Computational Study of Competition Between Direct Abstraction and Addition-Elimination in the Reaction of Cl Atoms with Propene

Balazs Hornung, T J Preston, Shubhrangshu Pandit, Jeremy N Harvey, Andrew J Orr-Ewing

Research output: Contribution to journalArticle (Academic Journal)peer-review

12 Citations (Scopus)
281 Downloads (Pure)

Abstract

Quasi-classical trajectory calculations on a newly constructed and full-dimensionality potential energy surface (PES) examine the dynamics of the reaction of Cl atoms with propene. The PES is an empirical valence bond (EVB) fit to high-level ab initio energies and incorporates deep potential energy wells for the 1-chloropropyl and 2-chloropropyl radicals, a direct H atom abstraction route to HCl + allyl radical (CH2CHCH2) products (ΔrH298K = −63.1 kJ mol–1), and a pathway connecting these regions. In total, 94 000 successful reactive trajectories were used to compute distributions of angular scattering and HCl vibrational and rotational level populations. These measures of the reaction dynamics agree satisfactorily with available experimental data. The dominant reaction pathway is direct abstraction of a hydrogen atom from the methyl group of propene occurring in under 500 fs. Less than 10% of trajectories follow an addition–elimination route via the two isomeric chloropropyl radicals. Large amplitude motions of the Cl about the propene molecular framework couple the addition intermediates to the direct abstraction pathway. The EVB method provides a good description of the complicated PES for the Cl + propene reaction despite fitting to a limited number of ab initio points, with the further advantage that dynamics specific to certain mechanisms can be studied in isolation by switching off coupling terms in the EVB matrix connecting different regions of the PES.

Original languageEnglish
Pages (from-to)9452-9464
Number of pages13
JournalJournal of Physical Chemistry A
Volume119
Issue number36
DOIs
Publication statusPublished - 19 Aug 2015

Fingerprint Dive into the research topics of 'Computational Study of Competition Between Direct Abstraction and Addition-Elimination in the Reaction of Cl Atoms with Propene'. Together they form a unique fingerprint.

Cite this