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.