An experimental and computational investigation of the reaction between pent-1-en-3-yl radicals and oxygen molecules under autoignition conditions

Abstract

We have measured the kinetics of the reaction between pent-1-en-3-yl (▪) 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 (1.27–1.79×10−15cm3 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 – 102 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 (2R/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.