Reaction kinetics of hydrogen shift isomerization of 1-hexyl radicals

Abstract

Isomerization reactions form an important class of alkyl reactions. In this work, the kinetics of five types of 1-hexyl radical hydrogen shift reactions, i.e. 1-2, 1-3, 1-4, 1-5 and 1-6 hydrogen shift reactions, were investigated. The electronic structure calculations were performed by M06-2X/6-311 + G(2df,2p), and the high-pressure limit rate constants were obtained by using the conventional transition state theory including the multi-structural torsional anharmonicity and tunneling corrections with the Eckart approximation. The calculated rate coefficients of 1-hexyl radical 1-5 hydrogen shift isomerization agree very well with literature experimental data, which validates our methods. The results show that the 1-5, 1-6, 1-4 hydrogen shift reactions dominate in the low temperature region, and the multi-structural torsional anharmonicity factors of the five 1-hexyl radical isomerization reactions vary from 0.03 to 1.12 and reduce with the increasing ring structure size of the transition states.