Correlations between odour activity and the structural modifications of acrylates
Acrylates (acrylic esters) are versatile monomers that are widely used in polymer formulations because of their highly reactive α,β-unsaturated carboxyl structure. Commonly used acrylates such as butyl acrylate are known to emit a strong unpleasant odour, and the monomers are therefore potential off-odorants in acrylic polymers. However, up to now, the odour properties of structurally related acrylic esters have not been characterised in detail. To obtain deeper insights into the smell properties of different acrylates, we investigated the relationship between the molecular structure and odour thresholds as well as the odour qualities of 20 acrylic esters, nine of these synthesised here for the first time. The OT values of 16 acrylates fell within the range from 0.73 to 20 ng/Lair, corresponding to a high-odour activity. Moreover, sec-butyl acrylate and 2-methoxyphenyl acrylate showed even lower OT values of 0.073 and 0.068, respectively. On the other hand, the OT values of the hydroxylated acrylates 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate were 5–244 times higher than those of the other compounds, demonstrating that the presence of a hydroxyl group obviously favours odour inactivity.
KeywordsAcrylates Off-odour Olfactometry Synthesis Odour threshold Odour quality
This study was carried out within the framework of the Campus of the Senses, a joint endeavour of the Fraunhofer Institutes for Process Engineering and Packaging IVV and Integrated Circuits IIS, together with Friedrich-Alexander-Universität Erlangen-Nürnberg as an academic partner. The Campus of the Senses initiative is financially supported by the Bavarian Ministry of Economic Affairs, Regional Development and Energy (STMWI) and the Fraunhofer-Gesellschaft.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The study was conducted in agreement with the Declaration of Helsinki. The study (registration number 180_16B) was approved by the Ethical Committee of the Medical Faculty, Friedrich-Alexander-Universität Erlangen-Nürnberg. Informed consent was obtained from all subjects participating in the study.
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