Activity coefficients and partial molar excess enthalpies at infinite dilution for four esters in water

Infinite dilution activity coefficients (γ1∞) of four esters, namely dimethyl carbonate, diethyl carbonate, vinyl acetate, and methyl methacrylate in water were measured at several temperatures in the range from 273 K to 333 K. The inert gas stripping technique, and for methyl methacrylate also the headspace analysis with solid-phase microextraction sampling, was employed for the purpose. Infinite dilution partial molar excess enthalpies (H¯1E,∞) of these aqueous solutes were further measured at several temperatures in the range from 288 K to 318 K using isothermal flow mixing microcalorimetry which allowed reliable derivation of respective heat capacities (C¯p,1E,∞). For each ester, the data measured in this work together with those reported previously in the literature were correlated with a suitable model equation providing adequate simultaneous description of the equilibrium measurements and the calorimetric information. As a result, a recommended thermodynamically consistent temperature dependence of γ1∞ of superior accuracy was established. Analogous recommendations were derived also for the temperature dependence of the Henry's law constants (KH). In addition, literature data on mutual solubilities of esters and water were employed to calculate the γ1∞ values which in turn were compared with the recommended γ1∞(T) dependences.