José Muñoz Embid

Excess enthalpies of 1-iodoalkane + n-alkane mixtures. Measurement and analysis in terms of group contributions (DISQUAC)

Abstract Molar excess enthalpies at 303.15 K and atmospheric pressure are reported for 30 binary liquid mixtures of 1-iodoalkanes (iodomethane, iodoethane, 1-iodopropane, 1-iodobutane, 1-iodopentane, 1-iodohexane, 1-iodoheptane, 1-iodooctane, 1-iodododecane and 1-iodohexadecane) + n-alkanes (hexane, dodecane and hexadecane). These experimental results along with literature data on liquidvapour equilibria (excess molar Gibbs energies) and activity coefficients at infinite dilution are interpreted in terms of the DISQUAC group contribution model. The quasichemical interchange energies are the same for the whole series. The dispersive interchange energies of iodoethane and of all the higher 1-iodoalkanes are constant, but larger than for iodomethane. In general, the model reproduces the experimental data within the limits of errors. Larger discrepancies between the calculated and the experimental excess enthalpies are observed in mixtures of long-chain 1-iodoalkanes+short-chain n-alkanes. These may be attributed to conformational changes occurring in the long-chain 1-iodoalkane on mixing with the short-chain n-alkane. In contrast, it appears that 1-iodoalkanes do not significantly perturb the conformational equilibrium (or orientational order) in long-chain n-alkanes.

Excess enthalpies of dibromoalkane + tetrachloromethane mixtures. Measurement and analysis in terms of group contributions (DISQUAC)

Abstract Blanco S.T. Munoz Embid J. and Otin S., 1993. Excess enthalpies of dibromoalkane + tetrachloromethane mixtures. Measurement and analysis in terms of group contributions (DISQUAC). Fluid Phase Equilibria , 91: 281-290. Excess enthalpies at 298.15 K and atmospheric pressure are reported for binary liquid mixtures of dibromomethane, 1,2-dibromoethane, 1,3-dibromopropane, 1,4-dibromobutane, 1,5-dibromopentane and 1,8-dibromooctane + tetrachloromethane (CCl 4 ). These experimental results, along with literature data, on liquid-vapor equilibria (excess Gibbs energies) are interpreted in terms of the DISQUAC group contribution model. The systems are characterized by three types of contact surfaces: bromine (Br) and alkane, in α,ω-dibromoalkanes, and solvent CCl 4 . The interchange energies of the alkane/CCl 4 and alkane/Br contacts were determined independently from the study of n -alkane + CCl 4 , and α,ω-dibromoalkane + n -alkane systems, respectively. The interchange energies of the alkane/Br contact of dibromomethane and of the Br/CCl 4 contact were estimated in this work. The Br/CCl 4 parameters of α,ω-dibromoalkanes are entirely dispersive and increase regularly with increasing separation u of the two bromine atoms in the molecule (proximity effect) in the same regular manner as observed previously for α,ω-dichloroalkane + CCl 4 , mixtures, and reach the values of 1-bromoalkanes when u ≧ 5. In general, the model provides a fairly consistent description of H E and G E as a function of composition and dibromoalkane chain length.

Temperature and pressure dependence of the volumetric properties of binary liquid mixtures containing 1-propanol and dihaloalkanes

Densities of 1-propanol + dibromomethane, or +bromochloromethane, or +1,2-dichloroethane, or +1-bromo-2-chloroethane binary mixtures were measured at 288.15, 298.15 and 308.15 K, over the entire composition range. Thermal expansion coefficients, α, and excess molar volumes, , were calculated. Moreover, densities at 298.15 K and pressures up to 2 × 107 Pa were determined for the same mixtures. Isothermal compressibilities, κT, of the pure liquids and their mixtures were obtained.

Isothermal vapor–liquid equilibria of bromochloromethane or 1-bromo-2-chloroethane+tetrachloromethane or benzene. Experimental measurements and analysis in terms of group contributions

Abstract Isothermal vapor–liquid equilibria (VLE) have been measured for bromochloromethane+tetrachloromethane or benzene at 298.15 K and 313.15 K, and for 1-bromo-2-chloroethane+tetrachloromethane or benzene at 313.15 K. Bromochloromethane+tetrachloromethane shows azeotropic behaviour in the temperature range covered. These experimental results, along with our previous ones on excess enthalpies, are interpreted with two group contribution models: DISQUAC (DISpersive-QUAsiChemical) and modified (Dortmund) UNIFAC (UNIquac Functional group Activity Coefficients).

Analysis of {[α, ω-dichloroalkane or α, ω-dibromoalkane] + benzene and α, ω-dichloroalkane + tetrachloromethane} mixtures in terms of group contributions

Abstract Molar excess enthalpies, H E m, at 298.15K and atmospheric pressure have been determined for three binary liquid mixtures [x{1,3-dichloropropane or 1,4-dichlorobutane and 1,6-dichlorohexane} + (1 - x) tetrachloromethane]. These experimental results along with the data available in the literature on molar excess Gibbs energies, G E m, activity coefficients at infinite dilution, In γ∞ i , and molar excess enthalpies, H E m, for α,ω-dihaloalkanes + benzene or + tetrachloromethane mixtures are examined on the basis of the DISQUAC group contribution model.