We have measured the kinetics of the reaction between pent-1-en-3-yl ( CH2-. CH-. CH - CH2 - CH3) radicals and oxygen molecules using laser-photolysis/photoionization mass spectrometry at temperatures relevant for autoignition (600-710 K). The rate coefficient of the title reaction was found to be relatively large for an allylic radical in the studied temperature range (1.27-1 . 79 ×10 -15 cm3 s-1 ). With such a large rate coefficient the studied reaction is expected to be an important sink of pent-1-en-3-yl radicals under autoignition conditions. Quantum chemical calculations and master equation simulations were performed to complement the experimental work. Experimental data was used to fix the values of key parameters in the master equation model. The model was then used to investigate the title reaction over a wide range of conditions (200-1500 K and 10-5 - 10 2 bar ). The simulations predict that the title reaction mainly forms ( E/Z)-pent-1,3-diene and hydroperoxyl at elevated temperatures ( T > 500 K ), but non-negligible amounts of (2 R/S)-1,2-epoxypent-3-ene and hydroxyl are also formed. We found experimental evidence for both product channels, but it was not conclusive. Arrhenius representations are given for the product channels to facilitate the use of our results in combustion modelling.
Bibliographical noteFunding Information:
T.T.P. acknowledges support from the Doctoral Programme in Chemistry and Molecular Sciences of the University of Helsinki and the Magnus Ehrnrooth foundation for funding. Project no. K129140 for G.L. has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the OTKA funding scheme. M.D. and A.J.E. acknowledge support from the Academy of Finland , grant numbers 311967 , 294042 , 319353 , 325250 , and 288377 . The authors also acknowledge CSC IT Center for Science in Finland for computational resources.
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Fields of Science
- Allyl radical
- Laser-photolysis photoionization mass spectrometry
- Master equation modeling
- Reaction kinetics