Non-ideality of binary mixtures Water[ndash ]methanol and water[ndash ]acetonitrile from the viewpoint of clustering structure

Wakisaka, Akihiro; Abdoul‐Carime, H.; Yamamoto, Yoshitaka; Kiyozumi, Yoshimichi

doi:10.1039/a705777f

Cited by 147 publications

(126 citation statements)

References 15 publications

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“…On the basis of comparative studies of many aqueous systems Matteoli and Lepori stated that the hydrophilic group of acetonitrile reduces its hydrophobicity almost as strong as the OH or NH 2 groups do [1]. Let us note that the series of hydrophilic character of different groups proposed by Matteoli and Lepori is in contradiction with findings of Wakisaka et al [2], while according to the former authors methanol and acetonitrile should be similar in hydrophobic character (methanol should be even weaker). The number of authors who are in favour of unquestionable hydrophobic character of interactions of ACN with water is, however, prevailing.…”

Section: Introductioncontrasting

confidence: 53%

Structure of Aqueous Solutions of Acetonitrile Investigated by Acoustic and Positron Annihilation Measurements

et al. 2005

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We report the results of acoustic and positron annihilation measurements in aqueous solutions of acetonitrile (CH 3 CN). Hydrophobicity of the solute is discussed, as well as the possibility of describing the title system in terms of hydrophobic solvation. The concept of Levay et al. of calculating the "ideal" positronium lifetimes is applied, basing on the mean volume of cavities (holes) in liquid structure available for positronium pseudoatom. The same calculations performed using the Tao model of annihilation yield very different results. It can be concluded that either acetonitrile forms with water clathrate-like hydrates of untypical architecture, or it is too weak hydrophobic agent to form clathrate-like hydrates at all. The former interpretation seems to be more probable.

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Section: Introductioncontrasting

confidence: 53%

Structure of Aqueous Solutions of Acetonitrile Investigated by Acoustic and Positron Annihilation Measurements

et al. 2005

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“…Both acetonitrile and dimethyl sulfoxide (DMSO) are aprotic and dipolar solvents, and they are miscible with water at any mixing ratio. However, their thermodynamic properties for mixing with water are completely different: endothermic for acetonitrile-water 4 and exothermic for DMSO-water, 9 as shown in Figure 1. This suggests that the microscopic structures will be quite different in these aqueous binary mixtures.…”

Section: Resultsmentioning

confidence: 99%

“…For the aqueous alcohol solutions (Figure 9 a-d), the clusters composed of one alcohol molecule and twenty water molecules have the magic-number property, whereas for the aqueous phenol solution (Figure 9e), the cluster composed of one phenol molecule and twenty-one water molecules shows the magic-number property. 4 In consideration of the difference in the magic number properties and taking into account the similarity of mass distribution for each series of clusters, the difference in the interactions of alcohol and phenol with water clusters may be rationalized as follows. Alcohol has substitutional interaction with water clusters, that is, a hydrogen-bonding H 2 O in a water cluster is replaced by the alcohol, ROH.…”

Section: Solvation-controlling Factors In Acetonitrile-water and Dmsomentioning

confidence: 99%

“…The deviation from the thermodynamically ideal binary mixing system will be borne out as a microscopic structure, where water and organic solvent molecules are not homogeneously mixed at the cluster level. 4 When a solute is dissolved in such a nonideal binary mixture, the solvent composition in the solvation shell will not correspond to the mixing ratio of the binary solvent. As a consequence, preferential solvation takes place easily in these nonideal binary mixtures.…”

Section: Introductionmentioning

confidence: 99%

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On the Origin of Microheterogeneity: Mass Spectrometric Studies of Acetonitrile−Water and Dimethyl Sulfoxide−Water Binary Mixtures (Part 2)

et al. 2002

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The microscopic structures of acetonitrile-water and DMSO-water binary mixed solvents and their influence on the solvation for solutes (some alcohols and phenol) have been studied on the basis of the cluster structures observed through a specially designed mass spectrometer. In acetonitrile-water mixtures, the water clusters were observed at water mole fractions: X w > 0.2; on the other hand, in DMSO-water mixtures, the water clusters were observed only at much higher water mole fractions: X w > 0.93. In the mixing processes, the water clusters were stabilized in the acetonitrile-water mixtures, whereas the DMSO clusters were stabilized in the DMSO-water mixtures. It is demonstrated that these microscopic structures directly affect the solvation for alcohols and phenol in these binary mixed solvents.

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“…[18][19][20][21][22][23] Experimental studies, employing a wide range of experimental techniques, have thus far been inconclusive. [24][25][26] Neutron and X-ray diffraction studies of methanol-and ethanol-water mixtures have concluded that incomplete mixing alone can explain the negative excess entropy of mixing.…”

Section: -17mentioning

confidence: 99%

Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

Lam

Smith

Saykally

2016

The Journal of Chemical Physics

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While methanol and ethanol are macroscopically miscible with water, their mixtures exhibit negative excess entropies of mixing. Despite considerable effort in both experiment and theory, there remains significant disagreement regarding the origin of this effect. Different models for the liquid mixture structure have been proposed to address this behavior, including the enhancement of the water hydrogen bonding network around the alcohol hydrophobic groups and microscopic immiscibility or clustering. We have investigated mixtures of methanol, ethanol, and isopropanol with water by liquid microjet X-ray absorption spectroscopy on the oxygen K-edge, an atomspecific probe providing details of both inter-and intra-molecular structure. The measured spectra evidence a significant enhancement of hydrogen bonding originating from the methanol and ethanol hydroxyl groups upon the addition of water. These additional hydrogen bonding interactions would strengthen the liquid-liquid interactions, resulting in additional ordering in the liquid structures and leading to a reduction in entropy and a negative enthalpy of mixing, consistent with existing thermodynamic data. In contrast, the spectra of the isopropanol-water mixtures exhibit an increase in the number of broken alcohol hydrogen bonds for mixtures containing up to 0.5 water mole fraction, an observation consistent with existing enthalpy of mixing data, suggesting that the measured negative excess entropy is a result of clustering or micro-immiscibility. Published by AIP Publishing. [http://dx

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Non-ideality of binary mixtures Water[ndash ]methanol and water[ndash ]acetonitrile from the viewpoint of clustering structure

Cited by 147 publications

References 15 publications

Structure of Aqueous Solutions of Acetonitrile Investigated by Acoustic and Positron Annihilation Measurements

Structure of Aqueous Solutions of Acetonitrile Investigated by Acoustic and Positron Annihilation Measurements

On the Origin of Microheterogeneity: Mass Spectrometric Studies of Acetonitrile−Water and Dimethyl Sulfoxide−Water Binary Mixtures (Part 2)

Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

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