Fraunhofer-Institute for Process Engineering and Packaging, Giggenhauser Strasse 35, D-85354 Freising, Germany.
Chem Senses. 2011 Jul;36(6):539-53. doi: 10.1093/chemse/bjr009. Epub 2011 Mar 25.
The relationship between chemical structure and odor characteristics of aroma compounds is interesting in terms of establishing a fundamental understanding and, in the long term, a perspective for the prediction of odor qualities and intensities of unknown compounds; on the other hand, such studies provide a useful tool to analytically elucidate compounds that are exceptionally potent odor contributors to a specific smell. In this respect, a broad knowledge of compounds with regard to their odor threshold and smell specificities compiled in a comprehensive odor library would drastically simplify the chemoanalytical process in identifying aromas and smells. Whereas numerous odor-active substance classes have been investigated intensively, such relationships and fundamental data have hitherto not been established for volatile phenols. In this study, a homologous series and isomers of 30 volatile phenols, including monoalkylated phenols and di- and trimethylphenols, were evaluated by determining their aroma attributes and their odor detection thresholds in air. The investigation demonstrates that the odor qualities, among them leather-like, horse stable-like, and medicinal, as well as the respective threshold values clearly depend on the arrangement of the alkyl substituents at the phenol ring. In particular, phenols with monoalkyl groups in the meta-position were found with very low odor detection thresholds of <1 ng/L air. A comparison of some selected phenols and their corresponding toluenes, which were found to be almost odorless, showed in addition that the phenolic hydroxyl group is obviously an important factor for the odor characteristic of this substance class.
香气化合物的化学结构与气味特征之间的关系在建立基本理解方面很有趣，从长远来看，也为预测未知化合物的气味质量和强度提供了一个视角；另一方面，这些研究为分析鉴定对特定气味有特别强烈气味贡献的化合物提供了有用的工具。在这方面，广泛了解化合物的气味阈值和气味特异性，并将其汇编到一个全面的气味库中，将大大简化通过化学分析识别香气和气味的过程。尽管已经对许多具有强烈气味的物质类别进行了深入研究，但迄今为止，挥发性酚类化合物尚未建立这种关系和基础数据。在这项研究中，通过测定 30 种挥发性酚类化合物（包括单烷基酚类和二甲基和三甲基酚类）的同系物和异构体的香气属性及其在空气中的气味检测阈值，对其进行了评估。研究表明，气味质量，包括皮革味、马厩味和药味，以及各自的阈值值明显取决于酚环上烷基取代基的排列方式。特别是在间位具有单烷基基团的酚类化合物具有非常低的气味检测阈值，<1ng/L 空气。一些选定的酚类化合物及其相应的甲苯的比较表明，这些酚类化合物几乎没有气味，此外还表明酚羟基是该物质类别的气味特征的一个重要因素。
