Plant natural fragrances are volatile compounds, such as ketones, aldehydes, alcohols, and esters, which are produced in different parts of plants and influence their aroma. The aroma of the European red raspberry (Rubus idaeus) consists of a complex mixture of volatile compounds, among which the key compound is most commonly known as raspberry ketone. It is a colorless, poorly water-soluble substance with a characteristic fruity odor. Due to its low content and limited availability, the extraction of ketone from natural sources is demanding and expensive. It is most often used as a flavor and odor corrector in the pharmaceutical, cosmetology, food and perfume industries.
The thesis deals with the synthesis of volatile derivatives of raspberry ketone, which would have potential use in the cosmetic industry. By structural modifications of the starting molecule, we successfully synthesized a secondary alcohol, seven esters, an ether and an acetal using the methods of acetylation, reduction, nucleophilic substitution and acetalization. The synthesis of the second ether was unsuccessful. The synthesized compounds were purified and isolated by column adsorption chromatography and extraction. For identification, monitoring of the course of reactions and assessment of purity, analytical methods were used - thin-layer chromatography, nuclear magnetic resonance and infrared spectroscopy.
The starting compound and five synthesized derivatives were evaluated by olfactory analysis. Volunteers defined the pleasantness and strength of each odor, and for each sample they wrote down what it reminded them of. Most often, the participants rated the odors as medium-strong and pleasant and associated them with the smell of flowers and fruits. The most pleasant esters were 4-(3-(benzoyloxy)butyl)phenyl benzoate and 4-(3- hydroxybutyl)phenyl isobutyrate, with associations with sweet fruits, flowers and wood.
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