Measurement of Activity Coefficients at Infinite Dilution Using Gas−Liquid Chromatography. 5. Results for N-Methylacetamide, N,N-Dimethylacetamide, N,N-Dibutylformamide, and Sulfolane as Stationary Phases

Activity coefficients at infinite dilution are reported for more than 40 solutes (alkanes, alcohols, ketones, aromatic hydrocarbons, halocarbons, esters, nitriles, aldehydes, ethers, furan, pyridine, and water) in four selective solvents ( N -methylacetamide, N,N -dimethylacetamide, N,N -dibutylformamide and sulfolane) at 303, 318, and 333 K. These values were measured with the help of gas−liquid chromatography (GLC) and show a good agreement when comparing them with various activity coefficients at infinite dilution taken from the literature. The temperature dependence found in the GLC experiments could be confirmed using excess enthalpy data. An important application of the present data can be seen in the selection of a suitable solvent for selective separation processes such as azeotropic and extractive distillation or extraction, where it is usually sufficient to know the ratio of the limiting activity coefficients of the components to be separated (selectivity at infinite dilution) in order to determine the selective effect of a given solvent. Furthermore the data will be used to extend the range of application for existing group contribution methods (e.g. modified UNIFAC) for the synthesis and design of separation processes.