Thermodynamics of amide+ketone mixtures. 2. Volumetric, speed of sound and refractive index data for N,N-dimethylacetamide+2-alkanone systems at several temperatures. Application of Flory's model to tertiary amide+n-alkanone systems
Ana Cobos, Juan Antonio González, Fernando Hevia, Isaías García de la Fuente, Cristina Alonso Tristán
{"title":"Thermodynamics of amide+ketone mixtures. 2. Volumetric, speed of sound and refractive index data for N,N-dimethylacetamide+2-alkanone systems at several temperatures. Application of Flory's model to tertiary amide+n-alkanone systems","authors":"Ana Cobos, Juan Antonio González, Fernando Hevia, Isaías García de la Fuente, Cristina Alonso Tristán","doi":"arxiv-2409.11309","DOIUrl":null,"url":null,"abstract":"Data on density, $\\rho$, speed of sound, $c$, and refractive index,\n$n_{\\text{D}}$, have been reported at (293-303.15) K for the\nN,N-dimethylacetamide (DMA) + CH$_3$CO(CH$_2$)$_{u-1}$CH$_3$ ($u$ = 1, 2, 3)\nsystems, and at 298.15 K for the mixture with $u$ = 5. These data have been\nused to compute excess molar volumes, $V_{\\text{m}}^{\\text{E}}$, excess\nadiabatic compressibilities, $\\kappa_S^{\\text{E}}$, and excess speeds of sound\n$c^{\\text{E}}$. Negative $V_{\\text{m}}^{\\text{E}}$ values indicate the\nexistence of structural effects and interactions between unlike molecules. From\nexcess molar enthalpies, $H_{\\text{m}}^{\\text{E}}$, available in the literature\nfor N,N-dimethylformamide (DMF), or N-methylpyrrolidone (NMP) + n-alkanone\nsystems, it is shown: (i) amide-ketone interactions are stronger in DMF systems\nthan in those with NMP; (ii) they become weaker when $u$ increases in mixtures\nwith a given amide. Structural effects largely contribute to\n$H_{\\text{m}}^{\\text{E}}$ and are more relevant in mixtures containing NMP. The\napplication of the Flory's model reveals that the random mixing hypothesis is\nvalid to a large extent for DMF solutions, while NMP systems are characterized\nby rather strong orientational effects. From values of molar refraction and of\nthe product $P_{\\text{int}} V_{\\text{m}}$ (where $P_{\\text{int}}$ is the\ninternal pressure and $V_{\\text{m}}$ the molar volume), it is concluded that\ndispersive interactions increase with $u$, or when DMF is replaced by DMA in\nmixtures with a fixed ketone.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Chemical Physics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.11309","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Data on density, $\rho$, speed of sound, $c$, and refractive index,
$n_{\text{D}}$, have been reported at (293-303.15) K for the
N,N-dimethylacetamide (DMA) + CH$_3$CO(CH$_2$)$_{u-1}$CH$_3$ ($u$ = 1, 2, 3)
systems, and at 298.15 K for the mixture with $u$ = 5. These data have been
used to compute excess molar volumes, $V_{\text{m}}^{\text{E}}$, excess
adiabatic compressibilities, $\kappa_S^{\text{E}}$, and excess speeds of sound
$c^{\text{E}}$. Negative $V_{\text{m}}^{\text{E}}$ values indicate the
existence of structural effects and interactions between unlike molecules. From
excess molar enthalpies, $H_{\text{m}}^{\text{E}}$, available in the literature
for N,N-dimethylformamide (DMF), or N-methylpyrrolidone (NMP) + n-alkanone
systems, it is shown: (i) amide-ketone interactions are stronger in DMF systems
than in those with NMP; (ii) they become weaker when $u$ increases in mixtures
with a given amide. Structural effects largely contribute to
$H_{\text{m}}^{\text{E}}$ and are more relevant in mixtures containing NMP. The
application of the Flory's model reveals that the random mixing hypothesis is
valid to a large extent for DMF solutions, while NMP systems are characterized
by rather strong orientational effects. From values of molar refraction and of
the product $P_{\text{int}} V_{\text{m}}$ (where $P_{\text{int}}$ is the
internal pressure and $V_{\text{m}}$ the molar volume), it is concluded that
dispersive interactions increase with $u$, or when DMF is replaced by DMA in
mixtures with a fixed ketone.