Interactions between water and dimethylformamide in the liquid phase

Mishustin, A. I.; Kessler, Yu. M.

doi:10.1007/bf00746555

Cited by 7 publications

(6 citation statements)

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“…According to the experimental and theoretical studies, DMF forms complexes with water with a 1 : 2 or 1 : 3 composition and the degree of its self-association does not exceed a few percent. [39][40][41] Therefore, the most plausible solution microstructure is the mixture of H It should be mentioned that the described equilibrium does not affect the quantication of hydrogen peroxide in different matrices because the dependence of the integral intensity of all peaks from the hydrogen peroxide concentration is linear.…”

Section: Measurements Of Authentic Samplesmentioning

confidence: 99%

Rapid ¹H NMR determination of hydrogen peroxide in cosmetic products and chemical reagents

Monakhova

Diehl²

2016

Anal. Methods

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Section: Measurements Of Authentic Samplesmentioning

confidence: 99%

Rapid ¹H NMR determination of hydrogen peroxide in cosmetic products and chemical reagents

Monakhova

Diehl²

2016

Anal. Methods

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“…This assumption is confirmed by DTA [9]. Spectroscopic studies [10,11] suggest formation of the hydrates DMF(H 2 O) 2 in water-rich DMF3water mixtures and (DMF) 2 H 2 O in DMF-rich mixtures [6,7]. Monte Carlo simulation [12] confirms the coexistence of the heteroassociates DMF(H 2 O) 3 It should be noted that densimetry [2,3,13] is less informative in this respect, because the partial and excess volumes usually show monotonic concentration dependences.…”

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confidence: 67%

Characteristics of Heteroassociates in the System Dimethylformamide-Water, According to Data of 1H NMR Relaxation, Refractometry, Densimetry, and Acoustic Spectroscopy

et al. 2005

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The dimethylformamide3water system was studied by proton spin3spin relaxation (296 K) and refractometry (298 K), and the results in combination with published densimetric data (293 K) and data on the sound velocities (293 K) were used to simulate the associative equilibria. A consistent scheme of heteroassociative equilibria in the dimethylformamide3water system was suggested. The compositions of the heteroassociates were determined, and their stability constants (in the mole fraction scale), relaxation efficiency coefficients, limiting refractive indices, limiting sound velocities, and limiting densities were calculated.Traditional physicochemical methods often give ambiguous and contradictory data on intermolecular interactions in binary aqueous-organic systems, because the observed physicochemical property of a system is determined by a set of coexisting homo-and heteroassociates differing in the composition and stability.The viscometric data [133] and data on the sound velocity [3, 4], dielectric permittivity [5], and proton spin3lattice relaxation, obtained for the dimethylformamide (DMF)3water system, suggest the formation of stable heteroassociates DMF(H 2 O) 3 [7, 8]. This assumption is confirmed by DTA [9]. Spectroscopic studies [10, 11] suggest formation of the hydrates DMF(H 2 O) 2 in water-rich DMF3water mixtures and (DMF) 2 H 2 O in DMF-rich mixtures [6, 7]. Monte Carlo simulation [12] confirms the coexistence of the heteroassociates DMF(H 2 O) 3 , DMF(H 2 O) 2 , and DMF(H 2 O) 1 in the range of DMF mole fractions 0.0 3 0.4.It should be noted that densimetry [2, 3, 13] is less informative in this respect, because the partial and excess volumes usually show monotonic concentration dependences. However, analysis of these dependences led Scharlin et al.[13] to a conclusion that the structure of liquid water is broken owing to formation of heteroassociates, e.g., DMF(H 2 O) 2! 4 .Thus, the overwhelming majority of studies of the DMF3water system consisted in determination of the compositions of the heteroassociates and of the concentration ranges of their existence; possible schemes of heteroassociative equilibria and quantitative characteristics of such equilibria were not discussed. The only exception is the paper by Devyatov et al. [14] who examined the concentration dependence of the 1 H NMR chemical shifts in the range of DMF mole fractions 0.30 3 0.59. Based on these data, they discussed possible schemes of associative equilibria in the DMF3water system and calculated in the symmetrical mole fraction scale the stability constants of the heteroassociates DMF(H 2 O) 2 , DMF(H 2 O), and (DMF) 2 . H 2 O.In this study we examined the dimethylformamide3 water system by the methods of 1 H NMR spin3spin relaxation (296 K) and refractometry (298 K); we calculated the stability constants, relaxation efficiency coefficients, limiting refractive indices, limiting sound velocities, and limiting densities of the heteroassociates. This paper continues our studies of the structure of binary aqueous-organic systems...

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“…28 In diluted aqueous solutions, the DMF molecule is assumed to be bound by two water molecules with its amide oxygen in the first resonance structure, while the nitrogen atom cannot take part in the formation of hydrogen bonds for its free electron being protected by two methyl groups (see Figure 5). 29 The ratios between the number of hydrogen bonds to one and two water molecules increase with w DMF . Therefore, the dimer DMF•H 2 O seems to be Table 5.…”

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confidence: 99%

Enthalpies of Dilution of Penicillamines in N,N-Dimethylformamide + Water Mixtures at 298.15 K

Cheng

Zeng

et al. 2012

J. Chem. Eng. Data

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Dilution enthalpies of two penicillamine enantiomers, namely, d-penicillamine, l-penicillamine, and their racemate d,l-penicillamine, in N,N-dimethylformamide (DMF) + water mixtures of various compositions have been determined at 298.15 K respectively, using an isothermal titration calorimeter (MicroCal ITC200). According to the McMillan–Mayer theory, homochiral enthalpic pairwise interaction coefficients (h XX) of the three penicillamines in DMF + water mixtures of different mass fractions (w DMF = 0 to 0.3) have been calculated regressively. It is found that h XX coefficients of each enantiomer and their racemate change increasingly with w DMF to the maxima at w DMF = 0.20 and then decrease relatively rapidly, which follows the order h LL > h DD ≈ h RR > 0 (R represents the racemate mixture of penicillamine). The results are discussed from the point of view of competitive equilibrium between hydrophobic and hydrophilic interactions in solutions.

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Interactions between water and dimethylformamide in the liquid phase

Cited by 7 publications

References 9 publications

Rapid ¹H NMR determination of hydrogen peroxide in cosmetic products and chemical reagents

Rapid ¹H NMR determination of hydrogen peroxide in cosmetic products and chemical reagents

Characteristics of Heteroassociates in the System Dimethylformamide-Water, According to Data of 1H NMR Relaxation, Refractometry, Densimetry, and Acoustic Spectroscopy

Enthalpies of Dilution of Penicillamines in N,N-Dimethylformamide + Water Mixtures at 298.15 K

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Interactions between water and dimethylformamide in the liquid phase

Cited by 7 publications

References 9 publications

Rapid 1H NMR determination of hydrogen peroxide in cosmetic products and chemical reagents

Rapid 1H NMR determination of hydrogen peroxide in cosmetic products and chemical reagents

Characteristics of Heteroassociates in the System Dimethylformamide-Water, According to Data of 1H NMR Relaxation, Refractometry, Densimetry, and Acoustic Spectroscopy

Enthalpies of Dilution of Penicillamines in N,N-Dimethylformamide + Water Mixtures at 298.15 K

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Rapid ¹H NMR determination of hydrogen peroxide in cosmetic products and chemical reagents

Rapid ¹H NMR determination of hydrogen peroxide in cosmetic products and chemical reagents