Infrared spectra and the thermodynamics of alcohol-hydrocarbon systems

From experimental densities, viscosities, and refractive indexes for the acetylacetone + I-pentanol, + 2-Pentanol, + isoamyl alcohol, and + tert-amyl alcohol systems at 298.15 K, the excess molar volumes, excess viscosities, excess molar free energies of activation of flow. and excess internal pressures were calculated over the whole concentration range. Conclusions about the rnolecular interactions in these mixtures were drawn from the variations of the excess functions with the composition. ROQUE RIGGIO, HECTOR E. MARTINEZ ct NORMA Z . DE SALAS. Can. J. Chem. 70, 2859 (1992).Utilisant les densites, les viscositCs et les indices de refractions experimentaux des systemes acCtylacCtone + pentan-1-01, + pentan-2-01, + alcool isoamylique et + alcool tert-amylique, ii 298,15 K , on a calculC les volumes molaires en exces, les viscositCs en excks, les energies libres d'activation molaires en exctts de I'Ccoulement et les pressions internes en exctts, pour l'ensemble des concentrations. En se basant sur les variations des fonctions en exctts en fonction de la composition, on a pu tirer des conclusions relativement aux interactions niolCculaires presentes dans ces melanges.[Traduit par la redaction]

Section: Resultsmentioning

confidence: 99%

Excess properties for acetylacetone + pentanols systems at 298.15 K

Riggio¹,

Martinez²,

Salas³

1992

“…When mixing an alcohol, highly associated in the pure state (12)(13)(14), with a different polar solvent, certain phenomena Can. J. Chem.…”

Section: Discussionmentioning

confidence: 99%

Excess properties for cyclohexanone + butanols at 298.15 K

Riggio¹,

Martinez²,

Salas³

et al. 1995

Densities, viscosities, and refractive indexes of the binary systems cyclohexanone + n-butanol, + sec-butanol, and + 2-methyl-1-propanol have been measured at 298.15 K and atmospheric pressure, over the whole composition range. The excess values of molar volume, viscosity, Gibbs free energy of activation of viscous flow, and internal pressure were calculated from experimental measurements. Based on the variations of the excess functions with composition, conclusions about the molecular interactions in these kinds of mixtures were obtained.

“…At infinite dilution all the curves must meet at g = 1, thus in view of the small g values for the dilute solutions (f, < 0.2) especially in cyclohexane the initial association must predominantly involve the formation of multimers having smaller dipole moments than the free monomer. These multi- Evidence has been presented for all these species (4,5,8,13). At low temperatures the g values for some alcohols are found to be very close to zero (14) and in these cases small closed multimers must exist.…”

Section: Discussionmentioning

confidence: 99%

“…Relatively little work has been reported on the concentration dependence of these terms for alcohols in non-polar solvents. The powerful spectroscopic techniques have generally been limited to alcohols in dilute solution (1,5,6).…”

Section: Introductionmentioning

confidence: 99%

Association of the Butyl Alcohols and n-Decanol

Rajala¹,

Crossley²

1971

The dielectric constants at 0.1 MHz of n-, iso-, sec-, and t-butanol and n-decanol each at nine concentrations in the range 0.2-1.0 mole fraction in cyclohexane, p-dioxane, mesitylene, andp-xylene have been measured at 25 "C. Apparent dipole moments and Kirkwood correlation factors have been evaluated. Cyclohexane is regarded as an inert solvent in which alcohol self association alone is considered responsible for the anomalous electric polarization. The other three solvents have a disassociating effect which increases p-xylene < mesitylene < p-dioxane. At the lowest concentrations the alcohols have larger apparent dipole moments in these solvents than in cyclohexane. The opposite tends to be the case for the more concentrated alcohol solutions. The results suggest that alcohol association is initially dominated by the formation of small, weakly polar multimers, and eventually larger highly polar multimers predominate.Les constantes diClectriques a 0.1 MHz du n-, iso-, sec-, et t-butanol et du n-dCcanol, chacun avec neuf concentrations dans le domaine de 0.2-1.0 mole dans le cyclohexane, p-dioxane, mCsitylbne et le p-xylkne, ont 6tC mesurees 25 "C. Les moments dipolaires apparents et les facteurs de corrClation de Kirkwood ont Ct C 6valuCs. On considere le cyclohexane comme un solvant inerte dans lequel seule une association intermolkulaire de I'alcool est considBrCe comme responsable de la polarisation Cletrique anormale.Les trois autres solvants ont un effet de dissociation qui croft p-xylene d misitylene < p-dioxane. Aux concentrations les plus basses, les alcools ont des moments dipolaires apparents plus grands dans ces solvants que dans le cyclohexane. L'inverse a tendance a se produire pour des solutions alcooliques plus concentrBes. Les rksultats suggkrent que I'association de l'alcool est d'abord le fait de la formation de petites multimeres 1Cgerement polaires et Bventuellement une plus grande quantitC de multimeres hautement polaires prkdomine.