M. I. Paz Andrade

Analysis of thermodynamic properties of 1-alkanol + n-alkane mixtures using the nitta—chao group contribution model

Abstract In 1977, Nitta et al. published a group contribution molecular model for thermodynamic properties of polar and non-polar liquids and their solutions, including energy of vaporization, pVT relationships, excess properties and activity coefficients. At the same time they reported the corresponding characteristic parameters for methyl, methylene, hydroxyl and carbonyl groups and for their mutual interactions. Since the values predicted by the Nitta et al. model for certain excess properties of alcohol + alkane systems using these parameters differ significantly from experimental findings, we have recalculated the relevant parameters using data for a larger number of mixtures and for properties such as excess volumes that were not included in the original database.

Excess volumes and excess heat capacities of some mixtures: (an isomer of hexanol + an n-alkane) at 298.15 K

Abstract Excess molar volumes V m E at 298.15 K were obtained, as a function of mole fraction x for the ten mixtures { x C 6 H 13 OH + (1 − x )C 6 H 14 }; { x C 3 H 7 CH(CH 3 )CH 2 OH + (1 − x )C n H 2 n + 2 } for n = 6, 7, 10, and 14; { x (CH 3 ) 2 CHCH 2 CH(OH)CH 3 + (1 − x )C 6 H 14 }; { x C 2 H 5 CH(CH 3 )CH(OH)CH 3 + (1 − x )C n H 2 n + 2 } for n = 6 and 7; { x C 2 H 5 C(CH 3 )(OH)C 2 H 5 + (1 − x )C n H 2 n + 2 } for n = 6 and 7, from measurements of the density with a vibrating-tube densimeter. The excess molar volumes are either positive or positive-negative. The largest negative value of V m E is found for { x C 6 H 13 OH + (1 − x )C 6 H 14 }: | V m E |(max) = 0.252 cm 3 · mol −1 at x = 0.6451 the largest positive value being found for { x C 3 H 7 CH(CH 3 )CH 2 OH + (1 − x )C 14 H 30 }: V m E (max) = 0.507 cm 3 · mol −1 at x = 0.5058. In addition, a Picker flow microcalorimeter was used to determine excess molar heat capacities C p , m E at constant pressure at 298.15 K for five of these mixtures each with n = 6. The C p , m E s are positive in all cases, but are represented by rather asymmetrical curves of different shape depending upon whether the alkanol is primary, secondary, or tertiary.

Excess molar volumes of (ethyl formate or ethyl acetate + an isomer of hexanol) at 298.15 K

Excess molar volumes VmE were determined over the entire composition range at 298.15 K for ethyl formate or ethyl acetate + hexan-1-ol, +2-methylpentan-1-ol, +3-methylpentan-2-ol, +2-methylpentan-3-ol, +3-methylpentan-3-ol, +2-methylpentan-2-ol, +4-methyl-pentan-2-ol, and +hexan-2-ol. Excess volumes were determined from density measurements made with a vibrating-tube densimeter. The VmE values were all positive, decreasing with the n value of the ester: Cn−1H2n−1CO2C2H5.

Viscosity deviations of ternary mixtures di-n-butyl ether + 1-propanol + n-octane at several temperatures

Abstract Viscosities and densities of {x1 di-n-butyl ether+x2 1-propanol+(1−x1−x2) n-octane} and their corresponding binary mixtures were measured at the temperatures of 293.15, 298.15, 303.15 and 308.15 K under atmospheric pressure. Kinematic viscosities were determined using a capillary viscosimeter, and densities were measured by a vibrating tube densimeter. The viscosity deviations and Gibbs free energies of activation for flow were evaluated. All the experimental values were compared with the results obtained with different predictive methods.

Analysis of excess enthalpies of ethyl formate + n-alkane or 1-alkanol with two group contribution models

Abstract We present experimental values of enthalpies of mixing at 298.15 K for mixtures composed of ethyl formate with n-alkanes (from n-hexane to n-decane) or 1-alkanols (from 1-propanol to 1-decanol). Then hE data for the latter mixtures have been used to determine characteristic formate-alkanol interaction parameters for three group contribution models: the UNIFAC model with and without consideration of 1-alkanol association effects, and the Nitta-Chao model. The experimental data are reproduced within mean errors of less than 6% by all the used models.

Excess enthalpies of (secondary amine + alcohol) at 298.15 K

The excess enthalpies HmE of N-butyl methyl amine + 1-butanol, + 1-pentanol, and + 1-hexanol and of dibutylamine + 1-propanol, + 1-butanol, + 1-pentanol, + 1-hexanol, and + 1-heptanol were measured at 298.15 K, and normal atmospheric pressure, using a Calvet microcalorimeter. All mixtures give HmE < 0; the values do not vary significantly when the chain length of the alcohol increases.

Viscosities and Densities for the 1-Propanol + n-Heptane System at Several Temperatures

Viscosities and densities have been measured for 1-propanol + n-heptane at 20, 25, 30, and 35°C and atmospheric pressure. Kinematic viscosities were determined using a capillary viscosimeter; densities were measured using vibrating-tube densimetry. The viscosity deviations were evaluated. Viscosity results were fitted to the equations of Grunberg–Nissan, McAllister, Auslander, and Teja. The experimental excess molar volumes were compared with the results obtained with the Nitta–Chao model.

Excess enthalpies of five examples of (2-hexanone + an n-alkane) and five of (2-hexanone + an n-alkanol) at 298.15 K

Abstract Excess molar enthalpies H m E have been measured as a function of the mole fraction x at 298.15 K and atmospheric pressure for the 10 mixtures: {x CH 3 COC 4 H 9 + (1−x) C n H 2n+2 }, (n = 6, 7, 8, 9, and 10) ; {x CH 3 COC 4 H 9 + (1−x) C n H 2n+1 OH }, (n = 6, 7, 8, 9, and 10) . Measurements were carried out using a Calvet microcalorimeter, and variable-degree polynomials have been fitted to the results.

Excess enthalpies of (propyl ethanoate or ethyl propanoate + an n-alkane) at 298.15 K

Abstract The excess molar enthalpies H m E of (an ester + an n -alkane) have been determined experimentally at 298.15 K and normal atmospheric pressure in a Calvet microcalorimeter. A variable-degree polynomial has been fitted to the experimental results.

Thermodynamic properties of polyoxyethyleneglycol dimethyl ether+n-alkane mixtures

Abstract Excess molar volumes V m E at 278.15, 288.15, 298.15 and 308.15 K and atmospheric pressure were obtained from density measurements with a vibrating-tube densimeter for the mixtures CH 3 O(CH 2 CH 2 O) m CH 3 ( m =2, diglyme; m =3, triglyme; m =4, tetraglyme)+ n -dodecane. These results allowed us to calculate isobaric thermal expansivities α at 298.15 K. We also report excess molar isobaric heat capacities C p E at atmospheric pressure measured with a micro DSC II differential scanning calorimeter for the systems triglyme+ n -heptane at 288.15, 298.15 and 308.15 K and triglyme+ n -dodecane at 283.15, 288.15, 298.15 and 308.15 K.