Thioether Profragrances: Parameters Influencing the Performance of Precursor‐Based Fragrance Delivery in Functional Perfumery

Abstract

A series of thioether profragrances was prepared by reaction of different sulfanylalkanoates with δ-damascone and tested for their release efficiencies in a fabric-softener and an all-purpose cleaner application. Dynamic headspace analysis on dry cotton and on a ceramic plate revealed that the performance of the different precursors depended on the structure, but also on the particular conditions encountered in different applications. Moreover, profragrances derived from other α,β-unsaturated fragrance aldehydes and ketones were synthesized analogously and evaluated using the same test protocol. Thioethers were found to be suitable precursors to release the corresponding fragrances, but neither the quantity of profragrance deposited from an aqueous environment onto the target surface, nor the amount of fragrance released after deposition could be linearly correlated to the hydrophilicity or hydrophobicity of the compounds. Different sets of compounds were found to be the best performers for different types of applications. Only one of the compounds evaluated in the present work, namely the thiolactic acid derivative of δ-damascone, efficiently released the corresponding fragrance in both of the tested applications. Profragrance development for functional perfumery thus remains a partially empirical endeavour. More knowledge (and control) of the various application conditions are required for an efficient profragrance design.

Functionalized cellulose nanocrystals as nanocarriers for sustained fragrance release

“…8 moles of ethylene oxide per mole of alcohol), 4.0% Marlon® A 375 (75% w/w n-C10-C13-alkylbenzene sodium sulphonate), 2% sodium cumolsulphonate, 0.2% Kathon® CG (a preservative containing 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one) and 88.8% water. 24 All percentages are given in weight. The resulting formulation had a pH of around 5.…”

“…[20][21][22][23][24]49 Dry βD-CNCs (100 mg) were mixed directly with the aqueous surfactant emulsion (1.8 g) and deionized water (1 mL) was added to permit better mixing. The mixtures were stirred for 10 min, transferred into 1 L beakers and diluted with deionized water (600 g).…”

“…The tiles were dried under ambient conditions for three days and the β-damascone release was analyzed using dynamic headspace analysis at a flow rate of 200 mL min −1 and a constant humidity of 75% according to well-established protocols. 24 The volatiles were collected on Tenax® cartridges and subsequently thermally desorbed and analyzed by GC (ESI Fig. S13 †).…”

“…Typically, the precursor is stable at acidic pH and releases the fragrance under neutral or alkaline conditions. [22][23][24] In many cases, the application of personal care products is followed by rinsing with water, which dilutes the product and leads to neutralization of the pH. Therefore thioether pro-fragrances should be particularly suitable for acidic product formulations, because hydrolysis during the storage of the product is expected to be slow and the release of the fragrance preferentially occurs after application.…”

“…2,[42][43][44] We employed a short thioether linker that served to bind the fragrance molecules to the CNCs and permits their release under neutral or basic conditions via the previously explored retro 1,4-Michael-type reaction. [20][21][22][23][24] The release of β-damascone from the CNC-based pro-fragrances was studied in aqueous suspension as a function of pH, and after deposition of the nanoparticles onto different substrates under conditions that emulate the use in laundry applications as well as in an all-purpose surface cleaner.…”