Experimental and Theoretical Study on Electron Ionization and Fragmentation of Propylene Oxide─the First Chiral Molecule Detected in the Interstellar Medium

Rodrigo Rodrigues, Daniel Bou Debes, Mónica Mendes, Pedro Guerra, Gonçalo Mestre, Samuel Eden, Lucas M. Cornetta, Oddur Ingólfsson, F. Ferreira da Silva

Research output: Contribution to journalArticlepeer-review

Abstract

Propylene oxide, CH3CHOCH2, is the first chiral molecule detected in space and the third C3 oxide detected toward the Sagittarius B2 (Sgr B2 (N)) molecular cloud, the others being propanal, CH3CH2CHO, and acetone, (CH3)2CO. With homochirality being ubiquitous in the building blocks of living matter, the formation and decay paths of propylene oxide in space are of specific interest. Motivated by the significant role of photo- and secondary electrons in astrochemistry, we have studied electron ionization and fragmentation of propylene oxide. Ion appearance energies are determined and compared to threshold values for the respective processes calculated at the G4MP2 level of theory, and potential reaction pathways are computed at the DFT level of theory. Electron ionization is found to destabilize propylene oxide, leading to barrierless opening of the C1-C2 bond of the epoxy ring, hydrogen transfer, and fragmentation over the methyl vinyl ether or rupture of the C2-O bond of the epoxy ring and fragmentation of the allyl alcohol cation as an intermediate, rather than direct bond ruptures.
Original languageEnglish
Pages (from-to)4795-4805
Number of pages11
JournalJournal of Physical Chemistry A
Volume128
Issue number24
Early online date11 Jun 2024
DOIs
Publication statusPublished - 20 Jun 2024

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