Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Mixing enthalpies and densities of highly dilute aqueous solutions of four aroma compounds (propyl acetate, methyl butyrate, 2,3-butanedione, and cis-3-hexen-1-ol) were measured as a function of solution composition at several temperatures in the range from (288.15 to 318.15) K using a recently described tandem flow arrangement of isothermal mixing microcalorimeter and vibrating-tube densimeter. The dissolution of all the aroma compounds in water is strongly exothermic and accompanied with volume contraction. Based on the measured data, reliable values of infinite dilution partial molar excess enthalpy E, 1 H , partial molar volume 1 V , and partial molar excess volume E, 1 V of the studied solutes at infinite dilution in water were determined. Comparison to literature data is possible only for some of our results for esters and indicates excellent agreement. Thanks to high precision of our measurements, the temperature derivative properties, i.e. infinite dilution partial molar excess heat capacity and expansivity, could be evaluated also with a good accuracy. In addition, whenever necessary pure component data were available, enthalpies and heat capacities of hydration for the aroma compounds were calculated, too. The observed thermodynamic behavior for aqueous aroma solutes was briefly discussed in terms of molecular interactions.