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Special Issue "Solution Chemical Kinetics 2019"

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Physical Chemistry and Chemical Physics".

Deadline for manuscript submissions: 31 January 2020.

Special Issue Editor

Prof. Dr. Malcolm D´Souza
E-Mail Website
Guest Editor
Dean of Interdisciplinary/Collaborative Sponsored Research, Department of Chemistry, Wesley College, 120 N. State Street, Dover, DE 19901-3875, USA
Tel. +1-302-736-2301; Fax: +1 302-736-2301
Interests: chemical kinetics; solvolysis; LFERs (Linear Free Energy Relationships); QSARs (Quantitative Structure Activity Relationships); database user-needs analysis (database building)

Special Issue Information

Dear Colleagues,

In solutions, there are enormous numbers of solvent molecules that are in constant kinetic interaction with other solute reactants and amongst themselves. The quantitative study of these coupled collisions as a function of time, the stoichiometry of such chemical encounters, and any resultant changes in energy or in covalent and noncovalent chemical structures is relevant, complex, and interesting to chemical, biological, and environmental systems. This IJMS Special Issue is dedicated to papers that examine the significance and enhance our basic understanding of chemical reaction kinetics, molecular reaction dynamics, and reaction mechanisms that occur in solutions.

Related closed Special Issue in 2015: "Solution Chemical Kinetics".

Prof. Dr. Malcolm D´Souza
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

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Keywords

  • Chemical kinetics
  • Reaction mechanisms
  • Thermodynamics
  • Molecular reaction dynamics
  • Homogenous solutions
  • Equilibrium
  • Solution/solid interface
  • Arrehenius equation
  • Free energy
  • Hydrolysis
  • Solvolysis
  • Steady-state approximation

Published Papers (5 papers)

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Research

Open AccessArticle
The Effect of the ortho Nitro Group in the Solvolysis of Benzyl and Benzoyl Halides
Int. J. Mol. Sci. 2019, 20(16), 4026; https://doi.org/10.3390/ijms20164026 - 18 Aug 2019
Abstract
A kinetic study was carried out on the solvolysis of o-nitrobenzyl bromide (o-isomer, 1) and p-nitrobenzyl bromide (p-isomer, 3), and o-nitrobenzoyl chloride (o-isomer, 2) in a wide range of solvents under [...] Read more.
A kinetic study was carried out on the solvolysis of o-nitrobenzyl bromide (o-isomer, 1) and p-nitrobenzyl bromide (p-isomer, 3), and o-nitrobenzoyl chloride (o-isomer, 2) in a wide range of solvents under various temperatures. In all of the solvents without aqueous fluoroalcohol, the reactions of 1 were solvolyzed at a similar rate to those observed for 3, and the reaction rates of 2 were about ten times slower than those of the previously studied p-nitrobenzoyl chloride (p-isomer, 4). For solvolysis in aqueous fluoroalcohol, the reactivity of 2 was kinetically more reactive than 4. The l/m values of the extended Grunwald–Winstein (G–W) equation for solvolysis of 1 and 2 in solvents without fluoroalcohol content are all significantly larger than unity while those in all the fluoroalcohol solvents are less than unity. The role of the ortho-nitro group as an intramolecular nucleophilic assistant (internal nucleophile) in the solvolytic reaction of 1 and 2 was discussed. The results are also compared with those reported earlier for o-carbomethoxybenzyl bromide (5) and o-nitrobenzyl p-toluenesulfonate (7). From the product studies and the activation parameters for solvolyses of 1 and 2 in several organic hydroxylic solvents, mechanistic conclusions are drawn. Full article
(This article belongs to the Special Issue Solution Chemical Kinetics 2019)
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Open AccessArticle
Reaction Kinetic Models of Antibiotic Heteroresistance
Int. J. Mol. Sci. 2019, 20(16), 3965; https://doi.org/10.3390/ijms20163965 - 15 Aug 2019
Abstract
Bacterial heteroresistance (i.e., the co-existence of several subpopulations with different antibiotic susceptibilities) can delay the clearance of bacteria even with long antibiotic exposure. Some proposed mechanisms have been successfully described with mathematical models of drug-target binding where the mechanism’s downstream of drug-target binding [...] Read more.
Bacterial heteroresistance (i.e., the co-existence of several subpopulations with different antibiotic susceptibilities) can delay the clearance of bacteria even with long antibiotic exposure. Some proposed mechanisms have been successfully described with mathematical models of drug-target binding where the mechanism’s downstream of drug-target binding are not explicitly modeled and subsumed in an empirical function, connecting target occupancy to antibiotic action. However, with current approaches it is difficult to model mechanisms that involve multi-step reactions that lead to bacterial killing. Here, we have a dual aim: first, to establish pharmacodynamic models that include multi-step reaction pathways, and second, to model heteroresistance and investigate which molecular heterogeneities can lead to delayed bacterial killing. We show that simulations based on Gillespie algorithms, which have been employed to model reaction kinetics for decades, can be useful tools to model antibiotic action via multi-step reactions. We highlight the strengths and weaknesses of current models and Gillespie simulations. Finally, we show that in our models, slight normally distributed variances in the rates of any event leading to bacterial death can (depending on parameter choices) lead to delayed bacterial killing (i.e., heteroresistance). This means that a slowly declining residual bacterial population due to heteroresistance is most likely the default scenario and should be taken into account when planning treatment length. Full article
(This article belongs to the Special Issue Solution Chemical Kinetics 2019)
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Open AccessArticle
Activity Coefficients for Liquid Organic Reactions: Towards a Better Understanding of True Kinetics with the Synthesis of Jasmin Aldehyde as Showcase
Int. J. Mol. Sci. 2019, 20(15), 3819; https://doi.org/10.3390/ijms20153819 - 05 Aug 2019
Abstract
The aldol condensation of benzaldehyde and heptanal is taken as an example of reversible liquid phase organic reactions to show that inclusion of activity coefficients reveal distinct differences in conversion and product distribution when different solvents methanol, ethanol, n-propanol, or n-butanol are used. [...] Read more.
The aldol condensation of benzaldehyde and heptanal is taken as an example of reversible liquid phase organic reactions to show that inclusion of activity coefficients reveal distinct differences in conversion and product distribution when different solvents methanol, ethanol, n-propanol, or n-butanol are used. The purpose of this work is to show a pronounced solvent effect for a given set of identical kinetic parameters, i.e., the same liquid phase kinetics can result in different conversion and yield values, depending on the choice of solvent. It was shown that subsequent parameter estimation without inclusion of the activity coefficients resulted in a pronounced deviation from the ‘true’ kinetics, up to a factor of 30. It is proposed that the usage of average activity coefficients gives already a significant improvement, resulting in acceptable parameter estimates. Full article
(This article belongs to the Special Issue Solution Chemical Kinetics 2019)
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Open AccessArticle
Effect of Water Chemistry on Antimony Removal by Chemical Coagulation: Implications of ζ-Potential and Size of Precipitates
Int. J. Mol. Sci. 2019, 20(12), 2945; https://doi.org/10.3390/ijms20122945 - 17 Jun 2019
Abstract
The process of coagulation and precipitation affect the fate and mobility of antimony (Sb) species in drinking water. Moreover, the solubility and physico-chemical properties of the precipitates may be affected by the media chemistry. Accordingly, the present study aimed to investigate the removal [...] Read more.
The process of coagulation and precipitation affect the fate and mobility of antimony (Sb) species in drinking water. Moreover, the solubility and physico-chemical properties of the precipitates may be affected by the media chemistry. Accordingly, the present study aimed to investigate the removal of Sb(III, V) species by ferric chloride coagulation under various water chemistry influences with a particular focus on the role of the properties of the precipitates. The results indicated that the amount of Sb(III) removed increased with increasing solution pH, showing the insignificant effects of the hydrodynamic diameter (HDD) and ζ-potential of the precipitates. However, no Sb(V) removal occurred at alkaline pH values, while a highly negative ζ-potential and the complete dissolution of precipitates were observed in the aqueous solution. The solution pH was also useful in determining the dominant coagulation mechanisms, such as co-precipitation and adsorption. The Fe solubility substantially affects the Sb removal at a certain pH range, while the HDD of the precipitates plays an insignificant role in Sb removal. The presence of divalent cations brings the ζ-potential of the precipitates close to point of zero charge (pzc), thus enhancing the Sb(V) removal at alkaline pH conditions. Pronounced adverse effects of humic acid were observed on Sb removal, ζ-potential and HDD of the precipitates. In general, this study may provide critical information to a wide group of researchers dealing with environmental protection from heavy metal pollution. Full article
(This article belongs to the Special Issue Solution Chemical Kinetics 2019)
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Open AccessArticle
Mechanisms of Iodide–Triiodide Exchange Reactions in Ionic Liquids: A Reactive Molecular-Dynamics Exploration
Int. J. Mol. Sci. 2019, 20(5), 1123; https://doi.org/10.3390/ijms20051123 - 05 Mar 2019
Abstract
Efficient charge transport has been observed in iodine-doped, iodide-based room-temperature ionic liquids, yielding high ionic conductivity. To elucidate preferred mechanistic pathways for the iodide ( I )-to-triiodide ( I 3 ) exchange reactions, we have performed 10 ns reactive molecular-dynamics calculations [...] Read more.
Efficient charge transport has been observed in iodine-doped, iodide-based room-temperature ionic liquids, yielding high ionic conductivity. To elucidate preferred mechanistic pathways for the iodide ( I )-to-triiodide ( I 3 ) exchange reactions, we have performed 10 ns reactive molecular-dynamics calculations in the liquid state for 1-butyl-3-methylimidazolium iodide ([BMIM][I]) at 450 to 750 K. Energy-barrier distributions for the iodine-swapping process were determined as a function of temperature, employing a charge-reassignment scheme drawn in part from electronic-structure calculations. Bond-exchange events were observed with rate-determining energy barriers ranging from ~0.19 to 0.23 ± 0.06 eV at 750 and 450 K, respectively, with an approximately Arrhenius temperature dependence for iodine self-diffusivity and reaction kinetics, although diffusion dominates/limits the bond-exchange events. This charge transfer is not dissimilar in energetics to those in solid-state superionic conductors. Full article
(This article belongs to the Special Issue Solution Chemical Kinetics 2019)
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