jp402552t_si_001.pdf (213.86 kB)
Chirped-Pulse and Cavity-Based Fourier Transform Microwave Spectroscopy of a Chiral Epoxy Ester: Methyl Glycidate
journal contribution
posted on 2013-12-19, 00:00 authored by Javix Thomas, Jensen Yiu, Johannes Rebling, Wolfgang Jäger, Yunjie XuRotational
spectra of a chiral epoxy ester, methyl glycidate, were
measured using a chirped-pulse and a cavity-based Fourier transform
microwave spectrometer.
The two lowest energy conformers where the epoxy oxygen and the ester
oxygen atoms are in the syn and anti relative orientation with respect
to each other were identified experimentally. Spectra of four 13C isotopologues of the lowest energy conformer of methyl
glycidate were also measured and assigned. All of the observed rotational
transitions are split into doublets due to the presence of the ester
methyl internal rotor. The rotational constants and the internal rotation
barrier height for the ester methyl group were determined for both
conformers of methyl glycidate and for the four 13C isotopologues
of the most stable conformer. A value for the interconversion barrier
between the two most stable conformers was estimated. Furthermore,
comparison to strawberry aldehyde, a larger derivative of methyl glycidate,
shows how the syn-anti conformational equilibrium shifts as a result
of the additional bulky substituents at the epoxy ring and at the
ester oxygen atom.