Fixative effect of 2‐oxo‐2‐phenylacetates in fine fragrance and eau‐de‐toilette applications

The evaporation of fragrances with volatilities spanning over several orders of magnitude results in a shift of the olfactive impression of a perfume over time. Fixatives have repeatedly been used to slow fragrance evaporation in multiple perfumery applications. We developed a simple and reliable method to measure the evaporation kinetics of individual fragrances in a model perfume and analysed the fixative effect of 2‐oxo‐2‐phenylacetates (α‐ketoesters) on perfume evaporation. 2‐Oxo‐2‐phenylacetates, some of which have been described as light‐sensitive profragrances, are commercially available or readily prepared by esterification or transesterification of commercial starting materials. (−)‐Menthyl 2‐oxo‐2‐phenylacetate afforded single crystals that were suitable for X‐ray crystal structure analysis. 2‐Oxo‐2‐phenylacetates were found to have a fixative effect on the evaporation of fragrances with volatilities below 5000 μg L−1 in fine fragrance and eau‐de‐toilette applications. The molecular structure of the compound rather than its molecular weight had an impact on the fixative effect to some extent. Fixatives should retain volatiles from rapid evaporation and thus help balancing the changing olfactive impression of a perfume over time. By measuring the evaporation kinetics of individual fragrances in a model perfume, we demonstrated that the presence of 2‐oxo‐2‐phenylacetates (α‐ketoesters) provided a certain fixative effect in fine fragrance and eau‐de‐toilette applications.