Thermodynamic insights into the odour intensity of terpenols

Terpenols are flavourings that are frequently used in perfumery. Choosing the optimal perfume composition is no easy task, as the perception of fragrances is subjective and can vary greatly from person to person due to sensory and chemical differences in the human olfactory system. Thermodynamics can essentially contribute to the rational design of the perfume composition. The absolute vapour pressure as a fundamental thermodynamic property is directly related to the intensity of the odour. In this work, a set of reliable vapour pressures, enthalpies of vaporisation, enthalpies of sublimation and enthalpies of fusion for nine terpenols was evaluated with help of complementary measurements and empirical structure–property correlations and recommended for thermodynamic calculations for various processes involving the terpenols. The evaluated vapour pressures and the calculated activity coefficients of the terpenols in the standardised aqueous-ethanolic mixture were used to determine the odour indices that quantify the odour intensity.

Graphical abstract