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Updated: Jan 19, 2026
Author Spotlight: Sieving Fruit Pulp to Detect Immature Tephritid Fruit Flies in the Field
Published on: July 28, 2023
Large Amplitude Motions in Fruit Flavors: The Case of Alkyl Butyrates
Rihab Hakiri1,2, Najoua Derbel1, Wolfgang Stahl3
1Laboratoire de Spectroscopie Atomique, Moléculaire et Applications, Département de Physique, Faculté des Sciences de Tunis -, University of Tunis El Manar, 2092, Manar II, Tunis, Tunisia.
Abstract:
To accurately characterize the large amplitude motions and soft degrees of freedom of isolated molecules, sampling their conformational landscape by molecular mechanics and quantum chemical calculations may provide a valuable insight into the structure and dynamics. However, the resulting models need to be validated by a reliable experimental counterpart. For ethyl pentanoates, which belong to the family of fruit esters, benchmark calculations at different levels of theory showed that the C-C bond in proximity to the ester carbonyl group exhibits a large amplitude motion that is extremely sensitive to the choice of quantum chemical method and basis set. In such cases, insights from high-resolution molecular jet techniques are ideal to accurately identify and characterize soft degrees of freedom. Here, we report on the most abundant conformer of ethyl 2-ethyl butyrate using Fourier-transform microwave spectroscopy. We show that - unlike other structurally related pentanoates for which gas-phase and crystallographic data is available - ethyl 2-ethyl butyrate possesses a Cs symmetry plane under molecular jet conditions.
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