguishing mechanism of formation of secondary organic aerosol (SOA) is the partitioning of semivolatile hydrocarbon oxidation products between the gas and aerosol phases. While SOA formation is typically described in terms of partitioning only, the rate of formation and ultimate yield of SOA can also depend on the kinetics of both gas- and aerosol-phase processes. We present a general equilibrium/kinetic model of SOA formation that provides a framework for evaluating the extent to which the controlling mechanisms of SOA formation can be inferred from laboratory chamber data. With this model we examine the effect on SOA formation of gas-phase oxidation of first-generation products to either more or less volatile species, of particle-phase reaction (both first- and second-order kinetics), of the rate of parent hydrocarbon oxidation, and of the extent of reaction of the parent hydrocarbon. The effect of pre-existing organic aerosol mass on SOA yield, an issue of direct relevance to the translation of laboratory data to atmospheric applications, is examined. The importance of direct chemical measurements of gas- and particle-phase species is underscored in identifying SOA formation mechanisms.

A Confrontation between Two Doctrines: The Birth of Struggle for Hegemony in Hebrew Children's Literature during the 1930s and 1940s

2008 ◽  
Vol 1 (2) ◽  
pp. 139-155 ◽  
Author(s):  
YAEL DARR
Keyword(s):  
Children's Literature ◽  
Educational System ◽  
Single Channel ◽  
Children’S Literature ◽  
The Political ◽  
Literary Creation ◽  
History Of ◽  
High Level ◽  
First Time ◽  
Literary Quality

This article describes a crucial and fundamental stage in the transformation of Hebrew children's literature, during the late 1930s and 1940s, from a single channel of expression to a multi-layered polyphony of models and voices. It claims that for the first time in the history of Hebrew children's literature there took place a doctrinal confrontation between two groups of taste-makers. The article outlines the pedagogical and ideological designs of traditionalist Zionist educators, and suggests how these were challenged by a group of prominent writers of adult poetry, members of the Modernist movement. These writers, it is argued, advocated autonomous literary creation, and insisted on a high level of literary quality. Their intervention not only dramatically changed the repertoire of Hebrew children's literature, but also the rules of literary discourse. The article suggests that, through the Modernists’ polemical efforts, Hebrew children's literature was able to free itself from its position as an apparatus controlled by the political-educational system and to become a dynamic and multi-layered field.

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