Gas-Phase Formation of 1-Methylcyclopropene and 3-Methylcyclopropene via the Reaction of the Methylidyne Radical (CH; X 2 Π) with Propylene (CH 3 CHCH 2 ; X 1 A')
Abstract
The crossed molecular beam reactions of the methylidyne radical (CH; X2Π) with propylene (CH3CHCH2; X1A') along with (partially) substituted reactants were conducted at collision energies of 19.3 kJ mol–1. Combining our experimental data with ab initio electronic structure and statistical calculations, the methylidyne radical is revealed to add barrierlessly to the carbon–carbon double bond of propylene reactant resulting in a cyclic doublet C4H7 intermediate with a lifetime longer than its rotation period. These adducts undergo a nonstatistical unimolecular decomposition via atomic hydrogen loss through tight exit transition states forming the cyclic products 1-methylcyclopropene and 3-methylcyclopropene with overall reaction exoergicities of 168 ± 25 kJ mol–1. These C4H6 isomers are predicted to exist even in low-temperature environments such as cold molecular clouds like TMC-1, since the reaction is barrierless and exoergic, all transition states are below the energy of the separated reactants, and both the methylidyne radical (CH; X2Π) and propylene reactant were detected in cold molecular clouds such as TMC-1.
- Authors:
-
- Univ. of Hawaii at Manoa, Honolulu, HI (United States)
- Florida International Univ., Miami, FL (United States); Samara National Research Univ., Samara (Russian Federation)
- Florida International Univ., Miami, FL (United States)
- Publication Date:
- Research Org.:
- Univ. of Hawaii at Manoa, Honolulu, HI (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- OSTI Identifier:
- 1603231
- Grant/Contract Number:
- FG02-03ER15411
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
- Additional Journal Information:
- Journal Volume: 123; Journal Issue: 49; Journal ID: ISSN 1089-5639
- Publisher:
- American Chemical Society
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Citation Formats
He, Chao, Thomas, Aaron M., Galimova, Galiya R., Mebel, Alexander M., and Kaiser, Ralf I. Gas-Phase Formation of 1-Methylcyclopropene and 3-Methylcyclopropene via the Reaction of the Methylidyne Radical (CH; X 2 Π) with Propylene (CH 3 CHCH 2 ; X 1 A'). United States: N. p., 2019.
Web. doi:10.1021/acs.jpca.9b09815.
He, Chao, Thomas, Aaron M., Galimova, Galiya R., Mebel, Alexander M., & Kaiser, Ralf I. Gas-Phase Formation of 1-Methylcyclopropene and 3-Methylcyclopropene via the Reaction of the Methylidyne Radical (CH; X 2 Π) with Propylene (CH 3 CHCH 2 ; X 1 A'). United States. https://doi.org/10.1021/acs.jpca.9b09815
He, Chao, Thomas, Aaron M., Galimova, Galiya R., Mebel, Alexander M., and Kaiser, Ralf I. Wed .
"Gas-Phase Formation of 1-Methylcyclopropene and 3-Methylcyclopropene via the Reaction of the Methylidyne Radical (CH; X 2 Π) with Propylene (CH 3 CHCH 2 ; X 1 A')". United States. https://doi.org/10.1021/acs.jpca.9b09815. https://www.osti.gov/servlets/purl/1603231.
@article{osti_1603231,
title = {Gas-Phase Formation of 1-Methylcyclopropene and 3-Methylcyclopropene via the Reaction of the Methylidyne Radical (CH; X 2 Π) with Propylene (CH 3 CHCH 2 ; X 1 A')},
author = {He, Chao and Thomas, Aaron M. and Galimova, Galiya R. and Mebel, Alexander M. and Kaiser, Ralf I.},
abstractNote = {The crossed molecular beam reactions of the methylidyne radical (CH; X2Π) with propylene (CH3CHCH2; X1A') along with (partially) substituted reactants were conducted at collision energies of 19.3 kJ mol–1. Combining our experimental data with ab initio electronic structure and statistical calculations, the methylidyne radical is revealed to add barrierlessly to the carbon–carbon double bond of propylene reactant resulting in a cyclic doublet C4H7 intermediate with a lifetime longer than its rotation period. These adducts undergo a nonstatistical unimolecular decomposition via atomic hydrogen loss through tight exit transition states forming the cyclic products 1-methylcyclopropene and 3-methylcyclopropene with overall reaction exoergicities of 168 ± 25 kJ mol–1. These C4H6 isomers are predicted to exist even in low-temperature environments such as cold molecular clouds like TMC-1, since the reaction is barrierless and exoergic, all transition states are below the energy of the separated reactants, and both the methylidyne radical (CH; X2Π) and propylene reactant were detected in cold molecular clouds such as TMC-1.},
doi = {10.1021/acs.jpca.9b09815},
journal = {Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory},
number = 49,
volume = 123,
place = {United States},
year = {Wed Nov 13 00:00:00 EST 2019},
month = {Wed Nov 13 00:00:00 EST 2019}
}
Web of Science