Structures of Alkyl Benzoate Binary Mixtures. A Kirkwood−Buff Fluctuation Theory Study Using UNIFAC

Microwave dielectric relaxation spectroscopy study of alkan-1-ol/alkylbenzoate binary solvents

The structure and dynamics of alkan-1-ol/alkylbenzoate binary mixtures have been studied by microwave dielectric relaxation spectroscopy in the 200 MHz to 20 GHz frequency range. The binary mixtures of methanol, ethanol, propan-1-ol, butan-1-ol, and pentan-1-ol with methyl, ethyl, propyl, and butyl benzoates were studied at 298.15 K. The relaxational response of the pure alcohols, pure esters, and their binary mixtures over the full composition range is properly described by the Havriliak-Negami model. The alcohol content, alcohol length, and alkyl side-chain effects on the relaxational properties have been studied for these mixtures over the whole composition range. From the experimental readings, the effective and the corrective Kirkwood and Bruggeman correlation factors have been calculated. The data gathered have been interpreted in terms of the alkyl side-chain effect and their reliance on the mixture composition.

Structure-composition relationships in ternary solvents containing methylbenzoate

Thermophysical properties of the hexane+1-chlorohexane (or hexanoic acid or diisopropylether)+methylbenzoate ternary systems and their binary constituents are reported at 298.15 K and 0.1 MPa over the whole composition range. The properties and the optimized geometry of the gas-phase components were appraised from the density functional theory. To find out the causal link between the thermophysical measurements and the molecular level features, the derived mixing and excess functions of the ternary systems were looked into according to the scaled particle and Kirkwood-Buff analyses. The hydrogen bonding and dipole interactions along with the geometry effects brought about by the very different size and shape of the components give rise to complex mixed structures. Application of semiempirical models and use of simple cubic equations of state combined with a one-parameter van der Waals mixing rule has led to prediction of the ternary properties with variable degree of precision.

Properties and Structure of Aromatic Ester Solvents

This paper reports on an experimental and theoretical study of the aromatic ester solvents family. Several compounds were selected to analyze the different factors that influence their liquid-state properties and structures. The pressure-volume-temperature behavior of these fluids was measured accurately over wide temperature and pressure ranges and correlated successfully with the empirical TRIDEN equation. From the measured data the relevant derived coefficients of isothermal compressibility, isobaric expansibility, and internal pressure were calculated. The statistical associating fluid theory (SAFT) and perturbed chain statistical associating fluid theory (PC-SAFT) molecularly based equations of state were used to predict the PVT behavior with model parameters obtained from the correlation of available saturation literature data; the results provided by PC-SAFT equations of state were clearly superior for all of the studied solvents. The fluid's molecular level structure was studied by quantum computations at the B3LYP/6-311++g** level and classical molecular dynamics simulations in the NPT ensemble with the OPLS-AA forcefield. Molecular parameters, such as torsional barriers or cluster energetics, were analyzed as a function of ester structures. The molecular dynamics study provides, on one hand, theoretical values of thermophysical properties, which are compared with the experimental ones, and, on the other hand, valuable molecular level structural information. On the basis of both macroscopic and microscopic studies complex fluid structures were inferred with important effects arising from the geometries of the studied molecules and from the existence of remarkable intermolecular forces of dominating dipolar nature.