Henry V. Kehiaian

Thermodynamic properties of binary mixtures containing esters. I. Analysis of the properties of n-alkanoate + n-alkane and n-alkanoate + n-alkanoate mixtures in terms of a quasichemical group-contribution model

Abstract The thermodynamic properties of n-alkanoate + n-alkane and + n-alkanoate binary liquid mixtures are examined on the basis of the group-surface interaction version of the Guggenheim-Barker quasichemical pseudolattice theory. All the data available in the literature for liquid—vapor and liquid—liquid equilibria, excess enthalpies and activity coefficients at infinite dilution are taken into consideration. Using only four alkyl-group increments, in addition to the two group-interaction parameters for methyl ethanoate, the model provides a fairly consistent description of the properties of the mixtures as functions of composition, temperature and chain length. The results are discussed in comparison with other classes of systems investigated previously (alkanones and alkanals).

Thermodynamic properties of binary mixtures containing ketones. VI. Analysis of the properties of 2-propanone + n-alkane mixtures in terms of a quasi-chemical group contribution model

Abstract The thermodynamic properties of 2-propanone + n -alkane binary liquid mixtures are examined on the basis of a quasi-chemical theory using group surface interactions. All the data available in the literature on liquid-vapor equilibria, liquid-liquid equilibria, and excess enthalpies are taken into consideration. Using only three group interaction parameters, the model provides a fairly consistent description of the properties of the mixtures as functions of composition, temperature and n -alkane chain length. The discrepancies between theory and experiment are discussed and some ways of improving the model are indicated.

Enthalpies de melange des acetals avec les alcanes normaux, le benzene et le tetrachlorure de carbone

Abstract Enthalpies of mixing at 298.15 K are reported for the following binary mixtures: dimethoxymethane + n -heptane, +benzene; diethoxymethane + n -hexane, + n -heptane, + n -octane, + n -nonane, + n -decane, +benzene, +2,2-dimethoxypropane; 1,1-dimethoxyethane + n -heptane, +benzene; 1,1-diethoxyethane + n -heptane, +benzene; 1,1-diethoxypropane + n -heptane, +benzene; 2,2-dimethoxypropane + n -heptane, +benzene; 2,2-diethoxypropane + n -heptane, +benzene. These experimental results, along with the previously measured enthalpies of mixing of the same acetals + carbon tetrachloride, are interpreted in terms of molecular surface interactions in the zeroth approximation. The excess enthalpies can be reasonably well correlated with simple group contribution formulas. Comparison of the interchange parameters of acetals, with the corresponding values of ethers or polyethers containing ue5f8Oue5f8CH 2 ue5f8CH 2 ue5f8Oue5f8 groups, reveals a significant decrease of the intermolecular interactions between the ue5f8Oue5f8CH 2 ue5f8Oue5f8 groups of acetals.

Thermodynamics of binary mixtures containing tertiary amines. I. Excess enthalpies of some N,N-dialkylmethylamine+normal alkane mixtures. Measurement and analysis in terms of group contributions. Estimation of excess gibbs energies

Abstract A Tian-Calvet type calorimeter was used to determine molar excess enthalpies, HE, at 298.15 K, as a function of concentration, for the twelve mixtures: N,N-dimethylethylamine, N,N-dimethylbutylamine, N,N-diethylmethylamine, and N,N-dipropylmethylamine+n-hexane, +n-heptane, +n-dodecane, or + n-hexadecane. This data and the data available in the literature on the liquid-vapour equilibria of trimethylamine + n-hexane are examined based on the quasi-lattice theory, in the random-mixing approximation, using group surface interactions. With two adjusted group interaction parameters and three alkyl-group increments, the model provides a fairly consistent description of HE of the investigated mixtures and an estimate of the molar excess Gibbs energies, GE. The results are discussed in terms of steric and Patterson effects.

CALORIMETRIC EFFECTS OF SHORT-RANGE ORIENTATIONAL ORDER IN SOLUTIONS OF BENZENE OR n-ALKYLBENZENES IN n-ALKANES *

Abstract A Picker flow microcalorimeter was used to determine molar excess heat capacities, C E p , at 298.15 K, as function of concentration, for the eleven liquid mixtures: benzene+ n -tetradecane; toluene+ n -heptane, and + n -tetradecane; ethylbenzene+ n -heptane, + n -decane, + n -dodecane; and + n -tetradecane; n -propylbenzene + n -heptane, and + n -tetradecane; n -butylbenzene+ n -heptane, and + n -tetradecane. In addition, molar excess volumes, V E , at 298.15 K, were obtained for each of these systems (except benzene+ n -tetradecane) and for toluene+ n -hexane. The excess volumes which are generally negative with a short alkane, increase and become positive with increasing chain length of the alkane. The excess heat capacities are negative in all cases. The absolute ¦ C E p ¦ increased with increasing chain length of the n -alkane. A formal interchange parameter, C p12 , is calculated and its dependence on n -alkane chain length is discussed in terms of molecular orientations.