Theoretical Study on Ethylamine Dissociation Reactions Using VRC-VTST and SS-QRRK Methods

Barrierless bond dissociation reactions play an important
role
in fuel combustion. In this work, the pressure-dependent dissociation
rate constants of ethylamine (EA) are accurately determined using
variable-reaction-coordinate variational transition-state theory combined
with the system-specific quantum Rice–Ramsperger–Kassel
method. Before the kinetics calculations, the performances of four
density functional theory methods in describing the bond dissociation
of EA are evaluated against the benchmark method, FIC-MRCISD(T)+Q/cc-pVTZ,
and the MN15-L/cc-pVTZ method is the best choice. By comparison of
the Gibbs free energies and the rate constants for the bond dissociation
reactions of EA, ethanol, and propane, the influence of functional
groups on the reaction kinetics is discussed. The kinetics calculations
show that the dissociation rate constants of EA are sensitive to pressure
at low pressures and high temperatures, and the dominant channel is
the reaction that yields C2H5 and NH2 radicals. A literature combustion model of EA is updated with our
calculations, and the satisfactory agreement between the model predictions
and reported ignition delay times of EA suggests the reliability of
our calculations.