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Updated: Dec 30, 2025

High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy
Published on: October 9, 2020
Microwave Spectrum and Internal Rotations of Heptan-2-one: A Pheromone in the Gas Phase
Maike Andresen1,2, Isabelle Kleiner2, Martin Schwell2
1Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , D-52074 Aachen , Germany.
Abstract:
The microwave spectrum of heptan-2-one (CH3COC4H8CH3) was recorded in the frequency range from 2 to 40 GHz using two molecular jet Fourier transform microwave spectrometers. The two energetically most favorable conformers could be identified and fitted with standard deviations close to measurement accuracy. The splittings arising from the internal rotations of two methyl groups, the acetyl methyl group CHCO- and the pentyl methyl group -C4H8CH, could be resolved. The barriers to internal rotation of the acetyl methyl group are 185.666(14) and 233.418(32) cm-1 for conformer I and II, respectively, and can be linked to their specific geometries. For the pentyl methyl group, the respective barrier heights are 982.22(86) and 979.2(21) cm-1.
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