Detection of a Criegee Intermediate with an Unsaturated Hydrocarbon Substituent: Fourier-Transform Microwave Spectroscopy of Methyl Vinyl Ketone Oxide

Yasuki Endo; Henryk A Witek; Chen-An Chung; Yuan-Pern Lee

doi:10.1021/acs.jpca.0c05817

Detection of a Criegee Intermediate with an Unsaturated Hydrocarbon Substituent: Fourier-Transform Microwave Spectroscopy of Methyl Vinyl Ketone Oxide

J Phys Chem A. 2020 Jul 30;124(30):6203-6206. doi: 10.1021/acs.jpca.0c05817. Epub 2020 Jul 16.

Authors

Yasuki Endo^{1

2}, Henryk A Witek^{1

2}, Chen-An Chung¹, Yuan-Pern Lee^{1

2

3}

Affiliations

¹ Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
² Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
³ Institute of Atomic and Molecular Science, Academia Sinica, Taipei 10617, Taiwan.

PMID: 32628026
DOI: 10.1021/acs.jpca.0c05817

Abstract

Pure rotational transitions of methyl vinyl ketone oxide, or the so called methyl-vinyl Criegee intermediate, were observed by Fourier-transform microwave spectroscopy. Among the four possible conformers of this species, predicted by theory within an energy window of 3 kcal/mol, only the lowest-energy conformer, the syn-trans form, was detected in a discharged jet of a 1,3-diiode-but-2-ene (either in Z- or E-conformation) and O₂ mixture diluted in Ar. Thirty pure rotational transitions with internal rotation splitting of the methyl top were observed. The observed frequencies were analyzed by the XIAM program, yielding an internal rotation barrier of 702.8(28) cm^-1, which reasonably agrees with a theoretical value of 680 cm^-1 determined with CCSD(T)/cc-pVTZ.