Chlorine atom-initiated low-temperature oxidation of prenol and isoprenol [electronic resource] : The effect of C=C double bonds on the peroxy radical chemistry in alcohol oxidation
- Washington, D.C. : United States. National Nuclear Security Administration, 2014.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- pages 401-408 : digital, PDF file
- Additional Creators:
- Sandia National Laboratories
United States. National Nuclear Security Administration
United States. Department of Energy. Office of Scientific and Technical Information
- The chlorine atom-initiated oxidation of two unsaturated primary C5 alcohols, prenol (3-methyl-2-buten-1-ol, (CH<sub>3</sub>)<sub>2</sub>CCHCH<sub>2</sub>OH) and isoprenol (3-methyl-3-buten-1-ol, CH<sub>2</sub>C(CH<sub>3</sub>)CH<sub>2</sub>CH<sub>2</sub>OH), is studied at 550 K and low pressure (8 Torr). The time- and isomer-resolved formation of products is probed with multiplexed photoionization mass spectrometry (MPIMS) using tunable vacuum ultraviolet ionizing synchrotron radiation. The peroxy radical chemistry of the unsaturated alcohols appears much less rich than that of saturated C4 and C5 alcohols. The main products observed are the corresponding unsaturated aldehydes – prenal (3-methyl-2-butenal) from prenol oxidation and isoprenal (3-methyl-3-butenal) from isoprenol oxidation. No significant products arising from QOOH chemistry are observed. These results can be qualitatively explained by the formation of resonance stabilized allylic radicals via H-abstraction in the Cl + prenol and Cl + isoprenol initiation reactions. The loss of resonance stabilization upon O<sub>2</sub> addition causes the energies of the intermediate wells, saddle points, and products to increase relative to the energy of the initial radicals and O<sub>2</sub>. These energetic shifts make most product channels observed in the peroxy radical chemistry of saturated alcohols inaccessible for these unsaturated alcohols. The experimental findings are underpinned by quantum-chemical calculations for stationary points on the potential energy surfaces for the reactions of the initial radicals with O<sub>2</sub>. Under our conditions, the dominant channels in prenol and isoprenol oxidation are the chain-terminating HO<sub>2</sub>-forming channels arising from radicals, in which the unpaired electron and the –OH group are on the same carbon atom, with stable prenal and isoprenal co-products, respectively. These results suggest that the presence of C=C double bonds in alcohols will reduce low-temperature reactivity during autoignition.
- Published through SciTech Connect.
Proceedings of the Combustion Institute 35 1 ISSN 1540-7489 AM
Welz, Oliver; Savee, John; Osborn, David; Taatjes, Craig.
- Funding Information:
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