An experimental and theoretical kinetic study of t-butyl radical reaction with molecular oxygen

Abstract

In this work, a unifying picture of the kinetics of the t-C4H9 + O2 reaction is presented by combining the current and previous experimental results with theory. Direct, time-resolved experiments were performed over a wide temperature range (200–500 K) at low pressures (0.3–6 Torr) using a photoionization mass spectrometry method. The kinetic measurements of the t-butyl + O2 reaction were initiated by laser photolysis of pinacolone at 193 nm or t-butyl bromide at 248 nm to produce t-C4H9 radicals. Energies calculated by quantum chemistry at the CCSD(T)/CBS and CASPT2/CBS levels of theory were used in master equation simulations of the kinetics of the t-C4H9 + O2 reaction. The calculations successfully reproduce the pressure and temperature dependencies of both the current low-pressure experiments and literature kinetic data at about atmospheric pressure as well as the literature kinetic data for the overwhelmingly most important bimolecular reaction channel, t-C4H9 + O2 → i-C4H8 + HO2 in the intermediate temperature range. The experimentally constrained master equation model was utilized to simulate the t-C4H9 + O2 reaction kinetics over wide range of conditions. The results of these simulations are provided in ChemKin compatible PLOG format for later use.