Pekkanen, Timo T.Timonen, Raimo S.Lendvay, GyorgyRissanen, Matti P.Eskola, Arkke J.2021-01-242025-08-272019Pekkanen, T T, Timonen, R S, Lendvay, G, Rissanen, M P & Eskola, A J 2019, 'Kinetics and thermochemistry of the reaction of 3-methylpropargyl radical with molecular oxygen', Proceedings of the Combustion Institute, vol. 37, no. 1, pp. 299-306. https://doi.org/10.1016/j.proci.2018.05.050ORCID: /0000-0003-0463-8098/work/54149105ORCID: /0000-0002-2249-2726/work/155652547http://hdl.handle.net/10138/325133We have measured the kinetics and thermochemistry of the reaction of 3-methylpropargyl radical (but-2-yn-1-yl) with molecular oxygen over temperature (223-681 K) and bath gas density (1.2 - 15.0 x 10(16)cm(-3)) ranges employing photoionization mass-spectrometry. At low temperatures (223-304 K), the reaction proceeds overwhelmingly by a simple addition reaction to the -CH2 end of the radical, and the measured CH3CCCH2 center dot+O-2 reaction rate coefficient shows negative temperature dependence and depends on bath gas density. At intermediate temperatures (340-395 K), the addition reaction equilibrates and the equilibrium constant was determined at different temperatures. At high temperatures (465-681 K), the kinetics is governed by O-2 addition to the third carbon atom of the radical, and rate coefficient measurements were again possible. The high temperature CH3CCCH2 center dot +O(2 )rate coefficient is much smaller than at low T, shows positive temperature dependence, and is independent of bath gas density. In the intermediate and high temperature ranges, we observe a formation signal for ketene (ethenone). The reaction was further investigated by combining the experimental results with quantum chemical calculations and master equation modeling. By making small adjustments (2 - 3 kJ mol(-1)) to the energies of two key transition states, the model reproduces the experimental results within uncertainties. The experimentally constrained master equation model was used to simulate the CH3CCCH2 center dot+ O-2 reaction system at temperatures and pressures relevant to combustion. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.8engcc_by_nc_ndinfo:eu-repo/semantics/openAccessExperimental gas kineticsMaster equation modelingAb initio quantum chemistryCombustion chemistryPropargyl radicalRATE COEFFICIENTSC3H3+C3H3 REACTIONSELF-REACTIONTEMPERATUREQUALITYChemical sciencesPhysical sciencesArticleopenAccess9939adb3-5d71-4f30-906d-b0c8310a160985049566548000456612200025