1 research outputs found
Kinetics of Thermal Unimolecular Decomposition of Acetic Anhydride: An Integrated Deterministic and Stochastic Model
An
integrated deterministic and stochastic model within the master
equation/ÂRice–Ramsperger–ÂKassel–Marcus
(ME/RRKM) framework was first used to characterize temperature- and
pressure-dependent behaviors of thermal decomposition of acetic anhydride
in a wide range of conditions (i.e., 300–1500 K and 0.001–100
atm). Particularly, using potential energy surface and molecular properties
obtained from high-level electronic structure calculations at CCSDÂ(T)/CBS,
macroscopic thermodynamic properties and rate coefficients of the
title reaction were derived with corrections for hindered internal
rotation and tunneling treatments. Being in excellent agreement with
the scattered experimental data, the results from deterministic and
stochastic frameworks confirmed and complemented each other to reveal
that the main decomposition pathway proceeds via a 6-membered-ring
transition state with the 0 K barrier of 35.2 kcal·mol<sup>–1</sup>. This observation was further understood and confirmed by the sensitivity
analysis on the time-resolved species profiles and the derived rate
coefficients with respect to the ab initio barriers. Such an agreement
suggests the integrated model can be confidently used for a wide range
of conditions as a powerful postfacto and predictive tool in detailed
chemical kinetic modeling and simulation for the title reaction and
thus can be extended to complex chemical reactions