The effect of temperature on association constants and conductivities of ferrous chloride and ferric chloride in DMF-water mixtures

Ergin, Süheyla Pura

doi:10.5155/eurjchem.3.4.399-403.675

Cited by 6 publications

(3 citation statements)

References 30 publications

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“…DMF is miscible with water in all proportions but has a considerably higher boiling point and, consequently, a slower rate of evaporation than water . DMF and its aqueous mixtures are used in the production of resins, acrylic fibers, synthetic leathers, plastics, pesticides and adhesives, cellulosic biomass processing, as well as in electrochemical applications, − hydrolysis of highly charged metal ions, electrospinning, − synthesis of various nanoparticles, − and various organic syntheses − including microwave-enhanced reactions. , Further, DMF is one of the smallest molecules that contain the peptide bond; thus, its aqueous solutions often serve as biomimetic models of hydrated proteins. − …”

Section: Introductionmentioning

confidence: 99%

Local Structure of DMF–Water Mixtures, as Seen from Computer Simulations and Voronoi Analysis

et al. 2022

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Molecular dynamics simulations of mixtures of N,N-dimethylformamide (DMF) with water of various compositions, covering the entire composition range, are performed on the canonical (N,V,T) ensemble. The local structure of the mixtures is analyzed in terms of radial distribution functions and the contributions of the first five neighbors to them, various order parameters of the water molecules around each other, and properties of the Voronoi polyhedra of the molecules. The analyses lead to the following main conclusions. The two molecules are mixing with each other even on the molecular scale; however, small self-aggregates of both components persist even at their small mole fraction values. In particular, water–water H-bonds exist in the entire composition range, while water clusters larger than 3 and 2 molecules disappear above the DMF mole fraction values of about 0.7 and 0.9, respectively. The O atoms of the DMF molecules can well replace water O atoms in the hydrogen-bonding network. Further, the H-bonding structure is enhanced by the presence of the hydrophobic CH3 groups of the DMF molecules. On the other hand, the H-bonding network of the molecules gradually breaks down upon the addition of DMF to the system due to the lack of H-donating groups of the DMF molecules. Finally, in neat DMF, the molecules form weak, CH-donated H-bonds with each other; however, these H-bonds disappear upon the addition of water due to the increasing competition with the considerably stronger OH-donated H-bonds DMF can form with the water molecules.

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Section: Introductionmentioning

confidence: 99%

Local Structure of DMF–Water Mixtures, as Seen from Computer Simulations and Voronoi Analysis

et al. 2022

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“…Indeed, these mixtures are widely used in a number of fields both in chemistry and in the chemical industry. The areas of chemical and industrial applications include electrospinning, − electrochemistry, − synthesis of various nanoparticles ,− and organic molecules, − including microwave-enhanced reactions, − hydrolysis of highly charged metal ions, as well as cellulosic biomass processing, and the production of, among others, adhesives, fibers, pesticides, plastics, and synthetic leathers . Many of these applications involve, besides the bulk liquid phase, also the surface of DMF–water mixtures.…”

Section: Introductionmentioning

confidence: 99%

Surface Properties of N,N-Dimethylformamide–Water Mixtures, As Seen from Computer Simulations

et al. 2023

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The liquid–vapor interface of N,N-dimethylformamide (DMF)–water mixtures, spanning the entire composition range, is investigated in detail at 298 K by molecular dynamics simulation and intrinsic surface analysis. DMF molecules are found to adsorb strongly at the liquid surface, but this adsorption extends only to the first molecular layer. Water and DMF molecules mix with each other on the molecular scale even in the surface layer; thus, no marked self-association of any of the components is seen at the liquid surface. The major surface component prefers such orientation in which the molecular dipole vector lays parallel with the macroscopic plane of the surface. On the other hand, the preferred orientation of the minor component is determined, at both ends of the composition range, by the possibility of H-bond formation with the major component. The lack of H-donating ability of DMF leads to a rapid breakup of the percolating H-bond network at the surface; due to the strong adsorption of DMF, this breakup occurs below the bulk phase DMF mole fraction of 0.03. The disruption of the surface H-bond network also accelerates the exchange of both species between the liquid surface and bulk liquid phase, although, for water, this effect becomes apparent only above a bulk phase DMF mole fraction of 0.4. H-bonds formed by a DMF and a water molecule live, on average, 25–60% longer than those formed by two water molecules at the liquid surface. A similar, but smaller (i.e., about 10–20%) difference is seen in the bulk liquid phase. The enhanced surface mobility of the molecules results in 2–6 times larger diffusion coefficient and 2–5 times shorter H-bond lifetime values at the liquid surface than in the bulk liquid phase. The diffusion of both molecules is slowed down in the presence of the other species; in the case of DMF, this effect is caused by the formation of water–DMF H-bonds, whereas for water, steric hindrances imposed by the bulky DMF neighbors are responsible for this slowing down.

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“…Besides its theoretical importance, DMF is also a widely used solvent in a number of laboratory and industrial processes, such as in the hydrolytic reactions of highly charged metal ions, various organic syntheses − including microwave-enhanced reactions, , electrochemical applications, − synthesis of various nanoparticles, − and electrospinning. − This wide range of applications is enabled by the aforementioned interplay of the various interactions occurring in aqueous DMF solutions.…”

Section: Introductionmentioning

confidence: 99%

Calculation of the Free Energy of Mixing as a Tool for Assessing and Improving Potential Models: The Case of the N,N-Dimethylformamide–Water System

2021

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The Helmholtz free energy, energy, and entropy of mixing of N,N-dimethylformamide (DMF) and water are calculated in the entire composition range by means of Monte Carlo computer simulations and thermodynamic integration using all possible combinations of five DMF and three widely used water models. Our results reveal that the mixing of DMF and water is highly non-ideal. Thus, in their dilute solutions, both molecules induce structural ordering of the major component, as evidenced by the concomitant decrease in the entropy. Among the 15 model combinations considered, only 4 reproduce the well-known full miscibility of DMF and water, 3 of which strongly exaggerate the thermodynamic driving force of the miscibility. Thus, the combination of the CS2 model of DMF and the TIP4P/2005 water model reproduces the properties of the DMF–water mixtures far better than the other combinations tested. Our results also reveal that moving a fractional negative charge from the N atom to the O atom of the DMF molecule, leading to the increase in its dipole moment, improves the miscibility of the model with water. Starting from the CS2 model and optimizing the charge to be moved, we propose a new model of DMF that reproduces very accurately both the Helmholtz free energy of mixing of aqueous DMF solutions in the entire composition range (when used in combination with the TIP4P/2005 water model) and also the internal energy of neat DMF.

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The effect of temperature on association constants and conductivities of ferrous chloride and ferric chloride in DMF-water mixtures

Cited by 6 publications

References 30 publications

Local Structure of DMF–Water Mixtures, as Seen from Computer Simulations and Voronoi Analysis

Local Structure of DMF–Water Mixtures, as Seen from Computer Simulations and Voronoi Analysis

Surface Properties of N,N-Dimethylformamide–Water Mixtures, As Seen from Computer Simulations

Calculation of the Free Energy of Mixing as a Tool for Assessing and Improving Potential Models: The Case of the N,N-Dimethylformamide–Water System

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