X-ray diffraction study of formic, acetic, and propionic acids in the liquid state

Горбунова, Т В; Шилов, В. В.; Batalin, G. I.

doi:10.1007/bf00746986

Cited by 19 publications

(15 citation statements)

References 23 publications

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“…For ACA, some spectroscopic studies have been interpreted as indicating a predominance of dimers, [11][12][13][14][15][16] while other studies using the same techniques suggest an equilibrium between a variety of hydrogen-bonded complexes, such as dimers, other oligomers and chains. [17][18][19][20][21][22][23] More recent spectroscopic studies agree with the latter interpretation. [24][25][26] In an Xray diffraction study, [20] it was observed that the ratio between dimers and chains is shifted towards dimers in the case of PPA compared to ACA.…”

Section: Introductionmentioning

confidence: 68%

“…[17][18][19][20][21][22][23] More recent spectroscopic studies agree with the latter interpretation. [24][25][26] In an Xray diffraction study, [20] it was observed that the ratio between dimers and chains is shifted towards dimers in the case of PPA compared to ACA. In contrast, the methyl esters of monocarboxylic fatty acids have been found by theoretical calculations to be relatively structureless in the liquid phase.…”

Section: Introductionmentioning

confidence: 68%

“…This is in line with the experimental observations that PPA crystallises in dimers while ACA crystallises in chains, [7,10] and that the proportion of dimers versus chains is shifted towards dimers when going from ACA to PPA. [20] For both compounds, a temperature increase leads to a reduction of the total number of hydrogen bonds caused by increased thermal motion. At all fields, this change is accompanied by an increase in the population of dimers.…”

Section: Hydrogen-bonded Structuresmentioning

confidence: 99%

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Temperature Dependence of the Dielectric Permittivity of Acetic Acid, Propionic Acid and Their Methyl Esters: A Molecular Dynamics Simulation Study

et al. 2012

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For most liquids, the static relative dielectric permittivity is a decreasing function of temperature, because enhanced thermal motion reduces the ability of the molecular dipoles to orient under the effect of an external electric field. Monocarboxylic fatty acids ranging from acetic to octanoic acid represent an exception to this general rule. Close to room temperature, their dielectric permittivity increases slightly with increasing temperature. Herein, the causes for this anomaly are investigated based on molecular dynamics simulations of acetic and propionic acids at different temperatures in the interval 283-363 K, using the GROMOS 53A6(OXY) force field. The corresponding methyl esters are also considered for comparison. The dielectric permittivity is calculated using either the box-dipole fluctuation (BDF) or the external electric field (EEF) methods. The normal and anomalous temperature dependences of the permittivity for the esters and acids, respectively, are reproduced. Furthermore, in the EEF approach, the response of the acids to an applied field of increasing strength is found to present two successive linear regimes before reaching saturation. The low-field permittivity ε, comparable to that obtained using the BDF approach, increases with increasing temperature. The higher-field permittivity ε' is slightly larger, and decreases with increasing temperature. Further analyses of the simulations in terms of radial distribution functions, hydrogen-bonded structures, and diffusion properties suggest that increasing the temperature or the applied field strength both promote a relative population shift from cyclic (mainly dimeric) to extended (chain-like) hydrogen-bonded structures. The lower effective dipole moment associated with the former structures compared to the latter ones provides an explanation for the peculiar dielectric properties of the two acids compared to their methyl esters.

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Section: Introductionmentioning

confidence: 68%

Section: Introductionmentioning

confidence: 68%

Section: Hydrogen-bonded Structuresmentioning

confidence: 99%

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Temperature Dependence of the Dielectric Permittivity of Acetic Acid, Propionic Acid and Their Methyl Esters: A Molecular Dynamics Simulation Study

et al. 2012

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“…Finally we note that the method exploited here, based on the the quenching of the vibrational progression in RIXS, can be used for structure investigations with some generality: We have found that the intensity of the OH vibrational progression can be used as the "ruler " of the chain length. X-ray diffraction 21 shows that the ratio between dimers and chains is shifted towards dimers in the case of liquid propionic acids compared to ACA, and the proposed structure may be validated with this new method. We envision applications to a variety of liquids, such as formic acid, methyl acetate, and methyl propionate in the near future.…”

Section: Discussionmentioning

confidence: 85%

Vibrational Resonant Inelastic X-Ray Scattering Inliquid Acetic Acid: A Ruler for Molecular Chain Lengths

Savchenko

Brumboiu

Kimberg

et al. 2020

Preprint

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Quenching of vibrational excitations in resonant inelastic X-ray scattering (RIXS) spectra of liquid acetic acid is observed. At the oxygen core resonance associated with localized excitations at the O-H bond, the spectra lack the typical progressionof vibrational excitations observed in RIXS spectra of comparable systems. We interpret this phenomenon as due to strong rehybridization of the unoccupied molecular orbitals as a result of hydrogen bonding. This allows us to address the molecular structure of the liquid, and to determine a lower limit for the average molecular chain length.

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“…However, the type of association (cyclic dimers or chain entities) in liquid acetic acid remains an open question. IR and Raman spectroscopy data suggest the formation of dimers and several types of chain oligomers [6]. NMR and neutron diffraction data do not contradict the assumption about the presence of cyclic dimers [7][8][9].…”

mentioning

confidence: 97%

Effect of dielectric screening on positronium formation in acetone-acetic acid polar solvent blends

2005

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The influence of polarization of a medium in the vicinity of the positron-electron pair produced at the end of a fast-positron track on the formation of positronium (Ps) was considered. Weakening interaction between the positron and electron, polarization leads to a decrease in the Ps formation probability. The transience of Ps formation requires that the time delay of medium polarization should be taken into account. In turn, the magnitude of dielectric screening in acetone-acetic acid mixtures strongly depends on the ratio between the amounts of polar monomeric acetic acid and its nonpolar dimer. Sequentially taking account of these effects, it is possible to explain both the complex behavior of the Ps yield and the dependence of dielectric permittivity of the mixture on its composition.

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X-ray diffraction study of formic, acetic, and propionic acids in the liquid state

Cited by 19 publications

References 23 publications

Temperature Dependence of the Dielectric Permittivity of Acetic Acid, Propionic Acid and Their Methyl Esters: A Molecular Dynamics Simulation Study

Temperature Dependence of the Dielectric Permittivity of Acetic Acid, Propionic Acid and Their Methyl Esters: A Molecular Dynamics Simulation Study

Vibrational Resonant Inelastic X-Ray Scattering Inliquid Acetic Acid: A Ruler for Molecular Chain Lengths

Effect of dielectric screening on positronium formation in acetone-acetic acid polar solvent blends

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