Pressure and Temperature Effects on the Molecular Rotation in Acetonitrile-Water Mixtures

Ueno, Masakatsu; Ueyama, Satoshi; Hashimoto, Shigenori; Tsuchihashi, Noriaki; Ibuki, Kazuyasu

doi:10.1023/b:josl.0000043644.72771.b3

Cited by 20 publications

(12 citation statements)

References 42 publications

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“…The E a value for pure D 2 O was estimated to be 21.92 ± 0.04 kJ mol −1 as depicted by the dashed line. The value for pure D 2 O is comparable with that (22.5 kJ mol −1 ) previously reported . Figure indicates that the E a value for the EMI + BF 4 − −D 2 O solution at x D 2 O = 0.10 is much larger than that for bulk, suggesting that the rotational motion of water molecules is strongly restricted in the inherent structure of EMI + BF 4 − due to the bridged-structure of BF 4 − ···DOD···BF 4 − by hydrogen bonding .…”

Section: Resultssupporting

confidence: 86%

Effect of Water on Structure of Hydrophilic Imidazolium-Based Ionic Liquid

et al. 2009

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The state of water in room-temperature ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI(+)BF(4)(-)), has been investigated by measurements of absorption and desorption isotherms, attenuated total reflectance infrared (ATR-IR) spectroscopy, and (2)H NMR relaxation method. The absorption enthalpies of water for the ionic liquid were estimated from the absorption isotherms. The enthalpies in the water mole fraction range of x(w) approximately 0.3. In addition, the activation energies for the rotational motion of a water molecule estimated from the (2)H NMR relaxation rates have indicated that the motion of water molecules in EMI(+)BF(4)(-)-D(2)O solutions gradually becomes freer with increasing water content from x(w) = 0.10 to 0.30, but is retarded again at x(w) = 0.33. Therefore, all the present findings have suggested that the state of water molecules in EMI(+)BF(4)(-) significantly changes at x(w) approximately 0.3. On the other hand, to directly observe the effect of water on structure of EMI(+)BF(4)(-), LAXS experiments have been made on EMI(+)BF(4)(-)-water solutions. It has been suggested that the interactions between the C(2) atom within the imidazolium ring of EMI(+) and BF(4)(-) are strengthened with increasing water content, while those at the C(4) and C(5) atoms weaken. Thus, the present LAXS experiments have clarified the beginning of formation of ion pair in EMI(+)BF(4)(-) by adding water at the molecular level.

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Section: Resultssupporting

confidence: 86%

Effect of Water on Structure of Hydrophilic Imidazolium-Based Ionic Liquid

et al. 2009

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“…at 5 to 35 °C for 2 H spin‐lattice relaxation measurements in AN + D 2 O mixtures, shifting to lower values of x AN as the temperature decreased. Such maxima were observed in a 14 N spin‐lattice relaxation study at 30 °C and varying pressures up to 294 MPa also by Ueno et al ., the x AN values for the maximum shifting to higher ones as the pressure was increased. The decrease of τ c beyond this maximum was ascribed to the formation of AN oligomer aggregates, in which the AN–AN interaction is weaker than the AN–W one.…”

Section: Results From Spectroscopic Studiesmentioning

confidence: 99%

“…The fractions of free (not hydrogen bonded to water) and bound AN molecules obtained from 14 N NMR spin‐lattice relaxation measurements (“present study”) of Dawson and Wallen and from FT Raman C≡N stretch signal measurements of Reimers and Hall, from ref. 71 by permission of the publisher, Elsevier…”

Section: Results From Spectroscopic Studiesmentioning

confidence: 99%

The structure of and interactions in binary acetonitrile + water mixtures

Marcus

2012

J of Physical Organic Chem

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Binary liquid mixtures of acetonitrile (AN) and water (W) are widely used as reaction media in such fields of chemistry as physical organic chemistry, reverse phase liquid chromatography, and electrochemistry, among others. Much information on the structure of these systems and the interactions in them has accumulated since the author's often quoted comprehensive 1990 paper, so that a review is merited. Macroscopic physical properties, results from diffraction and spectroscopic studies, theoretical considerations and computer simulations, and results from the use of solute probes all bear on the structure (and less so on the dynamics) of the mixtures. These are discussed in terms of the microheterogeneity that occurs in them at intermediate contents (that leads eventually to liquid-liquid phase separation).

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“…But with the decrease of acetonitrile content, the acetonitrile clusters would be disrupted when the X AN of the mixtures becomes lower than 0.2. 10,47 This means more single acetonitrile molecules exists and is surrounded by water molecules at X AN < 0.2. When pressure is increased and the solidication point is approaching, there may be some uctuations of density or concentration and nal aggregation of same molecules to clusters.…”

Section: Resultsmentioning

confidence: 99%